Increased consumption of fruit and vegetables for the primary prevention of cardiovascular diseases

  • Review
  • Intervention

Authors


Abstract

Background

There is increasing evidence that high consumption of fruit and vegetables is beneficial for cardiovascular disease (CVD) prevention.

Objectives

The primary objective is to determine the effectiveness of i) advice to increase fruit and vegetable consumption ii) the provision of fruit and vegetables to increase consumption, for the primary prevention of CVD. 

Search methods

We searched the following electronic databases: The Cochrane Library (2012, issue 9-CENTRAL, HTA, DARE, NEED), MEDLINE (1946 to week 3 September 2012); EMBASE (1980 to 2012 week 39) and the Conference Proceedings Citation Index - Science on ISI Web of Science (5 October 2012). We searched trial registers, screened reference lists and contacted authors for additional information where necessary. No language restrictions were applied.

Selection criteria

Randomised controlled trials with at least three months follow-up (follow-up was considered to be the time elapsed since the start of the intervention) involving healthy adults or those at high risk of CVD. Trials investigated either advice to increase fruit and vegetable intake (via any source or modality) or the provision of fruit and vegetables to increase intake. The comparison group was no intervention or minimal intervention. Outcomes of interest were CVD clinical events (mortality (CVD and all-cause), myocardial infarction (MI), coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA), angiographically-defined angina pectoris, stroke, carotid endarterectomy, peripheral arterial disease (PAD)) and major CVD risk factors (blood pressure, blood lipids, type 2 diabetes). Trials involving multifactorial lifestyle interventions (including different dietary patterns, exercise) or where the focus was weight loss were excluded to avoid confounding.

Data collection and analysis

Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. Trials of provision of fruit and vegetables were analysed separately from trials of dietary advice.

Main results

We identified 10 trials with a total of 1730 participants randomised, and one ongoing trial. Six trials investigated the provision of fruit and vegetables, and four trials examined advice to increase fruit and vegetable consumption.The ongoing trial is examining the provision of an avocado-rich diet.The number and type of intervention components for provision, and the dietary advice provided differed between trials.

None of the trials reported clinical events as they were all relatively short term. There was no strong evidence for effects of individual trials of provision of fruit and vegetables on cardiovascular risk factors, but trials were heterogeneous and short term. Furthermore, five of the six trials only provided one fruit or vegetable. Dietary advice showed some favourable effects on blood pressure (systolic blood pressure (SBP): mean difference (MD) -3.0 mmHg (95% confidence interval (CI) -4.92 to -1.09), diastolic blood pressure (DBP): MD -0.90 mmHg (95% CI -2.03 to 0.24)) and low-density lipoprotein (LDL) cholesterol but analyses were based on only two trials. Three of the 10 included trials examined adverse effects, which included increased bowel movements, bad breath and body odour.

Authors' conclusions

There are very few studies to date examining provision of, or advice to increase the consumption of, fruit and vegetables in the absence of additional dietary interventions or other lifestyle interventions for the primary prevention of CVD. The limited evidence suggests advice to increase fruit and vegetables as a single intervention has favourable effects on CVD risk factors but more trials are needed to confirm this.

Resumo

Aumento do consumo de frutas e legumes para a prevenção primária de doenças cardiovasculares

Introdução

As evidências sugerem que o consumo de frutas e verduras em grandes quantidades poderia ser benéfico na prevenção de doenças cardiovasculares (DCV).

Objetivos

O objetivo principal desta revisão foi avaliar a efetividade de dois tipos de intervenções na prevenção primária de DCV: 1) orientações para aumentar o consumo de frutas e legumes e 2) o fornecimento frutas e legumes para aumentar o consumo desses alimentos.

Métodos de busca

Buscamos nas seguintes bases de dados eletrónicas: The Cochrane Library (2012, edição 9-CENTRAL, HTA, DARE, NEED), MEDLINE (1946 até a 3ª semana de setembro de 2012); EMBASE (1980 a 2012 semana 39) e the Conference Proceedings Citation Index - Science on ISI Web of Science (5 de outubro de 2012). A busca foi complementada por pesquisas nas plataformas de registos de ensaios clínicos e pela revisão das listas de referência dos artigos selecionados . Entramos em contato com os autores dos estudos originais para obtenção de informações adicionais, quando necessário. Não usamos restrições de idiomas.

Critério de seleção

Esta revisão sistemática incluiu ensaios clínicos randomizados envolvendo adultos saudáveis ou de alto risco para DCV que foram acompanhados por menos três meses, contados a partir do início da intervenção. Os estudos incluídos nesta revisão foram de dois tipos: a) aqueles que avaliaram orientações (dadas através de qualquer meio ou forma) para aumentar a ingestão de frutas e legumes ou b) estudos que ofereciam frutas e legumes como forma de incentivar os participantes a aumentar o consumo desses alimentos. Em ambos os tipos de estudos, os grupos de comparação não receberam nenhuma intervenção ou uma intervenção mínima. Os desfechos de interesse foram eventos clínicos de DCV (mortalidade por DCV e por todas as causas), infarto do miocárdio (IM), cirurgia de bypass de artéria coronária (CABG) ou angioplastia coronária transluminal percutânea (PTCA), angina pectoris diagnosticada por angiografia, acidente vascular cerebral, endarterectomia carotídea, doença arterial periférica (PAD) e os principais fatores de risco de DCV (pressão arterial, concentração de lipídeos circulantes, diabetes tipo 2). Para evitar viés de confusão, foram excluídos desta revisão os estudos com intervenções multifacetadas de modificação de estilo de vida (com diversos tipos de dietas e exercícios) e também os estudos cujo principal objetivo era a perda de peso.

Coleta dos dados e análises

Dois autores, de forma independente, selecionaram os estudos para inclusão nesta revisão, fizeram a extração dos dados e avaliaram o risco de viés desses estudos. Os estudos que forneciam frutas e legumes foram analisados separadamente dos estudos sobre aconselhamento dietético.

Principais resultados

Identificamos 10 estudos com um total de 1730 participantes randomizados e 1 estudo em andamento. Seis estudos avaliaram o fornecimento de frutas e legumes e 4 estudos avaliaram orientações para aumentar o consumo de frutas e legumes. O estudo em andamento está avaliando o fornecimento de uma dieta rica em abacate. Os estudos incluídos nesta revisão variavam quanto ao número e o tipo de intervenções sobre fornecimento de alimentos e ao aconselhamento dietético.

Como todos os estudos incluídos nesta revisão tinham seguimentos relativamento curtos, nenhum deles apresentou eventos clínicos relevantes entre os seus desfechos. Nenhum dos estudos individuais sobre fornecimento de frutas e legumes apresentou evidência forte da efetividade desta intervenção sobre os fatores de risco cardiovasculares; porém estes estudos foram heterogêneos e tinham um tempo de seguimento curto. Além disso, 5 destes 6 estudos forneceram apenas um tipo de fruta ou de vegetal. Os estudos sobre orientação nutricional apresentaram alguns efeitos favoráveis sobre a pressão arterial: diferença média (MD) da pressão sistólica (PAS) -3,0 mmHg (intervalo de confiança de 95% (IC) -4.92 a - 1,09) e da pressão arterial diastólica (PAD) -0.90 mmHg (IC 95% -2.03 a 0,24) e sobre a concentração de colesterol LDL. Porém as análises basearam-se em apenas 2 estudos. Três dos 10 estudos incluídos nesta revisão avaliaram efeitos adversos da intervenção, entre eles aumento das evacuações, mau hálito e odores corporais.

Conclusão dos autores

Existem pouquíssimos estudos que avaliaram a efetividade do fornecimento, ou de orientações para aumentar a ingestão de frutas e legumes como intervenção isolada (sem outras orientações nutricionais ou intervenções de mudança de estilo de vida) para a prevenção primária de DCV. A evidência existente indica que a orientação para aumentar o consumo de frutas e legumes como intervenção isolada produz efeitos favoráveis sobre os fatores de risco para DCV, porém mais estudos são necessários para confirmar este achado.

Résumé scientifique

Hausse de la consommation de fruits et légumes dans la prévention primaire de maladies cardiovasculaires

Contexte

Il existe des preuves de plus en plus probantes selon lesquelles une consommation élevée de fruits et légumes serait bénéfique pour la prévention de maladies cardiovasculaires (MCV).

Objectifs

L'objectif principal est de déterminer l'efficacité de i) conseils préconisant d'augmenter la consommation de fruits et légumes, ii) la distribution de fruits et légumes en vue d'accroître leur consommation, dans la prévention primaire de MCV.

Stratégie de recherche documentaire

Nous avons effectué des recherches dans les bases de données électroniques suivantes : The Cochrane Library (2012, numéro 9 - CENTRAL, HTA, DARE, NEED), MEDLINE (de 1946 à la semaine 3 de septembre 2012) ; EMBASE (de 1980 à la semaine 39 de 2012) et le Conference Proceedings Citation Index - Science on ISI Web of Science (5 octobre 2012). Nous avons effectué des recherches dans les registres d'essais, passé au crible les listes bibliographiques et contacté les auteurs en vue d'obtenir des informations complémentaires, le cas échéant. Aucune restriction de langue n'a été appliquée.

Critères de sélection

Des essais contrôlés randomisés avec un suivi d'au moins trois mois (le suivi correspond au temps écoulé depuis le début de l'intervention) impliquant des adultes en bonne santé ou présentant des risques élevés de MCV. Les essais examinaient des conseils visant à augmenter la consommation de fruits et légumes (via n'importe quelle source ou modalité) ou la distribution de fruits et légumes afin d'augmenter leur consommation. Le groupe témoin ne bénéficiait d'aucune intervention ou d'une intervention minimale. Les critères de jugement étaient des événements cliniques de MCV (mortalité (MCV et toutes causes confondues), un infarctus du myocarde (IM), un pontage aorto-coronarien (PAC) ou une angioplastie coronaire transluminale percutanée (ACTP) et des facteurs de risques de MCV majeures (pression artérielle, lipides dans le sang, diabète de type 2). Les essais impliquant des interventions multifactorielles dans le style de vie (notamment différentes habitudes alimentaires, exercice) ou privilégiant la perte de poids ont été exclus pour éviter toute confusion.

Recueil et analyse des données

Deux auteurs de la revue ont indépendamment sélectionné des essais en vue de leur inclusion, extrait des données et évalué les risques de biais. Les essais concernant la distribution de fruits et légumes ont été analysés séparément des essais portant sur des conseils alimentaires.

Résultats principaux

Nous avons identifié 10 essais totalisant 1 730 participants randomisés et un essai en cours. Six essais examinaient la distribution de fruits et légumes et quatre autres examinaient des conseils visant à accroître leur consommation. L'essai en cours examine la promotion d'une alimentation riche en avocat. Le nombre et les types de composants d'intervention pour la distribution et les conseils alimentaires fournis différaient entre les essais.

Aucun des essais n'a rapporté des événements cliniques car leur durée était relativement courte. Il n'y avait aucune preuve probante en termes d'effets des essais individuels concernant la distribution de fruits et légumes sur les facteurs de risques cardiovasculaires, mais ces essais étaient hétérogènes et à court terme. De plus, cinq des six essais disponibles ne distribuaient qu'un seul fruit ou légume. Les conseils alimentaires montraient quelques effets favorables sur la pression artérielle (pression artérielle systolique (PAS) : différence moyenne (DM) - 3,0 mmHg (intervalle de confiance (IC) à 95 % - 4,92 à - 1,09), pression artérielle diastolique (PAD) : DM - 0,90 mmHg (IC à 95 % - 2,03 à 0,24)) et sur le cholestérol de lipoprotéine de faible densité (LDL pour « Low-Density Lipoprotein »), mais les analyses n'étaient fondées que sur deux essais. Trois des 10 essais inclus examinaient des effets indésirables, qui incluaient une augmentation des selles, une mauvaise haleine et des odeurs corporelles.

Conclusions des auteurs

À ce jour il n'existe de quelques études examinant la distribution ou des conseils visant à accroître la consommation de fruits et légumes en l'absence d'interventions alimentaires supplémentaires ou d'autres interventions sur le style de vie pour la prévention primaire de MCV. Des preuves limitées suggèrent que les conseils visant à accroître la consommation de fruits et légumes comme intervention unique ont des effets favorables sur les facteurs de risques de MCV, mais d'autres essais seront nécessaires pour confirmer ce résultat.

アブストラクト

心血管疾患の一次予防における果物および野菜の摂取量増加

背景

果物および野菜の大量摂取が心血管疾患(CVD)の予防に有益であるというエビデンスが蓄積されつつある。

目的

CVDに対する一次予防のため、i)果物および野菜の増量摂取を指導した場合の有効性、ii)果物および野菜を提供して摂取量を増加させた場合の有効性を検証することが主な目的である。

検索戦略

以下の電子データベースを検索した:コクラン・ライブラリ(2012年第9版-CENTRAL、HTA、DARE、NEED)、MEDLINE(1946年〜2012年9月第3週)、EMBASE(1980年〜2012年第39週)およびConference Proceedings Citation Index - Science on ISI Web of Science(2012年10月5日)。 試験登録データベースを検索し、参考文献リストのスクリーニングを行い、必要に応じて追加情報を著者に問い合わせた。言語の制限は設けなかった。

選択基準

健康成人またはCVD高リスク者を対象とし、追跡期間(追跡期間とは介入開始からの期間を指す)が3カ月以上設けられたランダム化比較試験。果物および野菜の増量摂取を(摂取源または摂取方法は問わず)指導した場合、または増量摂取のために果物および野菜を提供した場合を検証した試験。対照群は無介入または最小限の介入とした。注目したアウトカムは、CVDの臨床イベント(CVDに起因する死亡率および全死因死亡率、心筋梗塞[MI]、冠動脈バイパス移植術[CABG]または経皮経管冠動脈形成術[PTCA]、血管造影所見による狭心症、脳卒中、頸動脈内膜剥離術、末梢動脈疾患[PAD])および主要CVD危険因子(血圧、血中脂質、2型糖尿病)であった。交絡を回避するため、多元的な生活様式介入(種々の食習慣、運動など)を行った試験または減量に焦点をおいた試験は除外した。

データ収集と分析

2名のレビュー著者が独立して、選択基準に適合する試験を選択し、データを抽出し、バイアスのリスクを評価した。果物および野菜の提供を行った試験は、食事指導を行った試験とは別に解析した。

主な結果

参加者計1730例をランダム化した10件の試験および進行中の試験1件を対象とした。6件の試験では果物および野菜を提供した場合について、4件の試験では果物および野菜の増量摂取を指導した場合について検証した。進行中の試験では、アボカドを中心とした食事を提供した場合について検証中である。果物および野菜の提供に関する介入の数および種類ならびに食事指導内容は、試験ごとに異なっていた。

いずれも比較的短期間の試験であったため、臨床イベントは報告されなかった。各試験では、果物および野菜を提供した場合の心血管危険因子に対する効果に関する強固なエビデンスは得られなかったが、これらの試験において異質性が認められ、かつ短期間であった。さらに、6件中5件の試験では果物または野菜が1種類のみ提供されていた。食事指導は、血圧(収縮期血圧[SBP]:平均差(MD)-3.0 mmHg(95%信頼区間[CI]-4.92〜-1.09、拡張期血圧(DBP):MD -0.90 mmHg[95%CI -2.03〜0.24])および低密度リポ蛋白(LDL)コレステロールに対して有益な効果を示したが、解析はわずか2件の試験に基づいたものであった。10件中3件の試験では、排便回数増加、口臭および体臭などの有害作用を検証した。

著者の結論

現時点では、CVDの一次予防を目的とした他の食事介入または生活様式介入を行わずに、果物および野菜の増量摂取を目的にこれらを提供した場合または増量摂取を指導した場合について検証した研究はほとんどない。限られたエビデンスから、単一介入として果物および野菜の増量摂取を指導した場合、CVD危険因子に対して有益な効果が認められることが示唆されるが、これを確認するためには、さらに試験が必要である。

訳注

《実施組織》厚生労働省「「統合医療」に係る情報発信等推進事業」(eJIM:http://www.ejim.ncgg.go.jp/)[2016.1.9]
《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。

Plain language summary

Increased fruit and vegetable intake to prevent cardiovascular disease

Cardiovascular disease (CVD) is a global burden and varies between regions. This regional variation has been linked in part to dietary factors and low fruit and vegetable intake has been associated with higher rates of CVD. This review assessed the effectiveness of increasing fruit and vegetable consumption as a single intervention without the influence of other dietary patterns or other lifestyle modifications in healthy adults and those at high risk of CVD for the prevention of CVD. We found 10 trials involving 1730 participants in which six examined the provision of fruit and vegetables to increase intake and four trials examined dietary advice to increase fruit and vegetable intake. There were variations in the type of fruit and vegetable provided but all interventions investigating provision involved only one fruit or vegetable component. There were also variations in the number of fruit and vegetables that participants were advised to eat. Some studies advised participants to eat at least five servings of fruit and vegetables a day while others advised at least eight or nine servings per day.The duration of the interventions ranged from three months to one year. Adverse effects were reported in three of the included trials and included increased bowel movements, bad breath and body odour. None of the included trials were long enough to examine the effect of increased fruit and vegetable consumption on cardiovascular disease events such as heart attacks. There was no strong evidence that provision of one type of fruit or vegetable had beneficial effects on blood pressure and lipid levels but most trials were short term. There was some evidence to suggest beneficial effects of dietary advice to increase fruit and vegetable consumption but this is based on findings from two trials. More trials are needed to confirm these findings.

Resumo para leigos

Aumento do consumo de frutas e legumes para a prevenção primária de doenças cardiovasculares

As doenças cardiovasculares (DCV) são um problema mundial cuja importância varia entre diferentes regiões. Esta variação regional tem sido atribuída, em parte, a fatores dietéticos. O baixo consumo de frutas e legumes tem sido associado com taxas mais elevadas de DCV. Esta revisão avaliou a efetividade de aumentar o consumo de frutas e legumes isoladamente, isto é sem outras modificações alimentares ou de estilo de vida, em adultos saudáveis e naqueles com alto risco de DCV para a prevenção de DCV. Encontramos 10 estudos envolvendo 1730 participantes, sendo que 6 avaliaram o fornecimento de frutas e legumes para incentivar o maior consumo desses alimentos e 4 estudos avaliaram o efeito de orientações nutricionais para aumentar a ingestão desses alimentos. Os tipos de frutas e legumes oferecidos eram diferentes nos diversos estudos; porém todas as intervenções se limitavam a oferecer apenas um tipo de fruta ou um legume. As orientações nutricionais também variaram quanto ao número de frutas e legumes que os participantes foram aconselhados a comer. Enquanto em alguns estudos as pessoas eram orientadas a comer pelo menos 5 porções de frutas e legumes por dia, em outros estudos elas eram aconselhados a comer pelo menos 8 ou 9 porções por dia. A duração das intervenções variou de 3 até 12 meses. Três dos estudos avaliaram efeitos adversos, entre eles aumento do número de evacuações, mau hálito e odores corporais. Nenhum dos estudos incluídos nesta revisão acompanharam os participantes por tempo suficiente para analisar o efeito do aumento do consumo de frutas e legumes sobre eventos cardiovasculares, como ataques cardíacos. Não foi encontrada nenhuma evidência forte indicando que o fornecimento de um tipo de fruta ou de legume poderia ter efeitos benéficos sobre a pressão arterial ou sobre os níveis de colesterol; porém, a maioria dos estudos foram de curto prazo. Existe alguma evidência de que orientações nutricionais para aumentar a ingestão de frutas e legumes sejam benéficas porém estes achados são baseados em apenas 2 estudos. Mais pesquisas são necessárias para confirmar esses achados.

Notas de tradução

Traduzido por: Brazilian Cochrane Centre
Tradução patrocinada por: None

Résumé simplifié

Hausse de la consommation de fruits et légumes pour prévenir des maladies cardiovasculaires

Les maladies cardiovasculaires (MCV) sont un fléau mondial et varient selon les régions géographiques. Cette variation régionale est en partie liée à des facteurs alimentaires et la faible consommation de fruits et légumes est liée à une hausse des taux de MCV. La présente revue a évalué l'efficacité liée à une augmentation de la consommation de fruits et de légumes comme intervention unique, sans l'influence d'autres habitudes alimentaires ou d'autres changements de style de vie, chez des adultes en bonne santé et ceux présentant des risques élevés de MCV dans la prévention de MCV. Nous avons trouvé 10 essais impliquant 1 730 participants dont six ont étudié la distribution de fruits et légumes en vue d'accroître leur consommation et quatre ont étudié des conseils alimentaires visant à accroître les apports en fruits et légumes. Il y avait des variations concernant le type de fruit et de légume fourni, mais toutes les interventions n'étudiaient la distribution que d'un seul fruit ou légume. Il y avait également des variations dans le nombre de fruits et légumes que les participants devaient manger. Certaines études conseillaient aux participants de manger au moins cinq portions de fruits et légumes par jour, alors que d'autres conseillaient au moins huit ou neuf portions par jour. La durée des interventions variait de trois mois à un an. Des effets indésirables étaient rapportés dans trois des essais inclus et concernaient une augmentation des selles, une mauvaise haleine et des odeurs corporelles. Aucun des essais inclus n'était suffisamment long pour examiner les effets liés à une augmentation de la consommation de fruits et légumes sur les événements de maladies cardiovasculaires, comme les crises cardiaques. Il n'y avait aucune preuve probante selon laquelle la distribution d'un type de fruit ou de légume avait des effets bénéfiques sur la pression artérielle et les niveaux de lipides, mais la plupart des essais ont été réalisés à court terme. Il y avait quelques preuves permettant de suggérer des effets bénéfiques de conseils alimentaires préconisant une augmentation de la consommation de fruits et légumes, mais elles se fondent sur les résultats issus de deux essais. D'autres essais sont nécessaires pour confirmer ces résultats.

Notes de traduction

Traduit par: French Cochrane Centre 16th July, 2013
Traduction financée par: Pour la France : Minist�re de la Sant�. Pour le Canada : Instituts de recherche en sant� du Canada, minist�re de la Sant� du Qu�bec, Fonds de recherche de Qu�bec-Sant� et Institut national d'excellence en sant� et en services sociaux.

Laički sažetak

Povećana konzumacija voća i povrća za prevenciju srčano-žilnih bolesti

Srčano-žilne bolesti pogađaju ljude u cijelom svijetu i njihova učestalost se razlikuje u pojedinim regijama. Te se regionalne varijacije djelomično pripisuju prehrani. Naime, mala količina voća i povrća u prehrani povezuje se s većom učestalošću srčano-žilnih bolesti. U ovom Cochrane sustavnom preglednom članku procijenjena je učinkovitost većeg unosa voća i povrća kao jedina intervencija za prevenciju srčano-žilnih bolesti, bez kontroliranja utjecaja ostalih prehrambenih navika ili drugih promjena životnog stila u zdravih odraslih osoba i u osoba s povećanim rizikom od srčano-žilnih bolesti. Pronađeno je 10 kliničkih ispitivanja u kojima je sudjelovalo ukupno 1730 ispitanika, od kojih je 6 istražilo davanje voća i povrća u svrhu povećanja unosa tih namirnica, dok je u 4 studije istražen učinak savjeta o potrebi povećanja količine voća i povrća u prehrani. Vrste voća i povrća koje su davane ispitanicima razlikovale su se, ali sve intervencije koje su uključile davanje voća i povrća uključivale su samo jednu vrstu voća ili povrća. Također su postojale razlike u količini voća i povrća koja je ispitanicima savjetovana. U dijelu studija je ispitanicima rečeno da trebaju jesti najmanje pet porcija voća i povrća dnevno, dok je u drugima savjetovano uzimanje najmanje osam ili devet porcija dnevno. Trajanje intervencija kretalo se od tri mjeseca do godine dana. U trima studijama ispitanici su prijavili nuspojave, uključujući brži rad crijeva, neugodan zadah i neugodan miris tijela. Nijedna od uključenih studija nije trajala dovoljno dugo da bi se ispitao učinak većeg unosa voća i povrća na srčano-žilne incidente kao što je srčani udar. Nije bilo jakih dokaza da davanje jedne određene vrste voća ili povrća ima blagotvoran učinak na krvni tlak ili vrijednosti lipida, ali većina istraživanja je kratko trajala. Nađeni su dokazi da povećan unos voća i povrća ima blagotvoran učinak na krvni tlak (sistolički i dijastolički) te na vrijednosti LDL kolesterola, ali se ovi dokazi temelje na svega dva ispitivanja. Potrebno je više istraživanja da bi se potvrdili ovi rezultati.

Bilješke prijevoda

Prevoditelj:: Croatian Branch of the Italian Cochrane Centre

எளியமொழிச் சுருக்கம்

இதய நாள நோயைத் தடுக்க அதிகப்படியான பழம் மற்றும் காய்கறியை உட்கொள்ளுதல்

இதய நாள நோய் (CVD) ஒரு உலகளாவிய சுமையாக உள்ளது மற்றும் உலக பிராந்தியங்களுக்கிடையே வேறுபடுகிறது. இந்த பிராந்திய வேறுபாடுகள் உணவு முறை காரணிகளோடு பகுதியளவில் இணைக்கப்பட்டுள்ளது, மற்றும் குறைந்த பழம் மற்றும் காய்கறி உட்கொள்ளுதலால் அதிகளவிலான இதய நாள நோயுடன் சம்பந்தப்பட்டிருக்கிறது. இந்த திறனாய்வு, பிற உணவு முறைகள் அல்லது பிற வாழ்க்கை முறை மாற்றங்களின் தாக்கம் இல்லாமல் ஆரோக்கியமான பெரியவர்களில் அல்லது இதய நாள நோய் உயர் அபாயத்தைக் கொண்டவர்களில், இதய நாள நோயைத் தடுப்பதற்கான பழம் மற்றும் காய்கறி நுகர்வு அதிகரிப்பு என்ற ஒரு ஒற்றை தலையீட்டின் திறனை மதிப்பீடு செய்தது. நாங்கள் 1730 பங்கேற்பாளர்கள் சம்பந்தப்பட்ட 10 சோதனைகளைக் கண்டோம், அவற்றில் ஆறு ஆய்வுகள் உட்கொள்ளுதலை அதிகரிக்க பழங்கள் மற்றும் காய்கறிகள் வழங்கப்பட்டதை ஆய்வு செய்தன; மற்றும் நான்கு சோதனைகள் பழம் மற்றும் காய்கறி உட்கொள்ளுதலை அதிகரிக்க வழங்கப்பட்ட உணவுமுறை ஆலோசனையை ஆய்வு செய்தன. கொடுக்கப்பட்ட பழம் மற்றும் காய்கறி வகையில் வேறுபாடுகள் இருந்தன, ஆனால் வழங்குதல் ஏற்பாட்டை சோதித்த அனைத்து தலையீடுகளும் ஒரே ஒரு பழம் அல்லது காய்கறி கூறை மட்டும் உள்ளடக்கியது. பங்கேற்பாளர்கள் சாப்பிட அறிவுறுத்தப்பட்ட பழங்கள் மற்றும் காய்கறிகள் எண்ணிக்கையிலும் வேறுபாடுகள் இருந்தன. சில ஆய்வுகள், பங்கேற்பாளர்கள் ஒரு நாளைக்கு குறைந்த பட்சம் ஐந்து பழம் மற்றும் காய்கறிகள் பரிமாறல்களை உட்கொள்ள வேண்டும் என்று அறிவுறுத்தின, ஆனால் மற்றவைகள் ஒரு நாள் ஒன்றுக்கு குறைந்தது எட்டு அல்லது ஒன்பது பரிமாறல்களாவது வேண்டும் என்று அறிவுறுத்தின. தலையீடுகளின் காலஅளவு மூன்று மாதங்கள் முதல் ஒரு வருடம் வரை விரிந்திருந்தன. சேர்க்கப்பட்டிருந்த சோதனைகளில், மூன்றில் எதிர்மறையான விளைவுகள் பற்றி அறிக்கையிட்டிருந்தது, மற்றும் அவை அதிகரித்த குடல் இயக்கங்கள், கெட்ட சுவாசம் மற்றும் உடல் நாற்றத்தை சேர்த்தது. சேர்க்கப்பட்டிருந்த பரிசோதனைகள் எவையும் மாரடைப்பு போன்ற இதய நாள நோய் நிகழ்வுகளின் மேல் அதிகப்படியான பழம் மற்றும் காய்கறி நுகர்வின் விளைவைப் பற்றி ஆய்வு செய்யும் அளவிற்கு நீண்ட-காலக்கட்டம் கொண்டதாய் இருக்கவில்லை. ஒரே வகை பழம் அல்லது காய்கறி என்று வழங்கப்பட்டதானது இரத்த அழுத்தம் மற்றும் கொழுப்பு அளவுகள் மீது பயனுள்ள விளைவுகளைக் கொண்டிருந்ததாக எந்த வலுவான ஆதாரமுமில்லை, ஆனால், பெரும்பாலான சோதனைகள் குறுகிய-காலக்கட்டதிற்கு இருந்தன. பழம் மற்றும் காய்கறி நுகர்வை அதிகரிப்பதற்கான உணவுமுறை ஆலோசனை பயனுள்ள விளைவுகளை அளித்தது என்பதற்கு சில ஆதாரங்கள் இருந்தது, ஆனால் அவை இரண்டு பரிசோதனைகளின் கண்டுபிடிப்புகளை அடிப்படையாக கொண்டது. இந்த கண்டுப்பிடிப்புகளை உறுதிப்படுத்த அதிகப்படியான பரிசோதனைகள் தேவைப்படுகிறது.

மொழிபெயர்ப்பு குறிப்புகள்

மொழி பெயர்ப்பாளர்கள்: ப்ளசிங்டா விஜய், சிந்தியா ஸ்வர்ணலதா ஸ்ரீகேசவன், தங்கமணி ராமலிங்கம், ஸ்ரீகேசவன் சபாபதி

平易な要約

果物や野菜の摂取量増加による心血管疾患予防

心血管疾患(CVD)は世界的な負荷となっており、地域間で差が認められる。この地域差は食物に関する因子と一部関連しており、果物や野菜の摂取量が少ないとCVDの発症率が上昇するといわれている。このレビューでは、他の食習慣や生活様式の変更による影響が存在しない状況下で単一介入として果物や野菜の摂取量を増加させた場合の、健康成人およびCVD高リスク者に対するCVDの予防効果を評価した。参加者1730例を対象とした10件の試験を選択し、このうち6件では摂取量を増加させるために果物や野菜を提供した場合を、残る4件では果物や野菜の摂取量を増加させるために食事指導を行った場合を検証した。提供された果物や野菜の種類は様々であったが、提供について検証した場合の介入内容は、いずれも1種類のみの果物または野菜で構成されていた。食事指導に関する試験でも、摂取を推奨した果物や野菜の数は様々であった。ある研究では、果物や野菜を1日あたり5品目以上食べるよう指導しており、別の研究では果物や野菜を1日あたり8または9品目以上食べるよう指導していた。介入期間は3カ月から1年であった。対象試験のうち3件で排便回数増加、口臭、体臭などの有害作用が報告された。 対象試験はいずれも実施期間が短く、果物や野菜の摂取量を増加した場合の心臓発作などの心血管疾患イベントに対する影響を検証することができなかった。1種類の果物または野菜の提供が、血圧や血中脂質に有益な効果を示すという強固なエビデンスは得られなかったが、大部分の試験は期間が短かった。果物や野菜の摂取量増加に対する食事指導効果の有益性を示唆するエビデンスがいくつか得られたが、わずか2件の試験から得られた知見に基づいたものである。これらの結果を確認するには、さらに試験が必要である。

訳注

《実施組織》厚生労働省「「統合医療」に係る情報発信等推進事業」(eJIM:http://www.ejim.ncgg.go.jp/)[2016.1.9]
《注意》この日本語訳は、臨床医、疫学研究者などによる翻訳のチェックを受けて公開していますが、訳語の間違いなどお気づきの点がございましたら、eJIM事務局までご連絡ください。なお、2013年6月からコクラン・ライブラリーのNew review, Updated reviewとも日単位で更新されています。eJIMでは最新版の日本語訳を掲載するよう努めておりますが、タイム・ラグが生じている場合もあります。ご利用に際しては、最新版(英語版)の内容をご確認ください。

Ringkasan bahasa mudah

Peningkatan pemakanan buah-buahan dan sayur-sayuran dalam pencegahan utama penyakit kardiovaskular

Penyakit kardiovaskular merupakan satu beban global dan berbeza diantara pelbagai kawasan. Variasi serantau ini dikaitkan dengan faktor diet dan kurangnya pengambilan buah-buahan dan sayuran yang mempunya kaitan dengan kadar penyakit kardiovaskular yang lebih tinggi. Ulasan ini menilai keberkesanan dalam meningkatkan pengambilan buah-buahan dan sayur-sayuran sebagai intervensi tunggal di kalangan orang dewasa yang sihat serta mereka yang mempunyai risiko penyakit kardiovaskular dalam pencegahan penyakit itu tanpa sebarang pengaruh dari corak diet lain atau modifikasi cara hidup . Kami mendapati 10 kajian merangkumi 1730 peserta di mana 6 kajian mengkaji penyediaan buah-buahan dan sayur-sayuran serta meningkatkan pengambilan manakala empat kajian mengkaji nasihat pemakanan untuk meningkatkan pengambilan buah-buahan dan sayur-sayuran. Terdapat variasi dalam jenis buah-buahan dan sayur-sayuran tetapi semua intervensi yang mengkaji peruntukan cuma melibatkan satu komponen buah-buahan atau sayur-sayuran. Terdapat juga variasi dalam jumlah buahan-buahan dan sayur-sayuran yang peserta dinasihatkan untuk makan. Beberapa kajian menasihatkan peserta untuk makan sekurang-kurangnya 5 hidangan buah-buahan dan sayur-sayuran sehari manakala kajian lain menasihatkan pengambilan paling kurang lapan atau sembilan hidangan sehari. Durasi intervensi diantara tiga bulan sehingga setahun. Kesan sampingan dilaporkan dalam tiga kajian dan ia termasuklah peningkatan pergerakan usus, mulut berbau serta bau badan. Semua kajian yang dimasukkan tidak mempunyai durasi yang cukup untuk mengkaji kesan peningkatan dalam pengambilan buah-buahan dan sayur-sayuran terhadap penyakit kardiovaskular seperti serangan sakit jantung. Tiada bukti yang kuat untuk membuktikan bahawa peruntukan untuk satu jenis buah-buahan atau sayur-sayuran mempunyai kesan yang berfaedah terhadap tekanan darah serta tahap lipid tetapi kebanyakan kajian merupakan kajian jangka pendek. Terdapat beberapa bukti untuk mencadangkan faedah nasihat pemakanan untuk meningkatkan pengambilan buah-buahan dan sayur-sayuran tetapi penemuan ini berdasarkan dua kajian. Lebih banyak kajian diperlukan untuk mengesahkan penemuan ini.

Catatan terjemahan

Diterjemahkan oleh Muhammad Yassin Ikbaal (Melaka-Manipal Medical College). Disunting oleh Lai Nai Ming, Taylor's University School of Medicine, Malaysia. Untuk sebarang pertanyaan berkaitan terjemahan ini sila hubungi yassin9221@yahoo.com. 

Streszczenie prostym językiem

Zwiększone spożycie owoców i warzyw w zapobieganiu chorobom układu krążenia

Choroby sercowo-naczyniowe (CVD) stanowią globalne obciążenie, którego wielkość jest zróżnicowana pomiędzy regionami. Regionalne zróżnicowanie częściowo wiąże się z nawykami żywieniowymi a niskie spożycie owoców i warzyw jest związane z częstszym występowaniem tych chorób. W niniejszym przeglądzie oceniano skuteczność zwiększenia spożycia owoców i warzyw w profilaktyce chorób sercowo-naczyniowych, jako pojedynczej interwencji, bez uwzględnienia wpływu innych wzorców żywieniowych lub innych zmian w stylu życia, u zdrowych osób dorosłych i u osób obciążonych dużym ryzykiem chorób sercowo-naczyniowych. Znaleźliśmy 10 badań, z udziałem 1730 uczestników, w sześciu badaniach uczestnikom zapewniano owoce i warzywa, aby zwiększyć ich spożycie, a w czterech badaniach oceniano skuteczność udzielania porad dietetycznych dotyczących zwiększenia spożycia owoców i warzyw. Istniały różnice w rodzaju dostarczanych owoców i warzyw, jednak wszystkie tego typu interwencje obejmowały zapewnienie uczestnikom tylko jednego owocu lub warzywa. Pomiędzy badaniami istniały też różnice w ilości owoców i warzyw, jakie były zalecane podczas porad dietetycznych. W niektórych badaniach zalecano uczestnikom spożywanie co najmniej pięć porcji owoców i warzyw dziennie, podczas gdy w innych zalecano co najmniej osiem lub dziewięć porcji na dzień. Czas trwania interwencji wahał się od trzech miesięcy do jednego roku. Działania niepożądane były zgłaszane w trzech, spośród włączonych badań i obejmowały częstsze wypróżnianie, nieświeży oddech i przykry zapach ciała. Żadne z włączonych badań nie trwało na tyle długo, aby można było ocenić wpływ zwiększonego spożycia owoców i warzyw na występowanie zdarzeń sercowo-naczyniowych, takich jak zawał serca. Nie odnaleziono wystarczająco silnych danych naukowych potwierdzających, że zapewnienie jednego rodzaju owocu lub warzywa korzystnie wpływa na ciśnienie tętnicze krwi i poziom lipidów, gdyż większość badań trwała krótko. Istniały pewne dane naukowe sugerujące korzystny wpływ zaleceń dietetycznych mających na celu zwiększenie konsumpcji owoców i warzyw, ale wniosek ten opiera się na wynikach pochodzących z dwóch badań. Konieczne są dalsze badania w celu potwierdzenia powyższych wniosków.

Uwagi do tłumaczenia

Tłumaczenie Joanna Zając Redakcja Magdalena Koperny

Background

Description of the condition

Cardiovascular disease (CVD) is one of the leading causes of death worldwide (WHO 2011). In 2008 it accounted for 30% of total global deaths, with 6.2 million deaths the consequence of stroke and 7.2 million due to coronary heart disease (CHD) (WHO 2011). The burden of CVD also varies substantially between regions (Müller-Nordhorn 2008), for example, death from Ischaemic heart disease in France is a quarter of that of the United Kingdom (UK) (Law 1999).

Dietary factors may play a vital role in the development of CVD and its risk factors and may contribute to the geographic variability in CVD morbidity and mortality (Scarborough 2011; Yusuf 2001). Such factors are important, not only because they have been linked to CVD development, but also because they can be modified. This makes them one of the main targets for interventions aimed at primary prevention and management of CVD.

One dietary factor that should be considered in the primary prevention of CVD is fruit and vegetable intake. Indeed, a low consumption of fruit and vegetables (less than 400 grammes [g] per day) is thought to be one of the top 10 risk factors for global mortality and is estimated to result in 1.7 million global deaths a year (WHO 2004). Of these global deaths, 14% are from gastrointestinal cancer, 11% are due to ischaemic heart disease and 9% are from stroke. In the European Union, New Zealand and Australia 3.5%, 2.1% and 2.8% respectively of disease burden is considered to be a consequence of low fruit and vegetable intake (Begg 2007; Pomerleau 2004; Tobias 2001), with, in particular, 9.6% of the CVD disease burden in Australia due to a low intake of fruit and vegetables (Begg 2007).

Conversely, it has been shown that a high consumption of fruit and vegetables can have a protective role for some chronic diseases including CVD (Hooper 2007). A number of cohort studies have shown that the risk of CHD is associated with lower consumption of fruit and vegetables (Bazzano 2002; Liu 2000; Liu 2001). Joshipura and colleagues, for example, showed in a large observational study (84,251 women and 42,148 men) that a high intake of fruit of vegetables was associated with reduced risk of developing CHD. This was particularly the case for those fruit and vegetables rich in vitamin C and leafy green vegetables (Joshipura 2001). It has been estimated that an increase in fruit and vegetable intake could reduce the burden of ischaemic stroke and ischaemic heart disease by as much as 19% and 31% respectively (Lock 2005). Furthermore, it is estimated that approximately 2.7 million lives a year could be saved by increasing fruit and vegetable consumption to 400 g per day or over (WHO 2004).

Observational studies have shown that high levels of fruit and vegetable intake are associated with increased psychological well being (Blanchflower 2012), a reduction in the risk of CVD (Joshipura 2001; Liu 2000; Liu 2001) and a reduction in type 2 diabetes (Carter 2010). As a result, many national and international guidelines recommend at least five portions of fruit and/or vegetables a day (a portion equates to 80 g) (Agudo 2004; NHS 2009; U.S. Department of Agriculture 2005). However, such guidelines are not always followed. This appears to be the case in the UK where it is estimated that only 27.7% of the general population reach this target (Maheswaran 2013).

Description of the intervention

There are many complex determinants involved in fruit and vegetable intake. As a consequence of this, a variety of conceptual frameworks are used to help develop interventions aimed at increasing fruit and vegetable consumption (Wolfenden 2012). For instance, a conceptual framework may suggest that interventions aimed at personal and cultural factors are more effective in increasing fruit and vegetable consumption than an intervention targeting only personal factors. It is suggested that for addressing changes to dietary intake, such as fruit and vegetable consumption, a social ecological framework that uses behaviour change theories at different levels of influence is best (Peterson 2002).

The interventions investigated in this review will include those that provide advice to increase fruit and vegetable consumption or those that provide fruit and vegetables themselves to increase consumption. Advice can take many forms in that it may be written or verbal, involve a single or multiple contact and may be delivered by commercial organisations, health professionals or government organisations. Provision may include only one, or more fruit(s) and/or vegetable(s) and be provided in the workplace, at community centres or in the home to name but a few.

How the intervention might work

Evidence from observational and experimental studies suggests that a high consumption of fruit and vegetables, that is more than 400 g or more than five portions a day, may be beneficial for the prevention and treatment of CVD (Ness 1997). However, the exact mechanisms by which increased fruit and vegetable consumption reduce CVD risk are not known. It may be due to fruit and vegetables containing protective elements including vitamins, minerals, antioxidants, micronutrients and phytochemicals (Department of Health 2010; Miller 2000; Van Duyn 2000). There are many potential mechanisms through which these protective elements can act to reduce blood pressure, reduce antioxidant stress, lower the serum level of low-density lipoprotein cholesterol and improve the regulation of haemostasis (Asgard 2007; Dauchet 2006; Suido 2002).

Theories have been developed to explain the mechanisms by which lifestyle changes such as fruit and vegetable provision and advice interventions influence fruit and vegetable intake. These tend to be based on the Health Belief Model (Rosenstock 1966), The Theory of Planned Behaviour (Ajzen 1991), Social cognitive theory (Bandura 1986) or the Stages of Change Model (Prochaska 1984). All four theories emphasise the dynamic nature of beliefs and suggest that in order for behaviours to change, changes need to be made to a person's perceived norms, attitudes, knowledge, skills, and expectancies (Ogden 2001; Wolfenden 2012). Social-ecological theories have also been used to explain the mechanisms by which interventions aimed at increasing fruit and vegetable intake may work. These theories suggest that a person's health behaviour is influenced by a multitude of factors including not only intra- and interpersonal factors but also organisational and community factors and those relating to public policy (Robinson 2008).

Why it is important to do this review

Many factors determine the intake of fruit and vegetables in adults (Pollard 2002). These include not only demographic and lifestyle factors but also sensory appeal and availability (Anderson 1994; Brug 1995; Clark 1998; Lennernas 1997; Thompson 1999). Although observational studies investigating the factors that determine fruit and vegetable intake provide considerable information to aid in the development of interventions, they do not examine the effectiveness of interventions to increase fruit and vegetable consumption. Some systematic reviews have attempted to do this (Ammerman 2002; Brunner 2007; Contento 1995; Miller 2000a; Pomerleau 2005). Pomerleau et al. (Pomerleau 2005), for example, conducted a systematic review that investigated the effectiveness of interventions designed to promote the intake of fruit and vegetables. They found that the largest increase in fruit and vegetable consumption was for interventions that targeted high-risk populations or those with a pre-existing disease, while a small increase of between 0.1 and 1.4 servings of fruit and vegetables a day was found for interventions promoting fruit and vegetable intake in healthy adults. This was similar to the findings of Brunner et al. (Brunner 2007) who found that dietary advice, when compared to no advice, increased the consumption of fruit and vegetables by 1.25 servings per day in healthy adults.

However, these systematic reviews do not always focus solely on the intake of fruit and vegetables (Brunner 2007; Contento 1995). The systematic review by Pomerleau (2005) does not solely focus on CVD (Pomerleau 2005), and other reviews include children (Burchett 2003; Miller 2000a).

We are focusing our attention on adults since a Cochrane review is already being undertaken in assessing the evidence for interventions for increasing fruit and vegetable consumption in children aged up to five years (Wolfenden 2012), and another on community-based interventions to increase fruit and vegetable consumption for five to 18 year olds (Ganann 2010). A comprehensive systematic review is needed that thoroughly examines interventions providing advice to increase fruit and vegetable consumption and the provision of fruit and vegetables to increase consumption, in healthy adults or those with cardiovascular risk factors to determine their effectiveness in CVD prevention. This will provide guidance not only for national and international governments but also for local authorities, practitioners and members of the public.

Objectives

The primary objective is to determine the effectiveness of i) advice to increase fruit and vegetable consumption ii) the provision of fruit and vegetables to increase consumption, on mortality (cardiovascular and all-cause), non-fatal CVD endpoints (myocardial infarction (MI), coronary artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), angina, or angiographically-defined coronary heart disease (CHD), stroke, carotid endarterectomy, peripheral arterial disease (PAD)), changes in blood pressure (systolic and diastolic blood pressure) and blood lipids (total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides), the occurrence of type 2 diabetes, health-related quality of life, adverse effects and costs.

Methods

Criteria for considering studies for this review

Types of studies

Randomised controlled trials (RCTs) including cluster-randomised trials and cross-over trials.

Types of participants

Adults (people from the age of 18 onwards) of all ages from the general population and those who are at high risk of CVD due to the presence of major CVD risk factors such as smoking, dyslipidaemia or hypertension. The review focused on the effects of fruit and vegetable consumption for the primary prevention of CVD. We therefore excluded studies where more than 25% of participants had CVD at baseline including those who have experienced a previous MI, stroke, revascularisation procedure (CABG or PTCA), those with angina, or angiographically-defined CHD, cerebrovascular disease (stroke) and PAD. We also excluded studies where more than 25% of the participants had type 2 diabetes as while patients with type 2 diabetes are at increased risk of CVD, interventions for diabetes are covered specifically by the Cochrane Metabolic and Endocrine Disorders review group.

Types of interventions

The interventions included i) specific dietary advice to increase fruit and vegetable consumption or ii) the provision of fruit and vegetables (participants are provided with fruits and vegetables as part of the intervention) as a means to increase consumption. All interventions were to include whole fruit and vegetables only, interventions involving fruit and vegetable extracts were excluded. Both provision and advice interventions could be delivered in any setting, by any individual or modality.

Studies examining advice to increase fruit and vegetable intake were examined separately from those investigating the provision of fruit and vegetables. Multi-factorial lifestyle interventions (including additional dietary interventions e.g. reduced fat and other lifestyle interventions e.g. exercise) and trials focusing on weight loss were not included in this review to avoid confounding.

We focused on follow-up periods of three months or more. Follow-up was considered to be the time elapsed since the start of the intervention and therefore any trials with an intervention duration of less than 12 weeks were excluded. Trials were only considered where the comparison group was no intervention (usual diet) or minimal intervention (e.g. leaflets (dietary or otherwise) with no person-to-person interaction or reinforcement).

Types of outcome measures

Endpoints were measured using validated measures.

Primary outcomes
  1. Cardiovascular mortality.

  2. All-cause mortality.

  3. Non-fatal endpoints such as MI, CABG, PTCA, angina, or angiographically-defined CHD, stroke, carotid endarterectomy, PAD.

Secondary outcomes
  1. Changes in blood pressure (systolic and diastolic blood pressure) and blood lipids (total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides).

  2. Occurrence of type 2 diabetes as a major CVD risk factor.

  3. Health-related quality of life.

  4. Adverse effects (as defined by the authors of the included trials).

  5. Costs.

Search methods for identification of studies

Electronic searches

The following electronic databases were searched: The Cochrane Library (2012, issue 9), (including the Cochrane Central Register of controlled Trials (CENTRAL) and NHS Centre for Reviews and Dissemination (CRD) databases Health Technology Assessment (HTA), Database of Abstracts of Reviews of Effectiveness (DARE) and NHS Economic Evaluation Database (NEED)); MEDLINE (1946 to week 3 September 2012); EMBASE (1980 to 2012 week 39) and the Conference Proceedings Citation Index - Science on ISI Web of Science (5 October 2012). We searched trial registers, screened reference lists and contacted authors for additional information where necessary. No language restrictions were applied.

Medical Subject Headings (MeSH) or equivalent and text word terms were use with searches designed in accordance with Cochrane Heart Group methods and guidance. There were no language restrictions.

Searches were tailored to individual databases. The search strategies for each database are shown in Appendix 1.

Searching other resources

Reference lists of reviews and retrieved articles were checked for additional studies.

We searched the metaRegister of controlled trials (mRCT) (www.controlled-trials.com/mrct), Clinicaltrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (http://apps.who.int/trialsearch/) for ongoing trials and unpublished or part-published trials.

Citation searches were performed on key articles. Google Scholar was also used to search for further studies.

We contacted experts in the field for unpublished and ongoing trials and authors were contacted where necessary for additional information.

Data collection and analysis

Selection of studies

Review authors (LH, EI, NF) independently reviewed the titles and abstracts identified from the searching. Following this initial screening, the full text reports of the potentially relevant studies were obtained and the same two review authors (LH, EI) independently selected relevant studies using predetermined inclusion criteria. In all cases, disagreements concerning study inclusion were resolved by consensus, a third review author (Karen Rees (KR)) was consulted if disagreement persisted.

Data extraction and management

Data extraction was carried out independently by two review authors (LH, Jennifer Holmes (JH)) using a proforma and chief investigators were contacted to provide additional relevant information if necessary.

The following details were extracted from each study.

  1. Study design.

  2. Study setting.

  3. Participant characteristics.

  4. Intervention (advice or provision of fruit and vegetables, personnel, intensity, duration, follow-up).

  5. Comparison group (no intervention or details of minimal intervention).

  6. Outcome data (outcome assessment, adverse effects).

  7. Methodological quality (randomisation, blinding, attrition).

Disagreements about extracted data were resolved by consensus and a third reviewer (KR) was consulted if disagreement persisted.

Assessment of risk of bias in included studies

Risk of bias was assessed independently by two review authors (LH, JH) by examining the quality of the random sequence generation and allocation concealment, description of drop-outs and withdrawals (including intention-to-treat analysis), blinding (participant, personnel and outcome assessment) and selective outcome reporting (Higgins 2011).

Measures of treatment effect

Data was processed in accordance with the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). For continuous outcomes net changes were compared (i.e. intervention group minus control group differences) and a mean difference (MD) and 95% confidence intervals (CI's) calculated for each study.

Assessment of heterogeneity

For each outcome, tests of heterogeneity were conducted (using Chi2 test of heterogeneity and I² statistic). If no heterogeneity was present a fixed-effect meta-analysis was performed. If there was substantial heterogeneity (Igreater than 50%) the review authors looked for possible explanations for this (e.g. intervention and participants). If the heterogeneity could not be explained, we considered the following options:

  1. provide a narrative overview and not aggregate the studies at all;

  2. use a random-effects model with appropriate cautious interpretation.

Subgroup analysis and investigation of heterogeneity

Results were stratified by i) advice to increase fruit and vegetable consumption and ii) the provision of fruit and vegetables to increase consumption. Trials could not be stratified by baseline risk and the effects of intensity and duration of the intervention due to the small number of trials included in the review.

Sensitivity analysis

We performed sensitivity analysis excluding studies at high risk of bias (e.g. those with loss to follow-up more than 20% without intention-to-treat analysis). We intended to examine the effects of "time and attention" given to participants in the intervention and control groups as potential confounders, and the effects of publication bias using funnel plots and tests of asymmetry (Egger 1997), but these could not be carried out due to the small number of trials included in the review.

Results

Description of studies

Results of the search

The electronic searches generated 7283 hits after duplicates were removed. Screening of titles and abstracts identified 298 papers to go forward for formal inclusion and exclusion. Of these, 10 RCTs met the inclusion criteria. We also identified one ongoing trial from trial registers. Details of the flow of studies through the review are shown in the PRISMA flow diagram in Figure 1.

Figure 1.

Study flow diagram.

Included studies

Details of the studies included in the review are shown in the Characteristics of included studies table. Ten trials with 1730 participants met the inclusion criteria. Four of the 10 trials recruited only female participants (Dichi 2011; Djuric 2006; Gravel 2009; Maskarinec 1999). Six trials were conducted in the U.S.A (Djuric 2006; Finley 2007; Fujioka 2006; Gardner 2007; Maskarinec 1999; Smith-Warner 2000), one trial in Canada (Gravel 2009), one in Brazil (Dichi 2011), and two in the UK (John 2002; Thies 2012).

None of the included studies had interventions that provided fruit and vegetables and gave advice. Six of the 10 trials examined the effects of providing fruit and vegetables to increase consumption (Dichi 2011; Finley 2007; Fujioka 2006; Gardner 2007; Gravel 2009; Thies 2012) and four examined the effects of dietary advice to increase fruit and vegetable intake (Djuric 2006; John 2002; Maskarinec 1999; Smith-Warner 2000). For those studies examining the effects of provision of fruit and vegetables there was variability in the types of fruit and vegetables provided and the portion size. Furthermore, five of the six provision trials only provided one fruit or vegetable. One study looked at the provision of 25 g/day of soy (Dichi 2011), one looked at the provision of 130 g of cooked pinto beans daily (Finley 2007), another examined the effects of half a grapefruit three times a day (Fujioka 2006), one study examined the provision of raw garlic on a sandwich (Gardner 2007), one study looked at a high tomato diet (Thies 2012) and one trial looked at the provision of 750 mL of legumes a week (Gravel 2009). Similarly, the type of dietary advice to increase fruit and vegetable consumption also varied between studies. Portions of fruit and vegetables included five or more portions a day (John 2002), at least eight servings daily (Smith-Warner 2000), and at least nine servings a day (Djuric 2006; Maskarinec 1999). In addition, the modality of the advice provided differed between studies. In two studies, advice was provided by individualised in-person dietary counselling with monthly group meetings (Djuric 2006; Maskarinec 1999). In another study participants were provided with a portion guide, leaflets on barriers to increasing fruit and vegetable consumption and an action plan to increase fruit and vegetable consumption by a research nurse who also introduced the benefits of increasing fruit and vegetable intake (John 2002). In the remaining study a nutritionist helped participants to formulate a plan to help them increase their fruit and vegetable intake and provided participants with educational materials on this topic. Participants were also taught behavioural modification strategies to identify personal barriers to adherence (Smith-Warner 2000). The dietary advice interventions took place in health centres (John 2002) and a digestive healthcare unit (Smith-Warner 2000). The two remaining studies did not state where there interventions took place (Djuric 2006; Maskarinec 1999).

The duration of the intervention and follow-up periods varied between the included studies. Four of the studies had three to six months follow-up (Dichi 2011; Finley 2007; Fujioka 2006; Thies 2012), four a follow-up of six months (Gardner 2007; Gravel 2009; John 2002; Maskarinec 1999), and two studies a follow-up of one year (Djuric 2006; Smith-Warner 2000).

Studies were also variable in the types of participants they recruited. Two studies were conducted in women with metabolic syndrome (Dichi 2011; Gravel 2009), one study was conducted in healthy post-menopausal women with a family history of breast cancer (Djuric 2006), one was conducted in participants with LDL concentrations of 130-190 mg/dL and triglyceride levels of less than 250 mg/dL (Gardner 2007), one study included participants who were obese (Fujioka 2006), another study was conducted in patients who had colorectal adenomatous polyps in the five years before the study (Smith-Warner 2000), one study included patients who were pre-metabolic or healthy (Finley 2007) and three studies were conducted in healthy participants (John 2002; Maskarinec 1999; Thies 2012).

Four studies examining the provision of fruit and vegetables to increase consumption are awaiting classification. Details of these studies are provided in the Characteristics of studies awaiting classification table. The first trial examined fruit and vegetable puree and juice drinks in healthy participants (George 2009). The second trial examined three different diets on serum cholesterol in healthy volunteers (Groen 1952). The third study awaiting classification looked at 45 g/day of blueberries or blackberries in postmenopausal women who smoked (Teeple (2011)), while the forth study examined seven or more portions of fruit and vegetables daily for 12 weeks in overweight participants (Wallace 2012).

One ongoing trial examining the provision of fruit and vegetables to increase consumption was identified (Wang 2011). Details of this study are shown in the Characteristics of ongoing studies table. The study examined an avocado-rich diet (Wang 2011). The anticipated end date for this study was May 2012 but as of yet, no results have been published.

Excluded studies

Details and reasons for exclusion for the studies that most closely missed the inclusion criteria are provided in the Characteristics of excluded studies table. Reasons for exclusion for the majority of studies were alternative designs (not RCTs), the intervention was not relevant, studies were short term with less than three months follow-up and the control group did not receive a minimal intervention or no intervention (see Figure 1).

Risk of bias in included studies

Details are presented for each of the included trials in the 'Risk of bias' tables in the Characteristics of included studies and summaries are presented in Figure 2 and Figure 3.

Figure 2.

'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.

Figure 3.

'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Allocation

The methods of random sequence generation were unclear in seven of the 10 included studies (Dichi 2011; Djuric 2006; Finley 2007; Gravel 2009; Maskarinec 1999; Smith-Warner 2000; Thies 2012). In the three studies where the random sequence generation methods were stated, the methods were judged to be of low risk of bias (Fujioka 2006; Gardner 2007; John 2002). The methods of allocation concealment were unclear in nine of the 10 included studies (Dichi 2011; Djuric 2006; Finley 2007; Fujioka 2006; Gravel 2009; John 2002; Maskarinec 1999; Smith-Warner 2000; Thies 2012). In the one study which stated the method of allocation concealment, the method was judged of low risk of bias (Gardner 2007).

Blinding

Blinding participants and personnel was unclear in three of the 10 included studies. Four trials were of dietary advice where blinding of participants to the intervention was impossible (Djuric 2006; John 2002; Maskarinec 1999; Smith-Warner 2000) and these were regarded as at high risk of bias. Similarly, it may also difficult to blind participants in trials of the provision of fruit and vegetables. One study stated that it was single-blind and so was regarded as at high risk of bias (Thies 2012), while two studies stated that they were double-blind and were regarded as at low risk of bias (Fujioka 2006; Gardner 2007). The blinding of outcome assessors was unclear in five of the included studies (Dichi 2011; Finley 2007; Gravel 2009; Smith-Warner 2000; Thies 2012) but five studies stated that outcome assessors were blinded (Djuric 2006; Fujioka 2006; Gardner 2007; John 2002; Maskarinec 1999).

Incomplete outcome data

Five of the 10 included studies reported losses to follow-up, had a similar number of losses between the intervention and control arms, and/or stated the reasons for losses to follow-up (Fujioka 2006; Gardner 2007; John 2002; Smith-Warner 2000; Thies 2012).These studies were considered to be at low risk of bias. In another five trials, the reporting of incomplete outcome data was judged as unclear as they either did not report losses to follow-up (Dichi 2011; Gravel 2009) or did not report the reasons for losses to follow-up (Djuric 2006;Finley 2007; Maskarinec 1999).

Selective reporting

For five of the 10 included studies the risk of bias for selective reporting was unclear as there was insufficient information available for a judgement to be made (Dichi 2011; Djuric 2006; Gravel 2009; John 2002; Smith-Warner 2000). For two studies, the risk of bias was judged as high (Finley 2007; Maskarinec 1999) because lipid levels were reported in graphical form with no usable numbers for meta-analysis (Finley 2007) or because lipid levels were presented in the analysis but were not stated in the methods as an outcome (Maskarinec 1999). Three of the 10 included studies were judged to be of low risk of bias as the studies clearly stated primary and secondary outcomes and reported their results (Fujioka 2006; Gardner 2007; Thies 2012).

Other potential sources of bias

For all included studies there was insufficient information to judge the risk of bias from other potential sources.

Effects of interventions

Advice to increase the consumption of fruit and vegetables

Four trials examined dietary advice to increase fruit and vegetable consumption with follow-up periods of over six months (Djuric 2006; John 2002; Maskarinec 1999; Smith-Warner 2000). No trials were found with a follow-up of three to six months.

Clinical Events

None of the included studies provided clinical event data.

Cardiovascular risk factors
Blood pressure

Two of the four studies that examined dietary advice to increase the consumption of fruit and vegetables measured blood pressure (John 2002; Smith-Warner 2000). In one study, this was at six months (John 2002) and in the other study at 12 months (Smith-Warner 2000). From the pooled analysis, advice to eat fruit and vegetables significantly reduced systolic blood pressure (mean difference (MD) -3.0 mmHg (95% confidence interval (CI) -4.92 to -1.09)) (Analysis 1.1) (891 participants) but the reduction in diastolic blood pressure was not statistically significant (MD -0.90 mmHg (95% CI -2.03 to 0.24)) (Analysis 1.2) (891 participants). No heterogeneity was found between trials (I2 = 0%).

Lipid levels

Four studies measured total cholesterol (Djuric 2006; John 2002; Maskarinec 1999; Smith-Warner 2000). Two studies measured total cholesterol at six months (John 2002; Maskarinec 1999) and two studies measured this at 12 months (Djuric 2006; Smith-Warner 2000). The pooled analysis showed no effect of the intervention on total cholesterol levels (MD -0.01 mmol/L (95% CI -0.11 to 0.09)) (Analysis 1.3) (970 participants). No heterogeneity was found between trials (I2 = 0%).

Two trials examined the effects of dietary advice on LDL cholesterol (Djuric 2006; Smith-Warner 2000); both at 12 months. Both trials could be pooled statistically and showed a reduction in LDL cholesterol but this did not reach statistical significance (MD -0.17 mmol/L (95% CI -0.38 to 0.03)) (Analysis 1.4) (251 participants). No heterogeneity was found between trials (I2 = 0%).

Two studies also measured HDL cholesterol (Djuric 2006; Smith-Warner 2000) at 12 months and the pooled data for these studies showed no effect of the intervention on HDL cholesterol levels (MD -0.01 (95% CI -0.10 to 0.08)) (Analysis 1.5) (251 participants). No heterogeneity was found between trials (I2 = 0%).

Three studies measured triglycerides (Djuric 2006; Maskarinec 1999; Smith-Warner 2000) and data were pooled from all three. Two trials measured triglycerides at 12 months (Djuric 2006; Smith-Warner 2000) and one study at six months (Maskarinec 1999). Overall, there was a tendency for triglyceride levels to increase with the intervention, but this did not reach statistical significance (MD 0.10 mmol/L (95% CI -0.06 to 0.27)) (Analysis 1.6) (280 participants). Furthermore, no heterogeneity was found between trials (I2 = 0%).

Provision of fruit and vegetables to increase consumption

Six trials examined the effects of provision of fruit and vegetables, four had a follow-up period of three months (Dichi 2011; Finley 2007; Fujioka 2006; Thies 2012), and two a follow-up period of over six months (Gardner 2007; Gravel 2009).

Clinical Events

None of the included studies provided clinical event data.

Cardiovascular risk factors
Blood pressure

Four of the five included studies measured blood pressure (Dichi 2011; Fujioka 2006; Gravel 2009; Thies 2012). One study reported medians and interquartile ranges suggesting the data were skewed (Dichi 2011), and authors of two studies were contacted for information on mean changes and variance but this was not forthcoming (Fujioka 2006; Gravel 2009). Two studies also did not provide information on effect size or statistical significance (Fujioka 2006; Gravel 2009)

Differences were seen for diastolic blood pressure in women with metabolic syndrome in both the intervention and control group (P < 0.05) (Dichi 2011) (30 participants) at 90 days. One study reported no effects on systolic (MD 1.00 mmHg, 95% CI 0.45 to 1.55) (Analysis 2.1) or diastolic blood pressure (MD 1.50 mmHg, 95% CI 1.18 to 1.82) (Analysis 2.2) with the provision of fruit and vegetables to increase consumption (Thies 2012) (157 participants) at three months. The remaining two studies also reported no effects on blood pressure with the provision of fruit and vegetables to increase consumption (Fujioka 2006; Gravel 2009) (180 participants) at three months (Fujioka 2006) and six months (Gravel 2009).

Lipid levels

Three trials measured total cholesterol (Dichi 2011; Finley 2007; Thies 2012). One study measured this at 90 days (Dichi 2011) while the other two studies measured total cholesterol at three months (Finley 2007; Thies 2012). One study reported data in graphical form and found a statistically significant reduction in total cholesterol (P < 0.014) for those who ate pinto beans (the intervention) compared with those who ate chicken soup (the comparison group) (Finley 2007) (80 participants) at three months. For the pooled analysis (187 participants), moderate heterogeneity was found between studies (I2 = 51%) so a random-effects meta-analysis was performed. From the pooled analysis, fruit and vegetable provision was found to lower total cholesterol slightly (MD -0.10 mmol/L, 95% CI -0.24 to 0.04) but this was not statistically significant (Analysis 2.3). Results were similar for the fixed-effect model but the random-effects results were reported as the effect estimate is more conservative with wider confidence intervals.

Four trials measured LDL cholesterol (Dichi 2011; Finley 2007; Gardner 2007; Thies 2012). One study reported the data in graphical form and found a reduction in LDL cholesterol with the intervention (P < 0.5, Finley 2007) (80 participants) at three months. The other three studies could not be combined as there was substantial heterogeneity between trials (I2 =59%) (Analysis 2.4) (284 participants). One study showed a significant reduction in LDL cholesterol with the intervention (MD -0.09 mmol/L, 95% CI -0.12 to -0.06) (Thies 2012) at three months while the two remaining studies found fruit and vegetable provision to have no effect on LDL cholesterol (Dichi 2011; Gardner 2007) at 90 days (Dichi 2011) and at six months (Gardner 2007).

All six studies examined the effects of provision of fruit and vegetables on HDL cholesterol. Usable data were not available for three studies, two reported that they found no significant effects of the intervention on HDL cholesterol levels (Fujioka 2006; Gravel 2009) at three months (Fujioka 2006) and six months (Gravel 2009), whereas the third study found significantly reduced HDL cholesterol levels (Finley 2007) at three months. Data for the remaining three studies could not be pooled as there was significant heterogeneity present (I2 = 90%) ( (Analysis 2.5) (284 participants). One study showed a significant increase in HDL cholesterol with soy (MD 0.17, 95% CI 0.02 to 0.32) (Dichi 2011) at 90 days and the second study with raw garlic (MD 0.08 mmol/L, 95% CI 0.00 to 0.16) (Gardner 2007) at six months. The third study showed a significant decrease in HDL cholesterol (MD -0.06 mmol/L, 95% CI -0.08 to -0.04) (Thies 2012) at three months.

Similarly, all six trials measured triglycerides and data were pooled for three trials with useable data (Analysis 2.6). For these three trials, triglycerides were measured at three months (Finley 2007; Fujioka 2006) and six months (Gravel 2009). No heterogeneity was found between trials (I2 = 0%). Overall, there was no effect of the intervention on triglyceride levels (MD -0.01 mmol/L (95% CI -0.03 to 0.01)) (284 participants). No effects on triglycerides were reported in the remaining three trials that did not contribute to the meta-analysis (Finley 2007; Fujioka 2006; Gravel 2009).

Adverse effects

Adverse effects of the provision of fruit and vegetables were noted in two of the six included studies (Fujioka 2006; Gardner 2007). One reported that there were few adverse effects over three months (Fujioka 2006). The second study reported that no serious adverse effects occurred over six months (Gardner 2007) but that bad breath and body odour were reported in 57% of those receiving the intervention (raw garlic) and flatulence was reported by three participants in the intervention group and one participant in the control group.

One of the three studies examining the effects of dietary advice to increase fruit and vegetable consumption examined adverse effects (Smith-Warner 2000).This study reported significantly increased bowel movements from 9.2 to 10.0 a week with the intervention and significantly more flatulence (P = 0.01), but this did not persist after three months.

Costs

None of the included studies provided data on costs.

Discussion

Summary of main results

Ten trials which randomised 1730 participants were identified from the 298 papers screened. None of the trials reported clinical endpoints. Six of these 10 trials examined the provision of fruit and vegetables to increase consumption. From these, there was no strong evidence in favour of the effects of fruit and vegetable provision on CVD risk factors, however, the trials were heterogeneous, and short term.

Four trials examined dietary advice to increase fruit and vegetable consumption. From these trials, there was some evidence of favourable effects of dietary advice to increase fruit and vegetable consumption on blood pressure and to a lesser extent on LDL cholesterol at six months. However, it should be noted that few trials contributed to each analysis.

Overall completeness and applicability of evidence

This review included adult participants who were at varying levels of CVD risk and included both men and women. The majority of trials were conducted in developed countries. None of the included studies examined our primary outcomes as trials were relatively short term and participants were relatively healthy. We were also unable to examine the effects of baseline CVD risk or the intensity of interventions due to the limited number of included studies.

The effectiveness of the provision of fruit and vegetables could not be rigorously assessed since only two trials (229 participants) assessed cardiovascular risk factors at six months.The remaining four were shorter term so it is unclear whether any effects of the intervention could be sustained. In most cases, these trials examined one type of fruit or vegetable so generalisability is limited.

Similarly, few trials were identified examining the effectiveness of dietary advice to increase fruit and vegetable consumption. Three trials were found with six months or more follow-up with 924 participants randomised.

For both trials of provision of fruit and vegetables and dietary advice to increase consumption of fruit and vegetables there was considerable variability in the interventions, the participants recruited and the outcomes measured. For dietary advice trials, there may have also been differences in the serving sizes recommended within interventions, however, the definition of portion size was not provided in these trials and so it is not possible to tell.

Quality of the evidence

Overall, the studies included in this review were at some risk of bias and results should be treated with some caution. In seven of the 10 included studies the methods of random sequence generation were not stated, while in nine of the included trials details of allocation concealment were not given. Eight of the 10 included studies did not state if the participants and personnel were blinded and five studies did not report the blinding of outcome assessment. Blinding of participants and personnel is difficult if not impossible for behavioural interventions, but outcome assessment can be blinded. Risk of bias due to incomplete outcome data was found to be low in four studies and unclear in six studies, and bias due to selective reporting was regarded as high in two studies, low in three and unclear in the remainder. In all studies there was insufficient information to judge the risk of other biases.

Potential biases in the review process

We conducted a comprehensive search across major databases for interventions to increase fruit and vegetable consumption. We also screened systematic review reference lists and contacted trial authors where necessary. However, from corresponding with authors we did not receive further unreported data from two trials which limited our analyses. Screening, inclusion and exclusion and data abstraction were conducted in duplicate by two review authors independently. Data entry and analyses were carried out by two review authors .

Our decision to restrict this review to interventions only investigating fruit and vegetables avoided the potential confounding effects of other behavioural interventions on our outcomes e.g. those involving other dietary interventions, exercise or weight loss, but limited the number of studies eligible for inclusion. By restricting our inclusion criteria in this way, we excluded some large trials, notably the Womens Health Initiative (WHI) trial, which examined also the effects of reducing dietary fat and increasing grain consumption, as well as increasing fruit and vegetable intake (WHI). The WHI trial randomised over 8000 postmenopausal women, follow-up is reported over eight years and showed no effect of dietary modification including fruit and vegetable intake on cardiovascular disease clinical endpoints. One could argue that assuming reducing dietary fat and increasing grain consumption is not actively harmful, then this trial demonstrates no effect of fruit and vegetable intake on CVD events, at least in this population of well nourished, middle-aged women.

Furthermore, limitations in reporting methodological quality, an unclear risk of bias in most trials and sparse or no data for primary and secondary outcomes mean that the findings of this review should be treated with caution due to the small number of trials on which they are based.

Agreements and disagreements with other studies or reviews

To our knowledge, no other systematic review involving only randomised controlled trials has been conducted solely to examine the effects of increasing fruit and vegetable consumption in adults for the primary prevention of CVD. Other systematic reviews have looked at dietary advice for the primary prevention of CVD that includes increasing fruit and vegetable consumption, but also other dietary modifications (Brunner 2007). Dietary advice was found to be effective at increasing fruit and vegetable consumption in the review by Brunner et al, but we cannot directly compare the effects on CVD risk factors between the two reviews as changes may be due to other dietary modifications such as decreasing fat, salt or increasing dietary fibre. All of the trials of dietary advice to increase consumption of fruit and vegetables are included in both reviews. CVD risk factors were not measured in the review by Pomerleau et al so again we are unable to compare our findings (Pomerleau 2005). These authors showed that interventions designed to increase fruit and vegetable consumption increased fruit and vegetable intake by ˜0.1 to 1.4 servings per day. Provision of fruit and vegetables is more difficult to compare with other studies as most of the studies we found focus on one particular fruit or vegetable, thereby limiting the findings. Other systematic reviews have looked at increasing fruit and vegetable consumption in children (Wolfenden 2012). The findings showed that there were few effective interventions aimed at improving fruit and vegetable consumption in children aged five years and under. Other systematic reviews are ongoing in different populations (Ganann 2010).

The current systematic review found few trials on interventions focused solely on increasing the consumption of fruit and vegetables in the absence of other dietary modifications, which limits the findings. In the four trials we found on dietary advice to increase fruit and vegetable consumption, favourable effects were seen on blood pressure and to a lesser extent lipid levels.

Authors' conclusions

Implications for practice

Very few trials met the inclusion criteria for our review and none reported our primary outcome. Our strict inclusion criteria was designed to look specifically at the effects of increased fruit and vegetable consumption in the absence of other dietary interventions, but this limited the number of trials included and excluded notably one large trial reporting clinical endpoints (WHI). In our review, favourable effects were seen for outcomes of cardiovascular risk factors in the four trials of dietary advice to increase the consumption of fruit and vegetables, which is promising, but more trials are needed to confirm this and to examine effects over the longer term. Results from trials of the provision of single fruits or vegetables were more limited. Given the limited evidence to date, our review does not make any recommendations about changing practice. Current guidance recommends consumption of at least five portions of fruit and vegetables per day.

Implications for research

There is a lack of randomised controlled trials examining solely the effects of advice to consume more fruit and vegetables and the provision of fruit and vegetables to increase consumption for the primary prevention of CVD. This is surprising given that national and international guidelines recommend the consumption of at least five portions of fruit and vegetables per day. In particular, and most importantly, there is a shortage of randomised controlled trials that look at the effects of interventions to solely increase fruit and vegetable consumption over the longer term to determine the sustainability of such behavioural change, and to examine effects on our primary outcome CVD events. Other large trials of multifactorial dietary interventions including increased fruit and vegetable consumption have shown no benefits of the intervention on CVD clinical events (WHI), and this finding may hold true also for interventions aimed solely at increasing fruit and vegetable consumption, assuming the other components of the dietary intervention did no harm. This evidence is however limited to middle-aged women and more research is needed in other groups. Furthermore, we found no trials reporting economic evaluations of interventions to increase fruit and vegetable consumption.

Acknowledgements

We are grateful to Nicole Martin and Jo Abbot for conducting the searches for this review. We would also like to acknowledge Dr Dichi for providing additional data from his trial (Dichi 2011).

Data and analyses

Download statistical data

Comparison 1. Advice to eat fruit and vegetables
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Systolic blood pressure, change from baseline (mmHg)2891Mean Difference (IV, Fixed, 95% CI)-3.00 [-4.92, -1.09]
2 Diastolic blood pressure, change from baseline (mmHg)2891Mean Difference (IV, Fixed, 95% CI)-0.90 [-2.03, 0.24]
3 Total cholesterol, change from baseline (mmol/l)4970Mean Difference (IV, Fixed, 95% CI)-0.01 [-0.11, 0.09]
4 LDL cholesterol, change from baseline (mmol/l)2251Mean Difference (IV, Fixed, 95% CI)-0.17 [-0.38, 0.03]
5 HDL cholesterol, change from baseline (mmol/l)2251Mean Difference (IV, Fixed, 95% CI)-0.01 [-0.10, 0.08]
6 Triglycerides, change from baseline (mmol/l)3280Mean Difference (IV, Fixed, 95% CI)0.10 [-0.06, 0.27]
Analysis 1.1.

Comparison 1 Advice to eat fruit and vegetables, Outcome 1 Systolic blood pressure, change from baseline (mmHg).

Analysis 1.2.

Comparison 1 Advice to eat fruit and vegetables, Outcome 2 Diastolic blood pressure, change from baseline (mmHg).

Analysis 1.3.

Comparison 1 Advice to eat fruit and vegetables, Outcome 3 Total cholesterol, change from baseline (mmol/l).

Analysis 1.4.

Comparison 1 Advice to eat fruit and vegetables, Outcome 4 LDL cholesterol, change from baseline (mmol/l).

Analysis 1.5.

Comparison 1 Advice to eat fruit and vegetables, Outcome 5 HDL cholesterol, change from baseline (mmol/l).

Analysis 1.6.

Comparison 1 Advice to eat fruit and vegetables, Outcome 6 Triglycerides, change from baseline (mmol/l).

Comparison 2. Provision of fruit and vegetables
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Systolic blood pressure, change from baseline (mmHg)1157Mean Difference (IV, Fixed, 95% CI)1.0 [0.45, 1.55]
2 Diastolic blood pressure, change from baseline (mmHg)1157Mean Difference (IV, Fixed, 95% CI)1.5 [1.18, 1.82]
3 Total cholesterol, change from baseline (mmol/l)2187Mean Difference (IV, Random, 95% CI)-0.10 [-0.24, 0.04]
4 LDL cholesterol, change from baseline (mmol/l)3 Mean Difference (IV, Fixed, 95% CI)Totals not selected
5 HDL cholesterol, change from baseline (mmol/l)3 Mean Difference (IV, Fixed, 95% CI)Totals not selected
6 Trigylcerides, change from baseline (mmol/l)3284Mean Difference (IV, Fixed, 95% CI)-0.01 [-0.03, 0.01]
Analysis 2.1.

Comparison 2 Provision of fruit and vegetables, Outcome 1 Systolic blood pressure, change from baseline (mmHg).

Analysis 2.2.

Comparison 2 Provision of fruit and vegetables, Outcome 2 Diastolic blood pressure, change from baseline (mmHg).

Analysis 2.3.

Comparison 2 Provision of fruit and vegetables, Outcome 3 Total cholesterol, change from baseline (mmol/l).

Analysis 2.4.

Comparison 2 Provision of fruit and vegetables, Outcome 4 LDL cholesterol, change from baseline (mmol/l).

Analysis 2.5.

Comparison 2 Provision of fruit and vegetables, Outcome 5 HDL cholesterol, change from baseline (mmol/l).

Analysis 2.6.

Comparison 2 Provision of fruit and vegetables, Outcome 6 Trigylcerides, change from baseline (mmol/l).

Appendices

Appendix 1. Search strategies

CENTRAL

#1 MeSH descriptor: [Fruit] explode all trees
#2 MeSH descriptor: [Citrus] explode all trees
#3 MeSH descriptor: [Vegetables] explode all trees
#4 fruit*
#5 vegetable*
#6 orange*
#7 apple*
#8 pear or pears
#9 grape or grapes
#10 banana*
#11 berry or berries
#12 citrus
#13 carrot*
#14 greens
#15 cabbage*
#16 brassica*
#17 blackberr*
#18 blueberr*
#19 cranberr*
#20 guava*
#21 kiwi*
#22 lingonberr*
#23 mango*
#24 melon*
#25 papaya*
#26 pineapple*
#27 raspberr*
#28 strawberr*
#29 tomato*
#30 potato*
#31 onion*
#32 grapefruit*
#33 mandarin*
#34 satsuma*
#35 tangerine*
#36 plum or plums
#37 apricot*
#38 cherry or cherries
#39 nectarine*
#40 peach or peaches
#41 celery
#42 spinach*
#43 salad or salads
#44 pea or peas
#45 bean or beans
#46 broccoli
#47 cauliflower*
#48 beetroot*
#49 turnip*
#50 rhubarb
#51 legume*
#52 cucumber*
#53 leek*
#54 aubergine*
#55 pepper*
#56 okra
#57 pumpkin*
#58 squash*
#59 artichoke*
#60 lettuce*
#61 kale
#62 chard
#63 parsnip*
#64 asparagus
#65 fennel
#66 chickpea*
#67 five-a-day
#68 5-a-day
#69 5 next a next day
#70 #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10
#71 #11 or #12 or #13 or #14 or #15 or #16 or #17 or #18 or #19 or #20
#72 #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30
#73 #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38 or #39 or #40
#74 #41 or #42 or #43 or #44 or #45 or #46 or #47 or #48 or #49 or #50
#75 #51 or #52 or #53 or #54 or #55 or #56 or #57 or #58 or #59 or #60
#76 #61 or #62 or #63 or #64 or #65 or #66 or #67 or #68 or #69
#77 #70 or #71 or #72 or #73 or #74 or #75 or #76
#78 MeSH descriptor: [Cardiovascular Diseases] explode all trees
#79 cardio*
#80 cardia*
#81 heart*
#82 coronary*
#83 angina*
#84 ventric*
#85 myocard*
#86 pericard*
#87 isch?em*
#88 emboli*
#89 arrhythmi*
#90 thrombo*
#91 atrial next fibrillat*
#92 tachycardi*
#93 endocardi*
#94 sick near sinus
#95 MeSH descriptor: [Stroke] explode all trees
#96 stroke or stokes
#97 cerebrovasc*
#98 cerebral next vascular
#99 apoplexy
#100 brain near/2 accident*
#101 brain* near/2 infarct*
#102 cerebral near/2 infarct*
#103 lacunar near/2 infarct*
#104 MeSH descriptor: [Hypertension] explode all trees
#105 hypertensi*
#106 peripheral next arter* next disease*
#107 high near/2 (blood next pressure)
#108 increased near/2 (blood next pressure)
#109 elevated near/2 (blood next pressure)
#110 MeSH descriptor: [Hyperlipidemias] explode all trees
#111 hyperlipid*
#112 hyperlip?emia*
#113 hypercholesterol*
#114 hypercholester?emia*
#115 hyperlipoprotein?emia*
#116 hypertriglycerid?emia*
#117 MeSH descriptor: [Arteriosclerosis] explode all trees
#118 MeSH descriptor: [Cholesterol] explode all trees
#119 cholesterol
#120 "coronary risk factor*"
#121 MeSH descriptor: [Blood Pressure] this term only
#122 blood pressure
#123 #78 or #79 or #80 or #81 or #82 or #83 or #84 or #85 or #86 or #87
#124 #88 or #89 or #90 or #91 or #92 or #93 or #94 or #95 or #96 or #97
#125 #98 or #99 or #100 or #101 or #102 or #103 or #104 or #105 or #106 or #107
#126 #108 or #109 or #110 or #111 or #112 or #113 or #114 or #115 or #116
#127 #117 or #118 or #119 or #120 or #121 or #122
#128 #123 or #124 or #125 or #126 or #127
#129 #77 and #128

MEDLINE OVID

1. exp Fruit/
2. exp Citrus/
3. exp Vegetables/
4. fruit*.tw.
5. vegetable*.tw.
6. orange*.tw.
7. apple*.tw.
8. (pear or pears).tw.
9. (grape or grapes).tw.
10. banana*.tw.
11. (berry or berries).tw.
12. citrus.tw.
13. carrot*.tw.
14. greens.tw.
15. cabbage*.tw.
16. brassica*.tw.
17. blackberr*.tw.
18. blueberr*.tw.
19. cranberr*.tw.
20. guava*.tw.
21. kiwi*.tw.
22. lingonberr*.tw.
23. mango*.tw.
24. melon*.tw.
25. papaya*.tw.
26. pineapple*.tw.
27. raspberr*.tw.
28. strawberr*.tw.
29. tomato*.tw.
30. potato*.tw.
31. onion*.tw.
32. grapefruit*.tw.
33. mandarin*.tw.
34. satsuma*.tw.
35. tangerine*.tw.
36. (plum or plums).tw.
37. apricot*.tw.
38. (cherry or cherries).tw.
39. nectarine*.tw.
40. (peach or peaches).tw.
41. celery.tw.
42. spinach*.tw.
43. (salad or salads).tw.
44. (pea or peas).tw.
45. (bean or beans).tw.
46. broccoli.tw.
47. cauliflower*.tw.
48. beetroot*.tw.
49. turnip*.tw.
50. rhubarb.tw.
51. legume*.tw.
52. cucumber*.tw.
53. leek*.tw.
54. aubergine*.tw.
55. pepper*.tw.
56. okra.tw.
57. pumpkin*.tw.
58. squash*.tw.
59. artichoke*.tw.
60. lettuce*.tw.
61. kale.tw.
62. chard.tw.
63. parsnip*.tw.
64. asparagus.tw.
65. fennel.tw.
66. chickpea*.tw.
67. five-a-day.tw.
68. 5-a-day.tw.
69. or/1-68
70. exp Cardiovascular Diseases/
71. cardio*.tw.
72. cardia*.tw.
73. heart*.tw.
74. coronary*.tw.
75. angina*.tw.
76. ventric*.tw.
77. myocard*.tw.
78. pericard*.tw.
79. isch?em*.tw.
80. emboli*.tw.
81. arrhythmi*.tw.
82. thrombo*.tw.
83. atrial fibrillat*.tw.
84. tachycardi*.tw.
85. endocardi*.tw.
86. (sick adj sinus).tw.
87. exp Stroke/
88. (stroke or stokes).tw.
89. cerebrovasc*.tw.
90. cerebral vascular.tw.
91. apoplexy.tw.
92. (brain adj2 accident*).tw.
93. ((brain* or cerebral or lacunar) adj2 infarct*).tw.
94. exp Hypertension/
95. hypertensi*.tw.
96. peripheral arter* disease*.tw.
97. ((high or increased or elevated) adj2 blood pressure).tw.
98. exp Hyperlipidemias/
99. hyperlipid*.tw.
100. hyperlip?emia*.tw.
101. hypercholesterol*.tw.
102. hypercholester?emia*.tw.
103. hyperlipoprotein?emia*.tw.
104. hypertriglycerid?emia*.tw.
105. exp Arteriosclerosis/
106. exp Cholesterol/
107. cholesterol.tw.
108. "coronary risk factor* ".tw.
109. Blood Pressure/
110. blood pressure.tw.
111. or/70-110
112. randomized controlled trial.pt.
113. controlled clinical trial.pt.
114. randomized.ab.
115. placebo.ab.
116. drug therapy.fs.
117. randomly.ab.
118. trial.ab.
119. groups.ab.
120. 112 or 113 or 114 or 115 or 116 or 117 or 118 or 119
121. exp animals/ not humans.sh.
122. 120 not 121
123. 69 and 111 and 122

EMBASE OVID

1. exp fruit/
2. exp vegetable/
3. fruit*.tw.
4. vegetable*.tw.
5. orange*.tw.
6. apple*.tw.
7. (pear or pears).tw.
8. (grape or grapes).tw.
9. banana*.tw.
10. (berry or berries).tw.
11. citrus.tw.
12. carrot*.tw.
13. greens.tw.
14. cabbage*.tw.
15. brassica*.tw.
16. blackberr*.tw.
17. blueberr*.tw.
18. cranberr*.tw.
19. guava*.tw.
20. kiwi*.tw.
21. lingonberr*.tw.
22. mango*.tw.
23. melon*.tw.
24. papaya*.tw.
25. pineapple*.tw.
26. raspberr*.tw.
27. strawberr*.tw.
28. tomato*.tw.
29. potato*.tw.
30. onion*.tw.
31. grapefruit*.tw.
32. mandarin*.tw.
33. satsuma*.tw.
34. tangerine*.tw.
35. (plum or plums).tw.
36. apricot*.tw.
37. (cherry or cherries).tw.
38. nectarine*.tw.
39. (peach or peaches).tw.
40. celery.tw.
41. spinach*.tw.
42. (salad or salads).tw.
43. (pea or peas).tw.
44. (bean or beans).tw.
45. broccoli.tw.
46. cauliflower*.tw.
47. beetroot*.tw.
48. turnip*.tw.
49. rhubarb.tw.
50. legume*.tw.
51. cucumber*.tw.
52. leek*.tw.
53. aubergine*.tw.
54. pepper*.tw.
55. okra.tw.
56. pumpkin*.tw.
57. squash*.tw.
58. artichoke*.tw.
59. lettuce*.tw.
60. kale.tw.
61. chard.tw.
62. parsnip*.tw.
63. asparagus.tw.
64. fennel.tw.
65. chickpea*.tw.
66. five-a-day.tw.
67. 5-a-day.tw.
68. or/1-67
69. exp cardiovascular disease/
70. cardio*.tw.
71. cardia*.tw.
72. heart*.tw.
73. coronary*.tw.
74. angina*.tw.
75. ventric*.tw.
76. myocard*.tw.
77. pericard*.tw.
78. isch?em*.tw.
79. emboli*.tw.
80. arrhythmi*.tw.
81. thrombo*.tw.
82. atrial fibrillat*.tw.
83. tachycardi*.tw.
84. endocardi*.tw.
85. (sick adj sinus).tw.
86. exp cerebrovascular disease/
87. (stroke or stokes).tw.
88. cerebrovasc*.tw.
89. cerebral vascular.tw.
90. apoplexy.tw.
91. (brain adj2 accident*).tw.
92. ((brain* or cerebral or lacunar) adj2 infarct*).tw.
93. exp hypertension/
94. hypertensi*.tw.
95. peripheral arter* disease*.tw.
96. ((high or increased or elevated) adj2 blood pressure).tw.
97. exp hyperlipidemia/
98. hyperlipid*.tw.
99. hyperlip?emia*.tw.
100. hypercholesterol*.tw.
101. hypercholester?emia*.tw.
102. hyperlipoprotein?emia*.tw.
103. hypertriglycerid?emia*.tw.
104. exp Arteriosclerosis/
105. exp Cholesterol/
106. cholesterol.tw.
107. "coronary risk factor* ".tw.
108. Blood Pressure/
109. blood pressure.tw.
110. or/69-109
111. random$.tw.
112. factorial$.tw.
113. crossover$.tw.
114. cross over$.tw.
115. cross-over$.tw.
116. placebo$.tw.
117. (doubl$ adj blind$).tw.
118. (singl$ adj blind$).tw.
119. assign$.tw.
120. allocat$.tw.
121. volunteer$.tw.
122. crossover procedure/
123. double blind procedure/
124. randomized controlled trial/
125. single blind procedure/
126. 111 or 112 or 113 or 114 or 115 or 116 or 117 or 118 or 119 or 120 or 121 or 122 or 123 or 124 or 125
127. (animal/ or nonhuman/) not human/
128. 126 not 127
129. 68 and 110 and 128

Web of Science

#22 #21 AND #20
#21 TS=(random* or blind* or allocat* or assign* or trial* or placebo* or crossover* or cross-over*)
#20 #19 AND #7
#19 #18 OR #17 OR #16 OR #15 OR #14 OR #13 OR #12 OR #11 OR #10 OR #9 OR #8
#18 TS=blood pressure
#17 TS="coronary risk factor*"
#16 TS=cholesterol
#15 TS=arteriosclerosis
#14 TS=(hyperlipid* OR hyperlip?emia* OR hypercholesterol* OR hypercholester?emia* OR hyperlipoprotein?emia* OR hypertriglycerid?emia*)
#13 TS=("high blood pressure")
#12 TS=(hypertensi* OR "peripheral arter* disease*")
#11 TS=(stroke OR stokes OR cerebrovasc* OR cerebral OR apoplexy OR (brain SAME accident*) OR (brain SAME infarct*))
#10 TS=("atrial fibrillat*" OR tachycardi* OR endocardi*)
#9 TS=(pericard* OR isch?em* OR emboli* OR arrhythmi* OR thrombo*)
#8 TS=(cardio* OR cardia* OR heart* OR coronary* OR angina* OR ventric* OR myocard*)
#7 #6 OR #5 OR #4 OR #3 OR #2 OR #1
#6 TS=(kale or chard or parsnip* or asparagus or fennel or chickpea* or five-a-day or "five a day" or 5-a-day or "5 a day")
#5 TS=(beetroot* or turnip* or rhubarb or legume* or cucumber* or leek* or aubergine* or pepper* or okra or pumpkin* or squash* or artichoke* or lettuce*)
#4 TS=(cherry or cherries or nectarine* or peach or peaches or celery or spinach* or salad or salads or pea or peas or bean or beans or broccoli or cauliflower*)
#3 TS=(pineapple* or raspberr* or strawberr* or tomato* or potato* or onion* or grapefruit* or mandarin* or satsuma* or tangerine* or plum or plums or apricot*)
#2 TS=(carrot* or greens or cabbage* or brassica* or blackberr* or blueberr* or cranberr* or guava* or kiwi* or lingonberr* or mango* or melon* or pap aya*)
#1 TS=(fruit* or vegetable* or orange* or apple* or pear or pears or grape or grapes or banana* or berry or berries or citrus)

Contributions of authors

All review authors contributed to the protocol development. The Trials Search Co-ordinators of the CHG ran the searches, LH and EI screened titles and abstracts and assessed studies for formal inclusion or exclusion. LH and JH abstracted data and assessed methodological quality. LH and KR conducted the analysis, and wrote the first draft of the review. All authors contributed to later drafts.

Declarations of interest

None known.

Sources of support

Internal sources

  • Warwick Medical School, University of Warwick, UK.

  • Norwich Medical School, University of East Anglia, UK.

External sources

  • NIHR Cochrane Programme Grant, UK.

Differences between protocol and review

It was our intention to perform stratified analyses to examine the effects of intensity and duration of interventions, and different components of the intervention, but there were insufficient trials included in the review to do this. Similarly, we intended to perform sensitivity analyses to examine the effects of low methodological quality and perform funnel plots to assess publication bias. We also intended to focus on studies with follow-up of six months or more but again studies with this length of follow-up were lacking and so studies with follow-up of three months or more were included. These will be addressed in future updates of this review when more evidence accrues.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Dichi 2011

MethodsRCT (Parallel group design) involving provision of fruit and vegetables to increase consumption.
Participants

Sixty women with metabolic syndrome who were 47.9 (SD = 9.98) years old were recruited and randomised in to four arms - control group who maintained their usual diet; 25 g/d of soy; 3 g/d of fish oil n-3 fatty acids; or 3 g/d of fish oil n-3 fatty acids plus 25 g/d soy. Fifteen participants were randomised to receive 25 g/d of soy and 15 participants were randomised to the control group.

Country of publication was Brazil.

Interventions

Soy group: received 25 g of soy a day.

Control group: followed their usual diet.

The follow-up period was at the end of the intervention period of 90 days.

OutcomesBlood pressure and lipid levels
NotesAuthors contacted for extra information on the diets used in the study and also for data on lipid levels and blood pressure for each point at which these were measured. Authors responded with all data requested.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot stated
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot stated
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot stated
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to judge
Selective reporting (reporting bias)Unclear riskInsufficient information to judge
Other biasUnclear riskInsufficient information to judge

Djuric 2006

MethodsRCT on advice to increase fruit and vegetable consumption
Participants

Post-menopausal women who were 21-50 years old were recruited by community advertisements. One hundred and twenty-two women were randomly assigned in a 2x2 factorial design to four arms - the control group; low-fat diet; high fruit and vegetable diet; a combination of low-fat and high fruit and vegetables diet.

Inclusion criteria: at least one first degree relative with breast cancer, current benign mammogram or breast exam with follow-up recommendation of 1 year or more, no expected changes in the use of oral contraception, good general health, no expected changes in lifestyle during the study, fat intake of 25% of total energy or greater, fruit and vegetable intake of five or fewer servings per day.

Exclusion criteria: those taking supplements containing more than 150% of RDA's for vitamins and minerals.

Twenty-seven participants were randomised to receive the fruit and vegetables diet and twenty participants were randomised to receive the control diet. The country of publication was the U.S.A.

Interventions

Fruit and vegetable group: received individualised in-person counselling every 2 weeks initially by a trained dietician, then monthly, and monthly group meetings for the intervention period of 12 months. The goal for the high F&V arm was to increase F&V to 9 servings/day in a specified variety to increase carotenoid intake - 1 serving of a dark green vegetable high in lutenin, 1 serving of a dark orange vegetable high in a-carotene, 1 serving of a red product high in lycopene, 2 servings of other vegetables, 2 servings of vitamin C rich fruits, 2 servings of other fruits (1 serving defined as approximately 60 kcal for fruit and 25 kcal for most vegetables). Monthly meetings provided additional education on a variety of topics consistent with their dietary assignment.

Control group: no dietary counselling and were told they should continue their usual diet. They received a one page daily food guide pyramid as a guide for healthy eating but this was not discussed. Follow-up was at 12 months. 

OutcomesLipid levels
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomisation method not stated
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
High riskNot stated but impossible to blind participants and personnel to advice
Blinding of outcome assessment (detection bias)
All outcomes
Low riskLaboratory personnel were blinded to diet arm assignment
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskIntention-to-treat analysis conducted but no reasons for loss to follow-up reported
Selective reporting (reporting bias)Unclear riskInsufficient information to judge
Other biasUnclear riskInsufficient information to judge

Finley 2007

MethodsRCT involving the provision of fruit and vegetable to increase consumption
Participants

Men and women aged 18-55 years who were either pre-metabolic (defined as a waist circumference of ≥ 96.5 cm for men and ≥ 88.9 cm for women and at least one of the following: serum HDL-C < 55 mg/dL; serum TG between 150 and 199 mg/dL; fasting blood glucose between 100 and 125 mg/dL; or BP between 120/85 and 140/85 mmHg.) or healthy were recruited locally by newspaper, radio, TV or Internet advertisements. Eighty participants were randomly assigned to two arms - the provision of beans or chicken soup.

Inclusion criteria were: waist circumference for women of 88.9 cm or above and for men of 96.5 cm or above. Pre-MetSyn patients also had to have at least 1 of the following - serum HDL-C < 55mg/dL, serum TG between 150-199 mg/dL, fasting blood glucose between 100 and 125 mg/dL or BP between 120/85 and 140/85 mm Hg. Healthy participants had values in the normal parameters.

Exclusion criteria - those with a possible need for medical attention and those who had taken antibiotics within 6 months of the start of the study.

Forty participants were randomised to receive beans and forty were randomised to receive chicken noodle soup. Participants lived at home and consumed their own self-selected diets with restrictions that included no beans of any type except those provided by the study, no dietary supplements, no pre- or probiotic foods or supplements, and no prescription or over-the-counter medication to reduce intestinal gases.

Country of publication was the U.S.A.

Interventions

Participants were asked to add one of four different bean or soup entrees per day to their normal diet. The entrees included with either beans or soup prepared by the Grand Forks Human Nutrition Research Centre.

Bean entree group: standard serving of cooked pinto beans (130 g or 1/2 cup) canned by Bush Brothers

Soup group: chicken soup entree that was isonitrogenous and isocaloric as near as possible to the bean entree.

The follow-up period was at the end of the intervention period of 12 weeks. This does not include the 4-week equilibration period.

OutcomesLipid levels
NotesAuthor contacted for extra information on numbers for lipid levels but the contact author had died and the leading author did not reply. The leading author was contacted twice via email.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot enough information provided and randomisation method not stated
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot stated
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot stated
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo intention-to-treat analysis and little information on attrition rates. No reasons given as to why participants dropped out or which group they were in.
Selective reporting (reporting bias)High riskThe numbers for lipid levels were not reported. Information on lipid levels were provided in a graph but without precise numbers and only a P value.
Other biasUnclear riskInsufficient information to judge

Fujioka 2006

MethodsRCT of the provision of fruit and vegetables to increase consumption
Participants

Obese male and female patients with a BMI between 30 and 40 kg/m² recruited from a single centre through advertisements and flyers in rooms of primary care physicians. Ninety-one participants were randomised to four arms - placebo capsules plus 7 ounces of apple juice; grapefruit capsules with 7 ounces of apple juice; 8 ounces of grapefruit juice with placebo capsules; and half a fresh grapefruit with placebo capsules.

Inclusion criteria: BMI between 30 and 40 kg/m2, stable weight in a 3 kg range in 3 months prior to study enrolment, willing to eat grapefruit and avoid other citrus products.

Exclusion criteria: Type 1 or 2 diabetes, those who have had gastrointestinal surgery for obesity, moderate to severe gastrointestinal disorder, known liver disease, chronic renal disease or cardiovascular disease. Also, those using cholesterol medications, planning on changing smoking habits, or using medications known to interact with grapefruit.

Twenty-four participants were randomised to receive fresh grapefruit plus placebo capsules (18 women, 6 men; 16 Caucasian, 5 Black, 0 Asian, 2 Hispanic, 1 other; Mean BMI = 36.8 (5.55)) and twenty-two participants were randomised to receive the placebo capsules plus apple juice (20 women, 2 men;16 Caucasian, 4 Black, 0 Asian, 2 Hispanic, 0 other; Mean BMI = 34.5 (3.05)).

Country of publication was the U.S.A.

InterventionsFresh grapefruit group: half a fresh grapefruit and a placebo capsule consumed 3 times a day before each meal. The fresh grapefruit was prepared by cutting it in half and then into four smaller pieces. The skin was pulled off and discarded and the rest of the grapefruit was eaten. Placebo group: placebo capsules plus 7 ounces (207 mL) of apple juice. The apple juice was reconstituted from frozen concentrate. The juice was supplied in individual servings and participants were provided with a 2-4 week supply at a time. All participants were encouraged to walk 20-30 minutes 3 or 4 times a week and consume their usual diet. The follow-up period was 12 weeks.
OutcomesBP, lipid levels, adverse effects
NotesAuthor contacted for extra data (standard deviations for BP and lipid levels at baseline and follow-up). The author did respond but was unable to provide the data requested.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskRandom number table
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
Low riskStates double-blind and uses a placebo
Blinding of outcome assessment (detection bias)
All outcomes
Low riskStates double blind
Incomplete outcome data (attrition bias)
All outcomes
Low riskMissing outcome data reasonable well balanced across groups
Selective reporting (reporting bias)Low riskPrimary and secondary outcomes clearly stated and reported.
Other biasUnclear riskInsufficient information to judge

Gardner 2007

MethodsRCT (parallel group design) involving the provision of fruit and vegetables for increased consumption
Participants

Adults aged 30-65 years recruited from the local community through advertisements with low-density lipoprotein cholesterol (LDL-C) concentrations of 130-190 mg/dL, triglyceride levels less than 250 mg/dL and a BMI of 19-30. One hundred and ninety-two participants were randomised to four arms: raw garlic; powdered garlic supplement; aged garlic extract supplement; and placebo.

Exclusion criteria: Self-reported pregnancy, lactation, current smoking, prevalent heart disease, cancer, renal disorder, diabetes mellitus, use of lipid or antihypertensive medication.

Forty-nine participants were randomised to receive raw garlic (27 women and 22 men; age 40 ± 9; non-Hispanic white 36, non-Hispanic black 2, non-Hispanic Asian 9, Hispanic 1, other or not disclosed 1; BMI 25 ± 3) and forty-eight participants were randomised to receive the placebo (24 women and 24 men; age 49 ± 9; non-Hispanic white 31, non-Hispanic black 0, non-Hispanic Asian 7, Hispanic 8, other or not disclosed 8; BMI 25 ± 3). The country of publication was the U.S.A.

Interventions

All groups consumed their intervention for 6 days a week for 6 months.

Raw garlic group: 4.0 g of blended raw garlic ( an averaged-sized clove crushed in a blender). Individually packaged aliquots of raw garlic were frozen at -80ºC. After distribution these were thawed and mixed with condiments to be served in sandwiches. All sandwiches were prepared and distributed by the General Clinical Research Centre. Participants were instructed to heat bread or filling as desired but not to heat condiment as it contained the raw garlic. Twelve types of sandwiches were prepared that were designed to contain approximately 375 kcal (mean and SD 373 ± 21 kcal) with no more than 10% energy from saturated fat. Identical sandwiches were also served to those not in the raw garlic group but these did not have garlic mixed into the condiments.

Placebo group: 4-6 placebo tablets 6 days a week. The follow-up period was at the end of the intervention period of 6 months.

OutcomesAdverse effects and lipid levels
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskResearch assistant drawing assignments in blocks of 24 without replacement until all 24 allocations were assigned
Allocation concealment (selection bias)Low riskOpaque envelopes
Blinding of participants and personnel (performance bias)
All outcomes
Low riskInvestigators and participants were blinded
Blinding of outcome assessment (detection bias)
All outcomes
Low riskStates that laboratory staff conducting analyses were blinded
Incomplete outcome data (attrition bias)
All outcomes
Low riskUsed intention-to-treat analysis and missing data were reasonably well balanced between groups
Selective reporting (reporting bias)Low riskPrimary and secondary outcomes clearly stated and reported.
Other biasUnclear riskInsufficient information to judge

Gravel 2009

MethodsRCT of the provision of fruit and vegetables to increase consumption
ParticipantsOne hundred and thirty-four women with abnormal metabolic profile were recruited and randomised to two arms - 750 mL of legumes per week or a control group who ate meals without legumes. Country of publication was Canada.
Interventions

Intervention group: 750 mL of legumes per week

Control group: Control meals without legumes

Follow-up period was at 24 weeks

OutcomesBP and lipid levels
NotesThe author was contacted for extra information on the diet each group followed and for data on lipid levels and blood pressure at each point measured. This was done twice via email. The author did not respond.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot stated
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot stated
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNot stated
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskInsufficient information to judge
Selective reporting (reporting bias)Unclear riskInsufficient information to judge
Other biasUnclear riskInsufficient information to judge

John 2002

MethodsRCT on advice to increase fruit and vegetable consumption.
Participants

Men and women aged 25-64 without serious chronic illnesses were recruited through the lists of two general practices based in a healthcare centre. Seven hundred and twenty-nine participants were recruited and randomised to two arms - advice to eat more fruit and vegetables (5 or more portions a day) or to the control group who where asked to continue as usual.

Exclusion criteria: cardiovascular diseases, gastrointestinal diseases, cancer, serious psychiatric disorders, hypercholesterolaemia, patients who had undergone a recent traumatic event, those unable to give informed consent, those using dietary supplements, pregnant, those attempting to conceive.

Three hundred and sixty-four participants were randomised to receive fruit and vegetable advice (161 women and 183 men; age 45.7 ± 10.1; current smoker 16%; male BMI 26.1 ± 3.2, female BMI 25.4 ± 4.6) and three hundred and sixty-five participants were randomised to continue as usual (191 women and 155 men; age 46.0 ± 10.1; current smoker 17%; male BMI 26.7 ± 3.6, female BMI 25.3 ± 4.6). The country of publication was the UK.

Interventions

Health checks done at both visits by study research nurse for both groups of participants.

Fruit and vegetable advice group: Brief negotiation method in which research nurse introduced the benefits of eating more fruit and vegetables and presented a pictorial portion guide (portion was defined as 80 g serving). Method was used to encourage participants to identify specific and practical ways to eat more fruit and vegetables with the recommendation being the consumption of 5 or more portions a day. Participants were also provided with leaflets and other materials that addressed barriers in eating more fruit and vegetables and were asked to discuss any potential barriers. For those who thought that five portions a day was an unrealistic goal a lower target was set while those who already ate five or more portions of fruit and vegetables a day were given a leaflet on the importance of eating a variety of these. Each participant was also given an action plan, a magnet with the 5-a-day logo, a portion guide and a 2-week self-monitoring record book. The intervention took about 25 minutes. Two weeks after the intervention the research nurse telephoned participants to reinforce the message and discuss any problems. At three months a letter was sent to participants to reinforce the 5-a-day message along with a booklet of seasonal recipes and a strategy check list that suggested ways of incorporating extra portions into their diet.

Control group: received the same health check but the nurse explained that they would receive specific advice at their 6-month follow-up appointment. They were asked to carry on as usual. The follow-up period was 6 months.

OutcomesBP
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputer-generated randomisation list
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
High riskNot stated but impossible to blind participants and personnel to advice
Blinding of outcome assessment (detection bias)
All outcomes
Low riskLaboratories were masked to patient assignment
Incomplete outcome data (attrition bias)
All outcomes
Low riskUsed Intention-to-treat analysis. At baseline there were more men in the intervention group than controls. Reasons for losses to follow-up reported
Selective reporting (reporting bias)Unclear riskInsufficient information to judge
Other biasUnclear riskInsufficient information to judge

Maskarinec 1999

MethodsRCT of advice to increase fruit and vegetable consumption
Participants

Healthy women at least 35 years old were recruited from an ongoing observational study. Thirty-three women were randomised to 2 arms - an individualised dietary counselling program or to nutritional counselling based on published guidelines.

Inclusion criteria: Not taking a high dose vitamin supplement, be free from chronic conditions and have at least 50% mammographic densities, eating less than 5 daily servings of fruit and vegetables and be at least 35 years old.

Sixteen participants were randomised to receive individual counselling (47.6 years; 11 Asian, 3 Chinese, 8 Japanese, 1 Caucasian, 1 Afro-American) and seventeen participants were randomised to nutritional counselling (50.2 years: 11 Asian, 5 Chinese, 4 Caucasian, 3 Filipino, 3 Japanese, 1 Vietnamese). The country of publication was the U.S.A.

Interventions

Participants in both groups were instructed to consume the same number of calories as before and to avoid weight gain.

Individual Counselling Group: individualised dietary counselling program developed to incorporate at least 9 servings of fruits and vegetables daily. The emphasis was on achieving the goal of 9 servings with the following recommendations on the type of fruits and vegetables: 3 servings of vitamin C fruits, 1 other fruit, 1 tomato product, 1 dark green vegetable, 1 yellow-orange vegetable, and 2 other vegetables. The definition of a serving was the same as used by the United States Department of Agriculture: 1 cup of raw or 1/2 cup of cooked vegetables or 3/4 cup of juice, 1 medium-sized fruit or 1/2 cup of fresh, cooked, or canned fruit or 3/4 cup of juice. A dietitian provided advice on purchasing produce, recipes, and easy-to-prepare dishes. Participants were also invited to attend group meetings with cooking instructions and demonstrations every month.

Nutritional Counselling: nutritional counselling based on published guidelines on how to maintain a healthy diet

The follow-up period was 6 months from the start of the intervention period.

OutcomesLipid levels
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNo information. Only states that trial was randomised
Allocation concealment (selection bias)Unclear riskNo information provided
Blinding of participants and personnel (performance bias)
All outcomes
High risk

Participants: Not stated but impossible to blind participants and personnel to advice

Physicians: Not stated

Blinding of outcome assessment (detection bias)
All outcomes
Low riskLab technicians were blinded to outcome assessment
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNo reasons for missing data provided
Selective reporting (reporting bias)High riskAlthough lipid levels have been reported their analysis was not mentioned in the section of the paper reporting statistical analyses
Other biasUnclear riskInsufficient information to judge

Smith-Warner 2000

MethodsRCT on advice to increase fruit and vegetable consumption
Participants

Digestive healthcare patients aged 30-74 years recruited from a large community based gastroenterology practice. Two hundred and one participants were randomised to two arms - Those asked to increase fruit and vegetable intake to at least eight servings per day or to continue their usual diet.

Inclusion criteria: a diagnosis of colorectal adenomatous polyps in the preceding five years.

Exclusion criteria: body weight > 150% of desirable weight-for-height, medical conditions including gastrointestinal disorders, diabetes mellitus, cardiovascular disease, cancer or any serious health condition that would limit participation, those following diabetic, vegetarian and renal-disease diets, those with food sensitivities, those with plans to relocate or travel extensively, involvement in any other study requiring dietary change, pregnant women, consumption of >35 alcoholic beverages a week, urinary protein levels of ≥ 30 mg/dL, urinary glucose levels of ≥ 0.25 g/dL and refusal to participate or sign consent.

One hundred participants were randomised to receive advice to increase fruit and vegetable intake (age 58.6; 71% men, 99% white; 17% smokers; Men BMI 28.3, Women BMI 25.8) and one hundred and one participants randomised to continue their usual diet (age 60.0; 71.3% men, 99% white; 17.8% smokers; Men BMI 28.4, Women BMI 26.2). The country of publication was the U.S.A.

Interventions

Advice group: Advice to increase fruit and vegetable consumption to at least 8 servings per day before 3-month clinic visit. After randomisation participants met with a nutritionist to formulate a plan for gradually increasing fruit and vegetables. Initial goal was to increase fruit and vegetable consumption to at least 2 servings per day. Participants were also taught behaviour modification strategies to identify personal barriers to adherence and to develop plans to overcome these. Education materials such as tip sheets and cookbooks were also provided along with quarterly newsletters, and a list of high b-carotene fruit and vegetables. Visit reminder cards, telephone follow-up for rescheduling missed visits, refrigerator magnets, newsletters, “carrot” birthday cards, and fruit and vegetable calendars were used as memory prompts and to enhance participant identification with the project. Positive reinforcement and feedback was also used by the study team and the intervention attempted to enhance spousal and family support. After the initial visit to the nutritionist, participants visited the nutritionist for individual dietary advice an additional four times.

Control group: asked to follow usual diet

The follow - up period was 1 year

OutcomesBP, lipid levels and adverse effects
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskMethod of randomisation was not given
Allocation concealment (selection bias)Unclear riskInformation on the method of allocation concealment was not provided
Blinding of participants and personnel (performance bias)
All outcomes
High riskNo information on blinding was provided but impossible to blind participants and personnel to advice
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information on blinding was provided
Incomplete outcome data (attrition bias)
All outcomes
Low riskIntention-to-treat analysis was used
Selective reporting (reporting bias)Unclear riskInsufficient information to judge
Other biasUnclear riskInsufficient information to judge

Thies 2012

  1. a

    BP: blood pressure
    CVD: cardiovascular disease
    DBP: diastolic blood pressure
    FV: fruit and vegetables
    g/d: grams per day
    HDL-C: high-density lipoprotein cholesterol
    RCT: randomised controlled trial
    SBP: systolic blood pressure
    SD: standard deviation
    TG: triglycerides

MethodsRCT of the provision of fruit and vegetables to increase consumption
Participants

Healthy men and women aged 40-65 years were recruited from the surrounding community of Aberdeen. Two hundred and forty-seven participants were recruited and randomised to three arms - High tomato diet, Lycopene or the control group (low tomato diet).

Exclusion criteria: diagnosed CVD, diabetes, fasting blood glucose of > 7.0 mmol/L, asthma, SBP > 160 mmHg and DBP > 99 mmHg, or a thyroid condition.

Eighty-four participants were randomised to receive the high tomato diet (age 51.0 ± 0.7) and eighty-one participants were randomised to the control ( age 51.1 ± 0.7). The country of publication was the UK.

Interventions

Provision group: provided with tomato-based products (tomato sauces, juice, ketchup, soup, puree and canned tomatoes) for 12 weeks. Aside from these products participants selected their own foods to eat.

Control group: Intake of tomato-based products was restricted. Participants could not consume passata, canned tomatoes, cooked tomatoes, tomato paste, puree, pizza, salsa, chutney, canned beans, spaghetti, ravioli in tomato sauce, barbecue sauce, brown sauce, pink grapefruit, guava, watermelon and apricots. They could consume up to one portion of tomato soup, juice or sauce per week and either ≤ 4 raw tomatoes or 24 cherry tomatoes a week or ≤ one portion of tomato ketchup a week.

The follow-up period was 12 weeks.

OutcomesBP and lipids
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskMethod of randomisation was not given
Allocation concealment (selection bias)Unclear riskInformation on the method of allocation concealment was not provided
Blinding of participants and personnel (performance bias)
All outcomes
High riskSingle-blind
Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskNo information was provided
Incomplete outcome data (attrition bias)
All outcomes
Low riskNumber of drop-outs given by group and reasonably well balanced across groups.
Selective reporting (reporting bias)Low riskPrimary and secondary outcomes were clearly stated and reported
Other biasUnclear riskInsufficient information to judge

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Ali 1995Not a randomised controlled trial
Appel 2000No relevant outcomes reported
Beresford 2001No relevant outcomes reported
Blum 2007No relevant outcomes reported
Broekmans 2000No relevant outcomes reported
DASH 1995Short term
Fielding 2005Not minimal control
Fuemmeler 2006No relevant outcomes reported
Havas 2003No relevant outcomes reported
Lehtonen 2010Authors were contacted several times for information on the lifestyle intervention used in the study but there was no response. Due to this we have had to assume that the lifestyle intervention for the control group was not minimal and therefore excluded the study.
Lutz 1999No relevant outcomes reported
Nomikos 2007No relevant outcomes reported
Porrini 2011Ongoing trial. Period of follow-up less than 3 months
Rock 2001No relevant outcomes reported
Singh 1992

BMJ claims fraudulent data.

http://www.bmj.com/content/suppl/2005/07/28/331.7511.281.DC1

Sorensen 1999No relevant outcomes reported
Staten 2004Multifactorial intervention
Steptoe 2004Not minimal control
Svetkey 2003Multifactorial intervention and includes weight loss
Takai 2003Not minimal control
Thomson 2011Ongoing trial. Period of follow-up less than 3 months
Verlangieri 1985Not a randomised controlled trial
WHIMultifactorial intervention
Winham 2007Not minimal control

Characteristics of studies awaiting assessment [ordered by study ID]

George 2009

MethodsTwo randomised, controlled, cross-over, dietary intervention studies
Participants

In the first study there were 39 volunteers and in the second study there were 24 volunteers

Blood and urine samples were collected throughout both studies and real-time measurements of vascular tone were performed using laser Doppler imaging with iontophoresis.

InterventionsIn the first study the volunteers consumed 200 ml fruit and vegetable puree and juice based drinks (FVPJ), or fruit-flavoured control, daily for six weeks. In the second study the volunteers consumed 400 mL FVPJ, or sugar-matched control, on the morning of the study day.
OutcomesMeasures of vascular tone, vasodilation
NotesWaiting for the library to find and send full text.

Groen 1952

MethodsUnknown
ParticipantsThirty men and 30 women were chosen from 100 volunteers on the basis of normal clinical and laboratory findings and estimated idealism and intelligence. Twenty-two men and 22 women were between 20 and 30 years of age, 6 men and 7 women were between 30 and 40 years of age, while 2 men and 1 woman were between 40 and 48 years of age.
InterventionsThree different diets were administered to the participants in 3 successive 12-week periods, under expert supervision in a communal dining room. Diet V was almost exclusively vegetable, except for skimmed milk and buttermilk ad lib., and 100 g. whole milk per day. Diet L consisted of 50 g. of meat, 30 g. of cheese, 0.5 litres of milk per day, 2 eggs per week, and vegetables ad lib. Diet H contained 250 g. of meat, 50 g. of cheese and 2 eggs per day besides unlimited milk, cream and butter.
OutcomesSerum cholesterol
NotesNeed Information on type of study as unsure if participants were randomised to groups. Waiting for the library to find and send full text.

Teeple (2011)

MethodsRandomised controlled Trial (states participants were randomly assigned to one of four treatment groups)
ParticipantsPostmenopausual women who smoked
Interventions45 g/day of blackberries, 45 g/day of blueberries, smokers, non-smokers
OutcomesLipids
NotesThis thesis has been ordered but is awaiting classification as lipid data are needed, as is clarification of the number of participants randomised and randomisation processes.

Wallace 2012

  1. a

    BMI: body mass index
    BP: blood pressure
    hsCRP: high-sensitivity C-reactive protein

MethodsRandomised controlled trial
Participants105 overweight, non-diabetic individuals with no history of cardiovascular disease - mean age 56 years (range 40 -77 years), 62% men, body mass index 30.8 kg/m2 (range 26.9 - 37.3 kg/m2), fasting plasma glucose 97 mg/dL (range 79 - 121 mg/dL).
InterventionsAfter a 4-week wash-out diet of 1-2 portions FV per day, participants were randomised to consume 1-2, 4 or 7 or more portions FV daily for 12 weeks.
OutcomesMeasures of whole-body, peripheral or hepatic insulin resistance (see table), adiponectin, hsCRP, BP or lipid concentrations.
NotesData on BP and lipids needed. Emailed author.

Characteristics of ongoing studies [ordered by study ID]

Wang 2011

  1. a

    BMI: body mass index
    LDL-C: low-density lipoprotein cholesterol
    MUFA: monounsaturated fatty acid
    NHANES: National Health and Nutrition Examination Survey
    PUFA: polyunsaturated fatty acid

Trial name or titleThe effect of one avocado per day on established and emerging cardiovascular disease (CVD) risk factors
MethodsOpen label randomised cross-over trial
Participants

Inclusion Criteria:

1.healthy non-smoking

2.overweight (BMI 25-35 kg/m2) men and women

3.LDL-C between the25-90th percentile from NHANES: 105-194 mg/dL for males; 98-190 mg/dL for females)

4) 21-70 years

Interventions

1) Lower fat diet

Provide ˜24% of calories from fat and meet the Saturated Fatty Acid (SFA) and cholesterol recommendations of a Step-II diet recommended by the National Heart, Lung, and Blood Association's National Cholesterol Education Program. SFA will provide 7% of calories, and cholesterol will be less than 200 mg/day. Vegetables and fruits in the Lower fat diet will be selected from foods that are low in antioxidants.

2) Moderate fat diet

This diet is designed to be the control diet for the avocado diet and will have an identical fatty acid profile. MUFA-enriched food (fats) will be substituted for avocado. The substitution foods will not contain antioxidant or cholesterol-lowering components similar to those in avocado.

3) Avocado diet

Designed to ensure that all participants incorporate 1 avocado (˜136g) per day into a moderate fat diet. Both the lower fat diet and avocado diet will be matched for SFA and dietary cholesterol, but will differ in total fat, primarily MUFA as provided by the avocado. The moderate fat plus avocado diet will provide 34% of calories from total fat, 18% calories from MUFA, and 9% calories from PUFA.

Outcomes

Primary outcomes:

1) Lipoprotein profile (Week 7)

2) Lipoprotein profile (Week 14)

3) Lipoprotein profile (Week 21)

Secondary outcomes:

1) Paraoxonase 1(PON1) activity

2) Oxidized-LDL

3) Lipid hydroperoxide

4) Macrophage cholesterol efflux

Starting dateNovember 2010
Contact information Li Wang - 814-863-8109 psudiet@gmail.com
Notes 

Ancillary