Intervention Review

You have free access to this content

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

  1. Louise Hartley1,
  2. Ewemade Igbinedion1,
  3. Jennifer Holmes2,
  4. Nadine Flowers1,
  5. Margaret Thorogood3,
  6. Aileen Clarke1,
  7. Saverio Stranges1,
  8. Lee Hooper4,
  9. Karen Rees1,*

Editorial Group: Cochrane Heart Group

Published Online: 4 JUN 2013

Assessed as up-to-date: 27 SEP 2012

DOI: 10.1002/14651858.CD009874.pub2


How to Cite

Hartley L, Igbinedion E, Holmes J, Flowers N, Thorogood M, Clarke A, Stranges S, Hooper L, Rees K. Increased consumption of fruit and vegetables for the primary prevention of cardiovascular diseases. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD009874. DOI: 10.1002/14651858.CD009874.pub2.

Author Information

  1. 1

    Warwick Medical School, University of Warwick, Division of Health Sciences, Coventry, Warwickshire, UK

  2. 2

    University of Warwick, Warwick Medical School, Coventry, UK

  3. 3

    Division of Health Sciences, Public Health and Epidemiology, Coventry, UK

  4. 4

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

*Karen Rees, Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, Warwickshire, CV4 7AL, UK. Karen.Rees@warwick.ac.uk. rees_karen@yahoo.co.uk.

Publication History

  1. Publication Status: New
  2. Published Online: 4 JUN 2013

SEARCH

 
Characteristics of included studies [ordered by study ID]
Dichi 2011

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


ParticipantsSixty 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.


InterventionsSoy 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


ParticipantsPost-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.


InterventionsFruit 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


ParticipantsMen 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.


InterventionsParticipants 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


ParticipantsObese 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


ParticipantsAdults 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.


InterventionsAll 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.


InterventionsIntervention 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.


ParticipantsMen 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.


InterventionsHealth 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


ParticipantsHealthy 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.


InterventionsParticipants 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 riskParticipants: 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


ParticipantsDigestive 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.


InterventionsAdvice 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

MethodsRCT of the provision of fruit and vegetables to increase consumption


ParticipantsHealthy 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.


InterventionsProvision 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 1992BMJ 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

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

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

ParticipantsInclusion 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

Interventions1) 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.

OutcomesPrimary 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

 
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]

 
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)3Mean Difference (IV, Fixed, 95% CI)Totals not selected

 5 HDL cholesterol, change from baseline (mmol/l)3Mean 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]