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Chromium picolinate supplementation for overweight or obese adults

  1. Hongliang Tian1,
  2. Xiaohu Guo2,
  3. Xiyu Wang3,
  4. Zhiyun He2,
  5. Rao Sun3,
  6. Sai Ge4,
  7. Zongjiu Zhang3,*

Editorial Group: Cochrane Metabolic and Endocrine Disorders Group

Published Online: 29 NOV 2013

Assessed as up-to-date: 15 DEC 2012

DOI: 10.1002/14651858.CD010063.pub2


How to Cite

Tian H, Guo X, Wang X, He Z, Sun R, Ge S, Zhang Z. Chromium picolinate supplementation for overweight or obese adults. Cochrane Database of Systematic Reviews 2013, Issue 11. Art. No.: CD010063. DOI: 10.1002/14651858.CD010063.pub2.

Author Information

  1. 1

    Lanzhou University, Evidence-Based Medicine Center, School of Basic Medical Sciences;The First Clinical Medical School, Lanzhou City, Gansu, China

  2. 2

    Lanzhou University, The Second Clinical Medical School, Lanzhou City, China

  3. 3

    Lanzhou University, Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou City, China

  4. 4

    Beijing University, Beijing Cancer Hospital, Beijing City, China

*Zongjiu Zhang, Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou City, China. zongjiuzhang@yeah.net.

Publication History

  1. Publication Status: New
  2. Published Online: 29 NOV 2013

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Summary of findings    [Explanations]

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

 
Summary of findings for the main comparison.

Chromium picolinate supplementation for overweight or obese adults

Population: overweight or obese adults

Settings: community volunteers and outpatients

Intervention: chromium picolinate

Comparison: placebo

OutcomesRelative / absolute effect(s)
(95% CI)
No of participants
(studies)
Quality of the evidence
(GRADE)
Comments

Health-related quality of lifeSee commentSee commentSee commentNot investigated

Adverse events

Follow-up: 8 weeks to 6 months
2 serious adverse events and study dropouts after 1000 µg chromium picolinate (2/15 participants); 1 serious adverse event after 400 µg chromium picolinate (1/39 participants); 1 serious adverse event (1/18 participants) and 2 study dropouts on placebo (2/58 participants)189

(3)
⊕⊕⊝⊝
lowa
Only 3/9 studies provided information on adverse events

Death from any causeSee commentSee commentSee commentNot investigated

MorbiditySee commentSee commentSee commentNot investigated

Weight loss [kg]

Follow-up: 12 to 16 weeks
-1.1 (-1.7 to -0.4)392

(6)
⊕⊕⊝⊝
lowb
All chromium picolinate doses were pooled

Socioeconomic effectsSee commentSee commentSee commentNot investigated

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; RR: risk ratio

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 aDowngraded by two levels owing to high risk of performance and detection bias, and inadequate reporting in most of the included studies
bDowngraded by two levels owing to indirectness and conflicting evidence between different studies of various doses of chromium picolinate and duration of treatment

 

Background

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
 

Description of the condition

Obesity and overweight are common global health conditions. The prevalence of obesity and overweight has increased considerably in both developing and developed countries. The World Health Organization (WHO) have estimated that, globally in 2005, approximately 1.6 billion adults (aged 15 years or older) were overweight and that at least 400 million adults were obese (WHO 2006). The WHO projects that, by 2015, approximately 2.3 billion adults will be overweight and more than 700 million will be obese. Obesity is defined as the degree of fat storage associated with elevated health risks. However, because fat mass is difficult to measure, the pragmatic definition of obesity is based on body mass index (BMI). The WHO guidelines define a BMI of 18.5 to 24.9 kg/m2 as normal, 25 to 29.9 kg/m2 as grade 1 overweight and greater than 30 kg/m2 as grade 2 overweight (obesity) (WHO 1995).

Obesity is a concern because of its implications for the health of an individual, as it increases the risk of many diseases and health conditions, including coronary heart disease (Rimm 1995; Whitlock 2002), type 2 diabetes (Colditz 1995), hypertension, dyslipidaemia (Denke 1994), sleep apnoea and respiratory problems (Naimark 1960).

 

Description of the intervention

Chromium is an essential trace element required for the normal metabolism of carbohydrate, protein and fat. Chromium is a cofactor necessary for the activity of insulin, and dietary supplementation with chromium has produced modest improvements in glucose metabolism, insulin sensitivity and body composition in human trials (Drake 2012). Organic chromium is a compound of trivalent chromium and it assists in efficient chromium absorption. Chromium picolinate (CrP) is advocated in the medical literature for the reduction of body weight (Murray 1998; Pizzorno 1999) and preparations are sold as slimming aids in the USA and Europe, and on the Internet.

 

Adverse effects of the intervention

In a narrative review, most of the reported side effects of CrP supplementation were non-specific and the most frequent complaints were watery stools, weakness, dizziness, headaches, nausea and vomiting (Kleefstra 2006). Overall, chromium was well tolerated. There were no serious adverse events. Also, the number of individuals reporting adverse events in the supplemented groups was not significantly different from that in placebo groups (John 2007; Stephen 2008).

 

How the intervention might work

It is generally believed that chromium may exert its effects on weight loss by decreasing fat levels in the body and through insulin-sensitising effects. CrP has been suggested to impact on neurotransmitters involved in the regulation of eating behaviour, mood and food cravings (Docherty 2005). Chromium may suppress the appetite and stimulate thermogenesis through sensitisation of insulin-sensitive glucoreceptors in the brain (Wang 2007). Body fat distribution is related to insulin sensitivity; peripheral fat is more insulin-sensitive than central fat found in the chest and abdomen (Kahn 2006).

 

Why it is important to do this review

Chromium may improve impaired glucose tolerance, reduce elevated blood lipid concentrations, and result in weight loss and improved body composition in some individuals, but results have been equivocal (Volpe 2001). A meta-analysis of 10 double-blind, placebo-controlled trials provided evidence of a relatively small reduction in body weight in overweight and obese individuals receiving CrP (Pittler 2003). However, because of the limited number of trials and participants, the clinical relevance of this effect is debatable and a lack of robustness means that the results have to be interpreted with caution. Since the publication of this meta-analysis, the results of many studies including large numbers of individual shave become available. A systematic review of all available randomised controlled trials (RCTs) is needed, which could help clinicians, individuals and others decide whether chromium is a useful weight loss tool for overweight and obese individuals.

 

Objectives

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

To assess the effects of CrP supplementation in overweight or obese people.

 

Methods

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
 

Criteria for considering studies for this review

 

Types of studies

Randomised controlled trials (RCTs).

 

Types of participants

Adults (aged 18 years and older) defined as overweight or obese at baseline. We excluded studies including children, pregnant women or individuals with serious medical conditions.

 

Diagnostic criteria

Adults with a BMI between 25 and 29.9 kg/m2 were considered overweight; those with a BMI of 30 kg/m2 or higher were considered obese.

 

Types of interventions

We investigated the following comparisons of the intervention versus controls/comparators where the same letters indicate direct comparisons.

 

Intervention

  • (a) Chromium picolinate (CrP)
  • (b) CrP plus another treatment

 

Comparator

(a1) Placebo

(a2) Different CrP dosage

(b) Placebo plus another treatment

Concomitant treatments (e.g. diet or exercise) had to be identical between intervention and control groups.

 

Types of outcome measures

 

Primary outcomes

  • Weight loss (e.g. BMI, waist circumference, percentage body fat).
  • Adverse events (e.g. gastrointestinal, nervous system, metabolism).
  • Health-related quality of life (measured with a validated instrument).

 

Secondary outcomes

  • Death from any cause.
  • Morbidity (e.g. cardiovascular outcomes such as myocardial infarction or stroke).
  • Blood pressure.
  • Lipids (e.g. total cholesterol, HDL-C, LDL-C and triglycerides).
  • Fasting blood glucose.
  • Socioeconomic effects.

 

Timing of outcome measurement

  • Short-term: one to six weeks.
  • Medium-term: more than 6 weeks to 12 weeks.
  • Long-term: more than 12 weeks.

 

Search methods for identification of studies

 

Electronic searches

We searched the following sources from inception to the specified date to identify trials:

  • The Cochrane Library (Issue 10, 2012).
  • MEDLINE (to December 2012).
  • EMBASE (to December 2012).
  • ISI Web of Knowledge (to December 2012).
  • Chinese Biomedical Literature Database (CBM) (to December 2012).
  • China Journal full-text database (to December 2012).
  • Chinese Scientific Journals full-text database (to December 2012).

We also searched databases of ongoing trials (www.ClinicalTrials.gov/) and the Current Controlled Trials metaRegister (www.controlled-trials.com/).

For detailed search strategies please see Appendix 1 (searches were not older than six months at the moment the final review draft was checked into the Cochrane Information Management System for editorial approval). We used PubMed's 'My NCBI' (National Center for Biotechnology Information) email alert service for the identification of newly published studies using a basic search strategy (see Appendix 1).

If we detected additional key words of relevance during any of the electronic or other searches we planned to modify the electronic search strategies to incorporate these terms. We included studies published in any language.

 

Searching other resources

We tried to identify other potentially eligible trials or ancillary publications by searching the reference lists of retrieved included trials, (systematic) reviews, meta-analyses and health-technology assessment reports.

 

Data collection and analysis

 

Selection of studies

To identify the studies to be assessed further, two review authors (TH, GX) independently scanned the abstract or title, or both, of every record retrieved. We investigated the full text of all potentially relevant articles. Where there were differences in opinion between authors, these were resolved by a third author (ZZ). If resolution of disagreement was not possible, we intended to add the article to those 'awaiting assessment' and we contacted the trial authors for clarification. We present an adapted PRISMA (preferred reporting items for systematic reviews and meta-analyses) flow-chart showing the process of study selection (Figure 1) (Liberati 2009).

 FigureFigure 1. Study flow diagram.

 

Data extraction and management

For studies that fulfilled the inclusion criteria, two authors (TH, HZ) independently extracted relevant population and intervention characteristics using standard data extraction templates (for details see  Table 1 and Appendix 2; Appendix 3; Appendix 4; Appendix 5; Appendix 6; Appendix 7; Appendix 8; Appendix 9); any disagreements were resolved by discussion or, if required, by a third author.

We sent an email request to contact authors of published studies to enquire whether they were willing to answer questions regarding their trials. We published the results of this survey in Appendix 10. Thereafter, we sought relevant missing information on the trial from the original author(s) of the article, if required.

We planned to provide information, including the trial identifier, about potentially relevant ongoing studies in the table 'Characteristics of ongoing studies'. We also intended to include specific data from the protocol of each included study, obtained from databases of ongoing trials or from publications of study designs, or both, in Appendix 6 ('Matrix of study endpoints (protocol/trial documents)').

 

Dealing with duplicate publications and companion papers

In the case of duplicate publications and companion papers of a primary study, we tried to maximise the yield of information by the simultaneous evaluation of all available data.

 

Assessment of risk of bias in included studies

Two authors (TH, JL) assessed each trial independently. We resolved possible disagreements by consensus, or by consultation with a third author (ZZ). In cases of disagreement, we consulted the rest of the group and made a judgement based on consensus.

We assessed risk of bias using The Cochrane Collaboration’s tool (Higgins 2011; Higgins 2011a) and adopted the following bias criteria.

  • Random sequence generation (selection bias).
  • Allocation concealment (selection bias).
  • Blinding (performance bias and detection bias), separated for blinding of participants and personnel and blinding of outcome assessment.
  • Incomplete outcome data (attrition bias).
  • Selective reporting (reporting bias) - see Appendix 5.
  • Other bias.

We judged 'Risk of bias' criteria as low, high or unclear, and evaluated individual bias items as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We present a 'Risk of bias' figure and a 'Risk of bias summary' figure.

We assessed the impact of individual bias domains on study results at endpoint and study levels.

For performance bias (blinding of participants and personnel), detection bias (blinding of outcome assessors) and attrition bias (incomplete outcome data) we intended to evaluate risk of bias separately for subjective and objective outcomes.

We defined the following endpoints as subjective outcomes.

  • Adverse events.
  • Health-related quality of life.

We defined the following outcomes as objective outcomes.

  • Weight loss.
  • Death from any cause.
  • Blood pressure.
  • Lipids.
  • Fasting blood glucose.
  • Socioeconomic effects.

 

Measures of treatment effect

We expressed dichotomous data as odds ratios (ORs) or risk ratios (RRs) with 95% confidence intervals (CIs). We expressed continuous data as mean differences (MDs) with 95% CIs.

 

Unit of analysis issues

We took into account the level at which randomisation occurred, such as cross-over trials, cluster-randomised trials and multiple observations for the same outcome.

 

Dealing with missing data

We tried our best to obtain relevant missing data from authors if feasible, and carefully performed evaluations of important numerical data, such as screened, randomised participants as well as intention-to-treat (ITT), as-treated and per-protocol (PP) populations. We investigated attrition rates (e.g. dropouts, losses to follow-up and withdrawals), and critically appraised issues of missing data and imputation methods (e.g. last observation carried forward (LOCF)).

 

Assessment of heterogeneity

In the event of substantial clinical, methodological or statistical heterogeneity, our intention was not to report study results as meta-analytically pooled effect estimates.

We identified heterogeneity by visual inspection of the forest plots and by using a standard Chi2 test with a significance level of α = 0.1, in view of the low power of this test. We specifically examined heterogeneity using the I2 statistic, which quantifies inconsistency across studies to assess the impact of heterogeneity on the meta-analysis (Higgins 2002; Higgins 2003), where an I2 statistic of 75% or more indicates a considerable level of inconsistency (Higgins 2011).

If heterogeneity was found, we intended to attempt to determine potential reasons for it by examining individual study and subgroup characteristics.

We expected the following characteristics to introduce clinical heterogeneity:

  • Sex.
  • Age.
  • Chromium doses.
  • Body mass index (BMI).
  • Duration of treatment.

 

Assessment of reporting biases

We planned to use funnel plots when we included 10 or more studies for a given outcome, in order to assess small study effects. As there could be several explanations for funnel plot asymmetry we planned to interpret results carefully (Sterne 2011).

 

Data synthesis

We planned, unless there was good evidence for homogeneity across studies, to primarily summarise data at low risk of bias by means of a random-effects model (Wood 2008). We intended to interpret random-effects meta-analyses giving due consideration to the whole distribution of effects, ideally by presenting a prediction interval (Higgins 2009). A prediction interval specifies a predicted range for the true treatment effect in an individual study (Riley 2011). In addition, we performed statistical analyses according to the statistical guidelines contained in the newest version of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

 

Subgroup analysis and investigation of heterogeneity

We planned to carry out the following subgroup analyses of our primary outcome parameter(s) (see above) and investigate any interactions:

  • Dose (depending on data).
  • Duration of intervention (depending on data).

 

Sensitivity analysis

We planned to perform sensitivity analyses in order to explore the influence of the following factors on effect sizes.

  • Restricting the analysis to published studies.
  • Restricting the analysis, taking into account risk of bias, as specified above.
  • Restricting the analysis to very long or large studies to establish how much they dominate the results.
  • Restricting the analysis to studies using the following filters: diagnostic criteria, language of publication, source of funding (industry versus other), and country.

We also planned to test the robustness of the results by repeating the analysis using different measures of effect size (RR, OR etc.) and different statistical models (fixed-effect and random-effects models).

 

Results

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
 

Description of studies

For a detailed description of studies, see the 'Characteristics of included studies' and 'Characteristics of excluded studies' sections.

 

Results of the search

The initial search identified 359 records; from these, 25 full text papers were identified for further examination. We excluded the other studies on the basis of their titles or abstracts because they did not meet the inclusion criteria, were not relevant to the question under study or were a duplicate report (see Figure 1). After screening the full text of the selected publications, nine studies (nine publications) met the inclusion criteria. All studies were published in English. We contacted all authors of included studies and received no reply.

 

Included studies

A detailed description of the characteristics of included studies is presented elsewhere (see 'Characteristics of included studies' and Appendix 2; Appendix 3; Appendix 4; Appendix 5; Appendix 6; Appendix 7; Appendix 8; Appendix 9).

The following is a succinct overview.

 

Comparisons

Three studies evaluated CrP plus resistance training (RT) or weight training versus placebo with RT or weight training (Campbell 1999; Joseph 1999; Volpe 2001). The other studies investigated CrP alone versus placebo.

 

Overview of study populations

A total of 622 participants were included in the nine trials, 346 participants were randomised to CrP and 276 to placebo. A total of 320 (93%) participants receiving CrP and 256 (93%) participants receiving placebo finished the study.The individual total sample sizes ranged from 18 to 154.

 

Study design

All studies were RCTs. All trials adopted a parallel-group superiority design and all used a placebo control. No trial was multicentred. In terms of blinding, five studies were double-blinded for participants and personnel (Joseph 1999; Kaats 1996; Kaats 1998; Kleefstra 2006; Yazaki 2010). Outcome assessors were blinded in four studies (Joseph 1999; Kaats 1996; Kaats 1998; Kleefstra 2006). Studies were performed between the years 1996 and 2010. The duration of interventions ranged from eight weeks to six months, with a mean study period of 12 weeks. Only two trials had a duration of intervention longer than 24 weeks (Kleefstra 2006; Yazaki 2010); durations in the other trials were 16 weeks (Iqbal 2009), 12 weeks (Campbell 1999; Joseph 1999; Volpe 2001), 10 weeks (Kaats 1996), 13 weeks (Kaats 1998) and 8 weeks (Anton 2008).

 

Settings

All of the studies were conducted in the USA. Two studies had an outpatient setting (Kleefstra 2006; Iqbal 2009); the other studies included community volunteers.

 

Participants

The participating population comprised overweight and obese adults only (see Appendix 3 and Appendix 4). Females were recruited more often than males in four trials (Iqbal 2009; Kaats 1996; Kaats 1998; Kleefstra 2006); one trial recruited more male than female participants (Joseph 1999). Two trials included only women (Anton 2008; Volpe 2001) and one trial only men (Campbell 1999). Four trials reported age as a range of values (Campbell 1999; Iqbal 2009; Volpe 2001; Yazaki 2010), whereas five trials reported age as a mean value (Anton 2008; Joseph 1999; Kaats 1996; Kaats 1998; Kleefstra 2006). All trials included participants from economically developed countries. Two trials reported the ethnic proportion of participants (Anton 2008; Iqbal 2009). One trial included participants with diabetes mellitus reporting insulin treatment before the start of the trial (Kleefstra 2006). Across all studies, mean baseline BMI at baseline ranged from 28.4 to 37.8 kg/m2.

No trial reported participant comorbidities, six trials provided detail about cointerventions in participants (Anton 2008; Campbell 1999; Joseph 1999; Kaats 1998; Volpe 2001; Yazaki 2010) and one trial provided details of the concomitant medications used by participants (Kleefstra 2006). Criteria for entry into the individual studies are outlined in the 'Characteristics of included studies' section.

 

Diagnosis

Participants were diagnosed as overweight or obese according to BMI criteria. In all the studies, participants had a BMI greater than 25 kg/m2.

 

Interventions

No study had a titration period. CrP was applied by the oral route and varied in dosing schedule between one and two times a day. The daily dose of chromium varied between 0.4 mg and 1 mg, with an average daily dose of 0.5 mg. All studies used a matching placebo as the control intervention.

 

Outcomes

All studies explicitly stated a primary endpoint in the publication; five studies also stated secondary endpoints (Anton 2008; Iqbal 2009; Kleefstra 2006; Volpe 2001; Yazaki 2010).

Reporting of endpoints

BMI was measured in four studies (Iqbal 2009; Joseph 1999; Kleefstra 2006; Yazaki 2010), weight was measured in six studies (Anton 2008; Campbell 1999; Joseph 1999; Kaats 1996; Kaats 1998; Volpe 2001). Body fat (as a percentage) was measured in six studies (Campbell 1999; Joseph 1999; Kaats 1996; Kaats 1998; Volpe 2001; Yazaki 2010). Waist circumference was measured in three studies (Iqbal 2009; Joseph 1999; Volpe 2001). Lipids were measured in four studies (Iqbal 2009; Kleefstra 2006; Volpe 2001; Yazaki 2010). Fasting glucose was measured in four studies (Anton 2008; Iqbal 2009; Volpe 2001; Yazaki 2010). Three studies reported adverse events (Anton 2008; Kleefstra 2006; Yazaki 2010). Two studies assessed food intake (Anton 2008; Volpe 2001), and two studies assessed muscle size, and strength or power development during the trial (Campbell 1999; Volpe 2001).

No studies investigated death from any cause, health-related quality of life or the socioeconomic effects of treatment. For a summary of all outcomes assessed in each study, see Appendix 5.

 

Excluded studies

Sixteen publications were excluded after careful evaluation of the full-text article (Albarracin 2008; Bunting 1994; Diaz 2008; Docherty 2005; Earle 1989; Geohas 2007; Hoeger 1998; Joyal 2004; Pasman 1997; Pittler 2004; Rabinowitz 1983; Stupar 1999; Trent 1995; Wang 2010; Wilson 1995; Zenk 2007) - see Figure 1.

The reasons for exclusion were: intervention and control not comparable (Albarracin 2008; Diaz 2008; Geohas 2007; Hoeger 1998; Zenk 2007), study design (Bunting 1994; Joyal 2004; Pasman 1997; Pittler 2004; Stupar 1999; Wang 2010) and participants not being obese or overweight (Docherty 2005; Earle 1989; Rabinowitz 1983; Trent 1995; Wilson 1995). For further details, see 'Characteristics of excluded studies'.

 

Risk of bias in included studies

For details on the risk of bias of included studies see 'Characteristics of included studies'. For an overview of review authors' judgements about each 'Risk of bias' item for individual studies and across all studies, see Figure 2 and Figure 3. We investigated performance bias, detection bias and attrition bias separately for objective and subjective outcome measures. We defined weight loss (e.g. BMI, waist circumference, percentage body fat); blood pressure; lipids (e.g. total cholesterol, HDL-C and LDL-C; triglycerides); and fasting blood glucose as objective outcomes. We defined adverse events (e.g. gastrointestinal, nervous system, metabolism) and health-related quality of life as subjective outcomes.

 FigureFigure 2. Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
 FigureFigure 3. Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

 

Allocation

Four trials reported that allocation to groups was concealed (Joseph 1999; Kaats 1998; Kleefstra 2006; Yazaki 2010); the remainder did not explain how concealment was carried out, and were thus graded 'unclear' for the domain based on this criterion. Two trials provided details on random sequence generation (Joseph 1999; Kleefstra 2006).

 

Blinding

Five studies explicitly stated that blinding of participants and personnel was undertaken (Joseph 1999; Kaats 1996; Kaats 1998; Kleefstra 2006; Yazaki 2010). Four studies did not provide sufficient information about blinding procedures (Anton 2008; Campbell 1999; Iqbal 2009; Volpe 2001).

 

Incomplete outcome data

Numbers of study withdrawals were described in six studies that had losses to follow up (Anton 2008; Campbell 1999; Iqbal 2009; Kleefstra 2006; Volpe 2001; Yazaki 2010). Analysis was reported as ITT in one study (Iqbal 2009). No ITT analysis was undertaken in six trials (Anton 2008; Campbell 1999; Kaats 1996; Kleefstra 2006; Volpe 2001; Yazaki 2010). One study used PP analyses (Kleefstra 2006). Two studies did not report losses to follow up (Joseph 1999; Kaats 1998). Detailed descriptions of participants' withdrawals and reasons underpinning them were not provided in the study by Kaats 1996.

 

Selective reporting

All trials met a low 'Risk of bias' criteria for selective reporting, as they reported the prespecified primary outcomes and all expected outcomes.

 

Other potential sources of bias

Seven trials had a commercial source of funding possibly creating a risk of bias (Anton 2008; Campbell 1999; Iqbal 2009; Kaats 1996; Kaats 1998; Volpe 2001; Yazaki 2010).

 

Effects of interventions

See:  Summary of findings for the main comparison

 

Baseline characteristics

For details of baseline characteristics, see Appendix 3 and Appendix 4.

 

Chromium picolinate (pooled doses versus placebo)

We focused this review on investigating which dose of CrP versus placebo would prove most effective and therefore specified the comparisons ranked according to CrP dose.

However, in order to find out whether CrP works in general, we also analysed the effect on body weight of the pooled CrP doses versus placebo. The MD in weight between CrP and placebo groups after 12 to 16 weeks of treatment was in favour of CrP (MD -1.1 kg (95% CI -1.7 to -0.4); P = 0.001; 392 participants; 6 trials; I2 = 0%;  Analysis 1.1).

 

Chromium picolinate 200 μg versus placebo

 

Primary outcomes

 
Weight change outcomes

After 10 weeks of treatment, the one trial assessing weight loss (Kaats 1996) found no statistically significant differences in weight loss between the CrP 200 μg and placebo groups (MD -0.9 kg (95% CI -2.3 to 0.4); P = 0.18; 88 participants;  Analysis 2.1). However, participants in the CrP groups lost a greater percentage of body fat (MD -1.1 kg (95% CI -2.0 to -0.2); P = 0.02; 88 participants;  Analysis 2.2) and fat mass (MD -1.4 kg (95% CI -2.7 to -0.2); P = 0. 02; 88 participants;  Analysis 2.3) than participants in the control groups.

 
Health-related quality of life

Not investigated.

 
Adverse events

Not reported.

 

Secondary outcomes

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated.

 

Chromium picolinate 400 μg versus placebo

 

Primary outcomes

 
Weight change outcomes
 
Change in body mass index

There was no statistically significant difference between the two groups at six weeks (MD 0.2 kg/m2 (95% CI -2.4 to 2.8); P = 0.88; 42 participants; 1 trial;  Analysis 3.1.1) and 12 weeks (MD 1 kg/m2 (95% CI -1.3 to 3.3); P = 0.39; 42 participants; 1 trial;  Analysis 3.1.2).

 
Change in weight loss

In a short-term, six-week trial there were no statistically significant differences between the two groups (MD -0.7 kg (95% CI -7.5 to 6.1); P = 0.84; 42 participants; 1 trial;  Analysis 3.2.1). Three trials presented weight loss outcomes at around 12 weeks (Kaats 1996; Kaats 1998; Volpe 2001): participants in the CrP groups lost more weight than participants in the control intervention (MD -1.1 kg (95% CI -1.9 to -0.4); P = 0.003; 280 participants; 3 trials; I2 = 0%;  Analysis 3.2.2).

 
Change in percentage body fat

No statistically significant differences were apparent at six weeks (MD -0.9% (95% CI -2 to 0.2); P = 0.12; 122 participants; 1 trial;  Analysis 3.3.1) or at 12 weeks (MD -0.9% (95% CI -2 to 0.2); P = 0.10; 280 participants; 3 trials; I2 = 56%;  Analysis 3.3.2).

 
Change in fat mass

No statistically significant differences were detected at six weeks (MD -0.4 kg (95% CI -4.6 to 3.8); P = 0.84; 42 participants; one trial;  Analysis 3.4.1). At 12 weeks a decrease was observed in favour of CrP (MD -1.6 kg (95% CI -2.3 to -0.9); P < 0.0001; 280 participants; 3 trials; I2 = 0%;  Analysis 3.4.2).

 
Change in waist circumference

The change in waist circumference was not statistically significantly different between the two groups at six weeks (MD 0.2 cm (95% CI -5.8 to 6.2); P = 0.95; 42 participants; 1 trial;  Analysis 3.5.1) or 12 weeks (MD -1.4 cm (95% CI -7.7 to 4.9); P = 0.66; 37 participants; 1 trial;  Analysis 3.5.2).

 
Health-related quality of life outcomes

Not investigated.

 
Adverse events

One participant receiving CrP and one participant receiving placebo experienced a serious adverse event (see Appendix 8). Two participants receiving placebo left the study due to adverse events (see Appendix 9).

 

Secondary outcomes

 
Change in fasting glucose

Fasting glucose was examined in a single study (Volpe 2001). There were no statistically significant differences between the CrP and placebo groups at 12 weeks (MD -2 mg/dL (95% CI -12 to 8); P = 0.70; 37 participants; 1 trial;  Analysis 3.6).

 
Change in total cholesterol

There was no statistically significant difference between the CrP group and placebo group after 12 weeks of treatment (MD -0.5 mg/dL (95% CI -23 to 24); P = 0.97; 37 participants; 1 trial;  Analysis 3.7) (Volpe 2001).

 
Change in triacylglycerol

Change in triacylglycerol levels was not statistically significantly different between the two groups at 12 weeks (MD 2 mg/dL (95% CI -39 to 43); P = 0.92; 37 participants; 1 trial;  Analysis 3.8) (Volpe 2001).

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated.

 

Chromium picolinate 500 μg versus placebo

Two studies (Iqbal 2009; Kleefstra 2006) with a combined total of 91 participants included data on the effect of CrP 500 μg versus placebo.

 

Primary outcomes

 
Weight change outcomes
 
Change in body mass index

One study (Kleefstra 2006) found no statically significant differences between the CrP and placebo groups at six months (MD 0.2 kg/m2 (95% CI -0.45 to 0.9); P = 0.56; 31 participants;  Analysis 4.1). Results were similar at 16 weeks (MD -0.8 kg/m2 (95% CI -2.2 to 0.5); P = 0.23; 62 participants;  Analysis 4.2).

 
Change in waist circumference

The change in waist circumference at 16 weeks was not statistically significantly different between the two groups (MD 0.6 cm (95% CI -1 to 2.3); P = 0.45; 60 participants; 1 trial;  Analysis 4.3).

 
Health-related quality of life outcomes

Not investigated.

 
Adverse events

Not reported.

 

Secondary outcomes

 
Change in fasting glucose

No statistically significant differences were detected at 16 weeks between groups (MD 0.4 mg/dL (95% CI -0.2 to 0.9); P = 0.17; 60 participants; 1 trial;  Analysis 4.4).

 
Change in blood pressure

Change in blood pressure at 16 weeks was not statistically significantly different between the two groups, for either systolic blood pressure (MD 0 mm Hg (95% CI -12 to 12); P = 1.00; 31 participants; 1 trial;  Analysis 4.5) or diastolic blood pressure (MD 2 mm Hg (95% CI -5 to 9); P = 0.56; 31 participants; 1 trial;  Analysis 4.6).

 
Change in total cholesterol

Change in total cholesterol was reported in two studies (Iqbal 2009; Kleefstra 2006).There was no statistically significant difference between the intervention and placebo groups (MD -0.1 mg/dL (95% CI -0.5 to 0.4); P = 0.88; 91 participants; 1 trial; I2 = 0%;  Analysis 4.7).

 
Change in triacylglycerol

There was no statistically significant difference between the CrP and placebo groups (MD -0.3 (95% CI -0.8 to 0.2); P = 0.26; 93 participants; 2 trials; I2 = 0%;  Analysis 4.8).

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated.

 

Chromium picolinate 1000 μg versus placebo

Five studies (Anton 2008; Campbell 1999; Joseph 1999; Kleefstra 2006; Yazaki 2010) with a combined total of 207 participants included data on the effects of CrP 1000 μg versus placebo.

 

Primary outcomes

 
Weight change outcomes
 
Change in weight loss

After 12 weeks of treatment, two trials(Campbell 1999; Joseph 1999) found that there was no statistically significant difference in weight loss between groups (MD -0.7 kg (95% CI -7.3 to 5.9); P = 0.85; 50 participants; 2 trials; I2 = 0%;  Analysis 5.1.1). Also, there was no statistically significant difference in BMI change at 24 weeks (MD 0.11 kg/m2 (95% CI -0.1 to 0.3); P = 0.25; 90 participants; 2 trials;  Analysis 5.2.1) or 12 weeks (MD 0.3 kg/m2 (95% CI -0.01 to 0.6); P = 0.06; 99 participants; I2 = 0%; 2 trials;  Analysis 5.2.2).

 
Change in percentage body fat

There was no statistically significant difference with regard to percentage body fat change between intervention and comparator groups at 24 weeks (MD 1% (95% CI -0.4 to 2.6); P = 0.14; 58 participants; 1 trial;  Analysis 5.3.1) or 12 weeks (MD 0.9% (95% CI -0.4 to 2.2); P = 0.16; 117 participants; 3 trials;  Analysis 5.3.2).

 
Change in waist circumference

The change in waist circumference at 12 weeks did not differ statistically significantly between the two groups (MD -1.6 cm (95% CI -6.5 to 3.3); P = 0.52; 32 participants; 1 trial;  Analysis 5.4).

 
Health-related quality of life outcomes

Not investigated.

 
Adverse events

Two studies reported adverse events at six months and found no statistically significant differences between groups (RR 4.03 (95% CI 0.46 to 35.11); P = 0.21; 94 participants; I2 = 0%;  Analysis 5.9.1); one study also found no statistically significant difference at 12 weeks (RR 0.30 (95% CI 0.01 to 7.02); P = 0.46; 40 participants;  Analysis 5.9.2).

Two participants receiving CrP reported a serious adverse event (see Appendix 8) and left the study due to an adverse event (see Appendix 9).

 

Secondary outcomes

 
Change in fasting glucose

Fasting glucose was examined in two studies (Joseph 1999; Yazaki 2010) that found no statistically significant differences between groups at 12 weeks (MD 0.3 mg/dL (95% CI -1 to 1); P = 0.64; 99 participants; 2 trials; I2 = 43%;  Analysis 5.5.1) or 6 months (MD 0 mg/dL (95% CI -2 to 2); P = 1.0; 58 participants;  Analysis 5.5.2).

 
Change in total cholesterol

There was no statistically significant difference in total cholesterol between the two groups at 24 weeks (MD 0.1 mg/dL (95% CI -0.7 to 0.5); P = 0.81; 90 participants; 2 trials; I2 = 0%;  Analysis 5.6.1) or 12 weeks (MD -0.1 mg/dL (95% CI -0.6 to 0.3); P = 0.57; 67 participants; 1 trial;  Analysis 5.6.2).

 
Change in triacylglycerol

Change in triacylglycerol levels did not differ statistically significantly between the two groups at 6 months (MD -1 mg/dL (95% CI -3 to 1); P = 0.26; 90 participants; 2 trials;  Analysis 5.7.1) or 12 weeks (MD -4 mg/dL (95% CI 95% CI -13 to 6); P = 0.45; 67 participants; 1 trial;  Analysis 5.7.2).

 
Change in basal metabolic rate

Change in basal metabolic rate was not statistically significant between groups at 12 weeks (MD -0.4 MJ/day (95% CI 95% CI -1.4 to 0.6); P = 0.44; 18 participants; 1 trial;  Analysis 5.8.1).

 
Change in blood pressure

Change in blood pressure did not differ statistically significantly between the two groups at 12 weeks (systolic blood pressure: MD 2 mm Hg (95% CI -1 to 5); P = 0.18; 67 participants; 1 trial;  Analysis 5.10.1; diastolic blood pressure: MD 1 mm Hg (95% CI -2 to 4); P = 0.54; 67 participants; 1 trial;  Analysis 5.11.1) or at 24 weeks (systolic blood pressure: MD 3 mm Hg (95% CI 95% -0.4 to 6); P = 0.08; 90 participants; 2 trials; I2 = 0%;  Analysis 5.10.2; diastolic blood pressure: MD 3 mm Hg (95% CI -1 to 7); P = 0.13; 90 participants; 2 trials; I2 = 29%;  Analysis 5.11.2).

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated.

 

Chromium picolinate 200 μg versus chromium picolinate 400 μg

One three-arm study (Kaats 1996) with a combined total of 99 participants investigated the effects of 200 µg CrP versus 400 µg CrP.

 

Primary outcomes

 
Weight change outcomes

 
Change in weight loss

After 10 weeks of treatment, there was no statistically significant difference between the two groups (MD 0.3 kg (95% CI -1 to 1.7); P = 0.65; 99 participants;  Analysis 6.1).

 
Health-related quality of life outcomes

Not investigated.

 
Adverse events

Not reported.

Change in percentage body fat

No statistically significant difference between groups was apparent at 10 weeks (MD 0.5% (95% CI -0.5 to 1.5); P = 0.32; 99 participants;  Analysis 6.2).

Change in fat mass

No statistically significant difference between groups was observed at 10 weeks (MD 0.5 kg (95% CI -0.7 to 1.6); P = 0.46; 99 participants; one trial;  Analysis 6.3).

 

Secondary outcomes

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated

 

Chromium picolinate 500 μg versus chromium picolinate 1000 μg

One three-arm study (Kleefstra 2006) with 60 participants investigated the effects of 500 μg CrP versus 1000 μg CrP.

 

Primary outcomes

 
Weight change outcomes

After 24 weeks of treatment, one study found no statistically significant difference in change in BMI between groups (MD 0 kg/m2 (95% CI -0.8 to 0.8); P = 1.00; 29 participants;  Analysis 7.1).

 
Health-related quality of life outcomes

Not investigated.

 
Adverse events

Adverse events did not differ significantly between groups at six months (RR 5.00 (95% CI 0.26 to 97); P = 0.29; 34 participants;  Analysis 7.6).

 

Secondary outcomes

 
Change in total cholesterol

Total cholesterol change at 24 weeks showed no statistically significant difference between groups (MD -0.3 mg/dL (95% CI -0.8 to 0.2); P = 0.21; 29 participants;  Analysis 7.2).

 
Change in triacylglycerol

Triacylglycerol levels showed no statistically significant difference between groups at 24 weeks (MD 0.1 mg/dL (95% CI -0.4 to 0.6); P = 0.71; 29 participants;  Analysis 7.3).

 
Change in blood pressure

There was no statistically significant change in systolic blood pressure (MD -6 mm Hg (95% CI -19 to 7); P = 0.37; 29 participants; one trial;  Analysis 7.4) or diastolic blood pressure (MD -4 mm Hg (95% CI -12 to 4); P = 0.33; 29 participants;  Analysis 7.5) between groups at 24 weeks.

 
Death from any cause

Not reported.

 
Socioeconomic effects

Not investigated.

 

Subgroup analyses

As there was no statistical heterogeneity across the study results with regard to body weight, we did not analyse the data by subgroups.

 

Sensitivity analyses

We did not perform sensitivity analyses due to the low number of studies included.

 

Assessment of reporting bias

Not performed due to the low number of included trials.

 

Discussion

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
 

Summary of main results

Relatively few trials were identified that met the inclusion criteria for this review and most were relatively recent (published in the past 10 years). The trials were heterogeneous in nature, particularly in terms of interventions and outcomes, and sample sizes were small to medium, with 622 participants evaluated in total. The studies were conducted in the community setting, with interventions mainly delivered by health professionals, and provided outcome data at 12 to 16 weeks for weight and at 8 to 24 weeks for adverse events.

The findings of this review demonstrate that CrP supplements across all doses have some effect on weight loss after 12 to 16 weeks of treatment, but firm evidence for a specific dose could not be established.

Furthermore, there was no conclusive evidence for other outcomes of weight loss (e.g. BMI, waist circumference, percentage body fat), adverse events (e.g. gastrointestinal, nervous system, metabolism), blood pressure, lipids (e.g. total cholesterol, HDL-C, LDL-C, triglycerides) or fasting blood glucose.

 

Overall completeness and applicability of evidence

The duration of follow up of the included studies was a maximum of six months. Long-term efficacy was not evaluated, and only three trials (Anton 2008; Kleefstra 2006; Yazaki 2010) reported data on adverse events in each group. Therefore, the efficacy and safety of CrP could not firmly be established. Whether CrP supplementation should be used in clinical practice for overweight or obese people depends on the evaluation of its effects established by large double-blind RCTs investigating patient-important outcome measures.

 

Quality of the evidence

There was an unclear risk of selection bias for the majority of the included trials. Five studies explicitly stated that blinding of the participants and personnel was undertaken. Four studies did not provide sufficient information about blinding procedures. Numbers of study withdrawals were described in seven studies that had losses to follow-up. Analysis was reported as ITT in only one study. Two studies did not report losses to follow-up. No study could be clearly associated with selective reporting. Five trials had a commercial source of funding which may create a potential source of bias.

 

Potential biases in the review process

We used well-defined inclusion and exclusion criteria, independent data extraction by two assessors and the 'Risk of bias' assessment tool (Higgins 2009) in order to minimise potential biases in the review process. We conducted extensive electronic and manual searches to search for relevant articles. As we included only published data in our review, the possibility of publication bias cannot be ruled out. The major limitations of our review were that only a small number of studies met our inclusion criteria and a majority of these were of short-to-medium duration.

 

Agreements and disagreements with other studies or reviews

To date, one systematic review of 10 studies has been published that examined the effects of CrP in overweight or obese people (Pittler 2004). For body weight, a significant differential effect was found in favour of CrP (MD -1.1 kg (95% CI -1.8 to -0.4 kg); n = 489). This result is comparable to our pooled analysis of all CrP doses versus placebo. However, the clinical relevance of the effect is debatable. A definitive difference between our and Pittler's review is the fact that we included only participants who were overweight or obese at baseline.

 

Authors' conclusions

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

 

Implications for practice

We identified nine studies that met our inclusion criteria and most were relatively recent (published in the past 10 years). The trials were heterogeneous in nature, particularly in terms of interventions and outcomes, and sample sizes were small to medium, with 622 participants evaluated in total. The studies were conducted in the community setting, with interventions mainly delivered by health professionals, and were of short-to-medium follow up (six months or less). We found no current reliable evidence to inform firm decisions about the efficacy or safety of CrP supplements in overweight or obese adults.

 
Implications for research

An insufficient number of studies were included to enable us to examine the longer-term impact of CrP supplements in overweight or obese people. Only one study had a follow-up of six months. Further double-blind RCTs of CrP are required to provide more conclusive evidence. Trials evaluating patient-important outcomes, such as health-related quality of life and morbidity endpoints, should be large and of reasonable duration. In addition, future prospective studies that carefully investigate the underlying mechanisms of the potential effects of CrP in preventing people from becoming overweight or obese are encouraged.

 

Acknowledgements

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

The review authors would like to thank the following people for commenting on the review: Lun Li and Jinhui Tian who gave good advice for this review.

 

Data and analyses

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
Download statistical data

 
Comparison 1. Chromium (all dosages) versus placebo

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in weight at 12-16 weeks6392Mean Difference (IV, Random, 95% CI)-1.07 [-1.73, -0.42]

 
Comparison 2. Chromium (200 μg) versus placebo

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in weight at 10 weeks1Mean Difference (IV, Random, 95% CI)Subtotals only

 2 Change in percent body fat at 10 weeks [kg]1Mean Difference (IV, Random, 95% CI)Subtotals only

 3 Change in fat mass at 10 weeks [kg]1Mean Difference (IV, Random, 95% CI)Subtotals only

 
Comparison 3. Chromium (400 μg) versus placebo

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in body mass index1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    1.1 6 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

    1.2 12 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 2 Change in weight3Mean Difference (IV, Random, 95% CI)Subtotals only

    2.1 6 weeks
142Mean Difference (IV, Random, 95% CI)-0.7 [-7.51, 6.11]

    2.2 12 weeks
3280Mean Difference (IV, Random, 95% CI)-1.14 [-1.89, -0.39]

 3 Percent body fat change3Mean Difference (IV, Random, 95% CI)Subtotals only

    3.1 Short-term
1122Mean Difference (IV, Random, 95% CI)-0.87 [-1.95, 0.21]

    3.2 Medium-term
3280Mean Difference (IV, Random, 95% CI)-0.90 [-1.98, 0.18]

 4 Change in fat mass3Mean Difference (IV, Random, 95% CI)Subtotals only

    4.1 6 weeks
142Mean Difference (IV, Random, 95% CI)-0.43 [-4.61, 3.75]

    4.2 12 weeks
3280Mean Difference (IV, Random, 95% CI)-1.57 [-2.27, -0.87]

 5 Change in waist circumference1Mean Difference (IV, Fixed, 95% CI)Subtotals only

    5.1 6 weeks
142Mean Difference (IV, Fixed, 95% CI)0.20 [-5.81, 6.21]

    5.2 12 weeks
137Mean Difference (IV, Fixed, 95% CI)-1.40 [-7.72, 4.92]

 6 Change in fasting glucose1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    6.1 12 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 7 Change in total cholesterol1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    7.1 12 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 8 Change in triacylglycerol1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    8.1 12 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 
Comparison 4. Chromium (500 μg) versus placebo

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in body mass index at 6 months1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 2 Change in weight at 16 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 3 Change in waist circumference at 16 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 4 Change in fasting glucose at 16 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 5 Change in systolic blood pressure at 6 months1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 6 Change in diastolic blood pressure at 6 months1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 7 Change in total cholesterol291Mean Difference (IV, Random, 95% CI)-0.05 [-0.46, 0.37]

 8 Change in triacylglycerol293Mean Difference (IV, Random, 95% CI)-0.28 [-0.76, 0.21]

 
Comparison 5. Chromium (1000 μg) versus placebo

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in weight2Mean Difference (IV, Fixed, 95% CI)Subtotals only

    1.1 12 weeks
250Mean Difference (IV, Fixed, 95% CI)-0.66 [-7.25, 5.93]

 2 Change in body mass index3Mean Difference (IV, Random, 95% CI)Subtotals only

    2.1 6 months
290Mean Difference (IV, Random, 95% CI)0.11 [-0.08, 0.30]

    2.2 12 weeks
299Mean Difference (IV, Random, 95% CI)0.28 [-0.01, 0.58]

 3 Change in percent body fat3Mean Difference (IV, Random, 95% CI)Subtotals only

    3.1 6 months
158Mean Difference (IV, Random, 95% CI)1.1 [-0.35, 2.55]

    3.2 12 weeks
3117Mean Difference (IV, Random, 95% CI)0.93 [-0.35, 2.21]

 4 Change in waist circumference1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    4.1 12 weeks
1Mean Difference (IV, Fixed, 95% CI)-1.60 [-6.53, 3.33]

 5 Change in fasting glucose2Mean Difference (IV, Random, 95% CI)Subtotals only

    5.1 12 weeks
299Mean Difference (IV, Random, 95% CI)-0.25 [-1.29, 0.80]

    5.2 6 months
158Mean Difference (IV, Random, 95% CI)0.0 [-2.14, 2.14]

 6 Change in total cholesterol2Mean Difference (IV, Random, 95% CI)Subtotals only

    6.1 6 months
290Mean Difference (IV, Random, 95% CI)-0.07 [-0.68, 0.53]

    6.2 12 weeks
167Mean Difference (IV, Random, 95% CI)-1.80 [-8.03, 4.43]

 7 Change in triacylglycerol2Mean Difference (IV, Random, 95% CI)Subtotals only

    7.1 6 months
290Mean Difference (IV, Random, 95% CI)-1.16 [-3.19, 0.87]

    7.2 12 weeks
167Mean Difference (IV, Random, 95% CI)-3.7 [-13.38, 5.98]

 8 Change in basal metabolic rate1Mean Difference (IV, Fixed, 95% CI)Totals not selected

    8.1 12 weeks
1Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 9 Adverse events3134Risk Ratio (M-H, Random, 95% CI)1.75 [0.30, 10.43]

    9.1 6 months
294Risk Ratio (M-H, Random, 95% CI)4.03 [0.46, 35.11]

    9.2 12 weeks
140Risk Ratio (M-H, Random, 95% CI)0.30 [0.01, 7.02]

 10 Change in systolic blood pressure2Mean Difference (IV, Fixed, 95% CI)Subtotals only

    10.1 12 weeks
167Mean Difference (IV, Fixed, 95% CI)2.1 [-0.95, 5.15]

    10.2 6 months
290Mean Difference (IV, Fixed, 95% CI)2.88 [-0.36, 6.12]

 11 Change in diastolic blood pressure2Mean Difference (IV, Random, 95% CI)Subtotals only

    11.1 12 weeks
167Mean Difference (IV, Random, 95% CI)0.9 [-2.01, 3.81]

    11.2 6 months
290Mean Difference (IV, Random, 95% CI)2.83 [-0.88, 6.55]

 
Comparison 6. Chromium (200 μg) versus chromium (400 μg)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in weight 10 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 2 Change in percent body fat 10 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 3 Change in fat mass 10 weeks1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 
Comparison 7. Chromium (500 μg) versus chromium (1000 μg) at 6 months

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Change in body mass index1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 2 Change in total cholesterol1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 3 Change in triacylglycerol1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 4 Change in systolic blood pressure1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 5 Change in diastolic blood pressure1Mean Difference (IV, Fixed, 95% CI)Totals not selected

 6 Adverse effects1Risk Ratio (M-H, Random, 95% CI)Totals not selected

 

Appendices

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms
 

Appendix 1. Search strategies


Search terms and databases

Unless otherwise stated, search terms are free text terms.

Abbreviations:

'$': stands for any character; '?': substitutes one or no character; adj: adjacent (i.e. number of words within range of search term); exp: exploded MeSH; MeSH: medical subject heading (MEDLINE medical index term); pt: publication type; sh: MeSH; tw: text word.

The Cochrane Library

#1 MeSH descriptor Obesity explode all trees
#2 MeSH descriptor Weight Gain explode all trees
#3 MeSH descriptor Weight Loss explode all trees
#4 MeSH descriptor Body Mass Index explode all trees
#5 (overweight in All Text or (over in All Text and weight in All Text) )
#6 (adipos* in All Text or (fat in All Text and overload in All Text and syndrom* in All Text))
#7 (overeat* in All Text or (over in All Text and eat* in All Text) )
#8 (overfeed* in All Text or (over in All Text and feed* in All Text) )
#9 (weight in All Text and (gain in All Text or chang* in All Text) )
#10 (body in All Text and mass in All Text and ind* in All Text)
#11 MeSH descriptor Waist circumference explode all trees
#12 MeSH descriptor Waist-Hip Ratio explode all trees
#13 MeSH descriptor Abdominal fat explode all trees
#14 MeSH descriptor Body fat distribution explode all trees
#15 MeSH descriptor Skinfold thickness explode all trees
#16 MeSH descriptor Overweight explode all trees
#17 ((weight in All Text near/6 cyc* in All Text) or (weight in All Text near/6 reduc* in All Text) or (weight in All Text near/6 los* in All Text) or (weight in All Text near/6 maint* in All Text) or (weight in All Text near/6 decreas* in All Text) )
#18 ((weight in All Text near/6 watch* in All Text) or (weight in All Text near/6 control* in All Text) or (weight in All Text near/6 chang* in All Text) or (weight in All Text near/6 gain* in All Text))
#19 BMI in All Text
#20 (waist-hip in All Text and ratio* in All Text)
#21 (waist in All Text and circumferenc* in All Text)
#22 (body in All Text and (fat in All Text near/6 distribution* in All Text) )
#23 ((abominal in All Text and fat in All Text) or (skinfold in All Text and thickness in All Text))
#24 (obes* in All Text or adipos* in All Text)
#25 (#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12)
#26 (#13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24)
#27 (#25 or #26)
#28 MeSH descriptor chromium picolinate explode all trees
#29 chromium picolinate in All Text
#30 (#28 or #29)
#31(#27 and #30)

MEDLINE

1 exp Obesity/ or exp Obesity hypoventilation syndrome/ or exp Obesity, abdominal/ or exp Obesity, morbid/ or exp Prader-Willi Syndrome/ 

2 exp Overweight/ 

3 exp Adipose tissue/ 

4 exp Weight gain/ or exp Weight loss/ 

5 exp body fat distribution/ or exp body mass index/ or exp waist circumference/ or exp skinfold thickness/ or exp waist-hip ratio/ 

6 exp Body Composition/ 

7 (overweight$ or over weight$).tw,ot. 

8 fat overload syndrom$.tw,ot. 

9 (overeat$ or over eat$).tw,ot. 

10 (overfeed$ or over feed$).tw,ot. 

11 (adipos$ or obes$).tw,ot. 

12 (weight adj3 (cyc$ or reduc$ or los$ or maint$ or decreas$ or watch$ or control$ or gain$ or chang$)).tw,ot. 

13 (body mass ind$ or waist-hip ratio$).tw,ot. 

14 skinfold thickness$.tw,ot. 

15 abdominal fat$.tw,ot. 

16 ((abdominal or subcutaneous or intra-abdominal or visceral or retroperitoneal or retro peritoneal) adj3 fat*).tw,ot. 

17 or/1-16 

18 exp chromium picolinate/ 

19 chromium picolinate.tw,ot. 

20 18 or 19 

21 17 and 20 

22 randomized controlled trial.pt. 

23 controlled clinical trial.pt. 

24 randomi?ed.ab. 

25 placebo.ab. 

26 drug therapy.fs. 

27 randomly.ab. 

28 trial.ab. 

29 groups.ab. 

30 or/22-29 

31 Meta-analysis.pt. 

32 exp Technology Assessment, Biomedical/ 

33 exp Meta-analysis/ 

34 exp Meta-analysis as topic/ 

35 hta.tw,ot. 

36 (health technology adj6 assessment$).tw,ot. 

37 (meta analy$ or metaanaly$ or meta?analy$).tw,ot. 

38 (search* adj10 (medical databas*or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or current content* or systemat*)).tw,ot. 

39 or/31-38 

40 30 or 39 

41 (comment or editorial or historical-article).pt. 

42 40 not 41 

43 21 and 42 

44 (animals not (animals and humans)).sh. 

45 43 not 44 

EMBASE

1 exp Obesity/ 

2 exp weight change/ or exp weight control/ or exp weight gain/ or exp weight reduction/ 

3 exp body mass/ or exp waist circumference/ or exp waist hip ratio/ 

4 exp abdominal fat/ or exp body fat distribution/ 

5 exp skinfold thickness/ 

6 (obes$ or adipos* or overweight or over weight).tw,ot. 

7 (overeat or over eat or overfeed or over feed or fat overload syndrom$).tw,ot. 

8 (weight adj6 (cyc$ or reduc$ or los$ or maint$ or decreas$ or watch$ or control or chang$ or gain)).tw,ot. 

9 (body mass ind$ or waist hip ratio or waist circumferenc$).tw,ot. 

10 (body fat adj3 distribution*).tw,ot. 

11 (abdominal fat or skinfold thickness).tw,ot. 

12 or/1-11 

13 exp chromium picolinate/ 

14 chromium picolinate.tw,ot. 

15 13 or 14 

16 12 and 15 

17 exp Randomized Controlled Trial/ 

18 exp Controlled Clinical Trial/ 

19 exp Clinical Trial/ 

20 exp Comparative Study/ 

21 exp Drug comparison/ 

22 exp Randomization/ 

23 exp Crossover procedure/ 

24 exp Double blind procedure/ 

25 exp Single blind procedure/ 

26 exp Placebo/ 

27 exp Prospective Study/ 

28 ((clinical or control$ or comparativ$ or placebo$ or prospectiv$ or randomi?ed) adj3 (trial$ or stud$)).ab,ti. 

29 (random$ adj6 (allocat$ or assign$ or basis or order$)).ab,ti. 

30 ((singl$ or doubl$ or trebl$ or tripl$) adj6 (blind$ or mask$)).ab,ti. 

31 (cross over or crossover).ab,ti. 

32 or/17-31 

33 exp meta analysis/ 

34 (metaanaly$ or meta analy$ or meta?analy$).ab,ti,ot. 

35 (search$ adj10 (medical database$ or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or current content$ or systematic$)).ab,ti,ot. 

36 exp Literature/ 

37 exp Biomedical Technology Assessment/ 

38 hta.tw,ot. 

39 (health technology adj6 assessment$).tw,ot. 

40 or/33-39 

41 32 or 40 

42 (comment or editorial or historical-article).pt. 

43 41 not 42 

44 16 and 43 

45 limit 44 to human 

46 44 not 45 

ISI Web of Knowledge

#1 Topic= (Obesity) OR Topic= (Overweight) OR Topic= (Weight Gain) OR Topic= (Weight Loss) OR Topic= (Body Mass Index) OR Topic= (Waist circumference) OR Topic= (Waist-Hip Ratio) OR Topic= (Abdominal fat) OR Topic= (Body fat distribution) OR Topic= (Skinfold thickness) OR Topic= (BMI) 

#2 Topic= (chromium picolinate) 

#3 #1 AND #2 (201 citations)

Chinese Biomedical Database (CBM)

#1 "Obesity"[Mesh] 

#2 Obesity [ti/ab] 

#3 "Overweight"[Mesh]

#4 "Overweight"[ti/ab]  

#5 Weight Gain [ti/ab] 

#6 "Weight Gain"[Mesh]

#7 Weight Loss [ti/ab] 

#8 "Weight Loss"[Mesh]
#9 Body Mass Index [ti/ab] 

#10 "Body Mass Index"[Mesh]

#11 Waist circumference [ti/ab] 

#12"Waist circumference"[Mesh] 

#13 Waist-Hip Ratio [ti/ab] 

#14"Waist-Hip Ratio"[Mesh] 

#15 "Abdominal fat"[ti/ab] 

#16"Abdominal fat"[Mesh] 

#17 Body fat distribution [ti/ab] 

#18 "Body fat distribution"[Mesh] 

#19 Skinfold thickness [ti/ab] 

#20 Skinfold thickness [Mesh] 

#21 "BMI"[Mesh] 

#22 BMI [ti/ab] 

#23 #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16 OR #17 OR #18 OR #19 OR #20 OR #21 OR #22 

#24 chromium picolinate[ti/ab] 

#25 "chromium picolinate"[Mesh] 

#26 #24 OR #25 

#27 #23 AND #26 

#28 limit 27 to human 

China Journal Full-text Database

#1 Obesity OR Overweight OR Weight Gain OR Weight Loss OR Body Mass Index OR Waist circumference OR Waist-Hip Ratio OR Abdominal fat OR Body fat distribution OR Skinfold thickness OR BMI 

#2 chromium picolinate

#3 #1 AND #2 

Chinese Scientific Journals Full-text Database

#1 Obesity OR Overweight OR Weight Gain OR Weight Loss OR Body Mass Index OR Waist circumference OR Waist-Hip Ratio OR Abdominal fat OR Body fat distribution OR Skinfold thickness OR BMI 

#2 chromium picolinate

#3 #1 AND #2 

'My NCBI' alert service

("picolinic acid" [Supplementary Concept] OR "picolinic acid" [All Fields] OR "chromium picolinate" [All Fields]) AND Randomized Controlled Trial [ptyp]



 

Appendix 2. Description of interventions


CharacteristicIntervention(s) [route, frequency, total dose/day]Comparator(s) [route, frequency, total dose/day]

Kaats 1996I1: chromium picolinate once a day, 200 μg/dayPlacebo once a day

I2: chromium picolinate once a day, 400 μg/day

Kaats 1998 Chromium picolinate once a day, 400 μg/dayPlacebo once day

Joseph 1999Chromium picolinate twice daily, 1000 μg/day + RT (twice weekly for 12 weeks)Placebo + RT (twice weekly for 12 weeks)

Kleefstra 2006I1: Chromium picolinate twice daily, 500 μg/dayPlacebo capsule twice daily

I2: Chromium picolinate twice daily, 1000 μg/day

Iqbal 2009Chromium picolinate capsule twice daily, 500 μg/dayPlacebo capsule twice daily

Volpe 2001Chromium picolinate once a day, 400 μg/day + a supervised weight-training and walking program (twice weekly for 12 weeks)Placebo once a day + a supervised weight-training and walking program (twice weekly for 12 weeks)

Anton 2008Chromium picolinate 1000 μg/dayPlacebo

Campbell 1999Chromium picolinate twice daily, 924 μg/day + RT (twice weekly for 12 weeks)Placebo twice daily + RT (twice weekly for 12 weeks)

Yazaki 2010Chromium picolinate capsule twice daily, 500 μgPlacebo capsule twice daily, 815 mg

Footnotes

I: intervention; RT: resistance training



 

Appendix 3. Baseline characteristics (I)


CharacteristicIntervention(s) and comparator(s)Duration of
intervention
Participating populationStudy period
[year(s)]
CountrySettingDuration of disease
[mean/range years
(SD), or as reported]

Kaats 1996I1: CrP 200 μg/day72 daysParticipants were recruited from the first 233 volunteers who responded to a news story about the study run on the local central broad-casting system1996USACommunity volunteer-

I2: CrP 400 μg/day

C: placebo

Kaats 1998I: CrP 400 μg/day90 daysParticipants were recruited from a variety of fitness and athletic clubs in San Antonio and Houston, Texas1998USACommunity volunteer-

C: placebo

Joseph 1999I: CrP 1000 μg/day + resistance training12 weeksModerately overweight older men and women1999USACommunity volunteer-

C: placebo + resistance training

Kleefstra 2006I1: CrP 500 μg/day6 monthsParticipants with type 2 diabetes mellitus2006USAOutpatients-

I2: CrP 1000 μg/day

C: placebo

Iqbal 2009I: CrP 500 μg/day16 weeksNondiabetic participants aged 18 to 75 years with metabolic syndrome and abdominal adiposity2009USAOutpatients-

C: placebo

Volpe 2001I: CrP 400 μg/day + weight training12 weeksPre-menopausal women with a BMI between 27 and 41 kg/m22001USACommunity volunteer-

C: placebo + weight training

Anton 2008I: CrP 400 μg/day8 weeksHealthy, overweight adult women who reported craving for carbohydrates2008USACommunity volunteer-

C: placebo

Campbell 1999I: CrP 1000 μg/day + resistance training13 weeksOlder men1999USACommunity volunteer-

C: placebo + resistance training

Yazaki 2010I: CrP 400 μg/day24 weeksHealthy overweight adults2010USACommunity volunteer-

C: placebo

Footnotes

"-" denotes not reported

BMI: body mass index; C: comparator: CrP: chromium picolinate; I: intervention; SD: standard deviation



 

Appendix 4. Baseline characteristics (II)


CharacteristicIntervention(s) and comparator(s)Sex
[female %]
Age
[mean/range years (SD),
or as reported]
FBG
[mg/dl]
BP systolic/diastolic
[mm Hg]
BMI
[mean kg/m2]
Co-medications /
Co-interventions
Co-morbidities

Kaats 1996I1: CrP 200 μg/day-45.9 ± 11.9--30.3 ± 5.5--

I2: CrP 400 μg/day-45.7 ± 11.8--30.6 ± 5.1--

C: placebo-44.3 ± 11.2--30.6 ± 5.5--

Kaats 1998 I: CrP 400 μg/day-41.1 ± 10.5--30.2 ± 7.1--

C: placebo-43.5 ± 7.6--28.4 ± 5.4--

Joseph 1999I: CrP 1000 μg/day + resistance training47.163 ± 45.73 ± 0.43 mmol/L-28.9 ± 2.5Control diet + resistance training-

C: placebo + resistance training46.760 ± 45.73 ± 0.43 mmol/L-29.3 ± 2.4Control diet + resistance training-

Kleefstra 2006I1: CrP 500 μg/day86.260 ± 8.8-147 ± 24 / 85 ± 1035 ± 7.2Insulin-

I2: CrP 1000 μg/day84.959 ± 6.4-156 ± 25 / 84 ± 1433 ± 4.2Insulin-

C: placebo83.162 ± 7.5-159 ± 20 / 83 ± 1034 ± 4.3Insulin-

Iqbal 2009I: CrP 500 μg/day60.647.7 ± 104.74 ± 0.8 mmol/L130 ± 12 / 81 ± 1037.8 ± 9Insulin-

C: placebo30.051.1 ± 134.54 ± 0.6 mmol/L129 ± 15 / 79 ± 1035.2 ± 6Insulin-

Volpe 2001I: CrP 400 μg/day + weight training10042.6 ± 6.542.6 ± 6.591 ± 1327-41Weight training-

C: placebo + weight training10042.5 ± 4.242.5 ± 4.291 ± 627-41Weight training-

Anton 2008I: CrP 400 μg/day032 ± 10.287.1 ± 1.4115 ± 13 / 74 ± 1030.7 ± 4.2Control diet-

C: placebo034.5 ± 9.787.9 ± 6.8114 ± 11 / 74 ± 1031.9 ± 4.7Control diet-

Campbell 1999I: CrP 1000 μg/day + resistance training050-75--27-34Resistance training-

C: placebo + resistance training050-75--27-34Resistance training-

Yazaki 2010I: CrP 400 μg/day5025-75-133 ± 17 / 80 ± 1036.0 ± 6.7--

C: placebo5025-75-137 ± 18 / 81 ± 1136.1 ± 7.6--

Footnotes

"-" denotes not reported

"±" denotes single standard deviation

BP: blood pressure; BMI: body mass index; C: control; CrP: chromium picolinate; FBG: fasting blood glucose; I: intervention



 

Appendix 5. Matrix of study endpoints (publications)


Characteristic

Study ID
EndpointTime of measurementaOutcome reportingb
[analysed & reported
as not significant (e.g. P > 0.05)]
Outcome reportingb
[analysed but not reported]
Outcome reportingb
[measured & not analysed or analysed but not reported because of non-significant results ]
Outcome reportingb
[not mentioned but likely to have been measured & analysed but not reported because of non-significant results]

Kaats 1996Body composition improvement (P)0, 72 daysN/AN/AN/AN/A

Body weight (P)0, 72 daysxN/AN/AN/A

Fat weight (P)0, 72 daysN/AN/AN/AN/A

Percentage body fat (S)0, 72 daysN/AN/AN/AN/A

Non-fat mass (S)0, 72 daysxN/AN/AN/A

Kaats 1998  Body weight (P)0, 90 daysN/AN/AN/AN/A

Fat weight (P)0, 90 daysN/AN/AN/AN/A

Percentage body fat (S)0, 90 daysN/AN/AN/AN/A

Fat-free mass (S)0, 90 daysxN/AN/AN/A

Joseph 1999Fasting glucose (P)1, 13 weeksN/AN/AN/AN/A

Fasting insulin (P)1, 13 weeksxN/AN/AN/A

Fasting C-peptide (S)1, 13 weeksxN/AN/AN/A

Weight loss (S)1, 13 weeksN/AN/AN/AN/A

BMI (S)1, 13 weeksxN/AN/AN/A

Waist circumference (S)1, 13 weeksxN/AN/AN/A

Waist to hip ratio (O)1, 13 weeksxN/AN/AN/A

Kleefstra 2006A1c (P)0, 1, 3, 6 monthsxN/AN/AN/A

Lipid profile (S)0, 1, 3, 6 monthsxN/AN/AN/A

BMI (S)0, 1, 3, 6 monthsxN/AN/AN/A

Blood pressure (S)0, 1, 3, 6 monthsxN/AN/AN/A

Plasma chromium concentration (S)0, 1, 3, 6 monthsxN/AN/AN/A

Iqbal 2009Insulin sensitivity index (P)0, 16 weeksxN/AN/AN/A

Glucose metabolism (S)0, 16 weeksN/AN/AN/AN/A

Oxidative stress (S)0, 16 weeksxN/AN/AN/A

Fasting serum lipids (S)0, 16 weeksxN/AN/AN/A

C-reactive protein (S)0, 16 weeksxN/AN/AN/A

Weight (O)0, 16 weeksxN/AN/AN/A

Waist circumference (O)0, 16 weeksxN/AN/AN/A

Volpe 2001Percentage body fat (P)0, 6, 12 weeksN/AN/AN/AN/A

Fat mass (P)0, 6, 12 weeksN/AN/AN/AN/A

BMI (P)0, 6, 12 weeksxN/AN/AN/A

Body weight (P)0, 6, 12 weeksxN/AN/AN/A

Resting metabolic rate (P)0, 6, 12 weeksxN/AN/AN/A

Biochemical parameters (S)0, 6, 12 weeksxN/AN/AN/A

Anton 2008Food intake (P)0, 1, 8 weeksN/AN/AN/AN/A

Hunger levels (P)0, 1, 8 weeksN/AN/AN/AN/A

Adverse events (P)0, 1, 8 weeksN/AN/AN/AN/A

Body weight (S)0, 1, 8 weeksN/AN/AN/AN/A

Fat cravings (S)0, 1, 8 weeksN/AN/AN/AN/A

Glucose and insulin (O)0, 1, 8 weeksxN/AN/AN/A

Campbell 1999Fat-free mass (P)0, 6, 12 weeksN/AN/AN/AN/A

Body weight (P)0, 6, 12 weeksxN/AN/AN/A

Urinary creatinine excretion (P)0, 6, 12 weeksN/AN/AN/AN/A

Total body water (P)0, 6, 12 weeksN/AN/AN/AN/A

Body muscle mass (P)0, 6, 12 weeksN/AN/AN/AN/A

Vastus lateralis type II fibre area (S)0, 6, 12 weeksN/AN/AN/AN/A

Skinfold thickness (S)0, 6, 12 weeksN/AN/AN/AN/A

Resting metabolic rate (S)0, 6, 12 weeksxN/AN/AN/A

Percentage body fat (S)0, 6, 12 weeksN/AN/AN/AN/A

Fat mass (S)0, 6, 12 weeksN/AN/AN/AN/A

Yazaki 2010BMI (P)0, 12, 24 weeksxN/AN/AN/A

Waist to hip ratio (P)0, 12, 24 weeksxN/AN/AN/A

Percentage body fat (S)0, 12, 24 weeksxN/AN/AN/A

Blood pressure (S)0, 12, 24 weeksxN/AN/AN/A

Basic metabolic (S)0, 12, 24 weeksxN/AN/AN/A

Urinalysis (O)0, 12, 24 weeksxN/AN/AN/A

Footnotes:

"-" denotes not reported

"x" denotes "yes"

aUnderlined times of measurement denote data as reported in the results section of the publication (other times represent planned but not reported points in time)

bConstitutes 'high risk of bias' according to the Outcome Reporting Bias In Trials (ORBIT) study classification system for missing or incomplete outcome reporting in reports of randomised trials (Kirkham 2010)

(P) primary or (S) secondary endpoint(s) refer to verbatim statements in the publication, (O) other endpoints relate to outcomes which were not specified as 'primary' or 'secondary' outcomes in the publication

Endpoint in bold = review primary outcome

A1c: HbA1c (glycosylated haemoglobin A1c); BMI: body mass index; N/A: not applicable



 

Appendix 6. Matrix of study endpoints (protocol/trial documents)


Characteristic

Study ID (trial identifier)
EndpointTime of measurement

Kaats 1996--

Kaats 1998 --

Joseph 1999--

Kleefstra 2006--

Iqbal 2009Insulin sensitivity index, glucose metabolism, oxidative stress,

fasting serum lipids, C-reactive protein, weight, waist circumference
0, 16 weeks

Volpe 2001--

Anton 2008--

Campbell 1999--

Yazaki 2010--

Footnotes

"-" denotes no protocol was detected



 

Appendix 7. Definition of endpoint measurement


Characteristic

Study ID
Overweight and obesityCardiovascular mortalityMorbidityHealth-related quality of life

Kaats 1996WHO guidelines---

Kaats 1998 WHO guidelines---

Joseph 1999WHO guidelines---

Kleefstra 2006WHO guidelines---

Iqbal 2009WHO guidelines---

Volpe 2001WHO guidelines---

Anton 2008WHO guidelines---

Campbell 1999WHO guidelines---

Yazaki 2010WHO guidelines---

Footnotes

"-" denotes not reported

WHO: World Health Organization



 

Appendix 8. Adverse events (I)


Characteristic

Study ID
Intervention(s) and comparator(s)Randomised /
Safety [N]
Deaths [N]All adverse
events
[N]
All adverse
events
[%]
Severe/serious
adverse events
[N]
Severe/serious
adverse events
[%]

Kaats 1996I1: CrP 200 μg/day33No participant died----

I2: CrP 400 μg/day66No participant died----

C: placebo55No participant died----

Kaats 1998I: CrP 400 μg/day62No participant died----

C: placebo60No participant died----

Joseph 1999I: CrP 1000 μg/day + resistance training17No participant died----

C: placebo + resistance training15No participant died----

Kleefstra 2006I1: CrP 500 μg/day17No participant died0000

I2: CrP 1000 μg/day17/15No participant died213213

C: placebo19No participant died0000

Iqbal 2009I: CrP 500 μg/day33No participant died----

C: placebo30No participant died----

Volpe 2001I: CrP 400 μg/day + weight training22No participant died----

C: placebo + weight training20No participant died----

Anton 2008I: CrP 400 μg/day21No participant died0000

C: placebo19/18No participant died1616

Campbell 1999I: CrP 1000 μg/day + resistance training9No participant died----

C: placebo + resistance training9No participant died----

Yazaki 2010I: CrP 400 μg/day40/39No participant died1313

C: placebo40No participant died0000

Footnotes

"-" denotes not reported

C: control; CrP: chromium picolinate; I: intervention



 

Appendix 9. Adverse events (II)


CharacteristicIntervention(s) and comparator(s)Randomised /
Safety [N]
Left study
due
to adverse
events
[N]
Left study
due
to adverse
events
[%]
Hospitalisation
[N]
Hospitalisation
[%]
Outpatient
treatment
[N]
Outpatient
treatment
[%]
Symptoms
[N]
Symptoms
[%]

Kaats 1996I1: CrP 200 μg/day33--------

I2: CrP 400 μg/day66--------

C: placebo55--------

Kaats 1998I: CrP 400 μg/day62--------

C: placebo60--------

Joseph 1999I: CrP 1000 μg/day + resistance training17--------

C: placebo + resistance training15--------

Kleefstra 2006I1: CrP 500 μg/day1700------

I2: CrP 1000 μg/day17/15213------

C: placebo1900------

Iqbal 2009I: CrP 500 μg/day33--------

C: placebo30--------

Volpe 2001I: CrP 400 μg/day + weight training22--------

C: placebo + weight training20--------

Anton 2008I: CrP 400 μg/day2100000000

C: placebo19/1816------

Campbell 1999I: CrP 1000 μg/day + resistance training9--------

C: placebo + resistance training9--------

Yazaki 2010I: CrP 400 μg/day40/3900000000

C: placebo4016------

Footnotes

"-" denotes not reported

C: control; CrP: chromium picolinate; I: intervention



 

Appendix 10. Survey of authors' providing information on trials

We tried our best to obtain relevant missing data from all authors of included studies but received no reply.

 

Contributions of authors

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

Hongliang Tian (TH): protocol drafting, search strategy development, trial selection, data interpretation and review drafting.

Xiaohu Guo (GX): protocol drafting, trial selection, data extraction, data analysis, data interpretation and review drafting.

Xiyu Wang (WX): protocol drafting, search strategy development, acquiring trial reports and review drafting.

Zhiyun He (HZ): acquiring trial reports, trial selection, data extraction, data analysis, data interpretation and review drafting.

Rao Sun (SR): protocol drafting, search strategy development, acquiring trial reports, trial selection and review drafting.

Sai GE (GS): protocol drafting, search strategy development, data extraction, data analysis, data interpretation and review drafting.

Zongjiu Zhang (ZZ): protocol drafting, search strategy development, acquiring trial reports, trial selection, data extraction, data analysis, data interpretation and review drafting.

 

Declarations of interest

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

None known

 

Differences between protocol and review

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Differences between protocol and review
  15. Index terms

Timing of outcome measurement: changed from "Short-term: 1 to 4 weeks, medium-term: more than 4 weeks to 12 weeks" to "Short-term: 1 to 6 weeks, medium-term: more than 6 weeks to 12 weeks".

References

References to studies included in this review

  1. Top of page
  2. AbstractRésumé scientifique
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
Anton 2008 {published data only}
Campbell 1999 {published data only}
  • Campbell WW, Joseph LJ, Davey SL, Cyr-Campbell D, Anderson RA, Evans WJ. Effects of resistance training and chromium picolinate on body composition and skeletal muscle in older men. Journal of Applied Physiology 1999 ;86(1):29-39.
Iqbal 2009 {published data only}
  • Iqbal N, Cardillo S, Volger S, Bloedon LT, Anderson RA, Boston R, et al. Chromium picolinate does not improve key features of metabolic syndrome in obese nondiabetic adults. Metabolic Syndrome and Related Disorders 2009;7(2):143-50.
Joseph 1999 {published data only}
  • Joseph LJ, Farrell PA, Davey SL, Evans WJ, Campbell WW. Effect of resistance training with or without chromium picolinate supplementation on glucose metabolism in older men and women. Metabolism 1999;48(5):546-53.
Kaats 1996 {published data only}
  • Kaats GR, Blum K, Fisher JA, Adelman JA. Effects of chromium picolinate supplementation on body composition: a randomized, double-masked, placebo-controlled study. Current Therapeutic Research 1996;57(10):747-56.
Kaats 1998 {published data only}
  • Kaats GR, Blum K, Pullin D, Keith SC, Wood R. A randomized, double-masked, placebo-controlled study of the effects of chromium picolinate supplementation on body composition: a replication and extension of a previous study. Current Therapeutic Research 1998;59(6):379-88.
Kleefstra 2006 {published data only}
  • Kleefstra N,  Houweling ST,  Jansman FG,  Groenier KH,  Gans RO,  Meyboom-de Jong B. Chromium treatment has no effect in patients with poorly controlled, insulin-treated type 2 diabetes in an obese western population: a randomized, double-blind, placebo-controlled trial. Diabetes Care 2006;29(3):521-5.
Volpe 2001 {published data only}
  • Volpe SL,  Huang HW,  Larpadisorn K,  Lesser II. Effect of chromium supplementation and exercise on body composition, resting metabolic rate and selected biochemical parameters in moderately obese women following an exercise program. Journal of the American College of Nutrition 2001;20(4):293-306.
Yazaki 2010 {published data only}
  • Yazaki Y,  Faridi Z,  Ma Y,  Ali A,  Northrup V,  Njike VY, et al. A pilot study of chromium picolinate for weight loss. Journal of Alternative and Complementary Medicine 2010;16(3):291-9.

References to studies excluded from this review

  1. Top of page
  2. AbstractRésumé scientifique
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
Albarracin 2008 {published data only}
Bunting 1994 {published data only}
  • Bunting LD,  Fernandez JM,  Thompson DL Jr,  Southern LL. Influence of chromium picolinate on glucose usage and metabolic criteria in growing Holstein calves. Journal of Animal Science 1994;72(6):1591-9.
Diaz 2008 {published data only}
  • Diaz ML,  Watkins BA,  Li Y,  Anderson RA,  Campbell WW. Chromium picolinate and conjugated linoleic acid do not synergistically influence diet- and exercise-induced changes in body composition and health indexes in overweight women. The Journal of Nutritional Biochemistry 2008;19(1):61-8.
Docherty 2005 {published data only}
  • Docherty JP,  Sack DA,  Roffman M,  Finch M,  Komorowski JR. A double-blind, placebo-controlled, exploratory trial of chromium picolinate in atypical depression: effect on carbohydrate craving. Journal of Psychiatric Practice 2005;11(5):302-14.
Earle 1989 {published data only}
  • Earle KE,  Archer AG,  Baillie JE. Circulating and excreted levels of chromium after an oral glucose challenge: influence of body mass index, hypoglycemic drugs, and presence and absence of diabetes mellitus. The American Journal of Clinical Nutrition 1989;49(4):685-9.
Geohas 2007 {published data only}
  • Geohas J,  Daly A,  Juturu V,  Finch M,  Komorowski JR. Chromium picolinate and biotin combination reduces atherogenic index of plasma in patients with type 2 diabetes mellitus: a placebo-controlled, double-blinded, randomized clinical trial. The American Journal of the Medical Sciences 2007;333(3):145-53.
Hoeger 1998 {published data only}
  • Hoeger WW,  Harris C,  Long EM,  Hopkins DR. Four-week supplementation with a natural dietary compound produces favorable changes in body composition. Advances in Therapy 1998;15(5):305-14.
Joyal 2004 {published data only}
  • Joyal SV. A perspective on the current strategies for the treatment of obesity. Current Drug Targets CNS and Neurological Disorders 2004;3(5):341-56.
Pasman 1997 {published data only}
  • Pasman WJ,  Westerterp-Plantenga MS,  Saris WH. The effectiveness of long-term supplementation of carbohydrate, chromium, fibre and caffeine on weight maintenance. International Journal of Obesity and Related Metabolic Disorders 1997;21(12):1143-51.
Pittler 2004 {published data only}
Rabinowitz 1983 {published data only}
  • Rabinowitz MB,  Gonick HC,  Levin SR,  Davidson MB. Effects of chromium and yeast supplements on carbohydrate and lipid metabolism in diabetic men. Diabetes Care 1983;6(4):319-27.
Stupar 1999 {published data only}
  • Stupar J,  Vrtovec M,  Kocijancic A,  Gantar A. Chromium status of tannery workers in relation to metabolic disorders. Journal of Applied Toxicology 1999;19(6):437-46.
Trent 1995 {published data only}
Wang 2010 {published data only}
  • Wang ZQ,  Cefalu WT. Current concepts about chromium supplementation in type 2 diabetes and insulin resistance. Current Diabetes Reports 2010;10(2):145-51.
Wilson 1995 {published data only}
  • Wilson BE,  Gondy A. Effects of chromium supplementation on fasting insulin levels and lipid parameters in healthy, non-obese young subjects. Diabetes Research and Clinical Practice 1995;28(3):179-84.
Zenk 2007 {published data only}
  • Zenk JL,  Frestedt JL,  Kuskowski MA. HUM5007, a novel combination of thermogenic compounds, and 3-acetyl-7-oxo-dehydroepiandrosterone: each increases the resting metabolic rate of overweight adults. The Journal of Nutritional Biochemistry  2007;18(9):629-34.

Additional references

  1. Top of page
  2. AbstractRésumé scientifique
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Differences between protocol and review
  16. Characteristics of studies
  17. References to studies included in this review
  18. References to studies excluded from this review
  19. Additional references
Colditz 1995
  • Colditz GA,  Willett WC,  Rotnitzky A,  Manson JE. Weight gain as a risk factor for clinical diabetes mellitus in women. Annals of Internal Medicine 1995;122:481-6.
Denke 1994
  • Denke MA, Sempos CT, Grundy SM. Excess body weight an under recognized contributor to dyslipidaemia in white American women. Archives of Internal Medicine 1994;154:401-10.
Docherty 2005
  • Docherty JP, Sack DA, Roffman M, Finch M, Komorowski JR. A double-blind, placebo-controlled, exploratory trial of chromium picolinate in atypical depression: effect on carbohydrate craving. Journal of Psychiatric Practice 2005;11:302-14.
Drake 2012
  • Drake TC, Rudser KD, Seaquist ER, Saeed A. Chromium infusion in hospitalised patients with severe insulin resistance: a retrospective analysis. Endodontic Practice 2012;31:1-17.
Higgins 2002
Higgins 2003
Higgins 2009
Higgins 2011
  • Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. www.cochrane-handbook.org.
Higgins 2011a
  • Higgins JP, Altman DG, Gotzsche PC, Juni P, Moher D, Oxman AD, et al. The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ 2011;343:d5928.
John 2007
  • Zenk JL, Frestedt JL, Kuskowski MA. HUM5007, a novel combination of thermogenic compounds, and 3-acetyl-7-oxo-dehydroepiandrosterone: each increases the resting metabolic rate of overweight adults. The Journal of Nutritional Biochemistry 2007;18(9):629-34.
Kahn 2006
Kirkham 2010
Kleefstra 2006
  • Kleefstra N, Houweling ST, Jansman FG, Groenier KH, Gans RO, Meyboom-de Jong B, et al. Chromium treatment has no effect in patients with poorly controlled, insulin-treated type 2 diabetes in an obese Western population: a randomized, double-blind, placebo-controlled trial. Diabetes Care 2006;29(3):521-5.
Liberati 2009
  • Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JPA. The PRISMA statement for reporting systematic and meta-analyses of studies that evaluate interventions: explanation and elaboration. PLoS Medicine 1999;6(7):1-28. [DOI: 10.1371/journal.pmed.1000100]
Murray 1998
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Naimark 1960
Pittler 2003
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Pizzorno 1999
  • Pizzorno JE,  Murray MT,  editors. Textbook of Natural Medicine. London: Churchill Livingstone, 1999.
Riley 2011
  • Riley RD, Higgins JP, Deeks JJ. Interpretation of random effects meta-analyses. BMJ 2011;342:d549.
Rimm 1995
  • Rimm EB, Stampfer MJ, Giovannucci E, Ascherio A, Spiegelman D, Colditz GA, et al. Body size and fat distribution as predictors of coronary heart disease among middle-aged and older US men. American Journal of Epidemiology 1995;141(12):1117-27.
Stephen 2008
Sterne 2011
  • Sterne JA, Sutton AJ, Ioannidis JP, Terrin N, Jones DR, Lau J, et al. Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials. BMJ 2011;343:d4002.
Volpe 2001
  • Volpe SL, Huang HW, Larpadisorn K, Lesser II. Effect of chromium supplementation and exercise on body composition, resting metabolic rate and selected biochemical parameters in moderately obese women following an exercise program. The American College of Nutrition 2001;20(4):293-306.
Wang 2007
  • Wang ZQ, Qin J, Martin J, Zhang XH, Sereda O, Anderson RA, et al. Phenotype of subjects with type 2 diabetes mellitus may determine clinical response to chromium supplementation. Metabolism 2007;56:1652-5.
Whitlock 2002
  • Whitlock G,  Lewington S,  Ni Mhurchu C. Coronary heart disease and body mass index: a systematic review of the evidence from large prospective cohort studies. Seminars in Vascular Medicine 2002;2(4):369-81.
WHO 1995
  • World Health Organization. Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. Technical Report Series No. 854. www.who.int/childgrowth/publications/physical_status/en/index.html (accessed 16 July 2012).
WHO 2006
  • World Health Organization. Fact sheet No 311: Obesity and overweight. www.who.int/mediacentre/factsheets/fs311/en/  (accessed 6 August 2010).
Wood 2008
  • Wood L, Egger M, Gluud LL, Schulz KF, Juni P, Altman DG, et al. Empirical evidence of bias in treatment effect estimates in controlled trials with different interventions and outcomes: meta-epidemiological study. BMJ 2008;336(7644):601-5.