Are chromium supplements useful for reducing body weight in overweight or obese adults?
Chromium is an essential nutrient (trace element) required for the normal metabolism of carbohydrate, protein and fat (i.e. the chemical reactions involved in breaking down these molecules to a form suitable for absorption by the body). Chromium increases the activity of insulin, and dietary supplementation with chromium has produced improvements in glucose metabolism which may lower blood glucose being important for overweight people with diabetes. It is generally believed that chromium may help to reduce a person's weight by decreasing the amount of fat in the body. Chromium is also said to suppress the appetite and stimulate the production of heat by the body, thus increasing energy expenditure. This may contribute to weight loss. Chromium picolinate is one of several chemical compounds of chromium sold as a nutritional supplement as a potential aid to weight loss.
We included nine randomised controlled trials which compared the efficacy and safety of 8 to 24 weeks of chromium supplementation and placebo in overweight or obese adults (i.e. with a body mass index between 25 and 29.9 kg/m2 defining being overweight and a body mass index of 30kg/m2 or more defining obesity). A total of 622 participants took part in the studies, 346 participants received chromium picolinate and 276 received placebo. The evidence is current to December 2012.
When the results obtained from the doses of chromium picolinate investigated (200 µg, 400 µg, 500 µg, 1000 µg) were pooled, study participants lost around 1 kg of body weight more than participants receiving placebo. We were unable to find good evidence that this potential weight loss effect increased with increasing dose of chromium picolinate. Only three of nine studies provided information on adverse events, so we were unable to determine whether chromium picolinate supplements are safe and whether any potential harms may increase with dose. In addition, the length of studies included was rather short (maximum of 24 weeks), so we were unable to determine any long-term effects of supplementation. No study reported whether supplementation was associated with increases in deaths from any cause or illnesses (such as myocardial infarction or stroke), or the health-related quality of life or socioeconomic effects of supplementation.
Quality of the evidence
The overall quality of evidence was considered low and we have inadequate information from which to draw conclusions about the efficacy and safety of chromium picolinate supplementation in overweight or obese adults.