Effect of Chromium Supplementation on Glucose Metabolism and Lipids

Abstract

OBJECTIVE -A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels. RESEARCH DESIGN AND METHODS -A literature search was conducted in MED-LINE and the Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium supplement intake Ն3 weeks, with Ն10 participants receiving chromium. All trials with glucose metabolism outcomes and trials of individuals with diabetes or glucose intolerance for lipid outcomes were included. Meta-analyses were performed as appropriate.RESULTS -Forty-one studies met criteria, almost half of which were of poor quality. Among participants with type 2 diabetes, chromium supplementation improved glycosylated hemoglobin levels by Ϫ0.6% (95% CI Ϫ0.9 to Ϫ0.2) and fasting glucose by Ϫ1.0 mmol/l (Ϫ1.4 to Ϫ0.5) but not lipids. There was no benefit in individuals without diabetes. There were some indications of dose effect and differences among chromium formulations. Larger effects were more commonly observed in poor-quality studies. The evidence was limited by poor study quality, heterogeneity in methodology and results, and a lack of consensus on assessment of chromium status.CONCLUSIONS -No significant effect of chromium on lipid or glucose metabolism was found in people without diabetes. Chromium supplementation significantly improved glycemia among patients with diabetes. However, future studies that address the limitations in the current evidence are needed before definitive claims can be made about the effect of chromium supplementation. Diabetes Care 30:2154-2163, 2007C hromium is an essential mineral that is thought to be necessary for normal glucose and lipid homeostasis (1-3). Trivalent chromium in a complex known as glucose tolerance factor is considered the biologically active form. It was originally discovered in brewer's yeast (4). Chromium chloride, chromium nicotinate, and chromium picolinate are commonly used formulations of trivalent chromium. Chromium picolinate is a formulation designed to improve absorption (5). Severe chromium deficiency is known to cause reversible insulin resistance and diabetes (6 -8). However, the effect of chromium supplementation in individuals who are not severely chromium deficient is unclear. Manufacturers aggressively promote the benefits of chromium in the prevention and treatment of insulin resistance and its associated conditions (type 2 diabetes, dyslipidemia, and cardiovascular disease), and the public has embraced its use. Chromium supplement sales represent ϳ6% of the U.S. mineral supplement market (9).To clarify the role of chromium supplementation in the prevention and management of abnormal glucose and lipid homeostasis, we performed a systematic review of randomized controlled trials on the effect of chromium supplement intake on glucose metabolism and lipid profile. RESEARCH DESIGN AND METHODS Literature search and eligibility criteriaWe conducted a systematic review of the English-language literature on the effects of chromium supplementa...

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