Insulin resistance and body weight: recent human studies documenting the benefits of supplemental chromium

The essentiality of chromium for humans was confirmed more than three decades ago with the studies showing that patients on total parenteral nutritrion (TPN) developed severe diabetic-like symptoms that could be reversed by the addition of chromium to their parenteral nutrition solutions. Since these studies, chromium has been routinely added to TPN solutions and numerous human studies have reported significant beneficial effects of supplemental chromium on free living subjects with insulin resistance, including those that are overweight or obese. Some reports have questioned the essentiality of chromium, since not all studies have reported beneficial effects of chromium, and have also stressed the toxicity of trivalent chromium. However, these reports have not been confirmed. Recent double-blind, placebo controlled, human studies document the essentiality of trivalent chromium and demonstrate that the response to chromium is dependent upon the phenotype of the subjects. Other recent double blind, placebo controlled, human studies demonstrate that supplemental chromium improves QTc interval, fasting glucose, fasting insulin, insulin sensitivity and weight gain. However, not all well controlled studies report beneficial effects of supplemental chromium which is likely due to selection of subjects, chromium status of subjects, form of chromium used or unknown causes. Since overt chromium nutritional deficiencies are very unlikely to exist in populations eating varied diets, the lack of effects of supplemental chromium would be expected and well controlled chromium supplementation studies have documented this lack of response to supplemental chromium. This review will highlight human studies published within the last three years.