Chromium: celebrating 50 years as an essential element?

Fifty years ago the element chromium was proposed to be an essential element for mammals with a role in maintaining proper carbohydrate and lipid metabolism. Over the next several decades, chromium nutritional supplements became so popular for weight loss and muscle development that sales were second only to calcium among mineral supplements. However, the failure to identify the responsible biomolecules that bind Cr and their mode of action has resulted in the status of Cr being readdressed in recent years. This review considers research on the biochemistry of Cr(III) over the last two decades and how the results have affected the current status of Cr as an essential element.