Chromium: A Decade as a Nonessential Trace Element

Since chromium (Cr) was determined not to be an essential trace element over a decade ago, continued studies have been targeted at establishing whether super-nutritional, pharmacologically relevant doses of supplemental Cr provide beneficial effects for humans and elucidating what mechanism(s) at a molecular level for any such effects might be. The mechanisms of Cr transport from absorption via passive diffusion until loss in the urine have been largely determined during the last decade and will be discussed along with potential mechanisms for Cr action. Two models for Cr action at the molecular level have been proposed: one involving the alteration of adenosine monophosphate-activated protein kinase signaling and the other involving activation of the insulin signaling pathway. The available data do fit entirely consistently with either model. These studies also raise questions about any potential utility of Cr supplementation, even at pharmacological doses.