Chromium is a trace element that is necessary for glucose, insulin, and lipid metabolism in humans ^(1) (9). It is marketed as a dietary supplement for diabetes, weight loss, and to improve muscle mass. Trivalent chromium from yeast extract is sometimes referred to as glucose tolerance factor in over-the-counter products.

Although most people consume adequate amounts through diet, chromium deficiency has been implicated in the development of diabetes ⁽²⁵⁾. In vitro studies suggest that chromium produces beneficial modulatory effects under hyperglycemic conditions ⁽²⁶⁾. Animal models also suggest antidiabetic ^(27) (28), antidepressant ^{(29) (30) (31)}, and anxiolytic ⁽³²⁾ properties.

In human studies, chromium supplementation with biotin may help improve glycemic control in type 2 diabetes  ^{(4) (5) (6)}, but results from other studies on chromium alone are mixed ^(33) (44). Other data suggest chromium picolinate may increase satiety ⁽¹⁵⁾. However, many clinical studies failed to demonstrate improvements in glucose metabolism, weight loss, or muscle mass ^{(3) (7) (8) (9) (10) (11) (12) (13) (14)}. More recently one meta-analysis suggested that overall, chromium monosupplementation improved glycemic control and lipid profiles ⁽³⁴⁾, while another determined that chromium picolinate did not affect A1C or fasting plasma glucose ⁽³⁵⁾. It has been posited that mixed and modest effect sizes may reflect a greater glucoregulatory effect in complex patients with comorbid diabetes, depression, and binge eating ⁽³⁶⁾. A large population study suggests that those who consumed chromium-containing supplements have a reduced risk of diabetes, but more study is needed ⁽³⁷⁾.

In women with polycystic ovary syndrome, chromium supplementation did not affect endocrine profiles, and nitric oxide or glutathione levels, but did reduce acne, hirsutism, C-reactive protein, total antioxidant capacity, and malondialdehyde levels ⁽⁴⁵⁾. However, meta-analyses suggest that for PCOS patients, chromium supplementation may not have significant benefits ⁽⁴⁶⁾ or the magnitude of effect is small, with clinical relevance uncertain ⁽⁴⁷⁾.

Chromium is poorly absorbed following oral administration, but salt forms such as chromium picolinate, niacin-bound chromium, and chromium chloride, appear to have better bioavailability. Other novel chromium compounds also have improved bioavailability ^(40) (41). Adverse effects are rare but can include renal failure ^(18) (19), rhabdomyolysis ⁽²⁰⁾, liver damage ⁽²¹⁾, and dermatitis ⁽²²⁾.