Only 1 to 3% of biologically active trivalent chromium (Cr) is absorbed. Normal plasma levels are 0.05 to 0.50 mcg/L (1.0 to 9.6 nmol/L). However, it is not clear whether chromium should be considered an essential (required) trace element.
Chromium potentiates insulin activity; however, it is not known whether chromium picolinate supplementation is beneficial in diabetes mellitus. Patients with diabetes should not take chromium supplements unless use is supervised by a diabetes specialist. Chromium supplements do not enhance muscle size or strength.
High doses of trivalent chromium given parenterally cause skin irritation, but lower doses given orally are not toxic. Exposure to hexavalent chromium (CrO3) in the workplace may irritate the skin, lungs, and gastrointestinal tract and may cause perforation of the nasal septum and lung carcinoma.
(See also Overview of Mineral Deficiency and Toxicity.)