Chromium: Is It Essential and Is It Safe?

Elemental chromium (Cr) was discovered in crocoite, a mineral with a deep-orange red color, by Vaquelin in 1798. Schwartz and Mertz in 1959 were the first to reportCr was an essential element in rats while in 1977 Jeejebhoy et al.showed it wasessential in humans. Many research studies were conducted with Cr over the years  but the main focus was its relationship with diabetes mellitus. 

While the evidence supporting an anti-diabetic role for Cr appeared strong it was still far from definitive. Thetwo main forms of chromium are the trivalent CrIII (chromium III) and thehexavalent form CrVI (chromium VI). Of these, CrIII is the most stable oxidation state found in living organisms but unable to cross cell wall membranes easily. Complexing with certain organic ligands such as picolinic acid, however, allowed CrIII to be readily absorbed by cell membranes. A recent paper by Doddigarta and co-workers showed that male Wistar rats fed a high carbohydrate diet supplemented with chromium picolinate (CrPlc) and melatonin, given individually or in combination, prevented the development of insulin resistance and type 2 diabetes.