The element chromium (Cr) in the +3 oxidation state has been proposed to be an essential trace element for mammals [14]. The National Academy of Sciences of the United States has set the adequate intake (AI) of chromium at 35 µg daily for men and 25 µg daily for women [13]. Even though the typical American diet provides an adequate amount of chromium, chromium supplements are currently on the market and include chromium chloride, chromium picolinate, and chromium nicotinate. However, a consensus exists among researchers that chromium supplementation of healthy rats does not provide any therapeutic effects except for the compound Cr3 [10, 8, 15, 1]. Several reasons may explain this difference among Cr chloride, Cr nicotinate, Cr picolinate and the cation Cr3.

Olin et al. [9] and Anderson et al. [2] have shown that Cr chloride, Cr nicotinate, and Cr picolinate are absorbed with efficiencies between 0.5-1.3 % of the gavaged dose after 24 hours. However, for Cr3, 40% of the Cr at a pharmacological dose and 60% of the Cr at a nutritionally relevant dose are absorbed over a 24 hour period. (The nutritional dose was 3 µg Cr/kg body mass while the pharmacological dose was 3 mg Cr/kg body mass). The better absorption efficiency of Cr3 may explain its better effectiveness as a therapeutic agent.