Four-week old Sprague Dawley rats were fed a stock diet to which was added 0, 5, 25, 50, or 100 mg of chromium per kg of diet as chloride or picolinate. Thereafter, fasting blood samples of chromium were taken at 11 and 17 weeks and the animals were sacrificed at 24 weeks of age. The results showed lack of toxicity on tissues. All blood studies, including glucose, cholesterol, blood urea nitrogen, lactic acid dehydrogenase, transaminases, total protein and creatinine were within normal limits. Histological determination of liver and kidney tissues between control and rats fed 100 mg/kg of chromium did not show any detectable differences.

Dr. Richard Anderson and colleagues, from the Beltsville Human Nutrition Research Center, US Department of Agriculture, in Maryland, say, "These data demonstrate a lack of toxicity of trivalent chromium, at levels that are on a per kg bases, several thousand times the upper limit of the estimated safe and adequate daily dietary intake for humans."

An interesting observation was that the rats fed the picolinate version of chromium has several-fold higher chromium concentrations in both the liver and kidney than those fed the chloride form.

Anderson RA, Bryden NA, Polansky MM. Lack of toxicity of chromium chloride and chromium picolinate in rats. J Am College Nutr 16:3:273-279, 1997.

Comments: I'm even more reassured that adding 100 to 200 mg of chromium to the vitamin regimen of diabetics appears to be safe. As to the form of chromium, picolinate seems to be better absorbed, and thus a lower dose of the picolinate would be required compared to the hydrochloride form.