LACK OF TOXICITY OF CHROMIUM CHLORIDE AND CHROMIUM PICOLINATE IN RATS

Objective: To evaluate the safety of chromium (Cr) as a nutrient suppl ement. Several recent studies have reported beneficial effects of supp lemental Cr at levels higher than the upper limit of the suggested int ake for Cr. Trivalent Cr is considered relatively nontoxic but some re cent unconfirmed studies have questioned its toxicity. We evaluated th e toxicity of Cr chloride and a more bioavailable form of trivalent Cr , Cr tripicolinate. Methods: Harlan Sprague Dawley rats (4 weeks of ag e) were fed a stock diet to which was added 0, 5, 25, 50 or 100 mg of Cr per kg of diet as chloride or picolinate. Fasting blood samples wer e taken at 11 and 17 weeks and animals sacrificed at 24 weeks of age. Lack of toxicity was demonstrated by blood and histological measuremen ts. Chromium incorporation into tissues was determined by graphite fur nace atomic absorption. Results: There were no statistically significa nt differences in body weight, organ weights or blood variables among all the groups tested at 11, 17 and 24 weeks. Blood variables measured were glucose, cholesterol, triglycerides, blood urea nitrogen, lactic acid dehydrogenase, transaminases, total protein and creatinine. Hist ological evaluation of the liver and kidney of control and animals fed 100 mg/kg Cr as Cr chloride or picolinate also did not show any detec table differences. Liver and kidney Cr concentrations increased linear ly for both the Cr chloride and picolinate fed animals. Conclusions: T hese data demonstrate a lack of toxicity of trivalent Cr, at levels th at are on a per kg basis, several thousand times the upper limit of th e estimated safe and adequate daily dietary intake for humans. Animals consuming the picolinate supplemented diets had several-fold higher C r concentrations in both the liver and kidney than those fed Cr chlori de.