DIETARY CHROMIUM EFFECTS ON TISSUE CHROMIUM CONCENTRATIONS AND CHROMIUM ABSORPTION IN RATS

Chromium (Cr) absorption is low (<1%) and there is a need to find Cr c ompounds that are absorbed better than inorganic Cr salts. Therefore, the incorporation of nine different chromium (Cr) compounds on tissue Cr concentration of 6-week male Wistar rats was investigated. Chromium compounds tested were Cr chloride (Cr chloride), Cr acetate (Cr aceta te), Cr potassium sulfate (CrAlum), Cr trihistidine (Cr histidine), Cr triglycine (Cr glycine), Cr trinicotinic acid (CrNA), Cr dinicotinic acid dihistidine (CrNA-HIS), Cr tripicolinic acid (Cr picolinate), and Cr dinicotinic acid diglycine cysteine glutamic acid (CrNA-AA). Compl exes were fed to weanling rats for 3 weeks at 5,000 ng of Cr/g of diet . Basal control diet was a cornstarch-based diet containing 30 ng Cr/g . Chromium incorporation into the kidney was greatest for CrNA-AA comp lex (850 ng/g dry wt) followed by CrAlum (407 ng/g), Cr acetate (397), CrNA-HIS (394), Cr picolinate (368), Cr glycine (343), Cr nicotinate (166), Cr chloride (74), CrHIS (49), and control (23 ng/g). Chromium c oncentration of the liver was greatest for the Cr picolinate compound (50 ng/g) followed by CrNA-AA and Cr acetate. Liver Cr concentrations of remaining complexes were not significantly different from those of the control animals that received no added Cr. Chromium concentrations were significantly greater in the kidney than those for the liver, sp leen, heart, lungs, and gastrocnemius muscle. Supplemental Cr did not affect tissue zinc arid copper but did alter tissue iron concentration s. Absorption of radioactive forms of Cr did not explain the differenc es in tissue Cr concentrations. Chromium absorption after 4 hours and retention after 24 hours were not significantly different for the form s of Cr tested. These data demonstrate that Cr concentrations are grea t est in the kidney and that the form of dietary Cr significantly affe cts tissue Cr concentrations. Absorption of Cr does not correlate with tissue Cr concentrations and blood Cr is not in equilibrium with tiss ue Cr stores. (C) 1996 Wiley-Liss, Inc.