Dosage effects of chromium picolinate on growth and body composition in the rat

This 12-week study examined the effects of six different levels of dietary chromium (Cr) (0, 75, 150, 300, 600, 500 ppb Cr) in the form of Cr picolinate (CrPic) upon growth and body composition in the rat. Ninety male Harlan Sprague-Dawley weanling rats arrived in three groups of 30 animals (referred to as Blocks 1, 2, and 3). Five animals from each block were assigned to each treatment resulting in a 6 x 3 (treatment x block) Randomized Block Design. Body composition was assessed via dual energy X-ray absorptiometry (DEXA). At Week 5, significant treatment x block interactions were found for fat weight and percent body fat (P less than or equal to 0.05), but there were only trends at Week 10 (P less than or equal to 0.10). These interactions reflected decreases in body fat for Block 1 that corresponded with increasing CrPic levels in the diet. No interactions nor treatment effects were seen for growth rate, lean body mass, or tissue weights, but most block effects were highly significant (P less than or equal to 0.01). A significant treatment x block interaction for feed intake (P = 0.01) revealed a decrease for Blocks 1 and 2, but an increase for Block 3, at the highest CrPic level. Except for the highest dietary level, body fat reductions for Block 1 occurred without decreases in feed intake, implicating a possible dietary-induced thermogenic effect of CrPic. It was concluded that genetic differences between the blocks of animals could have accounted for some of the differential effects of CrPic supplementation. (C) 1997 Elsevier Science Inc.