Effects of various forms of dietary chromium on growth and body composition in the rat

Several human and animal studies of chromium (Cr) supplementation have reported increases in lean body mass, often with concurrent decreases in body fat. Since the majority of studies have tested Cr in the form of Cr picolinate (CrPic), this 12-week study contrasted the effects of three available forms of dietary Cr {300 ppb Cr as CrPic, Cr nicotinate (CrNic), or Cr chloride (CrCII)}, as well as no added dietary Cr, upon growth and body composition in the rat. Sixty male Harlan Sprague-Dawley weanling rats arrived in three groups of 20 animals (referred to as Blocks 1, 2, and 3). Five animals from each block were assigned to each treatment, resulting in a 4 X 3 (treatment X block) Randomized Block Design. Body composition was assessed at Weeks 5 and 10 via dual energy X-ray absorptiometry (DEXA). Significant treatment X block interactions were found for fat weight and percent body fat at both time points (P less than or equal to 0.05). These interactions reflected decreases in body fat with all forms of Cr supplementation for the Block 1 animals. No treatment interactions or 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), reflecting possible genetic differences between blocks. Since feed intake did not vary between dietary treatments, the reduced body fat levels for the Cr-supplemented animals of Block 1 may have been due to an enhancement of insulin-induced thermogenesis. Copyright (C) 1997 Elsevier Science Inc.