Chromium status of the rat as affected by phytate

Abstract

Interactions involving phytate and trace element absorption have largely dealt with iron and zinc. The purpose of this study was to explore the interaction of phytate as found in soy protein with Cr status. Male weanling Sprague-Dawley rats were assigned to 5 groups, 10 rats per group. The 5 groups had either ground beef (GB), textured soy protein (TSP), a combination of GB and TSP (GB:TSP), Torula yeast (TY), or TY with added Cr (TY+CR) as the protein source. At wk 4, 7, and 10, an intravenous glucose tolerance test (IVGTT) was conducted, while at wk 13 or 15 lipoprotein lipase activity (LPL), total plasma cholesterol and insulin were determined. All 5 groups had a glucose removal rate (GRR) of 2.7%/min or lower during wk 7 of the experiment. By wk 10, the GRR improved in TSP fed rats (p<0.05) and tended to improve in the TY+Cr, GB:TSP and GB fed animals. The fasting plasma insulin of the TY+Cr fed animals was significantly greater than the GB, TSP, and GB:TSP fed animals (p<0.05). Concurrent plasma glucose was not significantly different. Total plasma cholesterol was not significantly different among the 5 groups. In all groups, the fed LPL activity was significantly greater than the fasted LPL activity (p<0.05). These results suggest that 0.35% phytate as found in the TSP diet is not detrimental to Cr status.