Influence of phytates on chromium nutrition of the rat
Gates, Gail Esther
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Objectives of this research were to produce a chromium (Cr) deficiency in rats in our laboratory as assessed by glucose removal rate and to determine if phytate would exacerbate the chromium deficiency state. Weanling male Sprague-Dawley rats were randomly assigned to one of 5 dietary groups: negative control without added chromium or phytate, low sodium phytate with 0.8% phytate, high sodium phytate with 2.8% phytate for 3 weeks then 1.4% phytate, calcium phytate with 1.8% phytate, or 5 parts per thousand chromium (chromic chloride) added to the diet. Intravenous glucose tolerance tests were performed during weeks 5, 7, and 9, and non-fasting plasma glucose values were determined during the final week of the study. Results showed that plasma glucose removal rates indicative of impaired glucose tolerance were produced. The rats fed calcium phytate seemed to exhibit the lowest glucose removal rate (1.9%/min) despite the high dietary chromium content (737 ppb). However, there were no significant differences (p<0.05) between groups in week 9. The group fed excessive chromium did not maintain a normal removal rate throughout the study. Negative controls showed the highest mean non-fasting plasma glucose level of 166+7.20 mg/dl. It was significantly higher (p<0.05) than the values of the excessive chromium group (144+5.02 mg/dl) and the high sodium phytate group (138+2.50 mg/dl). Thus, it appears that a chromium deficiency was produced in our laboratory as assessed by plasma glucose removal rate and that phytates may make chromium unavailable for Zabsorption.