Dietary chromium and ascorbic acid deficiency effects on plasma cholesterol and glucose tolerance in guinea pigs
O'Ladut, Wolley K
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Weanling male albino Hartley guinea pigs weighing approximately 200 grams were randomly assigned to one of two diet groups. The negative control (-Cr) diet (0.106 ppm Cr) was adequate in all nutrients except chromium while the positive control diet (+Cr) contained 1.910 ppm chromium. Plasma cholesterol and oral glucose tolerance tests were conducted during weeks 7, 10, 13 and 16. Serum cholesterol and fasting glucose were also determined at autopsy (week 20). At week 14, positive (+Cr) and negative (-Cr) control were subdivided to a total of 4 groups as follows: chromium adequate, ascorbic acid adequate (+Cr+C); chromium adequate, ascorbic acid deficient (+Cr-C); chromium deficient, ascorbic acid adequate (-Cr+C); chromium deficient, ascorbic acid deficient (-Cr-C). Ascorbic acid was not given to groups (+Cr-C) and (-Cr-C). The levels of plasma cholesterol at weeks, 7, 10 and 13 were not significantly different (p > 0.05) but value for the (-Cr) groups were consistently higher than for the (+Cr) groups. However, a significance (p < 0.05) was observed due to chromium while the effect of ascorbic acid was not significant (p < 0.08) at week 16. Oral glucose tolerance tests at 7, 10 and 13 weeks were not significantly different. At week 16, the group that was deficient in both chromium and ascorbic acid (-Cr-C) showed a higher fasting glucose than any other groups. At 120 minutes after the glucose challenge, this group (-Cr-C) was 57 mg/dl above fasting, while the positive control (+Cr+C) was 14 mg/dl above fasting. A significant effect on glucose (p < 0.02) was observed due to chromium and ascorbic acid deficiency at 120 minutes. It appears that a combined chromium and ascorbic acid deficiency caused impaired glucose tolerance and elevated plasma cholesterol.