Vitamin C supplementation restores the impaired vitamin E status of guinea pigs fed oxidized frying oil.

To investigate the effect of dietary oxidized frying oil (OFO) on tissue retention of vitamin C, and to explore the effect of vitamin C supplementation on tissue vitamin E concentrations and lipid peroxidation, male weanling guinea pigs were divided into four groups. Guinea pigs were fed 15% OFO diets supplemented with vitamin C at 300, 600 or 1500 mg/kg diet. Control animals were fed a diet containing 15% fresh untreated soybean oil with 300 mg/kg of vitamin C. After 60 d of feeding, body weight gain, food intake, feed efficiency and plasma triglyceride concentration were significantly lower in guinea pigs fed OFO diets than in controls (P < 0.05). However, plasma cholesterol concentration was highest in guinea pigs fed the OFO diet supplemented with 300 mg/kg vitamin C. Increasing vitamin C in OFO diets significantly reduced plasma cholesterol concentration. Plasma and tissue vitamins C and E concentrations were significantly lower in the OFO-fed guinea pigs receiving 300 mg/kg vitamin C than in controls. Greater levels of supplemental vitamin C increased tissue vitamins C and E. Guinea pigs fed OFO diets had significantly higher tissue levels of thiobarbituric acid reactive substances (TBARS) (P < 0.05) than controls. Our results demonstrated that OFO feeding, which impaired alpha-tocopherol retention and increased TBARS, could be alleviated somewhat by vitamin C supplementation.