title: Tissue alpha-tocopherol retention in male rats is compromised by feeding diets containing oxidized frying oil.
abstract: To investigate the effect of dietary oxidized frying oil (OFO) on tissue retention of alpha-tocopherol (alpha-T). Long-Evans male weanling rats were divided to four groups based on a 2 x 2 factorial design. Two groups were fed 15% OFO diets, and the remaining two groups were fed control diets in which OFO was replaced by vitamin-E-stripped fresh soybean oil. Vitamin E as all-rac-alpha-tocopheryl acetate was added at the concentration of either 50 (normal E) or 500 (high E) mg/kg diet. The OFO sample was prepared by deepfrying sticks in fresh soybean oil at 205 +/- 5 degrees C for four 6-h periods. After 6 wks of feeding, alpha-T concentrations in most tissues were significantly lower in rats fed OFO diets (P < 0.05) than in the control groups. For rats fed the OFO diet with the normal vitamin E concentration, the alpha-T concentration is epididymal fat pad, plasma, liver, kidney, muscle, brain and lung were 29-64% those of the corresponding control group (P < 0.05). The interaction between the two dietary factors on tissue alpha-T was significant in liver, spleen, and adrenal gland. In these three tissues, the differences between the normal and high dietary vitamin E groups were less in rats fed the OFO diets than in rats fed the control diets. The tissue alpha-T concentrations of the high vitamin E OFO group were comparable with or higher (P < 0.05) than those of the normal vitamin E control group, indicating that the negative effect of OFO on tissue alpha-T concentration can be alleviated by dietary supplementation of vitamin E. Compared with the controls, rats OFO diets had significantly higher tissue thiobarbituric acid reactive substances (P < 0.05). Because the amount of alpha-T directly added into the test oil samples was not significantly decreased through an incubation (at 37 degrees C) period of up to 10 d, the inefficient absorption and/or enhanced catabolism or turnover of vitamin E may be involved in the inferior tissue alpha-T retention of OFO fed rats.
mesh_terms: D000311:Adrenal Glands / Q000737:chemistry / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D003296:Cooking; D004032:Diet / Q000592:standards*; D004435:Eating; D007408:Intestinal Absorption; D007668:Kidney / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008168:Lung / Q000737:chemistry / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011198:Solanum tuberosum / Q000592:standards; D013024:Soybean Oil / Q000378:metabolism / Q000494:pharmacology* / Q000592:standards; D013154:Spleen / Q000737:chemistry / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis / Q000378:metabolism; D014810:Vitamin E / Q000032:analysis / Q000097:blood / Q000378:metabolism*
chemical_list: D017392:Thiobarbituric Acid Reactive Substances; D014810:Vitamin E; D013024:Soybean Oil