ALPHA-TOCOPHEROL INFLUENCES IN-VIVO INDEXES OF LIPID-PEROXIDATION IN POSTMENOPAUSAL WOMEN GIVEN FISH-OIL

Although diets containing fish have been shown to be therapeutically v aluable, the vitamin E requirement when large quantities of (n-3) fatt y acids are consumed is not known. Additionally, as estrogens may func tion as an antioxidant, the requirement may be modified in postmenopau sal women using hormone replacement therapy (HRT). Consequently, the p urpose of this study was to measure the impact of graduated doses of R RR-alpha-tocopheryl acetate (TA) on in vivo indices of lipid peroxidat ion in postmenopausal women with and without hormone replacement thera py when given a supplement of fish on. Forty-eight postmenopausal wome n, half receiving (+HRT) and half not receiving (-HRT) hormone replace ment therapy, participated in a four-period, double-blind crossover tr ial. Each period lasted 5 wk followed by a 4-wk washout interval. Duri ng each period, the subjects consumed a 15-g supplement of fish oil an d either 0, 100, 200, or 400 mg TA/d in a balanced, single square dosi ng order. Plasma levels of (n-3) fatty acids were significantly higher after fish oil supplementation; alpha-tocopherol concentration of pla sma was significantly higher at each level of supplementation compared with the level without supplementation. Urinary excretion of thiobarb ituric acid reactive substances (TEARS) and malondialdehyde, measured as the thiobarbituric-malondialdehyde adduct (TBA-MDA adduct), and the plasma concentration of the adduct were significantly greater after t he fish oil supplement. Although urinary TEARS decreased linearly as t he dose of TA increased (P less than or equal to 0.05), urinary and pl asma concentrations of TBA-MDA adduct did not. This study suggests tha t the evaluation of highly unsaturated fatty acids as oxidative stress ors requires several measures of assessment.