alpha-Tocopherol influences in vivo indices of lipid peroxidation in postmenopausal women given fish oil.

Although diets containing fish have been shown to be therapeutically valuable, the vitamin E requirement when large quantities of (n-3) fatty acids are consumed is not known. Additionally, as estrogens may function as an antioxidant, the requirement may be modified in postmenopausal women using hormone replacement therapy (HRT). Consequently, the purpose of this study was to measure the impact of graduated doses of RRR-alpha-tocopheryl acetate (TA) on in vivo indices of lipid peroxidation in postmenopausal women with and without hormone replacement therapy when given a supplement of fish oil. Forty-eight postmenopausal women, half receiving (+HRT) and half not receiving (-HRT) hormone replacement therapy, participated in a four-period, double-blind crossover trial. Each period lasted 5 wk followed by a 4-wk washout interval. During each period, the subjects consumed a 15-g supplement of fish oil and either 0, 100, 200, or 400 mg TA/d in a balanced, single square dosing order. Plasma levels of (n-3) fatty acids were significantly higher after fish oil supplementation; alpha-tocopherol concentration of plasma was significantly higher at each level of supplementation compared with the level without supplementation. Urinary excretion of thiobarbituric acid reactive substances (TBARS) and malondialdehyde, measured as the thiobarbituric-malondialdehyde adduct (TRA-MDA adduct), and the plasma concentration of the adduct were significantly greater after the fish oil supplement. Although urinary TBARS decreased linearly as the dose of TA increases (P < or = 0.05), urinary and plasma concentrations of TBA-MDA adduct did not. This study suggests that the evaluation of highly unsaturated fatty acids as oxidative stressors requires several measures of assessment.

RCT Entities:   Population Interventions Outcomes