RESUMO
The present investigation is concerned with studying the effect of feeding adult female rats, standard synthetic diet, diets [deprived, deficient and supplemented] with high dose of vitamin B1 on vitamin B1 functional activity during prolonged administration of an oral contraceptive [O.C] [Containing 0.035 mg ethinyl estradiol and 0.5 mg norethindrone]. The experiment lasted for 165 days. Blood samples were withdrawn after 15, 45, 75, 105, 135 and 165 days from O.C administration, for the determination of vitamin B1 level by a functional test, i.e. erythrocyte transketolase [ETK] basal activity and after in-vitro thiamin pyrophosphate addition [TPP]. Results were discussed. It is proved that a proper high dose of vitamin B1 should be given during prolonged oral contraceptive administration