Effect of oral contraceptive agents on thiamin, riboflavin, and pantothenic acid status in young women

Oral contraceptive agents (OCAs) do not cause significant changes in biochemical parameters of thiamin, riboflavin, and pantothenic acid status when dietary intakes and times of sampling in the menstrual cycle are controlled. The activity of erythrocyte transketolase (ETK) or erythrocyte glutathione reductase (EGR) was not affected by OCA use, nor was the response of these enzymes to in vitro stimulation by their cofactors. However, the enzymes were responsive to the levels of thiamin and riboflavin fed during the study. ETK and EGR stimulation by their cofactors was significantly lower on day 12 than on day 1. In the non-OCA group, EGR stimulation was significantly decreased by day 12, but not ETK stimulation. Differences in blood and urinary pantothenic acid levels at the start, lower in the OCA group, were no longer apparent at the conclusion.