Dietary folate intake and concentration of folate in serum and erythrocytes in women using oral contraceptives.

Conflicting reports regarding the possible effect of oral contraceptives agents (OCA's) on folate status prompted us to evaluate the relationship between dietary folate intake and the concentration of folate in serum and erythrocytes among users and nonsuers of OCA's during two consecutive menstrual cycles. Twenty-two women (ages 19 to 28) had been on combination type OCA's for 4 months or more and a control group of 18 women (ages 18 to 29) had not used OCA's for at least 6 months prior to this study. The serum folate levels were lower in the OCA users than in the controls and the difference was statistically significant on day 5 of the menstrual cycle (P less t-an 0.05) but not on day 20. However, the differences in the erythrocyte folate levels and dietary folate intakes were not statistically significant between the two groups of subjects. There was a consistently higher degree of correlation between serum folate and folate intake among the control women than among the OCA users. Hematological parameters such as hemoglobin, hematocrit, mean corpuscular volume, mean corpusclar hemoglobin, mean corpuscular hemoglobin concentration and red cell count were similar in the two groups. It is concluded that the use of OCA's produces significantly lower serum folate levels during the first week of the menstrual cycle in spite of adequate folate intake.