Oral contraceptive use: impact on folate, vitamin B6, and vitamin B12 status


L Bailey, Department of Foods and Nutrition, 280 Dawson Hall, University of Georgia, Athens, GA 30602, USA. E-mail: folate@uga.edu, Phone: +1 706-542-4256, Fax: +1 706-542-5059.


Since many unplanned pregnancies occur while women are using oral contraceptives (OCs), it is important to understand the potential impact of these drugs on folate, vitamin B6, and vitamin B12 status. Although a number of early studies concluded that OCs negatively impact folate status, the majority of these studies were conducted when the estrogen content of OCs was much higher. In addition, the interpretation of findings from many of these studies is problematic since no controls were included for potentially confounding factors. The presently available data do not support a conclusion that currently used OCs negatively impact folate status. In regard to vitamin B6, however, existing population-based data do provide evidence that current low-dose OCs may negatively impact vitamin B6 status. The observed depression in plasma pyridoxal 5′-phosphate concentrations in OC users may reflect decreased body reserves of the vitamin, which could put women who discontinue OCs and become pregnant at risk for vitamin B6 inadequacy during pregnancy. Functional indicators of vitamin B12 status are not significantly impacted by OC use. Definitive conclusions, however, await further investigations.