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

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 B-6, and vitamin B-12 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 B-6, however, existing population-based data do provide evidence that current low-dose OCs may negatively impact vitamin B-6 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 B-6 inadequacy during pregnancy. Functional indicators of vitamin B-12 status are not significantly impacted by OC use. Definitive conclusions, however, await further investigations. (C) 2011 International Life Sciences Institute