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 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.