Oral contraceptives and vitamins: a review.

The literature concerning the influence of estrogen-containing oral contraceptives on vitamins is reviewed. The appearance of an elevated plasma concentration of vitamin A is probably without clinical importance, while there seems to be a clear connection between disturbances of vitamin B6 metabolism and mental symptoms. Low levels of folic acid and vitamin B12 have also been noted. Despite this, it is very rare that hematologic abnormalities develop during hormonal contraception. A reduced concentration of vitamin C in plasma and blood corpuscles has been reported. The clinical significance of these alterations is unknown.