Vitamin B6 status of Nigerian women using various methods of contraception.

The vitamin B6 status of Nigerian women, and the effects of three contraceptive methods--intrauterine contraceptive device, injectable progestogen, and combination estrogen-progestogen oral contraceptive pills--on the vitamin B6 status of these women were assessed by measuring the erythrocyte alanine aminotransferase (Ala-AT) activity both with and without in vitro stimulation by pyridoxal-5'-phosphate. The unstimulated Ala-AT activity and the Ala-AT index (ratio of pyridoxal-5'-phosphate-stimulated:unstimulated activity) were used as indications of vitamin B6 status. The criterion for vitamin B6 deficiency was an Ala-AT index greater than 1.25. Of the 238 women in the total sample, 11% were judged to be deficient. There were no significant differences in the mean Ala-AT activity, mean Ala-AT index or rate of deficiency foun in the control and three contraceptive groups. The absence of an effect of oral contraceptives on vitamin B6 status is in contrast with other cross-sectional studies, but in agreement with controlled longitudinal studies. The packed cell volume and reticulocyte count were also measured and were significantly affected by contraceptive steroids, but these effects are not thought to be of clinical importance.