A longitudinal study of pyridoxine and zinc supplementation of lactating women

Forty lactating women were randomly assigned to four treatment groups. Beginning at 1-d postpartum the women in each group received a daily vitamin-mineral supplement for 9 mo. The treatments differed only in the amount of vitamin B-6 (0.5 or 4.0 mg pyridoxine) and zinc (0 or 25 mg) included in the supplements. The 4.0-mg pyridoxine supplements significantly increased plasma total vitamin B-6, plasma pyridoxal phosphate (PLP), and milk total vitamin B-6, thus showing that maternal intake exerts a significant effect on vitamin B-6 concentration in milk. There was no effect of vitamin B-6 intake on plasma, erythrocyte, or milk zinc concentration. The 25-mg zinc supplement also had no effect on plasma, erythrocyte, or milk zinc concentration, suggesting that maternal zinc intake is not a major regulator of milk zinc concentration.