Vitamin B-6 status of breast-fed neonates: influence of pyridoxine supplementation on mothers and neonates.

Vitamin B-6 concentrations in human milk are known to respond rapidly to changes in maternal vitamin B-6 intake. In this study, mothers were supplemented during the first 28 d of lactation with 2 or 27 mg pyridoxine (PN)-HCl/d and a subgroup of breast-fed infants of the 2-mg/d-supplemented mothers were supplemented with 0.4 mg PN-HCl/d. Vitamin B-6 intakes of breast-fed infants reflected the amount of their mother's supplement; intakes were highest for the vitamin-supplemented infants. Vitamin B-6 intake of mothers was a strong indicator of infant vitamin B-6 status. Vitamin intake of infants correlated significantly with five measures of vitamin B-6 status. Plasma pyridoxal-5'-phosphate (PLP) concentrations and birth weight were the strongest predictors of infant growth that were examined. Alkaline phosphatase activity in the mother's milk and infant plasma reflected pyridoxal-PLP ratios in these fluids, suggesting that the enzyme acts in regulating circulating vitamer concentrations.