Vitamin K₁ Content of Maternal Milk: Influence of the Stage of Lactation, Lipid Composition, and Vitamin K₁ Supplements Given to the Mother

Abstract

ABSTRACT. Using a sensitive electrochemical assay for vitamin K₁ and standardized techniques for breast-milk collection, we studied the vitamin K₁ content of human milk during the first 5 wk of lactation with respect to 1) individual and interindividual differences, 2) the relationship of vitamin K₁ to other lipids, and 3) the influence of oral supplements of vitamin K₁ on breast milk concentrations. Comparison of fore and hind milk from the mothers revealed higher vitamin K₁ concentrations in hindmilks, suggesting that the lipid content influences the vitamin K₁ concentration in maternal milk. Samples of maternal milk from nine mothers collected from day 1 to day 36 of lactation showed significantly higher vitamin K₁ concentrations in colostral milk than in mature milk. For colostral milk there was a significant correlation of vitamin K₁ to cholesterol (r = 0.62) but not to total lipid or phospholipid suggesting a role for cholesterol in the secretion of vitamin K₁ into colostral milk. For mature milk correlation coefficients of vitamin K₁ with all lipids were low (r = 0.29- 0.37) suggesting that at later stages of lactation dietary fluctuations of vitamin K₁ may be a more important determinant of the vitamin K₁ content of breast milk than the lipid composition. To test the influence of diet, mothers were given oral supplements of vitamin K₁. Doses of 0.5- 3 mg produced substantial rises in breast milk vitamin K₁ with peak levels between 12 and 24 h. In one mother in whom the milk sampling was standardized, a dose-response relationship was observed: the lowest dose of 100 μg was similar to that which might be ingested in a meal and produced a 2-fold increase in the vitamin K₁ content of breast milk.