The content of phylloquinone (vitamin K1) in human milk, cows' milk and infant formula foods determined by high-performance liquid chromatography

Abstract

Phylloquinone (2-methyl-3-phytyl-1,4-naphthoquinone) in human and cows' milk and in infant formula foods has been assayed by a method based on high-performance liquid chromatography (HPLC). The method has three chromatographic steps consisting of a preliminary purification of lipid extracts by conventional liquid chromatography, a further fractionation by semipreparative HPLC and a final analytical step by reversed-phase HPLC in which phylloquinone was resolved from the remaining contaminants and quantified by reference to an internal standard (phylloquinone 2,3-epoxide). The identity of the chromatographic peak ascribed to phylloquinone (vitamin K1) was established by mass spectrometry. Mature human milk from 20 lactating mothers gave a mean concentration of phylloquinone of 2.1 micrograms/liter, and colostrum from 9 mothers gave a mean value of 2.3 micrograms/liter. These levels in human milk were significantly lower than those found in either Friesian (holstein) cows' milk (mean 4.9 micrograms/liter) or unsupplemented infant formula foods containing only cows' milk fat (mean 4.2 micrograms/liter). The mean phylloquinone content of two unsupplemented infant formula foods containing only vegetable oils was 11.5 micrograms/liter. After an oral dose of 20 mg phylloquinone, the concentration of K1 in the breast milk of one mother rose to 140 micrograms/liter after 12 hours and at 48 hours was still about twice the average endogenous level of human milk.