Vitamin K1 and K2 status and faecal flora in breast fed and formula fed 1-month-old infants

Faecal vitamin K1 (VK1, phylloquinone) and vitamin K2 (menaquinone, MK) concentrations were measured in 12 breast fed and 9 formula fed 1-month-old infants. Faecal concentrations of VK1 and MK-5 to -9 were significantly higher in the formula fed than in the breast fed infants. There was also a tendency for higher total faecal MK (4-10) concentrations in the formula fed [geometric mean (95% confidence intervals); 8995.0 (3872.6, 20,893.0) pmol/g of dry faeces] than in the breast fed infants [2937.7 (1285.3, 6714.3), P = 0.051]. The numbers of streptococci and Escherichia coli were 100 and 10 times higher, respectively, in the faeces of the formula fed than in those of the breast fed infants. Faecal concentrations of MK-6, -7 and -8, and MK-8 were correlated with the numbers of streptococci and E. coli in the faeces, respectively. Serum VK1 and MK concentrations were measured in 9 out of 12 breast fed and eight out of nine formula fed infants. The serum VK1 concentration was much higher in the formula fed infants [average (95% CI); 2.20 (1.48, 2.92) pmol/ml] than in the breast fed ones [0.30 (-0.10, 0.70), P = 0.000], but MKs were not detected in the sera of most of the formula fed infants.