Vitamin K1 and K2 in infant human liver.

It is not known to what extent humans store vitamin K in liver. We measured hepatic concentrations of vitamin K1 (phylloquinone) and K2 (menaquinones) in 11 human livers (eight infants and three adults). Relatively small amounts of vitamin K were found in the liver at any age compared to other fat soluble vitamins. Vitamin K1 was the predominant form with much smaller concentrations of vitamin K2. Long-chain menaquinones (vitamin K2) were readily identified in most liver specimens. Hepatic vitamin K2 concentrations also increased with increasing age. These observations have implications for vitamin K supplementation in infants.