A Hydrogenated form of Vitamin K: Its Relative Bioavailability and Presence in the Food Supply

Evidence that vitamin K may have a role in bone and cartilage metabolism has stimulated analysis of vitamin K in foods. These food composition data are being applied to dietary assessment and bioavailability studies. Representative samples from the U.S. food supply have been analysed for phylloquinone (vitamin K1). Among those foods containing hydrogenated vegetable oils, phylloquinone is hydrogenated to 2′,3′-dihydrophylloquinone (dK), which reduces the overall phylloquinone content of the oil. The presence of dK has been confirmed in the U.S. and U.K. food supplies. To compare the bioavailability of dK with phylloquinone, we conducted a metabolic study using a crossover design. Following a 15-d depletion of dietary phylloquinone, subjects (n=15) were fed 200 μg/d of either phylloquinone or dK. When compared to phylloquinone, dK had less biological activity in hepatic vitamin K-dependent proteins (P=0.006) and no biological activity in extra-hepatic vitamin K-dependent proteins (P>0.001). Even though dK has a lower relative bioavailability than phylloquinone, its presence in the food supply should be accounted for in food composition databases.