• VITAMIN K
• NUTRITION
• BLOOD COAGULATION
• BONE METABOLISM
• VASCULAR BIOLOGY
• K1 vs K2

Human volunteer studies have shown that the absorption of phylloquinone from vegetables is low (between 3 and 10%), and depends on the concomitant fat intake. The poor bioavailability of plant phylloquinone may be explained by its tight association with the chloroplasts. In contrast, the efficacy of absorption from pharmaceutical vitamin K₁ concentrates, was found to be much higher (>80%).

Table 2: Mean vitamin K-intake (µg/day) by quartiles. The data are median intakes (µg/day) calculated from validated food frequency questionnaires, which were obtained from subjects between 55 and 70 years of age. For these calculations we used a database containing the vitamin K content of several hundreds of food items. The data were not corrected for energy intake.

The data in table 2 show that in most cases the daily intake of vitamin K₁ will exceed that of menaquinones by far. Whereas it is relatively easy to prepare a meal containing 2 mg of K₁, it is hard to compose a palatable meal containing more than 0.2 mg of menaquinones. The intestinal absorption of menaquinones from dairy food is substantially better than that of K₁ from green vegetables.

The Japanese food natto (fermented soy beans) contains high concentrations of menaquinone-7. A linear dose-response curve for serum MK-7 was found after natto consumption, with a 10- fold better absorption of MK-7 than that of K₁ from spinach, eaten in the same meal (see Figure). These data demonstrate that the absorption of ingested K-vitamins depends on the type of the vitamin and on the food matrix. Other factors, such as the apolipoprotein E genotype may also affect the availability of vitamin K in the various target tissues.

Recommended literature:

• Gijsbers, B.L.M.G., Jie, K.-S.G., Vermeer, C. (1996). Effect of food composition on vitamin K absorption in human volunteers. Brit. J. Nutr. 76, 223-229.
• Geleijnse, J.M., Vermeer, C., Grobbee, D.E., Pols, H.A.P., Schurgers, L.J., Knapen, M.H.J., van der Meer, I.M., Hofman, A., Witteman, J.C.M. (2004). Dietary intake of vitamin K-2 reduces the risk of cardiac events and aortic atherosclerosis: The Rotterdam Study. J. Nutr. 134, 3100-3105.
• Schurgers, L.J., Vermeer, C. Determination of phylloquinone and menaquinones in food. Effect of food matrix on circulating vitamin K concentrations. Haemostasis 2000; 30: 298-307
• Schurgers, L.J., Geleijnse, J.M., Grobbee, D.E., Pols, H.A.P., Hofman, A., Witteman, J.C.M., Vermeer, C. Nutritional intake of vitamins K-1 (phylloquinone) and K-2 (menaquinone) in the Netherlands. J Nutr Environm Med 1999: 9: 115-122.