Vitamin K, MK-7 Benefits Blood

MAASTRICHT, NetherlandsVitamin K supports blood and vascular health, and long-chain menaquinone-7 (MK-7) may prove more efficacious than short-chain vitamin K1 in supplements, according to two new studies out of Maastricht University, both published in Blood, the official journal of the American Society of Hematology.

The first study (109:2823-831, 2007) examined the effect of a high vitamin K diet on arterial calcification (AC) in rats. AC is inhibited by Matrix Gla protein (MGP), and the activity of MGP depends on vitamin K. In this study, vitamin K uptake was blocked by warfarin (a coagulant drug), leading to rapid calcification of the arteries for six weeks; animals were then randomized to continue receiving warfarin, or a diet with a normal (5 mcg/g) or high (100 mcg/g) amount of vitamin K. After six weeks, both vitamin K-rich diets decreased AC by almost 50 percent.

In the second study (109:3279-83, 2007), researchers compared the absorption and efficacy of vitamin K1 and MK-7 in healthy adults. Serum vitamin K species were used as a marker for absorption, and osteocalcin carboxylation a marker for activity. Both K1 and MK-7 were absorbed well, with peak serum concentrations at four hours after intake. The greater difference between the forms was seen in the half-life time of MK-7, which resulted in more stable serum levels and greater accumulation (seven- to eight-fold) during prolonged intake. MK-7 also induced more complete carboxylation of osteocalcin.