How The Body Gets Its Vitamin K

NPC1L1, a protein involved in cholesterol transport, also doubles up as a vitamin K transporter, study shows.

AsianScientist (Mar. 20, 2015) – Scientists have identified how the essential nutrient vitamin K is taken up by the body. Their results, published in Science Translational Medicine, could inform the treatment of patients on blood thinning medication such as warfarin.

Vitamin K is an essential nutrient that activates blood coagulation. Recently, vitamin K has attracted considerable attention because of its physiological functions which include protective and/or therapeutic effects against osteoporosis and atherosclerosis. Since we cannot synthesize vitamin K in our body, it is necessary to ingest this nutrient as part of our diet. However, the molecular mechanism of intestinal vitamin K absorption remained unknown.

A research group including Associate Professor Tappei Takada, Assistant Professor Yoshihide Yamanashi, former graduate student Kentaro Konishi and Professor Hiroshi Suzuki at the Department of Pharmacy, the University of Tokyo Hospital, demonstrated for the first time that NPC1L1, a cholesterol transporter protein, has an important role in intestinal vitamin K absorption.

Ezetimibe, an NPC1L1 inhibitor clinically used for dyslipidemia, has been reported to enhance the pharmacological effect of warfarin, an anticoagulant drug. However, the mechanism of this drug-drug interaction was not clear. Based on the finding that vitamin K is mainly absorbed by the NPC1L1-mediated pathway, the research group found via pharmacological studies that the ezetimibe-warfarin interaction can be accounted for by the ezetimibe-related vitamin K malabsorption.

These findings will contribute to better understanding of regulatory mechanisms of intestinal vitamin K absorption and whole-body vitamin levels, and, in addition, promote effective pharmacotherapy and appropriate dose settings considering the alteration of vitamin absorption.

The article can be found at: Takada et al. (2015) NPC1L1 is a Key Regulator of Intestinal Vitamin K Absorption and a Modulator of Warfarin Therapy.


Source: University of Tokyo.
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