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Life Extension Magazine

LE Magazine June 2007
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Vitamin K & Warfarin


Stabilizing Anticoagulant Therapy—While Protecting Cardiovascular and Bone Health By Laurie Barclay, MD

Dosage and Safety

Currently, the recommended daily allowance (RDA) of vitamin K is 70-80 mcg/day for men and 60-65 mcg/day for women.23 Recent studies of vitamins K1 and K2 suggest that the present RDA is too low to fully protect against atherosclerosis and heart disease.17,35 Some experts now suggest that low-dose vitamin K supplementation (50-150 mcg/day) may help stabilize fluctuations in INR in individuals who use warfarin.5 If you use warfarin, discuss the possible benefits of vitamin K supplementation with your physician. Certain medications, including cholestyramine, colestipol, mineral oil, and orlistat may decrease the absorption of vitamin K. Large doses of salicylates such as aspirin may result in vitamin K deficiency. Cephalosporin antibiotics can cause vitamin K deficiency.23

Conclusion

Recent evidence clearly indicates that vitamin K is crucial not only for proper regulation of blood clotting, but also for optimal bone and cardiovascular health. In patients on long-term treatment with the anticoagulant warfarin, vitamin K may also facilitate control of anticoagulation therapy, so that the INR remains in ideal range, without frequent changes in the warfarin dose. The result may be more consistent benefits of therapy—such as decreased risk for heart attack and stroke, and fewer risks—such as hemorrhaging. If you use warfarin, discuss the benefits of modest vitamin K supplementation with your physician.

References

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5. Sconce E, Khan T, Mason J, et al. Patients with unstable control have a poorer dietary intake of vitamin K compared to patients with stable control of anticoagulation. Thromb Haemost. 2005 May;93(5):872-5.

6 Couris R, Tataronis G, McCloskey W, et al. Dietary vitamin K variability affects International Normalized Ratio (INR) coagulation indices. Int J Vitam Nutr Res. 2006 Mar;76(2):65-74.

7. Sconce E, Avery P, Wynne H, Kamali F. Vitamin K supplementation can improve stability of anticoagulation for patients with unexplained variability in response to warfarin. Blood. 2007 Mar 15;109(6):2419-23.

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27. Booth SL, Tucker KL, Chen H, et al. Dietary vitamin K intakes are associated with hip fracture but not with bone mineral density in elderly men and women. Am J Clin Nutr. 2000 May;71(5):1201-8.

28. Bolton-Smith C, McMurdo ME, Paterson CR, et al. Two-year randomized controlled trial of vitamin k(1) (phylloquinone) and vitamin d(3) plus calcium on the bone health of older women. J Bone Miner Res. 2007 Apr;22(4):509-19.

29. Cockayne S, Adamson J, Lanham-New S, et al. Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials. Arch Intern Med. 2006 Jun 26;166(12):1256-61.

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