Vitamin K prevents coronary artery calcification.

Three hundred eighty-eight healthy men and women (aged 60 to 80 years) were randomly assigned to receive, in double-blind fashion, a multivitamin with or without (control group) 500 mcg/day of vitamin K1 for 3 years. Among the 367 participants who took at least 85% of the assigned tablets, the rate of progression of coronary artery calcification was significantly less in the vitamin K1 group than in the control group (p = 0.03). Of participants with preexisting coronary artery calcification, the rate of progression was significantly lower by 6% in the vitamin K1 group than in the control group (p = 0.04).

Comment: Coronary artery calcification is an independent predictor of cardiovascular disease and cardiovascular-disease related mortality. Vitamin K plays a role in the synthesis of matrix-Gla protein, which is a strong inhibitor of vascular calcification. In rats fed a vitamin K-deficient diet, treatment with warfarin (a vitamin K antagonist) resulted in arterial calcification. The results of the present study suggest that increasing vitamin K1 intake (by consuming more leafy green vegetables or taking a supplement) can prevent cardiovascular disease. The study also raises questions about the long-term safety of warfarin. Although this drug reduces the incidence of strokes in patients with atrial fibrillation and is useful for other patients at high risk for thromboembolism, it might in the long run increase the progression of coronary artery disease. Unfortunately, there are no well-documented effective alternatives to warfarin in certain clinical situations. However, nutritional interventions (such as fish oil, garlic, and vitamin E) show promise, and should be investigated further.

Shea MK et al. Vitamin K supplementation and progression of coronary artery calcium in older men and women. Am J Clin Nutr. 2009;89:1799-1807.

by Alan R. Gaby, MD

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