Q.I have read that vitamin K supplements can help prevent heart disease. Should I take them?
A. Vitamin K — which is found in high levels in green leafy vegetables like spinach, kale, and romaine lettuce — plays a role in helping the body make blood clotting proteins. Although some observational studies have suggested a heart benefit from diets high in vitamin K, studies of supplements have not shown a protective effect.
There are two types of vitamin K: phytonadiones (K1), found in green leafy vegetables and vegetable oils, and menaquinones (K2), found in dairy and fermented foods. Both types have some antioxidant properties, which may slow the progression of atherosclerosis. Other research has suggested vitamin K plays a role in slowing calcium deposits in artery walls.
However, clinical trials of vitamin K supplements have not shown the same positive effects. This may mean other nutritional factors in vitamin K-rich foods are at play. It is also possible these studies don’t have long enough follow-ups to measure any true benefit. So, at this time, it is premature to recommend vitamin K supplements for helping to prevent heart disease.
— by William Kormos, M.D.
Editor in Chief, Harvard Men’s Health Watch
Image: © andriano_cz/Getty Images
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