Food & Fitness Advisor - Danger lies in certain food-drug combinations: knowing which foods to avoid can reduce your risk of serious complications
Q. Is vitamin K important for bones?
A. Yes, likely very important. A growing body of research suggests that healthy bones need vitamin K just as much as they need calcium. A recent review of 13 studies found that people who took vitamin K supplements suffered less bone loss and an amazing 80% fewer hip fractures than those who didn’t take extra K.
What K Can Do for Bones. Scientists have long known that vitamin K is critical for blood clotting; its role in strong bones is a relatively recent discovery. Researchers believe K improves bone mass and reduces fractures by helping the body produce more of the active form of a bone-building protein called osteocalcin.
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A Japanese study of women over 50 found that as blood levels of vitamin K went up, so did levels of active osteocalcin. Extremely high doses of a form of vitamin K called menaquinone have been used in Japan to treat osteoporosis for more than a decade.
Researchers with the long-running Framingham Heart Study have found that among a group of almost 700 older men and women, those who got about 250 micrograms of vitamin K a day–from both food and supplements–suffered fewer broken hips than those who got only 50 micrograms a day.
How Much You Need. Trouble is, the current recommended intakes for vitamin K–90 micrograms a day for women, 120 for men–aren’t based on what the body needs. Rather, they merely reflect what the average American ingests. There is growing support, however, for an increase in the recommendations.
Where to Get It. Vitamin K is found in many foods, including broccoli, Brussels sprouts, lettuce, parsley and vegetable oils, but the real K standouts are dark leafy greens like kale, spinach, beet greens and collards, which provide 700 to 1,100 micrograms per cup, cooked.
Additional vitamin K is found in supplements–multis, some bone supplements, single supplements–in amounts from zero to 500 micrograms.
K-Coumadin Caveat. While your bones will likely benefit from more vitamin K, be careful if you take the drug warfarin (Coumadin). Vitamin K encourages blood to clot, which can be at odds with Coumadin’s blood-thinning action. One study found that multivitamins containing as little as 25 micrograms of K a day are enough to alter Coumadin’s action.
Be sure you inform your doctor of your typical vitamin K intake–from both diet and supplements–so your Coumadin dosage can be adjusted accordingly. Then keep your intake consistent.
EN’s Bottom Line. Eating a diet rich in green, leafy vegetables and taking a multi with vitamin K should provide the K you need to protect your bones. If you take Coumadin, consult with your doctor before you increase K intake significantly.
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COPYRIGHT 2008 Gale, Cengage Learning
