The way of K

Vitamin K for Heart and Bone Health

Your bones and your heart want the same thing: plenty of vitamin K.

This past April, in the e-Alert “Fire in the Joint” (4/25/06), I told you how a deficiency of vitamin K may be associated with abnormalities in bone and cartilage – a factor that increases the severity of osteoarthritis.

Now we find that heart health might also require ample amounts of vitamin K as well.

Living well is the best prevention

Was it healthy living, or a high intake of vitamin K that helped thousands of men avoid coronary heart disease (CHD)?

That’s the question prompted by the results of a study conducted by a team of researchers from the Harvard School of Public Health, Tufts University and the University of Kuopio in Finland.

STUDY ABSTRACT

• Researchers examined CHD data and food frequency questionnaires gathered from more than 40,000 men
• During the 15-year study period, 1,860 CHD events were recorded
• On average, subjects had a daily intake of 165 mcg of vitamin K per day (Vitamin K RDA is 65 mcg for women and 80 mcg for men)
• Subjects with the highest K intake (about 312 mcg per day) reduced their risk of fatal CHD by nearly 20 percent

So – did this benefit come from the vitamin or the lifestyle? Probably both.

Researchers found that men with the highest K intake tended to follow diets and lifestyles that would naturally contribute to CHD prevention and cardiovascular health. Meanwhile, studies suggest that Vitamin K may play a key role in preventing calcification of the arteries.

Forms and sources

Almost our entire vitamin K intake comes in the form of K1, which is mostly found in dark, leafy green vegetables, broccoli, asparagus, tomatoes, avocados, olive oil, whole wheat, butter and green tea. It’s not surprising that people who include an abundance of these foods in their diets would also make healthy lifestyle choices, such as exercising regularly and avoiding smoking.

Vitamin K1 is converted into K2 in the intestine, but we get some amount of K2 directly from meat, liver, egg yolk, and especially from fermented products such as yogurt and cheese.

Vitamin K supplements are useful for addressing two important health issues. In his Nutrition & Healing newsletter, Jonathan V. Wright, M.D., noted that supplementing with K is a good idea if there’s a family history of osteoporosis. “There’s also enough preliminary evidence to say that if there’s a family history of arteriosclerosis (‘hardening of the arteries’), you probably should.”

Dr. Wright recommends 5 to 15 MILLIGRAMS of vitamin K per day – considerably more than the highest intake in the Harvard/Tufts/ Kuopio study.

When I asked HSI Panelist Allan Spreen, M.D., about vitamin K, he told me that K intake also provides another kind of protection: “An old study from the late ’40s showed that vitamin K was clearly helpful against tooth decay. But the biggest news more recently has been concerning vitamin K as a strong bone-builder.”

If you talk to your doctor about supplementing with K, keep these guidelines from Dr. Spreen in mind: “The synthetic form (K3, or menadione) has caused some liver toxicity and, rarely, a form of anemia when taken in high doses. There’s also K2 (or menaquinones), but K1 and K2 are fine. As usual, it seems best to avoid synthetic forms, if possible. If the individual is on coumadin (blood thinner), he needs to talk with his doctor, as vitamin K can interfere with its effect.”