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by Stephen T. Sinatra, M.D., FACC
Something Exciting Vitamin K2:
for Heart and Bone Health
I used to be a typical cardiologist. I did thousands of angiograms and emergency cardiac procedures. I rolled up my sleeves at all hours of the day and night and holidays in order to save patients a heartbeat away from death.
That was before I discovered nutritional medicine and discovered I could prevent many of my patients from getting so sick that they required medical heroics to save their lives. For more than two decades, I’ve been practicing what I call “smart medicine,” using the best of conventional and complementary care. I am as comfortable recommending nutritional supplements and mind/body approaches to my patients, as I am prescribing bypass surgery or a heart drug.
I integrate what works the best, and that includes many different cardiovascular-targeted supplements—fish oil, vitamin C, selenium, niacin, B6, B12, folic acid, L-arginine, CoQ10, L-carnitine, magnesium, and D-ribose, just to name a few. All are valuable weapons in the fight against arterial disease and plaque.
I’m always on the lookout for yet another food source or supplement that can add more firepower. I believe I have found one—and it’s a potential blockbuster. It’s vitamin K2, a subtype of vitamin K.
Savvy readers like you are probably familiar with vitamin K to some degree, but most people know little about it. Vitamin K is important because of its vital role in the coagulation of blood. The designation K comes from Denmark—where the vitamin was discovered in 1929—and the Danish word koagulation.
You are most familiar with the K1 form of the vitamin, found abundantly in green leafy vegetables, such as kale, spinach, broccoli, and Brussels sprouts. K2 is less abundant among foods. The highest concentration occurs in natto (pronounced NAH-toe), a traditional Japanese fermented breakfast soybean dish. Its use dates back hundreds of years to the age of Samurais who believed it increased their strength and quickened their reflexes. K2 is also present, though not quite as much, in cheese.
Both K1 and K2 are important for the health of bones and arterial tissue. However, recent studies indicate that K2 is the most medically significant of the vitamin K subtypes, and better able to deliver a powerful double dividend that should have most doctors eager to prescribe it for patients:
• It helps protect bones from osteoporosis.
• It helps protect arteries from calcification, a common
contributor to dangerous, vulnerable plaques prone to rupture and cause heart attacks and stroke.
Here are the exciting details in brief: Among the countless enzyme processes at work in the body are two that help keep calcium in the bones and out of the arterial walls. Both are vitamin K dependent. One uses a protein called osteocalcin to carry calcium from the blood and knit it into the bone matrix. Without the K, the calcium becomes deposited in arterial walls, where you definitely don’t want it. And in the arterial walls, K contributes to a protein called matrix GLA protein (MGP) that protects the tissue from calcium infiltration.
I first learned about K2 in my research on osteoporosis, the common bone loss problem affecting us as we get older. Many of my elderly patients have some degree of osteoporosis. It’s a big challenge for doctors—how to reverse the bone density loss that leaves you at risk for fractures? It’s a downhill process that starts affecting women about ten years or so before men.
Doctors have a number of standard prescriptions available, including Fosamax, a drug I have little regard for. It may make bone density tests look better but it does not really improve the strength of the bones. About the only nutritional supplement that most conventional doctors will recommend is calcium for bone health. But calcium supplements haven’t solved the osteoporosis problem either. One reason for that is a widespread deficiency of vitamin K. People just aren’t that fond of K foods. And in the West, hardly anybody has heard of natto.
Some interesting population studies illustrate the potential of K2. Japanese living in the general Tokyo area eat more natto than any other population on the planet. To determine the influence of natto, and K2, on osteoporosis, Japanese researchers compared the bone density and fracture incidence of nearly a thousand Tokyo and Hiroshima women, and for additional comparison, looked at British women as well. The consumptions of natto in Hiroshima, located in western Japan, is much less than in Tokyo, and British intake is nil. But Englishwomen do eat some cheese and curds, which contain K2, although to a lesser degree.
Among postmenopausal women, the age group most commonly affected by osteoporosis, the researchers found a strong relationship between higher natto intake, better bone density and lower incidence of fractures. The Tokyo women won hands down, followed by the Hiroshima women, and then the British women. No similar association was found for tofu. Natto, through the effect of K2, “may help prevent postmenopausal bone loss,” they concluded in an article last year in the Journal of Nutrition.
During my investigations I came across the work of Cees Vermeer and Leon Shurgers, biochemists at Holland’s Maastricht University, who are doing cutting-edge research with vitamin K2, not just related to osteoporosis but to critical cardiovascular disease issues as well. I was so impressed by their findings that I arranged to meet with them. They had set out to learn if dietary K2 could help in the prevention of arterial calcification in humans after conducting animal studies indicating the vitamin generated reversal of aortic plaque. Their studies with rodents dramatically demonstrated the role of MGP, the arterial wall protein that helps repel calcium. MGP-deficient rodents, otherwise normal at birth, begin to experience arterial calcification at one week of age. After three weeks, the arteries are so fragile that the animals will soon die unless they get vitamin K in their diet.
For the human study, the researchers examined the food intake and aorta scans of 4,800 elderly Dutch men and women. The aorta is the largest artery in the body, and the condition of the artery serves as a good indicator for the presence of arterial disease.
Their investigation showed that people who ingested the most K2 in their diets—mostly obtained from cheese—had the least calcified aortas. The higher the intake of cheese the less cardiovascular mortality and atherosclerosis the researchers found.
These revelations have been real eye openers for me as a cardiologist. The Holy Grail of cardiology is plaque stabilization and reversal. I believe that K2 really gives us a powerful new weapon for achieving that elusive goal. I think the potential here is huge and I have recommended the vitamin to many of my patients.
Unlike us Americans, the Dutch are tremendous cheese eaters, a national tradition that apparently serves the heart health of Dutchmen. Eating cheese as a protective effect against arterial calcification? This is a mind blower for cardiologists, who tend to steer people away from cheese because of its saturated fat content. So make it low fat cheese, the Dutch researchers told me. That way you get less fat but still get the K2.
They also suggested that the French fondness for cheese may be an unsuspected reason for the relatively low level of heart disease in France despite the notoriously high intake of fatty foods. We have long believed that the salvation of French hearts was due to copious consumption of red wine, however, the new K2 research indicates there may be more to the story. In cheese-eating societies like Holland and France, it looks like there’s super benefits from all that cheese. Who would have thought?
Cheese, whether hard or soft, will give you between 30 and 60 micrograms per 4 ounce. Compare that to natto, the Japanese soy dish, which contains a whopping 1,000 mcg. However, most Westerners don’t like the taste of natto. (Most Asian groceries, and some health food stores, carry natto, and you can also have it shipped to you through the Web site http://www.anasuper.com).
Cheese is a more palatable option for us. I have reintroduced a variety of cheese into my diet. My preference is organic, to avoid the pesticides and hormones contained in regular commercial products. I like organic skimmed cottage cheese and if you’re interested in a fatless cheese, this is the way to go. Cottage cheese also has good K2 content.
I am not very concerned about the saturated fat in cheese. Saturated fat is a source of cholesterol and if you eat a lot of it, your cholesterol level will rise. However, I’m not a big believer in the cholesterol explanation as the cause of heart disease so it’s not really a big deal for me.
As far as K2 supplementation is concerned, the therapeutic daily dosage I recommend to my patients is 150 mcg. If you are taking the blood-thinning medication Coumadin, don’t use a vitamin K supplement that might neutralize the effect of Coumadin. On the other hand, don’t omit green leafy vegetables from your diet, or natto if you can get it and camouflage the taste. Remember that vitamin K is critical for your arterial and bone health. Your doctor can adjust your level of Coumadin, if needed. That’s what I do with my patients.
One further point about K2. There are a number of subtypes of K2. Each has a slightly different chemical structure. Most of the research with K2 has been done with a form called MK-4, which has been commercially available for over 20 years. However, recent research with another form, called MK-7, shows greater promise: better absorption and much longer retention in the body. Both benefit bone strength and protect against cardiovascular calcification, however MK-4 requires much higher doses to do so (measured in milligrams) than MK-7 (in smaller microgram doses). MK-7 thus appears to be more efficient. Moreover, commercial MK-4 is synthetic, whereas MK-7 is extracted from natto.
Stephen T. Sinatra, M.D. is author of Reverse Heart Disease Now (Wiley) and the popular monthly newsletter, “Heart, Health, & Nutrition” (http://www.drsinatra.com). He is director of The New England Heart and Longevity Center in Manchester, CT.
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