Special K
By Jack Challem
Find out why vitamin K is key for treating osteoporosis, controlling blood sugar, and maybe even preventing cancer.

THE BASICS: Vitamin K has been known since the 1930s as the “coagulation” vitamin because it is essential for normal blood clotting. But recent research has shown that vitamin K supplements can have striking benefits in preventing and reversing osteoporosis, controlling blood sugar, and maybe even reducing the risk of cancer and coronary heart disease.

ALIAS: Vitamin K terminology can get very confusing. The two principal types of vitamin K supplements are K1 and K2. Vitamin K1 (phylloquinone) is found in leafy green vegetables. Vitamin K2 occurs in two forms, MK-4 (menatetrenone-4) and MK-7 (menaquinone-7). The MK-4 form of vitamin K is found in egg yolks, egg mayonnaise, chicken thighs, and dairy products. The MK-7 form of vitamin K is found in natto, a type of fermented soybean food (also sold as a supplement).

HOW VITAMIN K WORKS: Most of vitamin K’s benefits derive from its role in making several key proteins, particularly osteocalcin, needed for strong bones. More technically, vitamin K promotes the carboxylation of osteocalcin. (Carboxylation adds one carbon, one hydrogen, and two oxygen atoms.) Without carboxylation, these proteins cannot do their jobs. Vitamin K is also required for matrix Gla protein (MGP), and animal studies suggest that MGP helps regulate where the body deposits calcium.

HEALTH BENEFITS: Over the past several years, research has revealed multifaceted benefits to vitamin K. Here are the highlights:

Bone health. Low intake of vitamin K interferes with normal bone development and increases the risk of broken bones and osteoporosis. Both Dutch and Japanese researchers have used large amounts of vitamin K2 daily to treat and successfully reverse osteoporosis in women. Nearly all of these studies used 45 mg daily of the MK-4 form of vitamin K2. Vitamin K also reduces bone loss caused by cortisone, blood-thinning drugs, menopause, diabetes, and other health issues.

Blood sugar. In 2007, Columbia University researchers discovered that the bone protein osteocalcin also functions as a hormone. Osteocalcin regulates the number of insulin-producing cells in the pancreas, the secretion of insulin, sensitivity to insulin, and the size of fat cells. Of course, vitamin K is needed to make osteocalcin.

In 2008, researchers at Tufts University reported that vitamin K supplements led to improvements in glucose tolerance in men. The subjects had taken 500 mcg of vitamin K1 daily for three years.

Cardiovascular disease. Calcium deposits in the walls of blood vessels can lead to arterial calcification,
which contributes to hardening of the arteries. In an animal study, researchers found that both vitamin
K1 and K2 reduced arterial calcification by about 50 percent.

Cancer. Vitamin K may help reduce the risk of cancer. So far, two studies of women have shown that vitamin K supplements can significantly reduce the risk of different types of cancer.

BACKGROUND CHECK: You’ll hear a lot of competing claims for the MK-4 and MK-7 forms of vitamin K2. Unfortunately, human studies have not yet directly compared the health benefits or therapeutic effects of MK-4 and MK-7, so no one knows how large amounts of MK-4 might compare with small amounts of MK-7. As a result, there are still many unknowns when it comes to choosing between them. Several studies examining the benefits of MK-7 in people are currently under way in Europe, and the results should be released within one to three years.

GLEANINGS: The official government recommendation is for a scant 90 mcg daily. The evidence suggests that more optimal levels are 500 mcg and up.

HEADS UP: If you take the blood-thinning drug Coumadin, ask your physician to prescribe an anticoagulant that does not interfere with vitamin K activity. If that can’t be done, ask if you can safely take a low-dose (100 mcg) vitamin K supplement. If you are taking anticoagulants, do not take vitamin K without your doctor’s approval first.

WHAT YOU SHOULD TAKE: The amount depends on what you want to achieve. For illness prevention, 500 to 1,000 mcg daily of vitamin K should be fine. To reverse osteoporosis, consider taking as much as 45 mg (not mcg) of vitamin K2 in combination with calcium, magnesium, and vitamin D3.




Product Examples (from left to right)

New Chapter bone strength take care boasts vitamin K1 and K2, along with bone-building vitamin D and calcium.

life extension super k contains 2,100 mcg of vitamin K in both MK-4 and MK-7 forms.

Jarrow formulas mk-7 is a concentrated formula with vitamin K2 from natto.

Enzymatic therapy artery advantage (for circulatory support) is a new product with vitamin K2 (from natto), pomegranate, garlic, folic acid, and vitamin B12.

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