Vitamin K2 Benefits

A little-used supplement called vitamin K2 offers enormous benefits for both cardiovascular and bone health. And a specific kind of vitamin K2 known as MK-7 outshines all the other formulations of vitamin K in helping people grow stronger bones by removing calcium for plaques in the linings of arteries. Knowing how to choose the right vitamin K supplement, however, begins with knowing vitamin K by the numbers used to describe it.

Vitamin K by the Numbers

Vitamin K consists of a complex of chemicals variously named vitamin K1, vitamin K2, and vitamin K3. Actually, there are five numbered kinds of vitamin K, not just three, and some of the subtypes have up to 13 chemical variations. What is the difference? And why should you care?

Different kinds of vitamin K play different roles in health protection. The first recognized role of vitamin K was in regulating blood clotting factors. Back in the heyday of vitamin discovery, a Danish chemist named Henrik Dam noticed that chickens (thousands of vitamin research studies of the time involved chickens) placed on low-fat diets developed leaky blood vessels.

Further investigation revealed that the low-fat diets were deficient in a substance Dr. Dam called the "Koagulation Factor," Koagulation being the German word for coagulation. (Dam published his findings in a German medical journal.) This compound came to be known as vitamin K. Nowadays we would call the substances he discovered vitamin K1 and vitamin K2.

Vitamin K1, also known as phylloquinone, is found in plant foods. Natural sources of K1 include broccoli, iceberg lettuce, kale, collard greens, watercress, and spinach, as well as canola, soybean, and sunflower oil. Vitamin K2, also known as menaquinone, is found animal-derived foods and soy. Natural sources of K2 include butter, some kinds of cheese, fermented soy products, especially a product called natto, and chicken livers.

Nutritional science also recognizes vitamin K3, vitamin K4, and vitamin K5, although they are manufactured, not natural. Vitamin K3 is a synthetic chemical known as menadione. It's used in enormous quantities in the manufacturing of pet foods. Vitamin K4, menadiol acetate, is another synthetic chemical used as an injected medication to treat diseases that cause excessive bleeding. And vitamin K5, or 4-amino-2-methyl-1-napthol, is a synthetic chemical used as a fungicide.

Vitamin K1 and vitamin K2 have similar functions in the human body. However, it is a lot easier for the body to absorb vitamin K2 from animal-sourced foods and soy foods like natto than it is for the body to absorb vitamin K1 from plant foods.

A serving of spinach, for example, might contain enough vitamin K for a whole day's needs, but the vitamin K is so tightly bound in the tough fibers around the chloroplasts (where the leaf keeps chlorophyll), that only about 5% of the vitamin K1 in the spinach actually reaches the bloodstream. It is easier for the intestines to receive vitamin K1 when the plant foods containing it are combined with fat, but this only brings up the level of absorption to about 13%.

On the other hand, the human body has relatively little difficulty absorbing vitamin K2 from animal foods and fermented soy products. Adding to the confusion surrounding vitamin K nomenclature, vitamin K2 actually has two different forms.

One of these forms, menaquinone-4, also known as MK-4, is found in meat, eggs, and dairy products. The other, menaquinone-7, or MK-7 is made by the bacteria that ferment natto, the bacteria that ferment cheese (although most of the vitamin K in cheese is MK-4), and by friendly bacteria that live in the human colon. (There are actually 13 different menaquinone forms of vitamin K, but these two are the most important.) Even if you don't get vitamin K from food, you can still get small amounts of MK-7 from the bacteria that live inside you.

What is the importance of all this nomenclature? The important thing to remember is what kinds of vitamin K actually work for you if you take them. Here are the essentials:

• Both vitamin K1 and vitamin K2 "work" inside the human body.
• Vitamin K1 is in plant foods, but it is hard for the body to absorb it.
• Vitamin K2 is easier for the body to absorb, because it is usually found in fatty foods.
• The kind of vitamin K2 called MK-7, however, can be absorbed even the lining of the intestines is damaged by drugs or inflammatory disease. It doesn't have to be eaten with fatty food to enter the bloodstream.

The most useful form of vitamin K in supplements is the kind of vitamin K2 known as MK-7. It's made by bacteria, and it's effective for vegetarians. It can be absorbed by the body even on days when you've used over-the-counter pain killer than ordinarily interfere with vitamin K absorption. And it can be absorbed by the intestines even if you are on a low-fat diet or your digestive tract cannot process fat efficiently.

What Does Vitamin K Do In the Body?

The most important task of vitamin K in the human body is to help every cell use an amino acid called glutamic acid to make proteins. Glutamic acid is especially important in the brain, where it is used in the synthesis of proteins that ensure that neurons fire. Vitamin K is also used in making proteins that activate and deactivate certain genes and in regulating how the body uses the amino acids glutamine and proline.

The best-known task of vitamin K in the human body, however, is in helping the blood form factors that enable clotting to plug leaks. We'll discuss that in much greater detail in the next section.

Vitamin K-2 for Heart and Bones

Atherosclerosis is a process of hardening of the arteries that occurs when calcium infiltrates the mass of cholesterol and white blood cells stuck in the lining of the artery wall. Osteoporosis is the process of weakening of bone that occurs when bone-building cells called osteoblasts fail to replace calcium and other minerals that keep bone strong. Vitamin K2, it turns out, is important both in stopping unwanted calcification in the lining of arteries and for encouraging essential calcification in bone.

In the bones, vitamins K1 and K2 play a role in the formation of a substance called matrix Gla protein, or MGP. Vitamin K2 also is needed for a process called carboxylation that activates MGP so it can facilitate the rebuilding of bone to keep it strong after fractures and death of bone cells.

In the arteries, MGP turns out prevent calcification. People who don't have enough vitamin K to make MGP not only can suffer weak bones, they can suffer hardened arteries. Vitamin K is essential for the formation and activation both of MGP and another hormone, called osteocalcin, that ensure that calcium goes where it is needed in the body and not where it can cause harm.

A lot of what medical science knows about the role of vitamin K in cardiovascular health comes from the Rotterdam Study. In 1990, Dutch scientists began tracking the health of 10,994 men and women over the age of 55 who lived in Ommord, a suburb of Rotterdam. They tracked these study volunteers until their premature deaths, in a few cases, or for 10 years, ending the study in the year 2000. The researchers collected extensive dietary data from 4,807 of the participants.

One of the relationships the scientists studied was the connection between cholesterol and vitamin K. They found four beneficial connections between vitamin K and cholesterol.

1. Participants in the Rotterdam Study who had the highest consumption of vitamin K1 and vitamin K2 had the highest HDL (good) cholesterol.
2. Participants in the Rotterdam Study who had the highest levels of K2 had the lowest total cholesterol.
3. Participants in the study who were in the top third of vitamin K2 consumption had 41% fewer heart attacks (both fatal and non-fatal).
4. The fewest deaths from cardiovascular disease and the fewest deaths from all causes occurred in the study participants who consumed the most vitamin K.

Low vitamin K consumption was associated with higher rates of death from cardiovascular disease. High vitamin K consumption was associated with the lowest rates of hardening of the arteries (atherosclerosis).

Vitamin K2 and Bone Health

One of the many differences between people and, for instance, giant jellyfish, is that people have hundreds of bones that give the human body its interior framework. These hundreds of bones also protect the inner organs. They make it possible for different parts of the body to move in different directions. They transmit vibrations that actually play an important role in hearing and touch sensation.

To be precise, there are 206 bones from the crown of the head to the tips of the toes. If you took a course in anatomy, you probably learned all 206 bones by studying a skeleton, and it's easy to get into the mindset that maybe somehow the bones are not really living tissue. But the truth is that the bones are living tissue, and unlike a skeleton, they aren't really hard tissue.

Bones are made up of tissue that is almost as metabolically active as the heart, the liver, and the brain. The outer layer of the bone protects a spongy interior known as the trabecula. Holes in the trabecula can accumulate and eventually some kind of physical stress will fracture or break the bone.

To accommodate growth during childhood and adolescence, and to repair damage to bone at any point during life, the bones are constantly remodeling themselves. This process liberates calcium to be used by the rest of the body, especially by the kidneys as the regulate the body's pH (acidity vs. alkalinity). Remodeling also keeps bones strong and flexible, quite unlike the dry and brittle bones you might see in a skeleton. Every cell in bone is replaced about every seven years.

During the first 20 years of life, the growth process, accomplished by a group of cells known as osteoblasts, predominates over the recycling process, accomplished by a group of cells known as osteoclasts. After we mature, for about 10 years during our 20's, there is a nearly perfect balance of bone creation and bone destruction. After the age of 30, the balance between osteoblasts and osteoclasts slowly shifts in favor of the osteoclasts that break down bone.

Bone destruction begins to exceed bone creation by a factor of about 1% per year. In medical terms, the processes of bone synthesis and bone resorption become "uncoupled," and bones become progressively less resilient and more brittle throughout the rest of life. The less metabolically active the bones are, the more likely they are to have more resorption than synthesis, to break down more bone than they replace.

The reason older bones that are metabolically "slower" bones tend to break is that making bone is not the only thing a bone has to do. Bones are a kind of nursery for baby blood cells, and they also have to make proteins like collagen, the same protein that is also found in connective tissues and the skin. They store toxic heavy metals in their matrix so the rest of the body is not poisoned. They store essential fatty acids, and they also play roles in the ways the body stores fat and responds to insulin.

Stimulating the bones is not necessarily a good thing. Sometimes they manage to build new bone at normal rates, but excesses of stress hormones (cortisol), thyroid hormone, parathyroid hormone, or hormones released by cancerous tumors accelerate bone breakdown about 10 times more.

Or bad nutrition simply deprives the bones both of the calcium and magnesium they need to restore their mineral status and the vitamin K needed to make mineral absorption possible. Tiny fractures in bone accumulate so that shoulders slump and hip bones break, causing some of the predictable-and preventable-health catastrophes of aging.

Who Is At Greatest Risk for Osteoporosis?

The standard medical information is that certain groups are at greater risk for osteoporosis than others.

• Women are more likely to develop osteoporosis than men.
• Older people (50 years old and up) are more likely to develop osteoporosis than younger people.
• People of Asian and European descent are more likely to develop osteoporosis than people of Hispanic or African descent.
• People whose parents or siblings develop osteoporosis are more likely to develop osteoporosis themselves.
• Men who have low levels of testosterone and women who have low levels of estrogen are more likely to develop osteoporosis than men who have normal or high levels of testosterone and women who have normal or high levels of estrogen.
• People who have "small bones" are more likely to develop osteoporosis than people who have "big bones."
• People who weigh less than 127 pounds (57 kilos) are more likely to develop osteoporosis than people who weigh more than 127 pounds (57 kilos).
• Women who have their first period after the age of 16 are more likely to develop osteoporosis than women who have their first period before the age of 16.
• Women who enter menopause before the age of 45 (without having had hysterectomy) and more likely to develop osteoporosis than women who enter menopause after the age of 45.

There is not a lot to be done about those factors except to recognize them and take all possible precautions. But there are other predisposing factors for osteoporosis over which we and our physicians have some degree of control.

• Smokers are more likely to develop osteoporosis than non-smokers.
• Heavy drinkers and people who never drink alcohol are more likely to develop osteoporosis than people who take 2 or 3 alcoholic drinks each week.
• People who never exercise are more likely to develop osteoporosis than people who exercise regularly.
• People who only do aerobic exercise are more likely to develop osteoporosis than people who do resistance training (weight lifting and similar activities).
• People who eat the highest amounts of meat and dairy products are more likely to develop osteoporosis than people who eat moderate amounts of meat and dairy products, due to the use of calcium by the kidneys to prevent acidification of the bloodstream.

Vitamin K Supplements for Bone Health

More than for any other condition, vitamin K supports recovery from osteoporosis. More than any other kind of vitamin K, the form of vitamin K2 known as MK-7, the kind of vitamin K made by bacterial fermentation, supports bone health.

Japanese researchers first found MK-7 in the slimy, stringy soybean snack called natto. If you happen to spend a "night out with the guys" watching baseball in one of hundreds of thousands of tiny sports bars all over Japan, chances are you will be offered a beer and a bowl of natto.

The first time I was offered natto, when I was out with the president of a nutritional supplements company in Tokyo, I thought that the soybean snack had to be some kind of joke. The tiny fermented soybeans are coated with a stringy, gelatinous substance that looks something like mucus. I even fumbled through my Japanese dictionary to ask if I were being served freshly fertilized sea urchin eggs. (I wasn't. That happens to be a breakfast food.)

The "slime" is where the MK-7 is found. Even with my limited command of the Japanese language, I quickly learned that I was being offered a treat, not a trick, and once you get past the texture of the dish, natto is actually tasty. (Or maybe this was after I had a second beer. I really don't remember.)

The Ministry of Health in Japan has sponsored clinical investigations that confirm that MK-7 prevents and treats osteoporosis. In Japan, you can't get a bowl of natto under your health insurance plan, but you certainly can get a bottle of MK-7. This soybean-derived nutritional supplement has entered the leagues of supplements that are almost medicinal, also including SAM-e.

How do doctors know MK-7 promotes bone health?

Scientists at the Research Center for Genomic Medicine affiliated with Saitama Medical University in Saitama, Japan have found that this form of vitamin K2 activates a growth activation factor in the osteoblasts that build up bone.

Along with bee pollen and, interestingly, wasabi (the real thing, not the fake wasabi powder you get in many Western sushi bars), natto in the diet helps prevent osteoporosis in laboratory animals. And Japanese researchers have found that providing natto fortified with vitamin K2 (in the form of MK-7), in a product called kinnotsubu hogenki reduces rates of osteoporosis in women.

It's important to note that some clinical trials haven't found positive results. A study published in the journal Osteoporosis International in October 2010 failed to find a benefit in just eating natto for preventing osteoporosis in women who had gone through early menopause.

And researchers at Kobe International University have found that vitamin K1, the kind of the vitamin found in green vegetables, is essential for preventing fractures, too. But taking products that combine vitamin K1 with vitamin K2 in the form of MK-7 seem to promote bone health.

Is Vitamin K2 Enough for Bone Health?

A lot of the writing about vitamin K2 is product-focused, on the lines of "Here is why you should buy my vitamin K product." The picture painted by research, however, is that vitamin K2 is just part of the nutritional foundation for bone health. It is necessary to get enough calcium, magnesium, phosphorous, and vitamin D, and it turns out that vitamins K1 and K2 need isoflavones, like those in soy, and beta-cryptoxanthin, a phytonutrient found in yellow vegetables, to be maximally protective.

I'm not going to tell you that you really need to go out and buy seven supplements instead of one. I'm just going to tell you that vitamin K for bone health works best when you get its six factors, and here is one way to do it:

• The body can only absorb about 550 mg of calcium in any 4-hour period. Larger amounts of calcium only cause constipation. Don't take any calcium supplement that contains more than 550 mg of calcium per dose, and only take 1 dose at a time. Up to 1,200 mg a day may be helpful, but it's best to eat a variety of foods that contain calcium. Not just dairy products but also fish and green vegetables are rich in calcium.
• Magnesium is also provided by green vegetables. If you don't eat vegetables, take at least 400 mg of supplemental magnesium every day. Up to 1,800 mg a day may be helpful, but increase your dosage slowly (adding 200 mg a day) to make sure you don't trigger stomach upset. Better yet, eat four or five servings of green vegetables every day.
• Phosphorous is provided by protein foods. Almost no one in the Western world suffers a phosphorous deficiency.
• You really can get your vitamin D from sunshine, assuming you can get 20 minutes of strong sun on unprotected skin every day during the summer and 1-2 hours of strong sun on unprotected skin every day during the winter. If you can't, take at least 1,000 IU of supplemental vitamin D every day. Like calcium and magnesium, vitamin D is a very inexpensive supplement.
• Soy isoflavones are absorbed in small amounts. If you have ever lived or visited in Japan, you may have noticed that the servings of tofu and miso are tiny, just enough to provide about 15 grams (1/2 oz) of minimally processed soy every day. Your body cannot absorb the isoflavones from any more soy than just that tiny amount, although it can absorb the vitamin K2 from up to about 60 grams (2 oz) of natto.
• Cryptoxanthin is found in apples, papayas, egg yolks, butter, and beef blood. Of all the cofactors of vitamin K2, cryptoxanthin is probably the most important to take as a supplement (unless you eat a lot of beef blood or eggs). If you are also concerned about eye health, just take one of the supplements providing both lutein and beta-cryptoxanthin to reduce risk of macular degeneration.

There are several excellent vitamin K products for support of bone health on the market. The one with which I am the most familiar is Bone-Protec by Xtend-Life. It provides vitamin K2, calcium, magnesium, vitamin D, and mangosteen extract for the beta-cryptoxanthin source. It also contains bone-protective silicon, boron, and lycopene. When you consider that it's got 8 supplements in one serving, it's a bargain, and like all Xtend-Life products, there is a limited-time guarantee.

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