The necessity of supplementing with vitamin K2 can not be overstated. While it is possible to get utilizable K2 from the diet, as we will see, most of us do not have a diet focussed sufficiently on grass-fed meat and dairy to allow us to thrive without taking a K2 supplement. Now, let’s dive into the ever expanding world of vitamin K2 and its newly revealed broad range of benefits.
What is Vitamin K?
In 1929, a Danish scientist discovered the nutrient later to be identified as vitamin K. Henrik Dam was studying the effects of cholesterol by feeding chickens a diet lacking in it. He observed that after a few weeks the chickens started bleeding and he could not reverse this by adding purified cholesterol back into their diet. At that point he realized that there was another element in the unpurified cholesterol which he referred to as the “coagulation vitamin”.
This substance later became known as vitamin K simply because in German coagulation begins with a K. Following Dam’s discovery, the scientific community determined that serious vitamin K deficiencies would manifest as bleeding disorders, or malfunction in blood clotting functions. And from that point on, this became what vitamin K was primarily associated with. But, like with all nutrients, this vitamin would prove to have many, many more important roles to play in the human body.
It is now known that vitamin K is a family of vitamins that exists in various forms including K1 (phylloquinone), K2 (menaquinone) and K3. Now, vitamin K3 is a synthetic form that is toxic in high doses, and has already been banned by the FDA from over-the-counter sales, due to side effects (though it may still be prescribed as a drug). Since it is of no value to us here, I will speak of it no more.
Vitamin K1
Vitamin K1 (phylloquinone) is the most commonly available form in the modern diet and is found in plant foods. The foods richest in vitamin K1 include avocado, broccoli, Brussels sprouts, cabbage, cauliflower, kale, kiwi, grapes, parsley, spinach, and Swiss chard. While the absorption of K1 from green plants is usually fairly low (cooked spinach is 5% bio-available) it can be improved by adding fat to the greens (with added fat the bio-availability of K1 jumps to 13%). This is because vitamin K is a fat-soluble vitamin.
While the famed Framingham Study showed a lower risk for hip fracture in those who consumed the most K1 from food, another study that attempted to get the same results with supplemental K1 showed no benefits. Some studies suggest that low intake of vitamin K1 is associated with increased risk of hip fracture, however there is no conclusive evidence that vitamin K1 supplementation reduces the incidence of hip fractures. Any benefit of vitamin K1 in preventing hip fracture seems to result exclusively when K1 is derived from plant foods (which implies that the other nutrients in those foods are as important as the K1 for protecting the bones.) Therefore, K1 is not really recommended for use in supplemental form. This implication that vitamin K1 is not effective in supplement form does not hold true when we examine vitamin K2.
Vitamin K2
We now know that the type of vitamin K that is most utilized by the body is the K2 form, found mostly in butter, egg yolks, and meat products (especially organ meats) from animals fed grass. In North America most food animals are fed grains because it is cheaper than grazing them on grass (industrial feedlots being the norm) and fattens them up more. Therefore, vitamin K2 deficiency in the West has become widespread.
Vitamin K2 (menaquinone) exists primarily in two forms, MK4 (menaquinone-4)and MK7 (menaquinone-7), although it does exist in other forms as well. However, for our purposes we will focus on these two forms since they are the most studied and the ones that are available in supplemental form.
Vitamin K2, as MK7, is also created during fermentation, so some is found in certain cheeses, and a lot in the soybean product called Natto, a Japanese food that is considered quite unpalatable by most North Americans.
Why is K2 So Important?
The critical importance of vitamin K2 for us, in the modern age, is due to its link to two widespread ailments: osteoporosis, and heart disease in the form of atherosclerosis (calcification of the arteries).
It is well established that vitamin K2 develops bones during growth by directing calcium where to go in the cells and in the skeleton. When we have enough vitamin K2 it will direct calcium to the bones and teeth and keep it away from the areas where it could do harm, such as the cardiovascular system and soft tissues.
A European study of more than 8,000 people over the age of 55 found that those with the highest intake of vitamin K2 had a 50% reduction in death by coronary heart disease. (Geleijnse J.M., et al, “Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease, The Rotterdam study,” Journal of Nutrition, 143 (11): Nov; 2004)
Furthermore, a few studies done on animals have indicated that calcification of the arteries can even be reversed with supplemental vitamin K2. (Source) Just consider the implications of that: reversing arteriosclerosis with a simple supplement. This is stunning information considering that heart disease kills about 20% of us. (Vitamin K1 was also tested but shown to not prevent arterial calcifications.)
K2 Deficiency
Up until recently, it was believed that vitamin K deficiency only occurred if the intestinal tract was damaged, forbidding absorption of the nutrient. Since K2 (in the MK7 form) is mostly produced from K1 by friendly bacteria in the gut, a deficiency was also often found in people who had been on long term broad spectrum antibiotic use. Heavy antibiotic use has been shown to reduce vitamin K2 production in the body by almost 75%.
Vitamin K2 production is also reduced as we get older, much like B-12 production. Since much of the K2 in the body is converted from K1, a diet too low in the plant foods containing K1, will also reduce the amounts of K2 in the body. The ability of supplemental K2 to keep bones healthy and strong has even been demonstrated in people experiencing bone loss from steroid use, dialysis and/or paralysis.
Unfortunately, the amount of the MK7 form that is made in the intestines may not be sufficient to meet the needs of the body. The MK4 version of K2, unlike MK7, does not appear to be dependent on friendly bacteria to be created in the body. It is also converted from K1 but that conversion occurs in the arterial walls, pancreas and testes (for guys).
Supplemental Forms of K2
Both the MK4 and MK7 versions of K2 are available in supplemental form, though the effective dosages are very different. While K2 may not make claims for preventing osteoporosis in North America, in Japan MK4 has been recommended by the health authorities since 1995 for this purpose. Japanese studies have indicated that MK4 can reduce fractures by up to 87%. However, this original study has since been retracted, and other studies have called this research into question, thus it is currently hard to find a definitive answer on the value of MK4 as an osteoporosis preventative. (Source)
One answer to this issue is as follows: “It should be noted that inconsistencies in the trial outcomes may be due to differences in controlling for other nutrient factors such as calcium and vitamin D. In two interventional studies using MK-4, there appeared to be synergistic effect when vitamin K, calcium and vitamin D were concurrently supplemented.54,55 Japanese data suggests that there is greater benefit of MK-4 intervention when vitamin D is adequate. This suggests underlying vitamin D deficiencies may be a confounding factor when reviewing clinical trials to date.” (Source)
Nonetheless, for those of us in Canada, this is hardly an issue since we cannot take MK4 in any amount near the recommended dose of 45 mg daily. In this country (but not the U.S.), the maximum amount of K2 allowed in a product is 120 mcg (a mcg being one thousandth of a mg).
Since MK4 is not effective in microgram doses, we in Canada can only use MK7, which does appear to be effective at these low doses. The recommended amount of MK7 is about 120 mcg for maintenance and two to three times that much for therapeutic purposes.
Originally there was much more science on the MK4 version of vitamin K2, but in the last few decades the research on MK7 has caught up. And, even in the early 2000s, one Japanese study found the MK7 form of K2 showed effectiveness in stimulating bone formation and inhibiting bone decline. (Yamaguchi M (November 2006). “Regulatory mechanism of food factors in bone metabolism and prevention of osteoporosis”. Yakugaku Zasshi)
And another MK7 study, from 2004, showed elevation in biomarkers of bone formation, along with inhibition of bone-reabsorbing factors found in parathyroid hormones. (Tsukamoto Y (2004).“Studies on action of menaquinone-7 in regulation of bone metabolism and its preventive role of osteoporosis”.)
As well, in 2011, the Singapore government approved a health supplement that contains the MK7 form of vitamin K2, along with vitamin D3, for increasing bone density.
Finally, before we move on, there is this study from 2013, published in Osteoporos International Journal which concluded that: “MK-7 intake significantly improved vitamin K status and decreased the age-related decline in BMC and BMD at the lumbar spine and femoral neck, but not at the total hip. Bone strength was also favorably affected by MK-7. MK-7 significantly decreased the loss in vertebral height of the lower thoracic region at the mid-site of the vertebrae.” (Source)
All this data, and more, indicate that, while we Canadians do not have the choice as to which form of K2 we can purchase, we can at least rest comfortably in the knowledge that the form that the government is so kind as to allow us to buy, does have scientific validity behind it.
It is currently believed that vitamin K2 maintains the teeth as well as the rest of the skeletal system, and this seems to be confirmed by the fact that, after the pancreas, the highest amount of K2 found in the tissues is found in the salivary glands.
Don’t Forget Vitamins A & D
As we saw above, the weakness of some Japanese studies on vitamin K2 may have been due to the researchers ignoring the vitamin D status of their subjects. Combining vitamin D3 with K2 has been shown to be more effective on building bones than either one alone. (Weber P., “Vitamin K and Bone Health,” Nutrition, 17: 2001) While vitamin D helps us to absorb calcium, vitamin K directs it into the skeletal structure.
A little known fact is that vitamin A is also necessary for bone health. Sadly, bad science has convinced many people, and even some Naturopaths, that vitamin A can be a detriment to bone health, possibly even leading to reduced bone density. This is based on giving rats high amounts of vitamin A without the important cofactors of vitamins D and K2. Put simply, vitamin A breaks down old bone (which is what it did when given to the rats), then vitamin D uses that raw material to build new bone material, and finally, vitamin K2 shuttles that material into the skeletal structure.
The relationship of these three vitamins can be observed when we consider one of the most healthful foods, one commonly consumed by our ancestors, and virtually the only appreciable source of vitamin A in the diet: animal livers. The liver of a grazing animal in the wild is rich in vitamins A, D, and K2. Nature’s perfect food. Fortunately for those of us squeamish about eating liver (or philosophically opposed), supplemental forms of all three vitamins work just as well.
Warnings
There is no known toxicity associated with high doses of vitamin K2 in the forms of MK4 or MK7. While the body uses vitamin K2 for purposes of blood clotting, studies have indicated that doses of MK4 at 135 mg daily (divided dose) showed no risk of abnormal blood clotting. Blood thinning drugs, such as Warfarin and Coumadin, work by inhibiting the actions of vitamin K, therefore K1 and K2 can block the action of these types of drugs. (People on these drugs are even told not to eat too many greens.) Deficiency of vitamin K2 has been linked to birth defects and it is generally considered safe to take during pregnancy and lactation.
In Part 2 we will look at more of the proven benefits of supplementing with vitamin K2. (NutriStart Quick K2 liquid supplement.)