Vitamin K2 is a little-known vitamin that is essential for strong, healthy bones and teeth, as well as for cardiovascular health. It was discovered in 1929 by Danish scientist Henrik Dam, but it’s only recently that researchers have begun to reveal the many health benefits of vitamin K.
How does vitamin K support the health of your bones, teeth, and arteries? Before we take a look at the research, it’s important to understand the different types of vitamin K and why vitamin K2 is the one to look out for to support good health.
What is Vitamin K?
There are three types of vitamin K: K1, K2, and K3. Vitamin K3 is a synthetic form of vitamin K and does not have recognized health benefits. Vitamin K1 (phylloquinone) is made by plants and is found in green leafy vegetables and some other foods. Vitamin K2 (menaquinone) is found in the fermented soybean food natto, egg yolk, and dairy products from animals fed primarily on grass.
A predominantly plant-based diet that does not include fermented foods may lack sufficient vitamin K to support good health, especially because it appears that vitamin K2 is key to solving the calcium paradox (more on this below!).
Vitamin K2 as Menaquinone-7 – Bioactive and Highly Available
Vitamin K2 has different chemical variants, known as vitamers or menaquinones. These are abbreviated as MK-n, where “n” represents the length of the vitamer. In humans, the most common MK is the short-chain MK-4, which the body can produce from vitamin K1. The long-chain forms of MKs, MK-7 through MK-10, are produced by intestinal bacteria in all mammals. Menaquinone-7 (MK-7) is now known to be both highly bioavailable and bioactive, meaning it may promote good health.
MK-7 is a fat-soluble form of vitamin K and is typically obtained from natto when used in vitamin K supplements. Vitamin K2 as MK-7 stays in the bloodstream much longer than lower menaquinones. Studies involving adult volunteers who took either vitamin K1 or MK-7 revealed that over a 24-hour period, the level of MK-7 present in the blood was two-and-a-half times higher than for K1. Over a four-day period, MK-7 levels were six times higher than K1.
MK-7 has also been found to be three times more effective than vitamin K1 at promoting activated osteocalcin, an important factor in bone health.
The Health Benefits of Vitamin K2
While vitamin K2 might not be as well known as vitamins C or D, it’s no less important to your health. So far, researchers have identified 14 vitamin K-dependent proteins found in blood, bone, dentin (one of the major components of teeth), kidney stones, atherosclerotic plaques (plaques that build up inside your arteries), semen, lung surfactant (cells made up of protein and lipids), neural tissue, and urine.
Unsurprisingly, vitamin K deficiency is now suspected as a contributing factor in many health conditions. Indeed, vitamin K2 is known to play a key role in what is sometimes referred to as the “calcium paradox”.
The Calcium Paradox – Vitamin K2 and Bone Health
The calcium paradox is a phenomenon where a dangerous lack of calcium in the bones (osteoporosis) occurs even when there is a dangerous excess of calcium in the arteries (atherosclerosis). This is, in part, because vitamin K2 stimulates the production of a protein called osteocalcin. Osteocalcin is a bone-building protein that helps bones retain calcium.
Vitamin K2 also inhibits the expression of a gene known as RANKL. This gene plays a role in regulating the activity and lifespan of cells that break down bone.[2,3] What this means in practice is that vitamin K2 helps the body maintain normal bone metabolism, which helps promote bone density and decrease the risk of fractures.
Clinical studies have shown that vitamin K2 helps maintain bone density in the lumbar spine and decrease the incidence of fractures in people with age-related osteoporosis or osteoporosis caused by glucocorticoid drugs. In one placebo-controlled trial involving 244 healthy Dutch postmenopausal women, those who took 180 mcg daily of MK-7 for three years had a small but significant decrease in bone loss in their thigh bones and spine compared to those taking a placebo.
Vitamin K2 and Cardiovascular Health
In addition to supporting bone health, vitamin K2 helps prevent and even reverse arterial calcification, where arteries become hardened and inelastic. Vitamin K2 does this by activating matrix GLA protein (MGP), which helps move calcium into the bones and away from the arteries.
In The Rotterdam Heart Study, which involved almost 5,000 people aged 55 and older, people with the highest dietary intake of vitamin K2 had a 57% lower risk of death from coronary heart disease than people with the lowest intake of the nutrient. Those with a higher intake of vitamin K2 as menaquinone also had a 52% reduced likelihood of severe aortic calcification (narrowing of the aeortic valve). The same was not true of people taking vitamin K1, highlighting the difference between vitamin K1 and vitamin K2.
How much vitamin K should you take?
For many people, diet alone does not provide sufficient amounts of vitamin K2 to support optimal health of the cardiovascular system and bones. Daily use of a vitamin K2 supplement makes it easy and convenient to ensure an ideal intake of this important nutrient.
Adults need about 120 mcg of vitamin K2 daily, though there is no known toxic dose. Children can take 55 mcg per day. If you are taking blood thinning or anti-coagulant therapy medications, consult your doctor before taking vitamin K2.
Only vitamin K2 as MK-7 offers 24-hour protection from a single daily dose, helping to direct calcium away from the arteries and into bones and teeth. Vitamin K2 100 mcg from Natural Factors is a vegetarian-friendly, one-a-day, non-GMO supplement providing MK-7 to support strong bones and a healthy heart.
 Schurgers LJ, Teunissen KJ, Hamulyak K, et al. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007 Apr 15;109(8):3279-3283.
 Kameda T, Miyazawa K, Mori Y, et al. Vitamin K2 inhibits osteoclastic bone resorption by inducing osteoclast apoptosis. Biochem Biophys Res Commun. 1996;220:515-519.
 Koshihara Y, Hoshi K, Okawara R, et al. Vitamin K stimulates osteoblastogenesis and inhibits osteoclastogenesis in human bone marrow cell culture. J Endocrinol. 2003 Mar;176(3):339-348.
 Iwamoto J, Takeda T, Sato Y. Effects of vitamin K2 on osteoporosis. Curr Pharm Des. 2004;10(21):2557-2576.
 Knapen MH, Drummen NE, Smit E, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24:2499-2507.
 Geleijnse JM, Vermeer C, Grobbee DE, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: The Rotterdam Study. J Nutr. 2004;Nov;134(11):3100-3105.