Vitamin K: The Forgotten Vitamin

  • 2 Jul 2012
  • Reading time 6 mins
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Vitamin K is vital for bone health, heart health, cancer and more. It is not a single nutrient but a family of related vitamins. One member of the family was misunderstood for decades due to a case of mistaken identity. New research is finally bringing to light the life-saving importance of adequate intake of this particular form of vitamin K.

Major benefits of vitamin K2

  • Osteoporosis prevention and treatment – Vitamin K2 activates a protein called osteocalcin that directs calcium into bones and teeth. Vitamin K2, in conjunction with vitamin D, has been shown to boost bone density far better than either nutrient alone. Perhaps more importantly, K2 has been shown to reduce fracture risk and improve bone health above and beyond bone mineral density. [2]
  • Heart disease prevention and reversal – Vitamin K2 intake is inversely associated with cardiovascular morbidity and mortality while Vitamin K1 intake shows no correlation. [3] Animal studies show a reduction of up to 50% of atherosclerotic calcifications in only six weeks with vitamin K2 supplementation. [4] Results from the largest and most definitive human clinical trials will be released in June 2012. Vitamin K2 prevents and reverses heart disease by activating a protein called MGP, that essentially removes calcium deposits from arteries and other soft tissues where the mineral accumulates causing harm.
  • Cancer protection – Vitamin K2 regulates a third protein that governs cellular growth. That makes this nutrient a potent inhibitor of cancer, especially lung and prostate – the two big cancer killers of men – but also breast cancer, liver cancer and leukemia. [5]

Other health benefits of vitamin K2
If osteoporosis, heart disease and cancer prevent aren’t enough, there are many other condition associated with K2 deficiency and documented health benefits of optimal K2 intake. These include improving insulin sensitivity for diabetics, preventing brain damage in conditions like stroke, preventing kidney disease and boosting male fertility.

Who benefits from vitamin K2?
The benefits of vitamin K2 extend throughout life. Vitamin K2 is as important as folic acid for pregnant women and their growing babies. In the first trimester the nutrient is essential for the development of primary teeth and healthy facial structure; in the second trimester the formation of adult teeth and skeleton require K2.[6]

Children and adolescents have especially high requirement for this nutrient because of their growing bodies, where K2 promotes healthy teeth and bones. [7] Vitamin K2 has been shown to counteract the negative changes in bone density seen in menopausal women, [8] and both men and women over 50 show high levels of vitamin K2 deficiency, accelerating the rate of bone loss and vascular calcification. [9]

Vitamin K2 food sources, supplements and optimal intake
Dietary vitamin K2 comes from two main sources: animal fat, such as egg yolks and butter, and from select fermented foods. Animals accumulate vitamin K2 in their tissues in direct proportion to the K1 in their diets. [10] That means grass-fed meat and dairy products are much richer in this nutrient than their grain-fed counterparts.

Certain bacteria produce vitamin K2, which is why some fermented dairy products, notably Gouda and Brie cheeses, are rich in vitamin K2. Natto, a fermented Japanese soybean food, is the highest known food in vitamin K2. One 40 g serving contains as much as 450 mcg of vitamin K2. If you can’t find natto at a local Asian market – nor learn to appreciate its unique taste and texture – then look for natto-derived vitamin K2 supplements. These will indicate “natto source” or have the designation “menaquinone-7 (MK-7)” somewhere on the label.

About 200 mcg of MK-7 per day is required to meet the body’s need for K2 and activate all K2 dependent proteins. [11] 200 mcg of MK-7 would be a basic recommendation for optimal health. This is also in the therapeutic range used in most recent clinical trials. That's because - unlike other vitamins where there might be a maintenance dose and higher therapeutic dose - K2 will only activate the amount of K2 proteins it can find.

The goal in both "healthy" and condition specific treatment is to activate all K2 proteins. This seems to take about 200 mcg. So far there is no data to suggest there is greater benefit at higher doses. That being said, people who eat natto daily are getting about 400 mcg of K2, so maybe there is a case to be made for higher dose based on traditional diets. Supplements that contain menaquinone-4 (MK-4), a synthetic form of vitamin K2, are also available but require much higher doses, in the range of 45 mg (45,000 mcg).

Vitamin K2 safety and drug interactions
Vitamin K2 is very safe for adults and children with no known toxic effects, unlike other fat-soluble vitamins. A popular misconception is that high vitamin K1 or K2 intake will promote blood clots and this is not true.11 Vitamin K supplements have no clotting effect since clotting proteins are already fully activated by vitamin K1 in people who are not on blood thinning medications. Vitamin K2 from food and supplements has no drug interaction, except warfarin (Coumadin or acenocoumeraol). This type of blood thinner works by limiting the body’s vitamin K metabolism, so vitamin K supplements may interfere with the action of these drugs. Other “blood thinning” medications such as aspirin, anti-platelet aggregators (e.g. Plavix), non-warfarin-type blood thinners (e.g. Pradax), cardiac or other medication do not interact with vitamin K2.

Kate Rhéaume Bleue, ND is the author of Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life (Wiley & Sons, 2012).

1. Vermeer C, Shearer MJ, Zittermann A, et al. Beyond deficiency: potential benefits of increased intakes of vitamin K for bone and vascular health.Eur J Nutr. 2004 Dec;43(6):325-35
2. Vermeer, C. Vitamin K: the effect on health beyond coagulation - an overview. Food & Nutrition ......

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