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Vitamin K has been known as the coagulation vitamin, because of its role in the blood-clotting process. However, research over the last few decades has shown that the role of K Vitamins - and natural Vitamin K2, the menaquinones, in particular - has been greatly expanded. Of note, K Vitamins activity outside the liver is required for calcium utilization, the key factor in maintaining both bone and cardiovascular health.\n\nVitamin K2 helps to activate vitamin K-dependent proteins responsible for healthy tissues. In bone, it activates osteocalcin, a protein required to bind calcium to the mineral matrix, thus strengthening the skeleton. In circulation, Vitamin K2 participates in carboxylation of Matrix Gla Protein (MGP), the most potent inhibitor of arterial calcification known, lowering the risk of vascular damage.

Deficiency of K2 in both mice and humans is associated with coronary calcification; low vitamin K2 levels are associated with increased activity of Gla matrix protein, an enzyme that causes calcium deposition in artery walls. People who take warfarin (Coumadin®), a potent blocker of vitamin K2, experience more arterial and heart valve calcification. The 2004 Rotterdam Heart Study was the experience that really brought this concept closer to our interests. This well-conducted study of 4800 Dutch demonstrated an association of vitamin K2 intake with 57% reduction in cardiovascular events and lesser degrees of aortic calcification (another surrogate for atherosclerosis). Benefit appeared to be associated with a daily K2 intake of 32.7 micrograms per day (Geleijnse JM et al 2004). An important corollary of this study is that it suggests that a vitamin K2-mediated reduction in coronary calcification is accompanied by reduced likelihood of heart attack and other events.

"[Vitamin K and Bone Update. The biological effects of vitamin K(2) on bone quality.] Amizuka N, Li M, Guo Y, Liu Z, Suzuki R, Yamamoto T. Clin Calcium. 2009 Dec;19(12):1788-96. Japanese. PMID: 19949270 Post-transcriptional maturation with the presence of vitamin K(2) promotesgamma-carboxylation of osteocalcin, enabling further binding to hydroxyapatite, from which one could infer that vitamin K(2) increased the quality of bone matrix. For instance, vitamin K(2) rescued the impaired collagen mineralization caused by Mg insufficiency, by promoting a re-association of the process of collagen mineralization with mineralized nodules. Sodium warfarin, which antagonizes the function of vitamin K(2), reduced the binding of osteocalcin to bone matrices, and consequently resulted in crystalline particles being dispersed throughout the osteoid without forming mineralized nodules. Therefore,gamma-carboxylated Gla proteins mediated by vitamin K(2) appear to play a pivotal role in normal mineralization in bone."

Shannon J, King IB, Moshofsky R, Lampe JW, Li Gao D, Ray RM, Thomas DB. Erythrocyte fatty acids and breast cancer risk: a case-control study in Shanghai, China. Am J Clin Nutr. 2007 Apr;85(4):1090-7. PMID: 17413110 [PubMed - in process]

Differential killing of human carcinoma cells supplemented with n-3 and n-6 polyunsaturated fatty acids. Bégin ME, Ells G, Das UN, Horrobin DF. J Natl Cancer Inst. 1986 Nov;77(5):1053-62. PMID: 3464797

Strong correlations have been noted between cardiovascular diseases and low bone density / osteoporosis-connections so strong that the presence of one is considered a likely predictor of the other. This relationship has led to the hypothesis that these conditions share core pathophysiological mechanisms. Recent advances in our understanding of the complimentary roles played by vitamin D3 and vitamin K2 in vascular and bone health provide support for this hypothesis, along with insight into key metabolic dysfunctions underlying cardiovascular disease and osteoporosis. Part II, The Vitamin K Connection to Cardiovascular Health, reviews the ways in which vitamin K regulates calcium utlization, preventing vascular and soft tissue calcification while complimenting the bone-building actions of vitamin D, and also discusses vitamin K safety and dosage issues, and the necessity of providing vitamin K and vitamin A along with vitamin D to preclude adverse effects associated with hypervitaminosis D.

Tufts University Confirms That Vitamin A Protects Against Vitamin D Toxicity by Curbing Excess Production of Vitamin K-Dependent Proteins Tufts University confirmed my hypothesis that vitamin A protects against vitamin D's induction of renal calcification (kidney stones) by normalizing the production of vitamin K-dependent proteins in December, 2008, without citing my hypothesis or telling me they had confirmed it. I am, of course, very grateful that they thought it significant enough to investigate.

Dietary supplementation with eicosapentaenoic acid, but not with other long-chain n-3 or n-6 polyunsaturated fatty acids, decreases natural killer cell activity in healthy subjects aged >55 y. Thies F, Nebe-von-Caron G, Powell JR, Yaqoob P, Newsholme EA, Calder PC. Am J Clin Nutr. 2001 Mar;73(3):539-48. PMID: 11237929

Arachidonate 5-lipoxygenase (5-lipoxygenase, 5-LO, 5-LOX or Alox5), which transforms EFAs into leukotrienes, is a current target for pharmaceutical intervention in a number of diseases. 5-LO is a target for pharmaceutical intervention in CAD.

The actions of the ω-3 and ω-6 essential fatty acids (EFAs) are best characterized by their interactions; they cannot be understood separately.

Regression of warfarin-induced medial elastocalcinosis by high intake of vitamin K in rats. Schurgers LJ, Spronk HM, Soute BA, Schiffers PM, DeMey JG, Vermeer C. Blood. 2007 Apr 1;109(7):2823-31. PMID: 17138823 DOI 10.1182/blood-2006-07-035345. This is the first study in rats demonstrating that AC and the resulting decreased arterial distensibility are reversible by high-VK intake