Vitamin K, What is Good For? A Few Things, Actually.

Vitamin K? Isn’t that the blood clotting vitamin? Sounds boring, why should I care about my vitamin K intake?

In an attempt to answer that question I’ll post the available research from randomized controlled trials demonstrating the beneficial effects on vitamin K. However, first an explanation of what vitamin K is.

Vitamin K is actually not one molecule, but a number of several similar molecules. These molecules all posses the ability to perform the same essential function, I.E. carboxylatation of the gamma carbon on the glutamic acid residue of a variety of proteins, rendering them biologically active. If you just read that last sentence and went “Huhh?” then let me simplify: There are several types of vitamin K and each has the ability to stick a CO2 molecule onto certain proteins, allowing these proteins to do certain things (and yes, some of these proteins are involved in blood clotting).

Understandably the ability to perform this action may vary depending on the form of vitamin K, so this review will cite specific forms when discussing vitamin K’s beneficial effects.

  • The first form of vitamin K is phylloquinone, also known as phytonadione or phytomenadione. Most commonly this form is called vitamin K1. This form is found abundantly in green vegetables, particularly dark green leafy vegetables.
  • The second form is menaquinone or vitamin K2. The forms of vitamin K2 are differentiated by a number following the acronym MK (for menaquinone). The common varieties of vitamin K2 are MK4 (aka menatetrenone) and MK7. MK4 is found in egg yolks, organs, meat, and dairy fat, particularly when coming from animals eating green grass. MK7 is found in fermented foods like aged cheese and natto (never heard of natto? It’s made from soybeans. Look it up, but you probably wouldn’t like it).

With all that in mind here are the ailments likely to be improved or prevented by vitamin K:

Vitamin K (K2 MK4 and K1) Exerts Beneficial Effects on Insulin Sensitivity:

Vitamin K, in the forms K2 MK-4 and K1, have been shown to have beneficial effects on insulin sensitivity in short term studies, suggesting vitamin K may play a role in the prevention and treatment of diabetes.

  • Choi HJ, Yu J, Choi H, An JH, Kim SW, Park KS, Jang HC, Kim SY, Shin CS. Vitamin K2 supplementation improves insulin sensitivity via osteocalcin metabolism: a placebo-controlled trial. Diabetes Care. 2011 Sep;34(9):e147. doi: 10.2337/dc11-0551
  • Yoshida M, Jacques PF, Meigs JB, Saltzman E, Shea MK, Gundberg C, Dawson-Hughes B, Dallal G, Booth SL. Effect of vitamin K supplementation on insulin resistance in older men and women. Diabetes Care. 2008 Nov;31(11):2092-6. doi: 10.2337/dc08-1204. Epub 2008 Aug 12
  • Sakamoto N, Nishiike T, Iguchi H, Sakamoto K. Possible effects of one week vitamin K (menaquinone-4) tablets intake on glucose tolerance in healthy young male volunteers with different descarboxy prothrombin levels. Clin Nutr. 2000 Aug;19(4):259-63

Vitamin K (K2 MK4 and Possibly K1) Effective at Preventing Bone Fractures:

Because several of the proteins vitamin K activates are involved in bone growth it seems reasonable to think vitamin K might be beneficial to bone health. Sure enough, vitamin K2 MK4 has been shown to reduce the number of bone fractures in older people. One study also found vitamin K1 also prevented fracture risk.

  • Ishida Y, Kawai S. Comparative efficacy of hormone replacement therapy, etidronate, calcitonin, alfacalcidol, and vitamin K in postmenopausal women with osteoporosis: The Yamaguchi Osteoporosis Prevention Study. Am J Med. 2004 Oct 15;117(8):549-55
  • Iwamoto J, Takeda T, Ichimura S. Effect of menatetrenone on bone mineral density and incidence of vertebral fractures in postmenopausal women with osteoporosis: a comparison with the effect of etidronate. J Orthop Sci. 2001;6(6):487-92
  • Shiraki M, Shiraki Y, Aoki C, Miura M. Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis. J Bone Miner Res. 2000 Mar;15(3):515-21
  • Cheung AM, Tile L, Lee Y, Tomlinson G, Hawker G, et al. (2008) Vitamin K supplementation in postmenopausal women with osteopenia (ECKO Trial): A randomized controlled trial. PLoS Med 5(10): e196. doi:10.1371/journal.pmed.0050196
  • Sato Y, Kanoko T, Satoh K, Iwamoto J. Menatetrenone and vitamin D2 with calcium supplements prevent nonvertebral fracture in elderly women with Alzheimer’s disease. Bone. 2005 Jan;36(1):61-8. Epub 2004 Nov 24

Vitamin K (K1 and K2 MK4) Promising for Cancer Prevention and Treatment:

Some studies of vitamin K suggest it may be beneficial in cancer prevention and treatment. In several studies vitamin K2 MK4 has been shown to prevent the occurrence and reoccurrence of liver cancer. And in the ECKO trial a vitamin K1 supplement significantly lowered cancer incidence in older women, due in part to the vitamin lowering rates of breast cancer. Cancer death was also lower in this trial.

  • Cheung AM, Tile L, Lee Y, Tomlinson G, Hawker G, et al. (2008) Vitamin K supplementation in postmenopausal women with osteopenia (ECKO Trial): A randomized controlled trial. PLoS Med 5(10): e196. doi:10.1371/journal.pmed.0050196
  • Habu D, Shiomi S, Tamori A, Takeda T, Tanaka T, Kubo S, Nishiguchi S. Role of vitamin K2 in the development of hepatocellular carcinoma in women with viral cirrhosis of the liver. JAMA. 2004 Jul 21;292(3):358-61
  • Kakizaki S, Sohara N, Sato K, Suzuki H, Yanagisawa M, Nakajima H, Takagi H, Naganuma A, Otsuka T, Takahashi H, Hamada T, Mori M. Preventive effects of vitamin K on recurrent disease in patients with hepatocellular carcinoma arising from hepatitis C viral infection. J Gastroenterol Hepatol. 2007 Apr;22(4):518-22
  • Mizuta T, Ozaki I, Eguchi Y, Yasutake T, Kawazoe S, Fujimoto K, Yamamoto K. The effect of menatetrenone, a vitamin K2 analog, on disease recurrence and survival in patients with hepatocellular carcinoma after curative treatment: a pilot study. Cancer. 2006 Feb 15;106(4):867-72
  • Fujita H, Tomiyama J, Tanaka T (1998) Vitamin K2 combined with all-trans retinoic acid induced complete remission of relapsing acute promyelocytic leukaemia. Brit J Haematol 103: 584–585.

Conclusion

There seems to be strong evidence that vitamin K MK4 can reduce bone fracture risk and a small amount of evidence vitamin K1 can do the same. There is also good evidence that vitamin K1 and K2 MK4 can improve insulin sensitivity and some evidence they oppose cancer.

Although MK7 was not mentioned this is due to a lack of evidence, not because it doesn’t help these conditions. I suspect MK7, MK4, and K1 all have some ability to improve insulin sensitivity, prevent bone fractures, and oppose cancer but without enough data these are the conclusions we must draw.

Finally, if you’ve spent much time on the internet hearing about vitamin K2 you’ve probably heard something about it preventing heart attacks. My take on that? Reasonable, but untested. Epidemiology like the Rotterdam study simply don’t cut it since they fall victim to the many potential confounding factors of observational evidence.

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2 thoughts on “Vitamin K, What is Good For? A Few Things, Actually.

  1. Ian Flett October 29, 2013 / 11:43 pm

    You have ignored Mk9, highest in natto and Jarlsberg cheese. It seems to have additional benefits based on Japanese epidemiology, especially for breast and prostate cancers. Natto is also high in pqq.

    • Morgan October 31, 2013 / 1:01 pm

      Unfortunately there isn’t much, if any, clinical evidence for MK-9’s benefits in humans. We can look at observational evidence to try and figure out if it was the MK’s lowering cancer risk and not other components of the food (like the CLA in cheese, or the pqq in natto) but this can be quite tricky.

      I’m sure the MK 5-9’s have some anti-cancer capabilities but I wanted this post to draw only from randomized, controlled trials so those vitamin K’s got no love.

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