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Vitamin K2

  1. Wikepedia


      1. Vitamin K is involved in the carboxylation of certain glutamate residues in proteins to form gamma-carboxyglutamate residues (abbreviated Gla-residues). The modified residues are often (but not always) situated within specific protein domains called Gla domains. Gla-residues are usually involved in binding calcium. The Gla-residues are essential for the biological activity of all known Gla-proteins.

      2. At this time, 14 human proteins with Gla domains have been discovered, and they play key roles in the regulation of three physiological processes:

        1. Blood coagulation: (prothrombin (factor II), factors VII, IX, X, protein C, protein S and protein Z).

        2. Bone metabolism: osteocalcin, also called bone Gla-protein (BGP), and matrix gla protein (MGP).

        3. Vascular biology.

      3. Recommended amounts - The U.S. Dietary Reference Intake (DRI) for an Adequate Intake (AI) of Vitamin K for a 25-year old male is 120 micrograms/day. The Adequate Intake (AI) of this phytonutrient for adult women is 90 micrograms/day, for infants is 10-20 micrograms/day, for children and adolescents 15-100 micrograms/day.

      4. Toxicity - although allergic reaction is possible, there is no known toxicity associated with high doses of the phylloquinone (vitamin K1) or menaquinone (vitamin K2) forms of vitamin K.

      5. Deficiency - osteoporosis [1][2] and coronary heart disease[3] [4]are strongly associated with lower levels of K2 (Menaquinone).  Menaquinone is not inhibited by salicylates as happens with K1, so Menaquinone supplimentation can alleviate the chronic vitamin K deficiency caused by long term aspirin use.

      6. Vitamin K and Bone Health

        1. Recently vitamin K has also been lauded for its potential role in the increase of bone mass. Studies have proved that supplemental vitamin K promotes osteotrophic processes and slows osteoclastic processes via calcium bonding. In Japan, a form of vitamin K2 is recognized as a treatment for osteoporosis [40][41]. However the long term effects and benefits are unknown and it remains controversial.[citation needed] Data from the 1998 Nurses Health Study found an inverse relationship between dietary vitamin K1 and the risk of hip fracture. After being given 110 micrograms/day of vitamin K, the main results showed that women who consumed lettuce one or more times per day had a significantly lower risk of hip fracture than women who consumed lettuce one or fewer times per week. In addition to this, high intakes of vitamin D but low intakes of vitamin K may still pose an increased risk of hip fracture hinting at a relationship between these two vitamins [Kanai, T. et al. Serum Vitamin K level and Bone Mineral Density in Postmenopausal Women. International Journal of Gynecology and Obstetrics; 1997; 56:25-30.].

  2. Dr. Joseph Pizzorno -

    1. Joseph E. Pizzorno, Jr., N.D., appointed by President Clinton in December 2000 to the White House Commission on Complementary and Alternative Medicine Policy and by President Bush's administration to the Medicare Coverage Advisory Committee in November 2002, is one of the world's leading authorities on science-based natural medicine.
      1. Vitamin K aids bone health in a number of ways:
        After it's carboxylated by vitamin K2, osteocalcin can latch on to calcium and bind it to hydroxyapatite crystals forming the bone matrix. (Think of carboxylation as adding a trailer hitch to calcium, allowing it to be towed into and attached to bone.) (Bügel S, Proc Nutr Soc 2003)

        Vitamin K2 also teams up with vitamin D3 to increase the production of Gla-proteins, including osteocalcin in osteoblasts (the cells that build bone), while also inhibiting the production of osteoclasts (the cells that break down bone). (Plaza S, Lamson D. Alt Med Rev 2005, Masterjohn C. Med Hypotheses 2007; Yamaguchi M, Sugimoto E, et al. Mol Cell Biochem 2001; Yamaguchi M, Uchiyama S, et al. Mol Cell Biochem 2003)

      2. Research has linked osteoporotic fracture with vitamin K insufficiency for more than 20 years. A study published in 1984 found that patients who suffered fractures caused by osteoporosis had vitamin K levels 70% lower than age-matched controls. This association has been repeatedly confirmed with one recent trial involving almost 900 men and women finding those with the lowest blood levels of vitamin K had a 65% greater risk of hip fracture compared to those with the highest levels of the nutrient. (Hart JP, Lancet 1984; Bitensky L, Hart JP et al, J Bone Surg Br 1988; Hodges SJ, Pilkington MJ, et al. Bone 1991; Booth SL, Tucker KL, et al. AJCN 2000 )

      3. Supplementation with vitamin K2 has been shown to be an effective treatment against osteoporosis. A review study of randomized controlled human trials of at least 6 months duration that assessed the use of vitamin K1 or K2 to lower fracture risk identified 13 trials. In all but one, vitamin K reduced bone loss with K2 being most effective, reducing risk of vertebral fracture by 60%, hip fracture by 77%, and all non-vertebral fractures by 81%. (Cockayne S, Adamson J, et al. Arch Intern Med 2006)

      4. Want to Check Your Vitamin K Status? - A normal prothrombin time (the test for clotting activity that has been the standard used to check vitamin K sufficiency) is not sufficient indication that enough vitamin K is present to maintain vascular matrix-Gla protein activity or bone osteocalcin activity.
        Request an osteocalcin test; it measures how much uncarboxylated osteocalcin is present in the blood. High levels of uncarboxylated osteocalin indicate insufficient vitamin K is present to promote optimal bone health. Similarly, high levels of undercarboxylated matrix-Gla protein (MGP) indicate that insufficient vitamin K is present to protect against vascular calcification. (Berkner KL, Rune KW, J Thromb Haemost 2004; Cranenburg EC, Schurgers LJ et al. J Thromb Haemost 2007; Bugel S. Proc Nutr Soc 2003)

      1. How Bisphosphonates Work - Bisphosphonates suppress bone turnover and remodeling.
        Our bones, unless inhibited by bisphosphonates, are constantly rebuilding themselves throughout our lives. Cells called osteoclasts break down old or damaged bone, signaling other cells called osteoblasts to replace it with strong new bone. Bisphosphonates kill osteoclasts. Bone density goes up on these drugs, but the bone they leave in place is worn out tissue your body would normally clear out and replace with strong new bone.

        This is why bisphosphonates put people at risk for osteonecrosis (jaw bone death). Because these drugs suppress osteoclastic activity, damaged bone is left in place rather than resorbed, so the amount of damaged old tissue accumulates until it reaches a level when any trauma or insult will result in extremely poor healing, the exposure of necrotic bone to the oral environment, development of pain, and increased risk of microbial infection, which is precisely what is seen in bisphosphonate-associated cases of osteonecrosis of the jaw.


      1. Vitamin K, specifically vitamin K2 or menaquinone, activates a group of proteins (the Gla-proteins), which are responsible for where calcium gets delivered in the body. Vitamin K2 ensures that the calcium you consume (and which will be getting into your circulation in higher amounts now that you are taking vitamin D) is deposited where you want it—in your bones, and not where you don't—in your blood vessels and other soft tissues.
      2. When your vitamin K2 levels are adequate, two of the Gla-proteins that are activated are: (1) osteocalcin, the protein responsible for anchoring calcium within bone, and (2) matrix Gla-protein, which prevents calcium from depositing in the heart, arteries, breast and kidneys.
      3. Both vitamin K1 (phylloquinone) and vitamin K2 (menaquinone) are available as supplements. Vitamin K1 is primarily involved in helping your blood clot normally, although our bodies are able to convert a small amount of K1 into K2.
      4. For bone health, K2 (menaquinone), particularly natural menaquinone derived from natto, which may be labeled MK-7 (menaquinone-7) is the most potent form. You may also see K2 as menatretrenone; this is MK-4, a synthetic version that must be taken in much higher doses because its half-life in the body is quite a bit shorter.
      5. If you are taking MK-7, a daily dose of 45 mcg is sufficient. If taking MK-4, take 5 mg daily.
      6. Best food sources of vitamin K (K1) include kale, spinach, Swiss chard, broccoli, Brussels sprouts, parsley and romaine lettuce. Natto, from soy, is an excellent source of K2, but is not easily available in the U.S., nor would the taste appeal to most Americans.
  3. Tufts University - Jean Mayer USDA Human Nutrition Research Center on Aging

    1. Vitamin K Laboratory -

  4. About Vitamin K2

  5. Atherosclerosis - (ath-er-o-skleh-RO'sis)

    1. The physiology of vitamin K nutriture and vitamin K-dependent protein function in atherosclerosis
      K. L . BERKNER and K. W. RUNGE*
      Departments of Molecular Cardiology and *Molecular Biology, Lerner Research Institute, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, OH, USA

      1. To cite this article: Berkner KL, Runge KW. The physiology of vitamin K nutriture and vitamin K-dependent protein function in atherosclerosis.
        J Thromb Haemost 2004; 2: 2118–32.

      2. Direct link


                       (This page was last edited on April 15, 2011 .)