Vitamin K is a group of vitamins that share methylated naphthoquinone ring. There are two naturally occurring forms of vitamin K; vitamin K1 and vitamin K2. Vitamin K1, also known as Phylloquinone, is present in green plants like leafy vegetables and fruits. Vitamin K2, also known as menaquinones (MK), is present in some animal foods and also synthesized by anaerobic bacteria of the gastro-intestinal tract.
Vitamin K2 is found in animal foods such as dairy products (especially from grass-fed cows), fish, egg, meat and fermented foods like cheese, natto, miso, sauerkraut. Animal foods have vitamin K2 (MK-4), while fermentation produces other menaquinones, MK-5 through MK-14. Mammals can synthesize K2 (MK-4) from K1 to some extent, therefore dietary K1 and other forms of vitamin K may contribute to K2 (MK-4) status.
Vitamin K (VK) serves many functions in the body, but its most important functions are carboxylation or activation of a class of proteins known as Gla-proteins and blood clotting. Vitamin K1 (Phylloquinone) activates clotting factors (a number of substances involved in the clotting of blood), while vitamin K2 (Menaquinones) activates Gla-proteins such as osteocalcin (a protein responsible for the deposition of calcium in the bones) and matrix Gla-protein (a protein that prevents calcification of soft tissues of the body).
The studies have shown that vitamin K2 (MK-4) might help in fighting against cancer and Alzheimer's disease. Some other important associated benefits may include maintenance of bone density and prevention of osteoporosis and cardiovascular diseases.
Some recent study demonstrated that there is a strong inverse relationship between heart attack mortality and vitamin K2 (MK-4 to MK-10). A similar study was carried out in the Netherlands on about five thousand males. The study results showed that men with the highest consumption of K2 had a tremendously lower heart attach mortality (about 51%) and a lower risk of death (26%) from all causes as compared to control group which were consuming the least amount of K2.
Warfarin is a drug used to prevent clotting of blood. It is most widely used anticoagulant in the world. Warfarin inhibits recycling of K2 in the body. When rats were given warfarin, they develop arterial calcification, while feeding K2 to rats completely inhibit this effect. The mice lacking MGP (as warfarin inhibit K2 and K2 is needed for normal functioning of MGP) develop calcified aortas and die prematurely. The MGP (Matrix Gla Protein) is a VK dependent protein that prevents arterial calcification. So, there is no doubt in the association between cardiovascular disease and vitamin K2.
There are sufficient research studies to support vitamin K2 (MK-4) role in the prevention of osteoporosis. Osteoblasts are cells found in the bones. These cells produce osteocalcin, a protein that is vital in the process of bone formation. The newly produced osteocalcin is non-functional, it must be activated/carboxylated by the vitamin K2. So, K2 acts as coenzyme in the activation of osteocalcin. Vitamin K2 is much potent activator of osteocalcin than vitamin K1 or other factors. Some research trials have shown that there is 60-80% reduction in vertebral fracture and non-vertebral fractures in the population taking supplements of vitamin K2. Further trial in Japan showed that the vitamin K2 can completely reverse the bone loss and even in some cases increase bone mass in patients with osteoporosis.
Vitamin A, vitamin D and vitamin K2 act synergistically and are essential for proper growth and subsequent health. This combination is important for proper mineral absorption and metabolism. Vitamin A and D initiate production of highly important proteins while vitamin K2 is necessary to activate these newly formed proteins. Osteocalcin is an important protein produced by the signals of vitamin A and D, but it is not activated without vitamin K2. This protein directs calcium (Ca) and phosphorus (P) in the bones and teeth. So, it can be derived that vitamin K2 could amplify the vitamin D effects on bone health. Vitamin K2 is also highly protective against bone fractures in elderly people.
Vitamin K2 has shown some evidences (published in internationally renowned scientific journals) that it can reduce the risk of some types of cancers and also shown a thirty percent lower risk of dying from cancer. National Cancer Institute studies showed that vitamin K2 might help reduce the risk of non-Hodgkin lymphomas (NHLs). Non-Hodgkin lymphoma is a cancer that starts in cells called lymphocytes. Lymphocytes are found in the blood and are part of the immune system of the body. People taking high amounts of K2 have shown 45% lower risk of this type of cancer as compared to control group (people the taking less amount of K2). This lower risk is attributed to vitamin K2 role of inhibiting inflammatory cytokines related to this type of cancer.