The K vitamins are coagulants that help blood to clot, according to VitaminK2.org. Vitamin K2, also known as menaquinone, is naturally occurring and acts as a catalyst for proteins that rely on K vitamins. In particular, K vitamins are critical to bone and heart health. Vitamin K2 may be found in many foods or taken as a supplement.
Vitamin K2 may be broken down and measured in subsets--MK-4, MK-7, MK-8, MK-9 and MK-10--athough Dr. William Davis, a Milwaukee cardiologist, states that it is unclear which of these forms of K2 offer the most benefit to either bone or heart health. The MK-8, MK-9 and MK-10 forms of K2 are found almost exclusively in fermented foods.
Popular in Japan, "natto" is has the highest natural concentration of K2 vitamins, according to Davis. Natto is a form of fermented soybeans often served on rice. According to Davis, a 99.2gr serving of natto has 1,000 micrograms of MK-7 and 84mcg of MK-8.
Many hard and soft cheeses as well as raw egg yolks contain relatively high amounts of K2. Other dairy products rich in this vitamin include egg whites, curd cheeses, butter and whole and low-fat milk.
Vitamin K2-rich animal proteins include gooseliver paste, goose leg, chicken liver, salami, chicken breast, chicken leg, minced meat, bacon, calf's liver, salmon and mackerel.
One non-animal protein or dairy product that contains a significant amount of vitamin K2 is sauerkraut. Many green, leafy vegetables--such as kale, spinach or Swiss chard--contain significant amounts of vitamin K1, which the body can convert to K2, according to Mark Sisson, author of The Primal Blueprint, on his website marksdailyapple.com.
Vitamin K is available in supplement form at many health-food stores or online. You may purchase the supplement in pill or liquid form. The recommended supplement amount is about 100mcg/day. As with any supplement or medication, you should check with your doctor before beginning a new regimen.