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 3.5-ounce serving of natto has 1,000 micrograms of MK-7 and 84 mcg 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 goose-liver paste, goose leg, chicken liver, salami, chicken breast, chicken leg, ground beef, 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.
Read more: Vitamin K2 Food Sources | eHow.com Vitamin K2 Food Sources | eHow.com