One of the best natural sources of vitamin K2 comes from an ancient Japanese food called natto. This is a fermented soybean food, which comes loaded with a healthy bacteria called bacillus subtilus, and may also serve as a probiotic. Fermented foods, like natto, typically have the highest concentration of vitamin K2 in the human diet. Levels of vitamin K2 found in natto (K2) have been shown to far exceed those amounts found in dark green vegetables (K1). In fact, vitamin K2 concentration after the consumption of natto has been shown to be about 10 times higher than that of vitamin K1 after eating spinach. Unfortunately, most people do not eat or enjoy many fermented foods especially natto because it is slimy, unpalatable with a strong flavour and pungent aroma.
While natto is the most potent natural source of vitamin K2, the nutrient is also readily available in fermented dairy products, especially cheese (especially from grass fed cows) such as Gouda, Edam, and Gorgonzola. Curd cheese is also a good vitamin K2 source because it`s lower in fat (animal fat) than regular cheese.