Vitamin K is found in foods such as green leafy vegetables, soy products, egg yolks and cauliflower. The average daily consumption is 100mcg (0.1mg) or less. All forms of vitamin K should be taken with fat/oil, as it is an oil-soluble (also called fat-soluble) vitamin. 5-15mg of K1 is a common recommendation among holistic doctors.

While K1 is preferentially used by the liver to activate blood clotting proteins, K2 is preferentially used by other tissues to deposit calcium in appropriate locations, such as in the bones and teeth, and prevent it from depositing in locations where it does not belong, such as the soft tissues.

Vitamin K3 is one of the many man-made versions of vitamin K. It is also called menadione. It is converted into the active form of K2 inside of the body. K3 is less utilized medically than it was in former times, due to toxicity concerns.

Unusually large doses of any vitamin K should be avoided if one is also taking an anticoagulant drug. Coumadin (Warfarin Sodium) is used to lower the chance of blood clots forming. Your liver makes clotting factors that help the blood clot and prevent bleeding. Some blood clots can cause serious medical problems. Coumadin blocks the formation of clotting factors in the liver that are dependent on Vitamin K.

Vitamin K can interfere with the blood-thinning effects of Coumadin, so it is important to maintain a consistent amount of Vitamin K in your diet. Avoid drastic changes in your dietary habits. For instance, eating large amounts of green leafy vegetables, natto or supplementing extra vitamin K, when you normally do not, can increase the amount of Vitamin K in your system.

Although animals can convert vitamin K1 to vitamin K2, a significant amount of evidence suggests that humans require preformed K2 in the diet to obtain and maintain optimal health.

It is therefore important to distinguish between K1 and K2. Vitamin K1 (phylloquinone) enters the diet from the consumption of plants. Vitamin K2 (menaquinone) is made by bacteria that line the gastrointestinal tract. However, most of the vitamin K2 produced in the intestine is embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. Vitamin K2 is also made by bacteria, such as Bacillus subtilis, in the process of making natto. Significant amounts of vitamin K2 are produced during the fermentation process, making natto the best natural source of K2. It can also be found in both hard and soft cheese, and in lesser amounts in egg yolk, butter, chicken liver, salami, chicken breast, and ground beef.

Many people are not aware of the health benefits of vitamin K2. The K vitamins have been underrated and misunderstood until late in the 2000-2010 decade in both the scientific community and the general public. K2 has many benefits that K1 does not have, including:

• reducing the risk of prostate cancer
• improving bone loss seen in osteoporosis
• reducing the risk of heart disease
• maintaining skin health
• maintaining brain function

The most effective forms of K2 are MK4 and MK7. The much longer half-life in the body of MK7 make it the form of choice.
The best sources of K2 are natto, cheese and cheese curd:
-15gms (1/2 ounces) of natto contains roughly 200mcg of K2.
-100gms (3 1/2 ounces) of cheese contains roughly 45mcg of K2.