By Dr. Joseph Mercola
     with Rachael Droege

Vitamin K is a fat-soluble vitamin that is most well-known for the important role it plays in blood clotting. However, vitamin K is also absolutely essential to build strong bones and prevent heart disease, and it plays a crucial role in other bodily functions other than blood clotting. It is so important that, although I don’t typically recommend adding extra supplements to your diet, vitamin K is one of the few supplements you should seriously consider because many people do not get nearly enough of it on a daily basis through the foods they eat.

In fact, vitamin K is sometimes referred to as "the forgotten vitamin" because its major benefits are often overlooked. Following are 10 important facts about vitamin K that will help you to discover why vitamin K is one supplement you may need.

1. There are Three Types of Vitamin K--Which is Best?

Vitamin K1, or phylloquinone, is found naturally in plants and vitamin K2, also called menaquinone, is made by the bacteria that line the gastrointestinal tract. Vitamin K3, or menadione, is a synthetic form which I do not recommend. It’s important to note that toxicity has occurred in infants given this synthetic vitamin K3 by injection.

The vitamin K that I recommend is vitamin K2, which is natural and not toxic at even 500 times the RDA. Vitamin K2, which is made in your body and also produced by fermented foods, is also a superior form of vitamin K.

2. Vitamin K Prevents Arterial Plaque & Heart Disease

Vitamin K helps to prevent hardening of the arteries, which is a common factor in coronary artery disease and heart failure. Research suggests that vitamin K may help to keep calcium out of artery linings and other body tissues, where it can be damaging.

3. Build Strong Bones, Prevent Osteoporosis

Vitamin K is one of the most important nutritional interventions for improving bone density. It serves as the biological "glue" that helps plug the calcium into the bone matrix.

According to recent studies:

• Vitamin K was recently compared to a first-generation biphosphonate drug called Didronel in 72 osteoporotic women for two years and there was no difference found in the bone fracture rates between women taking vitamin K and women taking the biphosphonate drug for osteoporosis.
• Other recent studies have shown vitamin K to be equivalent to Fosamax-type osteoporosis drugs.

4. Fight Cancer

Studies have shown that vitamins K1 and K2 are effective against cancer. For instance, one study published in the September 2003 International Journal of Oncology, found that treating lung cancer patients with vitamin K2 slowed the growth of cancer cells, and previous studies have shown benefit in treating leukemia.

Further, a number of human trials have demonstrated the anticancer effects of vitamin K1. In a study published in the August 2003 Alternative Medicine Review, of 30 patients with hepatocellular carcinoma, a type of liver cancer, who took oral vitamin K1, the disease stabilized in six patients, seven patients had a partial response, seven others had improved liver function and in 15 patients the abnormal prothrombin normalized.

5. Additional Health Benefits

As written in the March 2004 Life Extension magazine, researchers have found many other beneficial effects of vitamin K including:

• Vitamin K deficiency may be a contributing factor to Alzheimer’s disease, and vitamin K supplementation may help to fight this disease
• Topical vitamin K may help to reduce bruising
• Vitamin K deficiency may interfere with insulin release and blood sugar regulation in ways similar to diabetes
• Vitamin K may have antioxidant properties

6. Vitamin K is a Fat-Soluble Vitamin

This is important because dietary fat is necessary for the absorption of this vitamin. This means that in order for you body to absorb it effectively, you need to eat some fat along with it. One easy way to do this is by adding the liquid vitamin K drops I recommend directly into your fish oil or cod liver oil. This will ensure that the vitamin K is well-absorbed by your body (plus you’ll be getting beneficial omega-3 from the fish oil!). Alternatively, you could add it to any other food that contains fat.

7. Food Sources of Vitamin K

Fermented foods, such as natto, typically have the highest concentration of vitamin K found in the human diet and can provide several milligrams of vitamin K2 on a daily basis. This level far exceeds the amount found in dark green vegetables. Unfortunately, most Americans do not eat many fermented foods.

Adding traditionally fermented foods to your diet is a must, and, although not widely known, the health benefits of these foods are tremendous. We will very shortly be introducing a simple and inexpensive way in which you can ferment your own foods to radically improve your source of beneficial bacteria and vitamin K2.

The following table lists some vegetable sources of vitamin K:

8. Who Needs Vitamin K?

If you have, or if your family has, a history of osteoporosis or heart disease, I strongly advise you to add vitamin K to your diet. Keep in mind that you’d have to eat over one pound of collard greens daily to get the equivalent amount of vitamin K. Clearly the collard greens or spinach would be better for you and would provide you with additional benefits, but if you already have heart disease a little extra vitamin K would seem a simple bit of insurance to make sure that your blood vessels don''t harden.

You will also want to consider adding vitamin K to your diet if you do not eat many vegetables and are concerned that, for whatever reason, you are unable to obtain enough vitamin K from your food. The following conditions may put you at an increased risk of vitamin K deficiency:

• Eating a poor or restricted diet
• Chron’s disease, ulcerative colitis, celiac disease and other conditions that interfere with nutrient absorption
• Liver disease that interferes with vitamin K storage
• Taking drugs such as broad-spectrum antibiotics, cholesterol drugs and aspirin

9. How Much Vitamin K do I Need?

Although the exact dosing is yet to be determined, one vitamin K expert, Dr. Cees Vermeer, recommends between 45 mcg and 185 mcg of vitamin K2 daily for adults. You must use caution on the higher doses if you take anticoagulants, but if you are generally healthy and not on these types of medications, I suggest 100 mcg of vitamin K2 daily.

It is quite likely that doses of several times that amount are safe for the average person, but we just lack the research to confirm it at this time.

10. Who Should Not Take Vitamin K?

Pregnant and nursing mothers should avoid vitamin K supplemental intakes higher than the RDA (65 mcg) unless specifically recommended and monitored by their physician. Those who have experienced stroke, cardiac arrest, and those prone to blood clotting should not take vitamin K without first consulting their physician.