Vitamin K deficiencies are not common, which is fortunate because vitamin K controls a very important life or death bodily function -- blood clotting. It does this by stimulating the manufacture of blood clotting substances within the liver. It's also essential for kidney function and bone metabolism. Your body can usually manufacture enough vitamin K on a daily basis to keep blood clotting functioning normally.

Although vitamin K is manufactured in your liver, your body also relies on the friendly bacterial organisms that occur naturally in your intestines for a supply of vitamin K. This explains why vitamin K deficiencies may occur after taking antibiotics and/or cortisone, for these drugs destroy friendly intestinal bacteria, as well as harmful bacteria. Liver or gall bladder disease, or any disease of the intestinal tract that interferes with the absorption of the fat soluble vitamins (E and A) may also cause vitamin K deficiency.

Unless you cannot absorb vitamin K normally, or have been taking antibiotics for a long time or have chronic diarrhea, you are unlikely to need a vitamin K supplement other than that found in a multivitamin/mineral tablet. If you fall into one of the above categories and if you bruise easily, have bleeding periodically from the nose or ears, or have bleeding gums (symptoms which you would likely already be getting help with), you should discuss the possibility of a vitamin K deficiency with your doctor. In the meantime, especially if your nutritional score indicates a possible Vitamin K deficiency, start eating many more vitamin K-rich foods, such as dark, leafy green vegetables (like kale, beet and turnip greens and spinach), oats, green tea, asparagus, kohlrabi, cauliflower, cheese, and organic beef or lamb liver. Alfalfa meal (from your health food store) would be a good supplement. If you have been taking antibiotics, take an acidophilus supplement with meals daily for the next couple of months.