Vitamin K matters

Philip J. Goscienski, M.D.

December 2010

Vitamin K was named for the Danish and German word Koagulation (coagulation), the medical term for blood clotting that was long thought to be its only function. Newborn infants sometimes lack the vitamin and they can die from bleeding into the brain or other vital organs. All babies receive an injection of vitamin K shortly after they leave the cushioned safety of the womb.

It's rare for adults to be so lacking in vitamin K that they experience abnormal bleeding. Inadequate levels that lead to other problems are common. These include osteoporosis and heart disease.

For several decades the scientific understanding of vitamin K was rather meager, considering that it was identified in 1929. Various natural sources yield different chemical forms of this vitamin. One variant (K1) occurs in green leafy vegetables and another (K2) in animal products, including milk, cheese and organ meats. The latter, such as liver, brain, intestine and kidney are not exactly favorite food items in the United States but the vitamin K2 that they contain is important in the regulation of calcium.

The recommended daily allowance of vitamin K is based on a level that is adequate for clotting, mostly K1, but considerably lower than what we need for maintaining bone strength and for preventing heart disease. Herein lies the vitamin K paradox: low levels of vitamin K2 result in loss of calcium from the skeleton but at the same time they lead to abnormal deposits of calcium in the valves of the heart and the lining of arteries. As we age we become more susceptible to both conditions.

Some healthy persons have relatively low levels of vitamin K that are not depressed enough to cause bleeding problems but that may contribute to heart disease and osteoporosis. Thousands of persons take daily doses of Coumadin®, or warfarin, which counteracts the clotting function of vitamin K, for the treatment of disorders in which blood clots pose a risk to health.

A diet that provides green, leafy vegetables, including cabbage, broccoli and Brussels sprouts will satisfy the requirement for vitamin K1. Meat and dairy products supply vitamin K2 but elderly persons may not eat enough of these foods and they tend to have lower levels of this vitamin than they need to prevent heart disease and the loss of bone.

Vitamin K2 tablets are widely available but patients on blood thinners should consult with their physician before taking any supplement.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at