Caring Medical
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Oak Park, Illinois 60301
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Vitamin K and Bone Health

One of the vitamins you don’t hear too much about is Vitamin K. It received its letter K designation from the Danish word “koagulation” since it was first discovered by a Danish scientist who was working with bleeding disorders of newborn chicks in 1935. Although its role in clotting is widely known (it allows the production of prothrombin, a necessary step in the clotting cacade), it recently has been shown to be very important in bone health as well, especially for the prevention of osteoporosis.

The main natural source of vitamin K is green leafy veggies like spinach. The greener the color, the more chlorophyll content, and the more vitamin K is present in the food. Vitamin K also naturally derives from the friendly flora of bacteria present in the intestinal tract, so vitamin K deficiency is sometimes triggered off by excessive antibiotic intake which removes this gastrointestinal source. Both forms of K require activation in the liver, so liver disease will be another consideration in patients showing signs of vitamin K deficiency.

Drugs that are known to impair the clotting process through inhibition of the vitamin K absorption are aspirin, some antibiotics, bile acid sequestrants like cholestyramine, and laxatives. Aspirin also inhibits platelet adhesion, thus increasing the chances of bleeding when prothrombin levels are low. Dilantin decreases the body’s ability to use vitamin K, while Coumadin directly antagonizes the primary effect of vitamin K and prevents the formation of prothrombin.

How does Vitamin K help our bones? It helps in the formation of the protein osteocalcin. This molecule is produced by the osteoblasts (bone building cells) and has affinity for and binds to calcium ions. It then is laid down as an integral part of newly formed bone. Two recent Japanese studies (ignored and frowned upon by their pharmacologically tainted American colleagues) found that vitamin K was essentially therapeutically equivalent to the bone drug etidronate in reducing vertebral fractures. In fact those results are consistent with demographic population studies that have found that higher vitamin K intake is directly correlated with decreased incidence of vertebral fractures. Another study also connected vitamin K intake in women with their bone density scores, and the Nurse’s Health Study of 72,327 women between the ages of 38 and 63 also found that low intake of vitamin K was associated with increased risk of hip fracture.

Our conclusions are clear and straightforward. Eating a diet higher in vitamin K will reduce the incidence of osteoporosis and hip fractures, especially in women. One serving per day of foods like spinach, kale, parsley, broccoli, turnip greens, and brussel sprouts will put you into the lower risk group with 300-400 micrograms of vitamin K complexed with other possible naturally occurring associated nutrients in the food.