Vitamin K and Bone Health

Throughout life, bone is constantly rebuilding itself. Bone serves as a storehouse for minerals, chiefly calcium, which can be tapped to meet the body's mineral requirements. Bone is broken down through a process called "resorption," releasing its minerals into the general circulation. New bone is then formed to replace the reabsorbed bone, preventing a net loss of bone. This is called bone "remodeling." As we age, however, bone formation begins to fall behind, causing the gradual bone loss. Vitamin K is essential for bone formation. The body requires vitamin K to produce a protein that binds calcium to bone.

Today, vitamin K deficiency is rare, except in infants, for whom such a deficiency can be fatal. The best sources of vitamin K are liver, green leafy vegetables and members of the cabbage family. Since vitamin K is produced by bacteria in the intestines, humans are not dependent upon diet for this nutrient. Recent research indicates that vitamin K deficiency contributes to osteoporosis, while supplementation may help prevent or reverse bone loss. One study of women with osteoporosis found they had 74 percent less vitamin K than normal.¹

In the October Journal of Nutrition, researchers reviewed the relationship between vitamin K and bone health. The review reported that there are many human studies that clearly establish that vitamin K can improve bone health. Vitamin K apparently increases bone density in osteoporosis patients, as well as reduces the fracture rates. There is also evidence that vitamin K and vitamin D work synergistically on bone density. In most of these studies however, high doses of vitamin K(2) were administered, a practice that has been criticized by other researchers. On the other hand, there have been positive studies on bone health that use low doses of vitamin K(1), especially when taken along with vitamin D. Growing evidence illustrates that this vitamin positively affects calcium balance, which is important in bone metabolism. The Institute of Medicine recently increased the daily dietary recommendations of vitamin K by approximately 50%.²