Researchers know that vitamin K deficiency impairs bone mineralization. Without vitamin K, osteocalcin--the major noncollagen protein in bone--can't be synthesized and bone metabolism is affected. There are two types of vitamin K: K1 and K2. Studies have shown that patients with fractures due to osteoporosis often have low blood levels of K1.

In a new 12-month study, researchers from Osaka Kosei-Nenkin Hospital in Osaka, Japan, measured blood levels of vitamin K, osteocalcin and other markers of bone metabolism in 71 postmenopausal women and 24 menopausal women who were receiving hormone replacement therapy. In the first group, women with reduced bone density had lower levels of vitamin K1 and K2 than those with normal bone density. In the second group, levels of osteocalcin decreased during hormone replacement therapy, but vitamin K showed no significant change.

Conventional therapy for osteoporosis includes vitamin D, calcium, calcitonin (a hormone that inhibits bone resorption) and estrogen. Because osteoporosis has multiple causes, these substances aren't always sufficient. The authors suggest that vitamin K may prove a useful adjunct to preventing postmenopausal bone loss. Vitamin K can either be obtained as a supplement or from foods such as yogurt, alfalfa, egg yolk, safflower oil, kelp, fish liver oils, leafy greens and milk.

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Serum vitamin K level and bone mineral density in post-menopausal women
Int J Gynaecol Obstet 1997 (Jan); 56 (1): 25-30

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