Vitamin K Supplements Greatly Reduce Risk of Bone Fractures and Cancer

Vitamin K has been garnering plenty of interest in nutrition circles, and the latest study has found that supplements of this vitamin can reduce the risk of bone fractures and cancer in women.

Angela M. Cheung, MD, PhD, of the University of Toronto, Canada, and her colleagues asked 440 postmenopausal women with osteopenia to take either 5 mg (5,000 mcg) of vitamin K1 or placebos daily for four years. Osteopenia describes a decrease in bone mineral density and is generally considered a prelude to osteoporosis. All of the women had normal levels of vitamin D, to eliminate that variable on fracture and cancer risk.

All of the women experienced decreases in bone mineral density at several sites including the lumbar spine, hip, and femoral neck. However, women taking vitamin K had substantial reduced risks of fractures and cancer during the study. Among the women taking vitamin K only nine had fractures, compared with 20 of the women taking placebos.

In addition, among the women taking vitamin K, only three developed cancer, compared with 12 in the placebo group.

Although vitamin K did not prevent the loss of bone, it "did protect against clinical fractures and cancers," wrote Cheung and her colleagues. The finding suggests that vitamin K's effect on bone may be mediated though mechanisms not directly related to bone density.

Additionally, while other studies have found an anticancer benefit from vitamin K2, this study "may be the first to suggest that vitamin K1 also has anticancer effects," the researchers wrote.

Several recent studies, conducted in the United States and Japan, have shown that vitamin K supplements can improve glucose tolerance, in effect boosting resistance to type-2 diabetes. Still other recent research suggests that vitamin K may regulate where the body deposits calcium. These studies found that vitamin K may prevent calcium deposits in the arteries, also known as hardening of the arteries.

Supplements are sold in three different forms: vitamin K1 and two different forms of vitamin K2, the MK-4 and MK-7 forms.

Reference: Cheung AM, Tile L, Lee Y, et al. "Vitamin K supplementation in postmenopausal women with osteopenia (ECKO trial): a randomized controlled trial." PLoS Medicine, 2008;5(10):e196.