Vitamin K & Bone Health

Vitamin K is an important nutrient, vital not only to blood clotting, but also to bone health. Studies have shown a link between levels of vitamin K and bone density and risk of bone fractures. This is particularly important for women over the age of 50 who are more at risk for osteoporosis, a disease of weakened bones.

Vitamin K Basics

A fat-soluble vitamin, vitamin K is found in high levels in green vegetables, but also in many other foods. Spinach, kale, collard greens, cabbage, Brussels sprouts and broccoli are excellent sources of vitamin K. Peas, strawberries, soybeans, carrots, tomatoes and whole milk are also good choices. It plays an important role in forming proteins that help the body's blood clotting mechanism. Without vitamin K, a penetrating injury would not clot normally, increasing the risk for blood loss.

Bone Density and Vitamin K

Bone density refers to how strong bones are. A weak bone is porous and more likely to break or fracture. A 2003 study in the "American Journal of Clinical Nutrition" found that low bone density in women was linked to low levels of vitamin K. The same result was not found for men. The mechanism by which vitamin K affects bone health is not known, but research is ongoing.

Hip Fracture and Vitamin K

A 1999 study in the "American Journal of Clinical Nutrition" found a link between low levels of vitamin K with increased risk for hip fractures in women. Women who took 110 mcg of vitamin K per day were found 30 percent less likely to suffer a hip fracture compared to women who consumed less vitamin K than that. A 2000 study in the same journal concluded risk for hip fractures in elderly men also increased with low vitamin K.

Recommendations

Adult women, ages 19 and older, should consume 90 mcg of vitamin K per day, increasing to 120 mcg of daily vitamin K for men of the same age. Both male and female children ages 9 to 13 should consume 60 mcg of daily vitamin K. This increases to 75 mcg per day for 14- to 18-year-olds. These recommendations are a 50 percent increase from previous values, showing the growing importance placed on vitamin K.