We've all heard that eating foods rich in calcium and vitamin D, such as milk, yogurt, and low-fat cheese, is important for maintaining strong, healthy bones. Now there is increasing evidence that foods rich in vitamin K, such as leafy greens, also play a role in bone health.

Among the latest research is a study that found that women with higher intakes of vitamin K have better bone mineral density (BMD) measurements compared with women with lower intakes. The results are published in the American Journal of Clinical Nutrition.

Vitamin K intake and bone mineral density

Researchers studied 1,112 men and 1,479 women (average age 59) who were part of the Framingham Offspring Study. The study participants filled out detailed questionnaires regarding their food and dietary supplement intake for the previous year. Using these questionnaires, the researchers were able to determine how much vitamin K (as well as other nutrients) the men and women had consumed.

The participants underwent comprehensive physical exams that included X-ray testing for bone mineral density of certain areas of the body, including the hip and spine. Low bone mineral density is a risk factor for fractures.

Vitamin K intake was significant in women but not men

The women with the lowest intakes of vitamin K had significantly lower bone mineral density measurements compared with women with the highest intakes. This was true even after the researchers accounted for other factors that could influence bone mineral density, such as smoking, exercise, and calcium and vitamin D intake. However, for reasons that remain unclear, there was no association between vitamin K intake and bone mineral density in men.

The role of vitamin K

It remains to be determined exactly how vitamin K affects bones. And the authors of this study point out that it may have been more than just vitamin K that influenced the participants' bone mineral densities. For example, the people with high vitamin K intakes may have led more healthful lifestyles overall, which contributed to their higher bone mineral density.

Eating and exercising for bone health

Still, this study adds to existing research that there is likely a role for vitamin K in overall bone health. To eat for optimal bone health, make sure your diet contains plenty of sources of calcium, vitamin D, and vitamin K, found most abundantly in leafy green vegetables. And be sure to engage in some form of weight-bearing exercise, as well.