New research on vitamin D and its apparent ability to reduce stress fractures in girls seems to raise as many questions as it answers. 

The authors of the study, published in the Archives of Pediatrics & Adolescent Medicine, found that vitamin D was “protective” based on the records of 6,712 adolescent girls throughout the United States. To read an abstract of the study, click here.

But they didn’t find a positive relationship between dairy intake and the reduced incidence of stress fractures. And they didn’t find a positive relationship with calcium intake, either.

Since dairy products are a prime source of vitamin D, why wouldn’t there be a positive correlation with dairy consumption? And, isn’t calcium essential to bone health?

Greg Miller, president of the Dairy Research Institute and executive vice president of the National Dairy Council, offers these thoughts:

  • While this study did not find an association between dairy or calcium and stress fracture risk, dairy and calcium intake are important for optimal bone health. In fact, the Dietary Guidelines for Americans, 2010 (released by the U.S. Department of Agriculture and the Department of Health and Human Serivces) stated that “moderate evidence shows that intake of milk and milk products is linked to improved bone health, especially in children and adolescents.”
  • It is important to note that this study only examined stress fracture risk and did not examine overall bone health, such as bone density and bone mineral content.
  • Also, only 3.9 percent of the girls suffered a stress fracture during the seven-year followup. Therefore, this small sample size may have contributed to the inconsistent finding that vitamin D, but not dairy, was associated with reduced stress fracture risk.

“Many different nutrients are important for bone health, especially vitamin D, so it’s not surprising that they found an association between low intake and risk of stress fracture,” Miller says. “It’s good to know milk is the number one food source of vitamin D in our diets and that it delivers many other bone-building nutrients like calcium.”