GIRLS and young women who took lots of vitamin D were half as likely to suffer a stress fracture as those who didn’t get much of the vitamin, according to a US study that followed thousands of girls.

Stress fractures are small cracks in the bones that typically affect people who do lots of high-impact exercise, such as running or gymnastics. They’re especially a concern for teen girls because bone strength at that age is tied to the risk of osteoporosis and more serious injuries later on. “This study can add to the existing thought that adolescent girls and young women should be particularly cognizant of getting their vitamin D,” said Kendrin Sonneville, from Children’s Hospital Boston, who worked on the study. Vitamin D is naturally present in fatty fish, but is also added to dairy products like milk and yogurt. Since it’s not always easy to get enough through food, doctors recommend taking supplements. Researchers have wondered whether eating a high-calcium diet with lots of dairy products might protect against stress fractures, but in the study it was high levels of vitamin D that were tied to fewer fractures, not calcium. For the study, published in the Archives of Pediatrics & Adolescent Medicine, the researchers followed close to 7,000 girls who were the daughters of women participating in the long-term Nurses’ Health Study. –Reuters