MONDAY, March 5, 2012 (HealthDay News) -- Preteen and teenage girls whose diets are rich in vitamin D may be at lower risk for stress fractures, particularly if they are involved in high-impact activities, according to a new study.
Researchers from Children's Hospital Boston followed over 6,700 girls, ranging in age from 9 to 15 at the start of the study, over the course of seven years. The study, published in the March 5 online edition of the Archives of Pediatrics & Adolescent Medicine, found nearly 4 percent of the girls developed a stress fracture during the follow-up period.
The investigators noted that vitamin D intake was associated with a lower risk for stress fracture, and they found that this link was stronger among girls who participated in at least one hour of high-impact activity every day.
Although increased calcium intake is often recommended for stronger bones, the study results indicated that dairy and calcium may actually be unrelated to the development of stress fractures.
"There was no evidence that calcium and dairy intakes were protective against developing a stress fracture or that soda intake was predictive of an increased risk of stress fracture," Kendrin Sonneville, of Children's Hospital Boston, and colleagues said in a journal news release.
The study authors said that their findings support the Institute of Medicine's recent increase in the recommended dietary allowance for vitamin D for teenagers to 600 international units (IU) daily.
However, more research is needed to determine whether vitamin D supplements provide the same benefits as vitamin D consumed through diet alone, the team noted.
And while the study uncovered an association between vitamin D intake and a lower risk of stress fractures, it did not prove a cause-and-effect relationship.
Sources of vitamin D include being out in the sunlight and foods including salmon, tuna, eggs and vitamin D-fortified milk.
The U.S. National Institutes of Health's Office of Dietary Supplements has more about vitamin D.