Young women may also benefit from vitamin D. Researchers studied more than 6,000 girls between 9 and 15 years old for seven years. They collected information about the girls’ intake of dairy products, calcium and vitamin D and also looked at stress fractures as a consequence of sports. Approximately 4 percent of the young women experienced a stress fracture during the study.
Calcium and dairy products did not seem to have any correlation with the risk of fracture, but the girls with the highest levels of vitamin D were only half as likely to develop stress fractures as those with the lowest levels. Surprisingly, the girls with the highest intake of calcium appeared to be at double the risk of stress fracture, but the investigators caution that this finding needs further investigation. The current recommendation for vitamin D intake is 600 international units a day for adolescents; the scientists say further research is needed to tell if higher levels would be more protective.