How effective is nutritional supplementation for the prevention of stress fractures in female military recruits?

Intensive physical training can cause stress fractures in both osteoporotic patients and healthy, young adults. Female military recruits are especially vulnerable to such fractures, with a reported frequency of 5-15% during prolonged periods of intense physical activity. In this Practice Point commentary, I discuss a randomized, controlled study of nutritional supplementation for prevention of stress fractures in female US navy recruits. Lappe et al. reported that intervention with a high dose of calcium (2g daily) plus a normal dose of vitamin D(3) (800IU daily) reduced the incidence of stress fractures by 20% (P<0.003) during the 8-week study period. The authors also confirmed additional risk factors for stress fractures, such as smoking, low physical fitness and amenorrhea. Predisposing risk factors and nutritional intervention strategies that influence stress fracture occurrence in young adults at the time of their peak bone mass, therefore, seem very similar to those known to affect osteoporotic fractures in the elderly.