This study followed adolescent girls for 7 years to determine if the intake of vitamin D, calcium, or dairy was related to the development of stress fractures, an indication of bone health. Researchers found that neither calcium or dairy intake was related to a reduction in bone fractures but that vitamin D intake was related to a decreased incidence of stress fractures.

Article Abstract:

“A total of 6,712 girls aged 9 to 15 years at baseline in the Growing Up Today Study, an ongoing prospective cohort study. Dairy, calcium, and vitamin D intakes assessed by food frequency questionnaire every 12 to 24 months between 1996 and 2001.
Main Outcome Measure: Incident stress fracture that occurred between 1997 and 2004 as reported by mothers of the participants in 2004. Cox proportional hazards models were used to examine associations.”

“During 7 years of follow-up, 3.9% of the girls developed a stress fracture. Dairy and calcium intakes were unrelated to risk of developing a stress fracture. However, vitamin D intake was inversely related to stress fracture risk.
The multivariable-adjusted hazard ratio of stress fracture for the highest vs the lowest quintile of vitamin D intake was 0.49 (95% CI, 0.24-1.01; Ptrend=.07). We conducted a stratified analysis to estimate the association between vitamin D intake and stress fracture risk among girls participating in at least 1 h/d of high-impact activity, among whom 90.0% of the stress fractures occurred, and found that higher vitamin D intake predicted significantly lower risk of stress fracture (Ptrend=.04).”

“Vitamin D intake is associated with lower stress fracture risk among adolescent girls who engage in high levels of high-impact activity. Neither calcium intake nor dairy intake was prospectively associated with stress fracture risk.”