Young Girls Need Vitamin D

Stress fractures in young active females may be prevented with vitamin D

(RxWiki News) The commonly held belief that drinking milk will prevent stress fractures may not be wholly true. Calcium may be less important than vitamin D when it comes to building strong bones.

A recent study followed a group of girls, aged 9 to 15, for seven years to compare their dairy, calcium and vitamin D intake to the incidence of stress fractures.

Researchers found that when it comes to the developing years, vitamin D helped protect more than calcium.

"Make sure your kids are getting enough vitamin D."

Kendrin Sonneville, ScD, director of nutrition training in the division of adolescent and young adult medicine at Boston Children’s Hospital and instructor at Harvard Medical School, led a study to investigate whether a lack of calcium and/or vitamin D are associated with stress fractures in girls.

Researchers used 6,712 girls aged 9 to 15 enrolled in the Growing Up Today Study (GUTS). Every 12 to 24 months between 1996 and 2001, the research team assessed the participant’s dairy, calcium and vitamin D intake.

Participants and their mothers were also asked to report any stress fractures that occurred from 1997 to 2004.

In those seven years, 4 percent of the girls reported stress fractures. Authors were able to conclude that more or less dairy and calcium intake did not have any relationship with the stress fractures.

Girls who spent at least one hour per day participating in a high-impact activity accounted for 90 percent of the stress fractures reported by the group.

Vitamin D intake lowered stress fracture incidence in this group.

Authors said, “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.”

“Girls in the highest quantile (consumption group) of vitamin D intake had a 50 percent lower risk of stress fracture compared with girls in the lowest quantile.”

These results did not hold true for fully developed women, suggesting that vitamin D intake is more important during growth years.

The authors admit that this data is limited because the GUTS participants were all daughters of registered nurses and do not represent a diverse group. They were also unsure if consuming vitamin D from food has a different reaction than from taking it as a supplement. 

This study was published in March in the Archives of Pediatrics & Adolescent Medicine. Funding for this study was provided by Boston Children’s Hospital and the National Institutes of Health; no conflicts of interest were found.

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Review Date: 
July 4, 2012