Vitamin D effect on bone density may be status-dependant

Vitamin D supplements may not improve bone density in healthy children with normal vitamin D status, a new Australian review suggests.

The meta-analysis included six randomized controlled trials that measured changes in bone density of 884 healthy children and adolescents (aged from one month to 19 years) receiving vitamin D supplements or a placebo for at least three months (1). The analysis indicates that vitamin D supplementation had no statistically significant effects on hip bone, forearm, or whole body bone density in healthy children with normal vitamin D blood levels. There was, however, indication that children who had low levels of vitamin D in their blood might benefit from supplementation.

The researchers commented that while there would be no reasonable evidence that vitamin D supplementation significantly improves bone health in the general population specific groups like vitamin D deficient children could benefit from supplementation.

Experts criticized the limited amount of data analyzed in the review. There are not enough studies on children to give a conclusive answer on the subject. In addition, the study should not overlook the fact that a lot of people – including children – have inadequate vitamin D status, or are fully deficient, and are recommended to increase their vitamin D intake, they said.

Low bone mineral density is a major risk factor for osteoporosis. Previous studies have suggested that up to 90 percent of bone mass is built during childhood, and increasing bone mass in childhood is seen as a potential way to reduce the risk of osteoporosis. It is estimated that a 10 percent increase in peak bone mass reduces the risk of an osteoporotic fracture in adult life by 50 percent. Vitamin D is known to improve calcium deposition in bones, and previous research has suggested children with vitamin D deficiency have reduced bone density.

1. Winzenberg T. M. et al. Vitamin D supplementation for improving bone mineral density in children. Cochrane Database of Systematic Reviews. Issue 10. 2010.