Supplementation does little to reduce fractures in schoolchildren with vitamin D deficiency

Among schoolchildren with a high baseline prevalence of vitamin D deficiency, oral supplementation with vitamin D for 3 years is safe but falls short of reducing the risk of fracture, according to a study.

The study recruited 8,851 children across 18 public schools in Ulaanbaatar, Mongolia, of whom 4,418 were assigned to receive vitamin D (oral dose of 14,000 IU, once per week) and 4,433 to receive placebo for 3 years. These children had a negative QuantiFERON-TB Gold In-tube assay (QFT) result, were not hypersensitive to vitamin D or immunocompromised, did not use vitamin D supplements, did not have clinical signs of rickets, and had no intention of leaving Ulaanbaatar within 3 years.

Outcomes such as the incidence of fractures and adverse events were determined using questionnaires.  Generalized linear models with binomial distribution and a log link function with adjustment for school of attendance were used to estimate the association between vitamin D supplementation and the outcomes.

A total of 8,348 participants (median age 9.2 years, 50.6 percent men, 92.2 percent of Khalkh ancestry) were included in the fracture and safety analyses: 4,176 in the vitamin D group and 4,172 in the placebo group. Most participants (95.5 percent) had baseline serum 25-hydroxyvitamin D concentrations <50 nmol/L.

Over a median follow-up of 3.0 years, the incidence of fractures did not significantly differ in the vitamin D group and the placebo group (6.4 percent vs 6.1 percent; adjusted risk ratio, 1.10, 95 percent confidence interval, 0.93–1.29; p=0.27).

Likewise, the frequency of adverse events was similar between the two treatment groups.