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Effects of Vitamin D Supplementation on Bone Density in Healthy Children

According to an article published in the British Medical Journal (2011;342:c7254), a study was performed to determine 1) the effectiveness of vitamin D supplementation for improving bone mineral density in children and adolescents and, 2) if effects vary with factors such as vitamin D dose and vitamin D status. The study involved a systematic review of the literature and meta-analysis.

Data sources included: 1) Cochrane Central Register of Controlled Trials, Medline (1966 to present); 2) Embase (1980 to present); 3) CINAHL (1982 to present); 4) AMED (1985 to present); 5) ISI Web of Science (1945 to present), and 5) manual searching of conference abstracts from key journals.

Study selection included placebo controlled, randomized controlled trials of vitamin D supplementation, for at least three months, in healthy children and adolescents (aged 1 month to <20 years) with bone density outcomes.

Data analyses included mean differences of the percentage change from baseline in bone mineral density of the forearm, hip, and lumbar spine and total body bone mineral content in treatment and control groups. Subgroup analyses were carried out by gender, pubertal stage, dose of vitamin D, and baseline serum vitamin D concentration. Compliance and allocation concealment were also considered as possible sources of heterogeneity.

Six studies, totaling 343 participants receiving placebo and 541 receiving vitamin D, contributed data to the meta-analyses. Results showed that vitamin D supplementation had no statistically significant effects on total body bone mineral content or on bone mineral density of the hip or forearm. There was a trend to a small effect on lumbar spine bone mineral density (mean difference 0.15; P=0.07). Effects were similar in studies of participants with high compared with low serum vitamin D levels, although there was a trend towards a larger effect with low vitamin D for total body bone mineral content (P=0.09 for difference). In studies with low serum vitamin D, significant effects on total body bone mineral content and lumbar spine bone mineral density were roughly equivalent to a 2.6% and 1.7% percentage point greater change from baseline in the supplemented group.

According to the authors, it is unlikely that vitamin D supplements are beneficial in children and adolescents with normal vitamin D levels. However, the planned subgroup analyses by baseline serum vitamin D level suggested that vitamin D supplementation of deficient children and adolescents could result in clinically useful improvements, particularly in lumbar spine bone mineral density and total body bone mineral content. However, this observation requires confirmation using prospective studies.

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