• Davaasambuu Ganmaa, Edward Giovannucci, Barry R Bloom, Wafaie Fawzi, Winthrop Burr, Dulguun Batbaatar, Nyamjav Sumberzul, Michael F Holick, and Walter C Willett.
• Department of Nutrition, Harvard School of Public Health, Boston, MA, USA. gdavaasa@hsph.harvard.edu
• Am. J. Clin. Nutr. 2012 Aug 1; 96 (2): 391-6.

BackgroundBy modulating immune function, vitamin D might increase innate immunity and inhibit the growth of initial bacterial invasion and protect against tuberculosis infection.ObjectiveWe examined the effect of vitamin D supplementation on tuberculin skin test (TST) conversion.DesignA double-blind, placebo-controlled study was conducted in 120 Mongol schoolchildren. We estimated the prevalence of latent tuberculosis infection at baseline and examined the effect of vitamin D (800 IU/d) on serum concentrations of 25-hydroxyvitamin D [25(OH)D] and TST conversion.ResultsAt baseline, the mean (±SD) 25(OH)D concentration was 7 ± 4 ng/mL, and all concentrations were <20 ng/mL. Vitamin D supplementation increased serum 25(OH)D by a mean of 12.7 ng/mL compared with placebo (P < 0.0001). At baseline, 16 children in the vitamin D group and 18 in the placebo group were TST positive (P = 0.7). Over 6 mo, TSTs converted to positive in 5 (11%) children receiving vitamin D compared with 11 (27%) receiving placebo (RR: 0.41; 95% CI: 0.16, 1.09; P = 0.06). Only one TST conversion occurred among those whose serum 25(OH)D concentration increased to >20 ng/mL, whereas 8 TST conversions occurred in those whose final 25(OH)D concentration remained <10 ng/mL (P = 0.05). The mean increase in stature was 2.9 ± 1.6 cm in the vitamin D group and 2.0 ± 1.7 cm in the placebo group (95% CI: 2.16, 2.81; P < 0.003).ConclusionsVitamin D supplementation for 6 mo had significant favorable effects on serum 25(OH)D concentrations and on growth in stature. A trend was seen toward fewer TST conversions in the vitamin D group. This trial was registered at clinicaltrials.gov as NCT01244204.

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