To the Editors The study by Ms Gallo and colleagues1 investigated the effect of vitamin D supplementation at different doses during the first 12 months of life. The major confounder with respect to vitamin D levels is endogenous synthesis from UV radiation, which at recommended exposure levels should equate to 1000 IU/d of vitamin D. The authors corrected for the effects of sun exposure using the results of the study by Barger-Lux et al.2 However, in that study the sample population was healthy men who had just completed a summer season of extended outdoor activity working in landscaping, construction work, and farming (as well as other outdoor jobs). This index has not been validated and the questionnaire has not been used for an infant population.
Sofiyan A, Nanan RKH. Vitamin D Supplementation During First 12 Months of Life. JAMA. 2013;310(8):853. doi:10.1001/jama.2013.124263