Vitamin D deficiency is increasingly recognized as a global public health problem affecting infants, children, and adolescents. Recent pooled data suggest that low serum 25-hydroxyvitamin D [25(OH)D] concentrations remain common across many regions of the world, including low and middle income countries. In India, suboptimal vitamin D status is frequent in children, adolescents, and pregnant or lactating mothers, often coexisting with inadequate dietary calcium intake.