To determine vitamin D requirements, dose response studies with various doses are essential. There is very little data on dose response to vitamin D in the Indian context. However, several studies have reported that if vitamin D is given together with calcium, and the compliance is adhered to, there is a significant increase in vitamin D concentrations [1].　

The action of vitamin D on bone is mainly through the absorption of calcium. One of the major problems in the Indian children is poor intake of calcium and low calcium-to-phosphorous ratio. As this is very specific to Indian circumstances, the guidelines have stressed that adequate intake of calcium at all age groups is critical. We have considered data pertinent to the Indian situation while drafting the guidelines. Another set of recent Global guidelines specifically meant for children has Indian representation, and they also considered Indian data [2].

While many reasons have been suggested for low vitamin D concentrations in Indians, lack of exposure to sunlight (the main source of vitamin D in Indians) is likely to be a major contributor. Thus, for the prevention of vitamin D deficiency in Indians, the ICMR report on recommended daily intake (RDI) for Indians states that increasing the RDI for vitamin D is not the solution but ensuring adequate exposure to sunlight is. Therefore, the ICMR Committee agreed outdoor physical activity as a mean to achieve adequate vitamin D. This is reflected in their recommendations and they make no specific suggestions for vitamin D intakes in different groups [3]. However, under situations of minimal sunlight exposure, a specific recommendation of a daily supplement of 400 IU (10 µg) has been suggested.　

In references quoted by authors of this correspondence around 95% subjects were vitamin D deficient; hence, doses to prevent vitamin D deficiency would be insufficient. However, other Indian studies have shown a good response to 600 IU vitamin D supplementation per day with little difference between 600 and 1000 IU doses [4,5].