When sunlight falls on the skin, it forms an essential nutrient, vitamin D. For people in India, which has an average of 300 clear sunny days in a year, this sunshine vitamin should be available in abundance. However, reports show as many as 80 per cent people in urban India and 70 per cent in rural India are deficient in the vitamin. According to studies, this could be because of changing lifestyle, dietary habits, rising air pollution levels and high concentration of toxins, like pesticides, in the environment. To make up for the shortage, doctors prescribe supplements. Some even propose mandatory fortification of food. But there seem to be gaps in understanding this paradox of vitamin D deficiency amid plenty of sunshine. Vibha Varshney sifts through research data and suggests it would be prudent to understand these gaps before resorting to supplementation and fortification