Vitamin D is a somewhat special, fat-soluble vitamin, in the sense that it is the only vitamin that the body itself can make. Vitamin D is produced inside body via the skin when ultraviolet rays from sunlight trigger its synthesis. However, for people residing in high latitudes, having a dark skin color, older age, being inside a lot, living in smoggy environments the diet is important to get enough vitamin D. Sources of food which are high in vitamin d are scarce. >1 billion people in the world have low vitamin D levels. This is found in all ethnicities and age groups.