Many milk are fortified with vitamins A and D. Vitamin D is found naturally in very few foods and was initially added to milk, a staple food, to reduce the incidence of rickets, a bone-softening condition in children that was at one time endemic in North America. Unfortified cow’s milk traditionally has been regarded as a poor source of vitamin D, supplying 5 to 35 IU/liter.
Before the fortification of milk was widely practice, many children grew up with severely bowed legs and other effects of vitamin D deficiency.
Another benefit of vitamin D supplementation is a lower rate of osteomalacia in the elderly, which is largely responsible for bone fractures. Studies showed that vitamin D might have other health benefits including improvement of the immune response.
The fortification of dried skim milk with vitamin A is viewed by the World Health Organization and the Food and Agricultural Organization was an important measure to combat vitamin A deficiency in developing countries, where 20, 000 to 100, 000 children yearly develop blindness from a lack of vitamin A in their diet.
Vitamin fortification of milk