One often wonders why the milk and edible oils are generally fortified with Vitamins A & D in many parts of the World. Association of Vit A with health of the eyes has been well established and concentrated annual administration is often recommended as an intervention program to children coming from poor families to protect them from losing eye sight and prevent blindness. Cod liver oil, a rich source of Vit A was used years ago to prevent any such deficiency in children, especially those hailing from vegetarian families and encapsulated cod liver oil was available in the market for a while to help people swallow them without experiencing the fishy odor. Vitamin D has a stellar role in bone formation and its deficiency has been implicated in bone related diseases and other ailments. A unique feature of Vit D is its formation under the skin from precursors already present by exposure to sun light(UV radiation 270-300 nm) and it is difficult to imagine how deficiency can develop with so much sun light available. Still we are told that almost 1 billion people are currently under Vit D deficient category.
Ergosterol (Vit D2) and cholecalciferol (Vit D3) are the most commonly found bio active forms that work in mediating metabolic functions related to bone and skeleton. The optimum level in blood is considered to be about 35-55 nanogram per ml while experts recommend a daily intake of 5 micro-gram(ug) for adults up to the age of 50 years, 10 ug for 51-69 years and 15 uc beyond 70 years. Some experts feel a daily intake of 1000 international units(IU) of Vit D equivalent to 25 ug for normal adults and 2000 IU for pregnant women and lactating mothers. Probably higher intake may be advisable as no overdose toxicity is known. Interestingly exposure to sun for 30 minutes thrice a week is adequate to generate the needed Vit D under the skin, from the precursor 7 dehydrocholesterol, while excess formed is always metabolized by the body with no ill effects. People living in tropical regions are better placed in this context but enough exposure of a major portion of the body to sun rays is necessary to Vit D generation. Darker the skin color higher will be exposure time required and those in temperate regions, especially during winter might not have adequate exposure for natural Vit D development. Deficiency syndrome usually develop only during winter times and in summer due to over protection against sun burn by using sun screen lotions.
Recent startling revelation that Vit D deficiency is associated with many deaths indicates a much wider role than its influence on bone development. According to most recent scientific findings, those with even marginal deficiency of Vit D have 26% more chance of death. This is attributed to the distinct possibility that Vit D is associated with influencing blood pressure, insulin response, obesity and other unknown areas of human health. The fact that increased human mortality occurs during winter due to cardiac problems and cancer survival rate is higher when it is detected and treated during summer support the above hypothesis of a more critical role for Vit D in maintaining good health. However confirmation of the above can come only from more elaborate scientific studies involving large number of volunteers. Even if there is some justification for Vit D fortification, milk and edible oils are not the right vehicles. Milk consumption per capita in India is very low while edible oils, besides being costly, are invariably used for high temperature frying. Probably encapsulation and mixing with any foods regularly consumed by the entire population, must be identified.
In India no reliable data is available regarding any wide spread Vit D deficiency and probably it might not be as prevalent as many think due to all year round sun shine in major part of the country and extended exposure of the population during day time doing their daily chores. God seems to be on the side of people from developing countries, most of them located in the tropical region, where abundance of 'free' sun shine is available to make them at least Vit D self sufficient!