Vitamin D deficiency a worry in India
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Research has shown that Indian skin pigmentation needs more exposure to sunlight, as compared to fair-skinned people in the West, in order to generate the same amount of Vitamin D. In general, the greater the skin pigmentation, higher the concentration of melanin and lesser the amount of vitamin D produced. Other reasons could be inadequate exposure to sunlight, particularly for those who remain indoors during the day, such as the elderly.
Vitamin D's association with bone, tooth and skeletal development is well-known. Apart from these, its role in several other conditions has now been identified. Low levels of vitamin D have been linked to impaired calcium absorption, osteoporosis, hypertension, heart disease, stroke, type II diabetes mellitus, infectious diseases, tuberculosis, asthma, psoriasis, schizophrenia and depression. Others include auto-immune conditions like type 1 diabetes, multiple sclerosis, systemic lupus erythematosus (SLE), rheumatoid arthritis, many common cancers including prostate, breast, ovarian, or colon cancer, birth defects, obesity, fibromyalgia, chronic fatigue syndrome and neuro-degenerative diseases including Alzheimer's.
Interestingly, infants who receive vitamin D supplementation (2,000 units daily) show 80 per cent reduced risk of developing type I diabetes over the next 20 years. Severe deficiency of this vitamin leads to brittle bones, commonly known as rickets in children and osteomalacia in adults. Individuals with kidney or liver damage are at increased risk of vitamin D deficiency as their body's ability to circulate active vitamin D is impaired.
Vitamin D is naturally present in very few foods, which include fish liver oils, ghee, butter and egg yolk. Fish liver oil is the best dietary source of vitamin D. Other foods are not as rich in this vitamin.
In developed countries, vitamin D is added to foods through fortification. To get minimum required levels of vitamin D in the diet, a person needs to drink at least 10 glasses of vitamin D fortified milk every day. Ideally, a diet that includes dairy, fish and egg yolk coupled with adequate exposure to sunlight should prevent vitamin D deficiency.
According to current recommendations, to prevent vitamin D deficiency, one should spend 15 to 20 minutes in the sunshine every day, with 40 per cent of the skin surface exposed between 11 am and 3 pm. These radiations cannot penetrate glass, therefore, the body does not generate vitamin D while sitting in a car or indoors. People with dark skin pigmentation may need 20-30 times more exposure than fair-skinned people. Sunscreens, commonly advised for prevention of skin cancers, can seriously impair absorption of vitamin D. Even weak sunscreens, with a sun protection factor of 8, reduce the body's ability to generate vitamin D by
95 per cent. Obesity also impairs vitamin D utilisation in the body. Obese people need twice the amount of vitamin D as healthy people.
It is impossible to generate too much vitamin D from sunlight exposure as the body self-regulates its needs. Most experts agree that the minimum daily intake of vitamin D should be at least 800-1,000 IU per day to maintain a healthy concentration of 25 (OH) D in the blood. In India, there are no policies for fortification of vitamin D, getting enough of this vitamin poses a challenge. If adequate sunshine exposure is not possible, supplements must be taken strictly under medical supervision. Chronic vitamin D deficiency requires supplementation and sunlight exposure to rebuild bones and nervous system.
Long-term strategies to address this deficiency should include public education, national health policies for screening and prevention through food fortification, and treatment with vitamin D supplementation.