The very big vitamin problem6 min read . Updated: 01 Dec 2014, 06:59 PM IST
Even though we live in a sunny country, most Indians are chronically deficient in vitamin D
Till the 1990s, people living in places with plenty of sunshine, like India, were considered to be safe from the risk of vitamin D deficiency (VDD). Vitamin D is synthesized in the body through exposure to sunlight, and it followed that the more sun you had, the easier it was for your body to get the amount of vitamin D it needed. Almost two decades of extensive medical studies and research have now revealed that this is not exactly the case.
Indians are chronically deficient in the “sunshine vitamin", irrespective of age, social status, geographic location (within India), and access to healthcare. The poor, the well-off, the newborn, the pregnant, men, women and children—VDD is endemic in India.
Countrywide studies have reported VDD in equal measure in urban and rural areas, in populations that have a diet rich in vitamin D sources (like fish) and populations that don’t. Young athletes as well as soldiers, with access to good nutrition and plentiful sun exposure, have been found deficient. A survey that looked at doctors across the subcontinent found most had low levels of the vitamin.
“Indubitably, vitamin D status in India is grim and needs to be reckoned with," concluded a study that did a meta-analysis of VDD surveys in India. Titled Vitamin D Deficiency In India: Prevalence, Causalities And Interventions, it was published in February in the journal Nutrients.
“It is an epidemic," says Urvashi Mehlawat, assistant professor, faculty of applied science, department of nutrition and dietetics, Manav Rachna International University, New Delhi. “It is also a rapidly growing public health concern, the significance of which is poorly understood in our country." Mehlawat was an author of a review article, Current Status Of Vitamin D Deficiency In India, published in April by the All India Institute of Medical Science, New Delhi. The article puts the prevalence of VDD as high as 90% among all age groups.
“Till recently, we doctors knew that VDD leads to brittle bones and other skeletal disorders like rickets and osteoporosis," says Gita Prakash, head, preventive healthcare, at Max Hospitals, New Delhi. “Now more and more research is establishing links between VDD and a very large number of diseases. Everything from cardiovascular diseases to hypertension, diabetes, tuberculosis and even cancer. And if you think about the fact that most of these diseases have very high rates in India, you understand why VDD needs to be given a lot of importance."
The first study cited in this article also comes to a similar conclusion: “Owing to its multifarious implications on health," it says, “the epidemic of vitamin D deficiency in India is likely to significantly contribute to the enormous burden on the healthcare system of India."
The D dilemma
Vitamin D is a fat-soluble vitamin that is required by the body to synthesize and maintain levels of calcium and phosphate in the body. Calcium and phosphate, in turn, are responsible for a host of critical functions, including formation, maintenance and repair of bones, muscle contraction, nerve conduction, and general cellular function. Vitamin D is also called a “prohormone" because it serves some endocrinal functions like regulating cell growth and differentiation. Vitamin D is also unique among vitamins because its most significant source is not dietary. It is synthesized by the body itself on exposure to ultraviolet B (UVB) rays in sunlight.
Why is it then that despite having plenty of sunshine, Indians suffer from VDD?
“There are many reasons for it," says Dr Prakash, “but possibly the two most important ones are that despite all the sunshine, Indians don’t get the right kind of exposure to UVB rays to produce enough of the vitamin, and because there is very little awareness of the deficiency. Even the medical community began doing serious research on it here only in the last 10 years."
Dr Prakash and Mehlawat list the various things that constitute the right kind of sun-exposure that leads to adequate amounts of vitamin D production:
Time of day: UVB rays from the sun reach us most when the sun is high in the sky, so 10am-2pm is ideal in most months. In summer, this period is extended. When the sun’s rays are at too much of an angle to the sun, as in the mornings and evenings, the atmosphere blocks the UVB wavelength.
Location: The closer you are to the equator, the more UVB you get from the sun.
Skin colour: This is where it gets tricky for Indians. The darker the skin, the more rich it is in the pigment melanin, which is a natural sunscreen. Where light-skinned people (like Caucasians) would need 15 minutes of exposure to the sun, the average Indian needs 30-45 minutes.
Amount of skin exposed: Yet another factor that makes Indians more prone to VDD—you need to expose as much of your skin as possible to produce vitamin D properly, not just your face and hands. The larger the surface area of skin exposed, like the back, the better the production. “The levels of pollution and that we are usually very well-covered when we are outside add to the VDD issue. Some of these difficulties are understandable—you desperately want to get out of the sun in the heat of summer, not stay in it," says Mehlawat.
Also, the use of sunscreen blocks UVB effectively and does not allow the synthesis of vitamin D. “That kind of explains why we have such endemic VDD," Mehlawat says.
Cloud cover: Cloudy days block UVB wavelengths.
Pollution: The more polluted the air, the less the UVB that reaches your skin.
Glass: Glass blocks all UVB, so if you are in a room flooded with sunshine that is coming through glass, you are producing no vitamin D.
D and diet
The paper Vitamin D Deficiency In India: Prevalence, Causalities And Interventions also lists other, even trickier, causes of VDD prevalence. The study found that there is also low calcium in the average Indian diet, and high levels of phytate, the main storage form of phosphorus in plant tissues, especially the bran portion of grains and other seeds. This leads to a complicated cycle in the body whose end result includes VDD, even if there is enough exposure to the sun. The study notes that this is the possible cause of VDD in farmers, who otherwise spend a fair amount of time in sunshine.
Though vitamin D is found in small amounts in food sources like fatty fish (mackerel, salmon, tuna, cod), cod liver oil, milk, egg yolk and mushrooms, the dietary sources are never sufficient. It is simply not possible to get the amount of vitamin D the body needs from food alone.
Many studies on VDD in India, therefore, recommend that common food products like milk and juice should be fortified with the vitamin as a public health measure. This already happens in countries like the US and Canada, where it is legally mandated.
“At the moment, there is only one way to get enough vitamin D," says Dr Prakash. “Take supplements. Though this should be done in consultation with a doctor who can determine just how much you need. The best way, of course, is to get enough sun on enough skin, but that is clearly easier said than done."
Though different organizations recommend different daily requirements for vitamin D, the most commonly followed guidelines, proposed by the US-based non-profit Vitamin D Council, are 1,000 IU/day per 25lbs (around 11kg) of bodyweight for children and 1,500-2,000 IU/day for adults. Our bodies can produce 10,000-25,000 IUs of the stuff in a day when exposed to proper amounts of sun—if we allow them to.