For two years the cause of her illness remained elusive. Sometime in 2010, the 22-year-old national-level rower from Kolkata experienced pain in the heels during morning runs. It got worse over time. A year later, the rower, who does not wish to be named, developed pain and stiffness in the back. Doctors suspected she was suffering from ankylosing spondylitis, or inflammation of joints of the spine, and put her on painkillers and anti-inflammatory medicines. Then in early 2012, a check-up revealed she was deficient in vitamin D.
The nutrient, chiefly obtained by exposure to ultraviolet (B) radiation from sunlight, ensures bone health by allowing absorption of calcium from the blood (see ‘Nuts and bolts of vitamin D’). The rower’s doctor advised her to take a mega dose of the nutrient—600,000 IU of Arachitol injections every week for six months, and then once a month for another six months, or until her vitamin D levels get up to the optimal range. The doctor told her that her lifestyle was responsible for her problem. The explanation was hard to swallow as until her sickness, she used to spend a minimum of three hours every day in the sun, rowing, and did not do anything to protect herself from the scorching sun. However, she does not complain now since the treatment worked. She plans to resume jogging, swimming and dancing after she gets her vitamin D levels tested again in two months.
Miracle vitamin?
About 90 per cent of the vitamin D, also known as calciferol, needed by a person is produced in the body. When skin is exposed to the ultraviolet (B) rays, provitamin D present in the skin gets converted into previtamin D. It is isomerised by body heat to the precursor of vitamin D3, which is then transported to the liver through blood. Here, vitamin D3 gets converted to 25-hydroxy vitamin D and is sent to the kidneys where its active form calcitriol is formed. Calcitriol is important for maintaining calcium balance in the body. It also functions as a hormone and regulates the concentration of calcium and phosphate in blood.
The recommended exposure time to obtain this UV dose depends on the skin type, time and location as well as ambient conditions and clothing. Studies carried out in developed countries show that a full body exposure to UVB radiation that results in pinkness of skin (one erythemal dose) is equal to an oral intake of 250–625µg (10,000–25,000 IU) of 25-hydroxy vitamin D. Exposing one-quarter of skin, for instance just hands, arms and face, to one erythemal dose of UVB rays can form dietary equivalent vitamin D dose of about 1,000 IU. However, no such calculation has been done for India, where the complexion of people varies from light to dark.
Initially, most of the known benefits of vitamin D were restricted to those to the bones. But in recent years, the vitamin has been given the status of a miracle molecule due to the large number of extra-skeletal benefits it seems to have. Research around the world shows that it can prevent multiple sclerosis, diabetes, cancer, pre-eclampsia during pregnancy, low birth weight, and also improve immune response to TB, cognitive decline, Parkinson’s disease, asthma and obesity.
But a recent report by USA’s Institute of Medicine (IOM) punctures the bubble—the 2011 report says the evidence that links vitamin D to all the myriad diseases is weak. The potential roles of vitamin D are currently best described as hypotheses of emerging interest, and the conflicting nature of available evidence cannot be used to establish health benefits with any level of confidence, IOM says.
At present standards for vitamin D are set down by using the level of 25D in the blood. But a study based on postmortems shows a large proportion of people who had less than 10 ng/ml of 25D had normal bone histology.
Moreover, vitamin D is not the only nutrient required for adequate calcium levels, which ensure bone health. Calcium levels are also controlled by sodium and potassium levels in the diet. For instance, high intake of sodium increases excretion of calcium through urine, but it can be checked by adding more potassium in the diet. Consumption of alcohol, coffee and tea too reduce calcium absorption. Experts suggest consumption of carbonated soft drinks with high levels of phosphate can also lead to reduced bone mass and heighten risk of fracture.
Like the Kolkata-based rower, a 42-year-old lecturer (who also does not wish to be named) from University of Delhi makes it a point to spend at least an hour in the afternoon sun every day after she returns from college. She recently visited her doctor, seeking relief from the discomfort in her knees that would also creak when she climbed the stairs. Tests showed her vitamin D levels were extremely low—5 nanograms per milliliter (ng/ml) against 25 ng/ml considered normal by the diagnostic centre. Two injections and eight pouches of vitamin D later the nutrient has reached the desirable level but her knees still creak.
The two women are part of the growing number of vitamin D-deficient people across the country. There is no consolidated data to show the prevalence of the deficiency. But estimates by doctors and researchers show that as many as 80 per cent of urban population and 70 per cent of rural population are deficient in the sunshine vitamin in the country, which receives anywhere between 1,500 and 2,000 hours of sunshine a year. Though the number of such studies are few, they are indicative of the spread.
Endocrinologists from Medanta-The Medicity in Delhi’s satellite city Gurgaon recently analysed vitamin D levels of 2,119 doctors from 18 cities across the country who had come to attend a conference. Only 6 per cent of them had sufficient levels of vitamin D. Seventy-nine per cent of the doctors were deficient in the vitamin and 15 per cent had insufficient levels. The study titled “Widespread vitamin D deficiency among Indian health care professionals” was published in Archives of Osteoporosis in December 2012. A few years ago, endocrinologists from Sanjay Gandhi Postgraduate Institute of Medical Sciences in Lucknow had tested vitamin D levels among residents of an Uttar Pradesh village. They found that 88.6 per cent adolescent girls and 74 per cent pregnant women were vitamin D-deficient. Boys were relatively protected, notes the study published in Clinical Endocrinology in 2009.
The deficiency has a debilitating effect on children as it causes rickets. The disease causes softening of bones, leading to deformity and fractures. A study by paediatricians from All India Institute of Medical Sciences (AIIMS), New Delhi, found the deficiency in 66.7 per cent of healthy, breastfed infants and 81.1 per cent of mothers. The study was published in Indian Journal of Medical Research in 2011.
These and other studies have caused a flutter among health professionals. Till the 1990s, nobody had suspected that a sub-tropical country like India could have vitamin D deficiency. “The deficiency could have always been there but we never checked,” says R K Marwaha, an endocrinologist who formerly worked with AIIMS and is currently the scientific adviser with the International Life Sciences Institute in Delhi. “It is a silent epidemic.”
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Why the deficiency
India seems to be a curious case. People in other tropical countries like those in Latin America, Australia and New Zealand have adequate levels of vitamin D. Deficiency in regions like West Asia and Africa that receive ample sunshine is easily explained. In West Asia people wear long robes and head coverings for religious reasons and avoid the scorching sun. This interferes with the production of vitamin D. In Africa, greater amounts of melanin pigments in the skin hinder synthesis of the vitamin. But people in India are neither overclad nor excessively dark. Experts pin down the deficiency in India to a combination of factors: changing lifestyle, dietary habits and rising pollution levels.
“The urban Indian has moved indoors,” says Ambrish Mithal, chairperson of the endocrinology division at Medanta-The Medicity.
A study published in the Journal of the Association of Physicians of India in 2008 shows the vitamin level is six and three times higher in men and women respectively in rural areas than those in urban areas. The study was carried out in a village near Delhi. Ravinder Goswami, one of the authors of the study and associate professor of endocrinology at AIIMS, explains that urban areas are congested, which limits exposure to sunlight. Besides, rising levels of pollution restrict penetration of UVB rays into the atmosphere, he adds.
Jacob Puliyel, head of the paediatrics department at St Stephen’s Hospital in Delhi, had demonstrated this a decade ago. He studied vitamin D levels in 34 children who lived in Delhi’s highly polluted area, Mori Gate. He compared the data with the vitamin D levels in children from a less polluted area in Gurgaon. The results showed that children from Mori Gate had less (12.4 ng/ml) vitamin D levels than those from Gurgaon (27.1 ng/ml). Measurement of haze levels as an indicator of the amount of sunlight reaching the ground showed Mori Gate was hazier.
Goswami provides another reason for the deficiency across the country: Indian diets are deplorably low in vitamin D. Oily fish like salmon and sardine and cod liver oil are two of the best sources of the vitamin in diet. These protect people in high latitude countries from the deficiency despite the fact that they receive less sunshine. People at higher altitudes have sun seeking behaviour coupled with the fact that their light-coloured skin quickly converts the sunlight into the nutrient. Added to this is their regular consumption of cod liver oil, which provides a whopping dose of vitamin D. Nordic people have the tradition of feeding cod liver oil to children and pregnant women as a nutritional supplement.
Though egg yolk and milk have some amount of vitamin D, the poor in India cannot afford them. The National Sample Survey Organisation’s report on key indicators of household consumer expenditure in 2009-2010 shows that in rural areas a person consumes about 4 litres of milk in a month. In urban areas, one consumes 5.3 litres of milk. Besides, vegetarians in the country do not have eggs and cod liver oil.
In such a scenario, doctors are increasingly testing their patients’ vitamin D levels and prescribing daily supplements to raise them. For health food manufacturers, this wonder treatment has become a selling point. They are fortifying their products with vitamin D even though the understanding of the science of the vitamin is awfully inadequate in India.
Sound science or hype?
As of now there is no standard in the country for determining how much 25-hydroxy vitamin D (25D), the form of vitamin D that circulates in blood, is adequate. While some diagnostic labs follow the standard set by the US National Osteoporosis Foundation, most researchers have set their own standards.
For instance, during the study on infants and their mothers, the paediatricians of AIIMS defined deficiency of vitamin D as 25D levels below 15 ng/ml and insufficiency as 15-20 ng/ml. This was different from the standards used by the endocrinologists of Medanta-The Medicity for their study on doctors and endocrinologists from Sanjay Gandhi Postgraduate Institute of Medical Sciences in Lucknow for the study on rural people. They termed those with less than 20 ng/ml of 25D levels as vitamin D deficient and those with 20-30 ng/ml of 25D levels as insufficient.
The lack of standards can result in overestimation of the prevalence of vitamin D deficiency as seen in the US.
In 2010, the Institute of Medicine (IOM), an advisory body to the US government, assessed over 1,000 studies on vitamin D and calcium. It found that there was an overestimation of the levels of vitamin D deficiency in the population due of different cut off points for 25D levels. Initial studies had set 11 ng/ml as the optimum level of 25D from birth through 18 years of age. In adults this was set at 12 ng/ml. Later on, some studies set the level for adults at 50 ng/ml, and this artificially increased the estimates of the prevalence of vitamin D deficiency, IOM said in its report. Following the assessment, IOM suggested new guidelines which say 20 ng/ml of 25D is adequate. The older guidelines had set the standard for adults at 30 ng/ml.
Using the new guidelines, researchers from Stritch School of Medicine of Loyola University Chicago calculated that 80 million Americans would not need vitamin D supplements. The researchers examined data from 15,099 adults who participated in the Third National Health and Nutrition Examination Study. More than 70 per cent of the adults had vitamin D levels that would be considered insufficient under the previous guidelines. Under the new guidelines, only 30.3 per cent of them had insufficient vitamin D levels. The results were published in the October 24, 2012, issue of journal, PLoS ONE.
The study underscores how imperative it is for the health experts to decide the optimum level of the vitamin for Indians. People’s vitamin D levels are influenced by whether they have light or dark skin, where they live, how much time they spend outdoors and whether they eat fish, milk or eggs.
In developed countries, there are recommendations on the amount of time people should spend in the sun to produce sufficient amounts of the vitamin. But in India, there is not much information available. The biggest gap is the fact that there is no long-term study on how much UVB radiations, the source of vitamin D, people receive. Sachchidanand Singh, senior scientist at Radio and Atmospheric Sciences Department of National Physical Laboratory in Delhi, says while there is some satellite-derived long-term data on UVB rays, it does not show any trend over India. “Short-term (two years) data for UVB is available for Delhi and it is difficult to comment on the trend of UVB over the city from this,” Singh adds.
In 1981, the National Institute of Nutrition had said exposure to sunlight for just five minutes is enough to produce sufficient amount of vitamin in the body. If this is correct, it becomes difficult to explain the reports of deficiency among people who stay out in the sun for long hours. The 2008 study by Goswami showed most people did not produce adequate levels of vitamin D even after five hours of exposure to sun.
In 2004, Jacob Puliyel from Delhi’s St Stephen’s Hospital sought answer to a similar question. To understand the impact of seasons on the production of vitamin D, Puliyel studied its levels in children from two adjoining slums of Delhi, first in the winter month of February and then in August. To his surprise, he found that in Rajiv Colony, 84 per cent children were deficient in vitamin D even in August. However, in the adjoining Sundernagari colony, the levels were normal in the majority of the children. To figure out the possible reason, his team met the community health workers in Sundernagari and found a diet awareness programme was underway in the area. Most of the diet fed to children was vegetarian, which is a poor source of vitamin D. “The better vitamin D levels seen in children from this area are, therefore, difficult to explain on the basis of good diet advice either,” the researchers said in journal, Indian Pediatrics. They called for more studies to understand better vitamin D levels seen in Sundernagari.
While Indian research fraternity may or may not look into the issue, there are some clear indications worth exploring. In areas like Rajiv Colony and rural areas, contaminated environment could be a reason for poor vitamin D levels. A recent study based on the data of the US National Health and Nutrition Examination Survey shows exposure to pesticides could suppress the production of vitamin D. The researchers studied blood samples of 1,275 adults in 2003-2004, and found those with high concentrations of organochlorine pesticides such as DDT had lower 25D levels. The study was published in PLoS ONE in January 2012.
For the skin colour-conscious Indian, here is another probable reason for the deficiency. The sunscreen creams and skin-lightening products that block the UVB radiation are often implicated in vitamin D deficiency. However, in 2010 Adam Handel and Sreeram Ramagopalan, scientists from University of Oxford, wrote in The Lancet that use of sunscreens did not reduce the incidences of skin cancer. This means sunscreens may not be blocking UVB radiation, they said. This means use of sunscreen might not impair vitamin D production in the body.
IOM has also suggested carrying out further studies to verify if sunscreen is indeed reducing vitamin D synthesis.
The epidemic of vitamin D deficiency could also be because of the rising levels of obesity in the country. Since vitamin D is a fat-soluble vitamin, it gets stored in fat cells. So more the fat, lesser is the amount of 25D circulating in the bloodstream. Finally, there seems to be a genetic basis to the amount of vitamin D a person can produce. A review of epidemiological studies, published in The Lancet in July 2010, shows at least three, and probably four, genes contribute to the variability of serum concentrations of 25D. This too is yet to be proved conclusively.
Market thrives on the hype
The result of this half-baked knowledge is indiscriminate sale of vitamin D supplements and use of diagnostic tests, which are expensive and unreliable (see ‘How accurate are tests?’).
How accurate are tests?
“Nearly everyone who comes to us for a test is deficient in vitamin D,” says Onjal Taywade, consultant biochemist at Dr Lal Pathlabs in Delhi. With symptoms of the deficiency ranging from aches in the bones to fatigue, almost everyone is eligible for the test. Biswajit Sen, a senior consultant pathologist at Dr Dangs Lab Pvt Ltd, says until three years ago, one or two patients came for this test. Now at least 40 patients visit his lab every day for the test. The test can cost anything from Rs 1,000 to Rs 3,000. But it is fast emerging that the diagnostic tests currently available in the country are not reliable.
World over, pathologists use seven technologies for estimation of 25D levels in the blood. “But due to various analytical issues, results from these methods are not comparable,” says B R Das, president, research and innovation at SRL Diagnostics, Mumbai. He adds, considering the available literature and experience, RIA and LC-MS/MS should be the method of choice for Vitamin D estimation. LC-MS/MS, though is considered the gold standard for testing vitamin D, it requires massive investment to the tune of couple of crores of rupees.
Though RIA is used in India, it needs technical expertise as well as compliance of radioactive safety norms as mandated by local governing authorities. So the preferred technology of most diagnostic labs is chemiluminescent immunoassay (CLIA), which offers automated estimation of Vitamin D. However, accuracy is the lowest in CLIA. It tends to overestimate the frequency of vitamin D deficiency, according to a study published in the January 2013 issue of Clinica Chimica Acta. The researchers tested the DiaSorin LIAISON test kit based on the CLIA technology for the quantitative determination of 25D. In the study, researchers from University of Calgary, Alberta, compared this instrument with LC-MS/MS. They found that the chance of error was 36 per cent in DiaSorin Liaison, and 9 per cent in LC-MS/MS. DiaSorin LIASON?is widely used in India.
A study by US researchers had also found inaccurate readings by similar test kits. They used Abbott Architect and Siemans Centaur2 to analyse the level of vitamin D in 163 blood samples. They compared the results with findings from LC-MS/MS. LC-MS/MS results showed that 33 of the 163 specimens showed vitamin D deficiency. The Abbott test showed that 45 specimens had vitamin D deficiency and the Siemens test showed that 71 subjects had vitamin D deficiency.
Earle W Holmes, professor at the Department of Pathology at Stritch School of Medicine of Loyola University Chicago, the US, who had carried out the study, said inaccurate test results could lead to misdiagnoses of patients and confound efforts of physicians, nutritionists and researchers to identify the optimal levels of vitamin D for good health.
“Since Vitamin D deficiency still does not fall under critical health problem category, there are no recommendations or strict guidelines for use of specific methodologies,” says Das. At SRL, both RIA and CLIA are being used. During the last financial year, 90,000 tests were carried out at SRL. They increased to 1,50,000 tests during this financial year. “We have recently acquired the LC-MS/MS technology. Vitamin D assay based on this cutting-edge technology would be available to the customer in a month’s time. We are the first lab in India to provide this technology,” Das says. In view of the affordability issues in India, the price for this test would be comparable to that of RIA or CLIA, Das reveals.
Biswajit Sen supports the rapid tests, which he says are reliable. But he emphasises that there is a need to keep tab over how samples are managed. Many diagnostic centres just collect samples, which are then sent to somewhere else for testing. There is a likelihood that the samples are spoiled in the process of transportation.
In many countries, the rising number of tests being carried out has increased the cost of healthcare to the government. In Auckland, New Zealand, annual requests for vitamin D measurement quadrupled between 2000 (8,500) and 2010 (32,800). In 2011, the total annual laboratory cost due to vitamin D testing was about NZ$1 million.
“Such findings have widespread consequences in terms of quality of care, unnecessary cost, and potential overdiagnosis. Further studies are needed to determine whether this increased testing translates into improved vitamin D status in the population and subsequent health outcomes.” Kellie Bilinski and Steven Boyages of The University of Sydney wrote in the British Medical Journal in July 2012.
The sales of vitamins and dietary supplements across the world increased from US $79.43 billion in 2010 to $84.26 billion in 2011, according to Euromonitor, a market research organisation. This is higher than the average annual percentage growth between 2006 and 2010. Of all the categories, vitamin D sales grew the most. Sales of the vitamin in 2011 were $897 million. This is a 24.8 per cent jump from the 2010 sales of $719 million, and a 284 per cent increase from the 2006 sales of $234 million (see graph). Most of this jump came from Latin America, eastern Europe, Australasia, India, West Asia and Africa, which logged cumulative sales of US $11.23 billion, or 13.4 per cent of the global market share.
In India, vitamins are among the drugs that are prescribed most irrationally, according to a recent survey by the Kolkata unit of non-profit Consumer Unity and Trust Society. Even though there is no study to determine how much vitamin D is adequate for Indians, doctors are prescribing 1,000 IU per day. Four tablets of cholecalciferol by Eris Lifesciences Pvt Ltd cost Rs 100; one sachet of Cadilla’s calcirol is for Rs 25. “Prescribing vitamin D to people who are not deficient in the nutrient is an irrational use,” says Ranjit Roy Chaudhury, former president of the Delhi Society for Promotion of Rational Use of Drugs.
Excess consumption of vitamin D is known to cause adverse health effects, which include elevated levels of calcium in blood and urine, which affects the kidney and retards growth in infants.
In the early 1990s, the National Institute of Health (NIH) in the US carried out a series of clinical trials and observational studies as part of a programme on women’s health. One of the studies was to check whether a combination of calcium and vitamin D could prevent breast cancer. This combination is popularly prescribed by doctors in the country. Researchers found that the combination had little role in preventing the disease. More over, the risk of breast cancer increased among women who were already consuming 600 IU of vitamin D per day, and were given an additional supplement of 400 IU a day.
Too much vitamin D could also trigger the onset of a dangerous heart condition, atrial fibrillation. An analysis of blood tests by researchers from Intermountain Medical Center Heart Institute, USA, shows risk of developing atrial fibrillation is 2.5 times greater in those with excess levels of vitamin D compared to patients with optimum levels. A study based on blood samples of 247,574 residents of Copenhagen, Denmark, shows mortality rate was high among people with high or low levels of vitamin D. The researchers compared the values with 20 ng/ml of 25D, considered optimum in the country, and found that mortality rate was 2.31 times higher if the blood contained less than 4 ng/ml of 25D. The risk increased by 1.42 times if the blood contained more than 56 ng/ml of 25D. The study was published in Journal of Clinical Endocrinology and Metabolism in 2012. This suggests that setting the correct value for the amount of vitamin D required by a person is imperative for good health.
It’s time to act
So far, the Indian authorities have not given much attention to the subject. In 2010, an expert committee of the Indian Council of Medical Research (ICMR), the apex body for the formulation, coordination and promotion of biomedical research in the country, said outdoor physical activity is a means of achieving adequate vitamin D, while controlling overweight and obesity in the population. The committee did not make any suggestions on the intakes for children or adults. It, however, recommended a daily supplement of 400 IU in situations of minimal exposure to sunlight.
In the absence of any guidelines, the Endocrine Society of India is in the process of setting down recommendations for the amounts Indians should consume as supplements. The recommendations are expected to be ready by the end of this year, says Mithal. The levels are likely to be around 2,000 IU per day, he says.
This is much higher than the levels set by IOM for the US, despite the fact that it is a high latitude country. The latest IOM recommendation for adults is 600 IU per day. There is a push for fortification too. In developed countries, milk, orange juice, cereals, margarine and butter are regularly fortified. The US and Canada are said to have achieved a better vitamin D status through extensive fortification of milk since the early 1900s.
Endocrinologist R K Marwaha says his team has produced evidence for the amount needed for fortification of milk. His team conducted a study on 1,000 children in Delhi. They were divided in three groups and each group was fed with milk supplemented with 0 IU, 600 IU and 1,000 IU of vitamin D daily. Milk with 1,000 IU resulted in 27 ng/ml of 25D in the blood. The study has been accepted by Osteoporosis International for publishing. “We have to find solutions for the entire country. If you give vitamin D to people with aches and low vitamin D levels, it helps,” says Marwaha.
Public health experts do not buy this argument. “You have to look into how and why a tropical country is deficient. We need to know why there is enough vitamin D produced in the bodies of some and not in others even though the exposure to sunlight is the same,” says Puliyel. “Unlike fortification and supplementation, advice on exposure to sunlight can be universal.”
Goswami says there has to be consolidated information on vitamin D deficiency from different parts of the country before a decision on universal fortification is taken. “We do not have data from the desert area where there is more sunshine and neither do we have data from coastal areas where people consume more fish.”
Before taking any step towards fortification, Ritu Priya Mehrotra, professor at the Centre of Social Medicine and Community Health at Jawaharlal Nehru University, Delhi, says it is important to figure out the deficiency levels in India. If it is moderate, it would mean the reference point for Indians might be lower.
Mandatory fortification is a major step. So more indigenous research needs to be done to figure out the optimum dose for Indians and food items to be fortified, says Suparna Ghosh Jerath, associate professor at the Indian Institute of Public Health, a non-profit in Delhi. “We have to be careful about the adverse effects of overconsumption especially in people with chronic diseases like that of the kidney,” she adds.
There is an urgency for taking a quick decision as fortified foods are already available in the market. For example, Glaxo SmithKline (GSK) produces Horlicks Junior which has 4.2 µg of vitamin D per 100 g. The regular Horlicks has 9 µg of vitamin D per 100 g. This translates into 168 IU and 360 IU per 100 g. This is much lower than what doctors are prescribing. The amount, GSK claims, meets 50 per cent of the recommended daily requirement. GSK was not available for comment.
Cadbury’s Bournvita Lil Champs has 10 µg of vitamin D per 100 g. “We constantly look at ways to improve our products. As part of this exercise we decided to bolster our nutrition bundle in 2011, keeping in mind the emerging nutritional needs of Indian population,” says spokesperson of Cadbury India.
These products are not considered as drugs and hence are not regulated under the Drugs and Cosmetics Act. They do not have to seek permission from Food Safety and Standards Authority of India.
Kalpagam Polasa, director of ICMR’s National Institute of Nutrition, Hyderabad says supplementation and fortification can be resorted to if needed, but adds that even in countries like the US where fortification is done, the problem of vitamin D deficiency is prevalent. “People in India should get exposure to sunlight at least 15-20 minutes per day between 9 am and 4 pm for making them vitamin D sufficient. There should be sufficient awareness towards this.”
ICMR plans to set up a task force to look into the evidence on vitamin D deficiency. With experts from all over the country, the task force would be set up within a couple of months, officials say.
Until ICMR issues its guidelines, there are options that might help people. A study by researchers from Canada shows two cups of cow’s milk could result in higher vitamin D in children. The effect was more pronounced than exposure to sun. Then there is some out-of-the-box thinking: mushrooms when exposed to UVB rays get fortified with 700 per cent more vitamin D than those that are not exposed to any light.
Michael Holick, professor of medicine, physiology and biophysics at Boston University School of Medicine in the US, who is also known as father of modern vitamin D research, recommends a three-pronged strategy for India. “It’s reasonable to consider fortifying flour, dairy products and other commonly used products with vitamin D. It is also reasonable and obviously inexpensive for the government to provide guidelines for sensible sun exposure. Finally, those unable to get vitamin D from sunlight and diet should take a vitamin D supplement,” he says.
But this is just a short-term strategy and might work for the time being. Long-term strategy to combat vitamin D deficiency in the country can be devised only when the impact of environment and lifestyle has been studied in detail. After all, one cannot live in darkness.
Gaps in understanding
- No standard in India to define vitamin D deficiency. Lack of standards can lead to overestimation of the prevalence of the deficiency and irrational use of vitamin D supplements
- No study to estimate how much vitamin D is adequate for Indians, who receive ample sunlight
- No understanding on why there is enough vitamin D produced in some and not in others even though their exposure to sunlight is the same
- No study in India to gauge how much vitamin D-producing UVB rays reach the ground and whether air pollution blocks it
- No study on how toxins affect the production or absorption of vitamin D in the body
- No study showing if sunscreen and skin-lightening products impair vitamin D production
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