Bangalore: In the land of abundant sun, Indians suffer from vitamin D deficiency. There’s been a set of studies to prove this, but new research suggests this deficiency, which can lead to life threatening emergencies in young population, has not led to protective bio-adaptation over time.
After their first systematic study of blood serum in 2000, which showed more than 75% of healthy people studied in northern India had vitamin D deficiency, researchers have now shown that though our skin has darkened while adapting to tropical climate, there is no bio-adaptation to this deficiency. In other words, the dark skin, which prevents ultraviolet rays mediated vitamin D to be formed in the body, does not lead to over-expression of vitamin D receptor, a hormone that regulates calcium levels in the body.
D FOR DEFICIENCY (PDF)
As a result, say researchers, this deficiency is prevalent in most parts of India, irrespective of people’s age, socio-economic and education status. “Now we know the role of vitamin D deficiency in bone disorders like rickets, osteomalacia and osteoporosis, which are widely prevalent in India,” says Ravinder Goswami at department of endocrinology and metabolism of the All India Institute of Medical Sciences in New Delhi. His two new studies were recently published in the British Journal of Nutrition and European Journal of Clinical Nutrition.
In the early stage of vitamin D deficiency, our body adapts by increasing the parathyroid hormone in the blood which helps in maintaining the normal calcium levels and, hence, the deficiency is not easily detectable. But, in the long run, says Dr Goswami, this leads to bone resorption (bone breaks down to release calcium in the blood) and osteoporosis (reduction in bone density which enhances risks of fracture). “About one-fourth of normal people we studied, including physicians and paramedical workers, have supra-normal levels of parathyroid hormone,” said Dr Goswami.
When it comes to bone health, vitamin D and calcium go hand in hand, as the former helps in the absorption of the latter. “The reason for widespread vitamin D deficiency is that, in rural population, vitamin D levels are better due to their exposure to sun but their dietary calcium is poor, whereas in urban population dietary calcium is better but vitamin D is deficient,” said C.V. Harinarayan, head of endocrinology at Wockhardt Hospital in Bangalore. The prevalent dietary calcium intake is 307 -340mg in urban population, 263-280mg in rural population, which is less than a third of the required calcium (1 gm/day).
While earlier at Sri Venkateswara Institute of Medical Sciences in Tirupati, Dr Harinarayan had the first documented evidence of this deficiency in Andhra Pradesh. “This is one of the sunniest parts of India and if people are deficient here, it speaks volumes about the prevalence of this deficiency in other parts of India,” he said. However, he cautions that north-eastern India is not covered in these studies and it’s essential to collect data from there.
Endemic fluorosis in many parts of the country worsens the deficiency. “Fluoride affects the kidney which is responsible for converting vitamin D to active form,” said Narayana P. Kochupillai, director-research, MS Ramaiah Medical College in Bangalore. Dr Kochupillai, who, along with Dr Harinarayan, was the first to study vitamin D deficiency in 1995, says it causes some of the bone lesions typical to India. He’s even had clinical evidence of acute respiratory failures which occur due to deformed thoracic cage, resulting from advanced bone loss in the thoracic cage and the spine. Studies have also linked vitamin D deficiency to increased risk of cancer and cardiovascular diseases.
Presenting data at a meeting of the Indian Academy of Sciences in Bangalore last week, Dr Goswami and other researchers called for a national policy on vitamin D fortification of food, just as in the West. “There is no systematic effort in the country to study this; there is need now to take this issue in a public forum,” says Dr Kochupillai. He and others believe a national programme of vitamin D fortification should be undertaken, on the lines of salt iodinization, as vitamin D can also aid tuberculosis and endemic goitre treatments. In fact, the department of biotechnology is already funding a research project to test vitamin D as an adjuvant (aid) in tuberculosis therapy.
The overarching claim for fortification comes from Goswami’s other study which shows that 60,000 units (IU) of vitamin D taken once a week for eight weeks along with 1g of elemental calcium every day restored the baseline vitamin D level of 5-7 nanogram/millilitre to the ideal level of 32ng/ml. The sufficient level is 20ng/ml. But the levels dropped to 9.6ng/ml one year after vitamin D supplements were stopped.
“We are now studying to see what could be the best regimen for long term restoration of ideal vitamin D levels in the body,” says Dr Goswami. However, direct exposure to sunlight, at least for half-an-hour a day, is what researchers suggest for good vitamin D intake.
So, keeping face to the sun can prevent bone loss, literally.