August 4, 2013
MUMBAI: Runny noses and stomach flu aren't the only ills associated with overcast skies. The absence of sunlight hits production of Vitamin D in the body, adversely affecting blood pressure. A recent study in London by an Indian-born researcher has proved beyond doubt that the lower the vitamin level, the higher the BP.
August 4, 2013
MUMBAI: Runny noses and stomach flu aren't the only ills associated with overcast skies. The absence of sunlight hits production of Vitamin D in the body, adversely affecting blood pressure. A recent study in London by an Indian-born researcher has proved beyond doubt that the lower the vitamin level, the higher the BP.
Vitamin D is synthesized when the sun's ultraviolet rays fall on the skin. But the high melanin pigment in the Indian skin deters it. So, even a hot and sunny India has high levels of deficiency. Some studies say every second Indian is affected, others peg it higher at eight out of every 10 Indians. The deficiency is worrying as it's linked to a range of diseases — from bone problems to cancer.
Researcher Vimal Karani's work from University College London only conclusively proves that low Vitamin D levels can send blood pressure soaring. Karani looked at 35 studies, covering 1.5 lakh people across Europe and North America, and found people with high concentrations of 25-hydroxyvitamin D (25(OH)D) had lower blood pressure and, therefore, a reduced risk of hypertension. A prehormone, 25-hydroxyvitamin D or calcidiol, is produced in the liver when Vitamin D3 is synthesized (a blood test to determine its levels is also an indicator of Vit D levels).
The study found that for every 10% increase in 25(OH)D concentrations, the risk of developing hypertension decreased by 8.1%.
In India, where every fifth grown-up has hypertension, the study has severe implications. Dr Siddharth N Shah, editor-in-chief of JAPI (Journal of the Association of the Physicians of India), said, "The association of lower levels of Vitamin D and high blood pressure can, in part, be associated with increasing number of hypertensives in India." Delhi-based endocrinologist Dr Anoop Misra, though, pointed out that hypertension has a strong hereditary component. "We know that salt, smoking, obesity and heredity are the causes for hypertension. We can at best consider Vitamin D deficiency as a fifth contributor," he said.
The theories about Vitamin D deficiency and its various implications have gained importance in the past decade. One reason could be easy availability of diagnostic tests. "When we started offering the test about 15 years back, we would get 5 to 10 cases a month," said Dr Vipla Puri from Hinduja Hospital, Mahim. Now her laboratory performs 1,500 tests a month.
Why the sudden focus on Vitamin D? Endocrinologist Dr Shashank Joshi from Lilavati Hospital, who has done several studies on both hypertension and Vitamin D deficiency, said, "There are over 200 Vitamin D receptors in the body. Previously, we thought that Vitamin D only affected skeletal aspects of the body." It is only now that the world is learning that it is connected to the body's entire metabolism. "Vitamin D has a link with metabolism of glucose, maintenance of blood pressure as well as acceleration of heart diseases," Joshi said.
Vitamin D levels dictate outcomes of ICUs as well. A study done by Dr HemantThacker in Jaslok Hospital, Peddar Road, showed that patients with lower levels of Vitamin D were more susceptible to infections than patients who had better levels.
Dr Thacker blames the smog-filled environment in cities for poor Vitamin D levels. "It is true we don't get adequate exposure to sunlight because we travel in cars and buses and don't come out even during weekends. Children these days watch TV instead of playing football in the grounds, but Vitamin D deficiency isn't only about paucity of sunlight." The quality of sunlight plays an important role too.
"A part of the ultraviolet radiation that is needed by the body to make Vitamin D, is filtered out by the smog. This is a leading cause for deficiency," Dr Thacker said.
Experts say a way of tackling this widespread deficiency would be to chart out a public health policy. "The government should look at solutions like fortifying milk with vitamin D as is done in the US and Europe," said Dr Joshi.
Courtesy: TOI
