Keep the sun screen lotions away if you are stepping out of the house between 11am and 1pm. Since this is the best time to soak in some sunlight for essential vitamin D.
A pan-India study has revealed that the best time to get exposed to the sun is between 11am and 1pm since the wavelength of ultraviolet B (UVB) rays is 290-320nm during this period which is essential for skin to make vitamin D.
As for seasonal changes in sunlight, the study, clearly showed that summer months are the time when the maximum UVB is available. It also suggested that winter months, due to decreased sunshine, may make Indians more prone to vitamin D deficiency .
The study has important implications for devising strategies to combat the epidemic of Vitamin D deficiency in the country . Seven cities, including Goa, Guwahati, Hyderabad, Madurai, Leh, Delhi and Pune from country’s four zones, were part of the study which was published in Osteoporosis International, a reputed journal in the field of bone health, last month.
The central co-coordinating body in the department of dermatology at the All India Institute of Medical Sciences (AIIMS), New Delhi, reviewed monthly data from all the seven regional study centres.
At a time when vitamin D deficiency has acquired epidemic proportion in the country, exposure to sun may be able to alleviate the burden of vitamin D deficiency as more than 90% of vitamin D is synthesized through solar UVB irradiation of the skin, said experts.
“Natural production of vitamin D from one’s own skin is definitely better than having to depend on pills. A majority of Indians have low vitamin D levels and this study suggests the correct sun exposure times,” said senior dermatologist G Sethuraman of the department of dermatology at AIIMS, who spearheaded the study.
Sharing his view, another lead researcher Raman K Marwaha of International Life Sciences Institute, New Delhi, said, “In addition to testing for vitamin D and treating deficiency, our study indicates that it is important to improve awareness among patients about natural means of increasing vitamin D levels. Also, during winter months, Indians may be even more prone to Vitamin D deficiency .”
Vitamin D, only vitamin that the human body can make on its own, helps the body absorb calcium from diet.Calcium is important for healthy bones and teeth. The action of the sun on the skin turns a compound called 7dehydrocholesterol into a form of vitamin D called vitamin D3.
“The skin converts 7 dehydro-cholesterol to pre-vitamin D. This step is triggered by the UVB present in sunlight at wavelength 290320nm, which was specifically measured in this study .This pre-vitamin D is later converted into vitamin D,” said city-based endocrinologist A G Unnikrishnan, one of the researchers involved in the study.
