R K Marwaha1, V K Yenamandra2, V Sreenivas3, R Sahay4, M P Baruah5, A Desai6, S Kurvilla7, S Joseph7, A G Unnikrishnan8, R Lakshmy9, C Apoorva2, V K Sharma2, G Sethuraman10. 1. International Life Sciences Institute, New Delhi, India. 2. Department of Dermatology, All India Institute of Medical Sciences, New Delhi, 110029, India. 3. Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India. 4. Department of Endocrinology, Osmania Medical College, Hyderabad, India. 5. Excel Center, Guwahati, India. 6. Endocrine Unit, Department of Medicine, Goa Medical College, Bambolim Goa, India. 7. Christian Fellowship Hospital, Oddanchatram, Dindigul, India. 8. Chellaram Diabetes Institute, Pune, India. 9. Department of Cardiac Biochemistry, All India Institute of Medical Sciences, New Delhi, India. 10. Department of Dermatology, All India Institute of Medical Sciences, New Delhi, 110029, India. kgsethu@yahoo.com.
Abstract
UNLABELLED: Evaluation of ultraviolet B index (UVBI) and its impact on vitamin D synthesis is important. We observed the maximum UVBI between 11 am and 1 pm. There was no increase in serum 25(OH)D levels following sun exposure during winter as the UVBI was significantly low, emphasizing the need for vitamin D supplementation during these months. INTRODUCTION: The amount of vitamin D3 synthesizing UVB irradiation (290-320 nm) reaching the earth's surface at different altitudes and seasons in different parts of India and it's impact on vitamin D synthesis has not been well studied. METHODS: The hourly UVB index (UVBI) from 10 am to 3 pm everyday for 12 months was measured by a solar meter in 4 different zones (North, Northeast, West and South) of the country. To study the impact of sun light exposure on vitamin D synthesis during winter, healthy school children aged 10-15 years were exposed to sunlight for a period of 30 min per day, between 11 am to 12 noon with 10 % body surface area, for 4 weeks. The main outcome measures were serum 25(OH)D, PTH, calcium, phosphate, and alkaline phosphatase levels before and after sun exposure. RESULTS: The mean UVBI was highest between 11 am and 1 pm throughout the year in all locations. The highest UVBI was recorded from the North zone (4.5 ± 2.7 μW/Cm(2)), while the least was recorded in the Northeast zone (2.1 ± 1.2 μW/Cm(2)). UVBI readings in the Northeast zone were consistently low throughout the year, while all the other three zones showed significant seasonal fluctuations. Surprisingly, we observed a significant decrease in serum 25(OH)D levels from baseline (6.3 ± 4.6 to 5.1 ± 2.7 ng/mL; p < 0.001) despite sun exposure. CONCLUSION: The mean UVBI was highest between 11 am and 1 pm throughout the year in all locations. No increase in the serum 25(OH)D levels was observed following sun exposure in winter, emphasizing the need for vitamin D supplementation during these months.
UNLABELLED: Evaluation of ultraviolet B index (UVBI) and its impact on vitamin D synthesis is important. We observed the maximum UVBI between 11 am and 1 pm. There was no increase in serum 25(OH)D levels following sun exposure during winter as the UVBI was significantly low, emphasizing the need for vitamin D supplementation during these months. INTRODUCTION: The amount of vitamin D3 synthesizing UVB irradiation (290-320 nm) reaching the earth's surface at different altitudes and seasons in different parts of India and it's impact on vitamin D synthesis has not been well studied. METHODS: The hourly UVB index (UVBI) from 10 am to 3 pm everyday for 12 months was measured by a solar meter in 4 different zones (North, Northeast, West and South) of the country. To study the impact of sun light exposure on vitamin D synthesis during winter, healthy school children aged 10-15 years were exposed to sunlight for a period of 30 min per day, between 11 am to 12 noon with 10 % body surface area, for 4 weeks. The main outcome measures were serum 25(OH)D, PTH, calcium, phosphate, and alkaline phosphatase levels before and after sun exposure. RESULTS: The mean UVBI was highest between 11 am and 1 pm throughout the year in all locations. The highest UVBI was recorded from the North zone (4.5 ± 2.7 μW/Cm(2)), while the least was recorded in the Northeast zone (2.1 ± 1.2 μW/Cm(2)). UVBI readings in the Northeast zone were consistently low throughout the year, while all the other three zones showed significant seasonal fluctuations. Surprisingly, we observed a significant decrease in serum 25(OH)D levels from baseline (6.3 ± 4.6 to 5.1 ± 2.7 ng/mL; p < 0.001) despite sun exposure. CONCLUSION: The mean UVBI was highest between 11 am and 1 pm throughout the year in all locations. No increase in the serum 25(OH)D levels was observed following sun exposure in winter, emphasizing the need for vitamin D supplementation during these months.
Authors: D A Wahl; C Cooper; P R Ebeling; M Eggersdorfer; J Hilger; K Hoffmann; R Josse; J A Kanis; A Mithal; D D Pierroz; J Stenmark; E Stöcklin; B Dawson-Hughes Journal: Arch Osteoporos Date: 2012-08-29 Impact factor: 2.617
Authors: G Sethuraman; V Sreenivas; V K Yenamandra; N Gupta; V K Sharma; R K Marwaha; N Bhari; M Irshad; M Kabra; S Thulkar Journal: Br J Dermatol Date: 2014-12-30 Impact factor: 9.302