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Journal of Hypertension:
doi: 10.1097/HJH.0b013e328349666d
Original papers: Pathophysiological aspects

No effect of ultraviolet radiation on blood pressure and other cardiovascular risk factors

Scragg, Roberta; Wishart, Johnb; Stewart, Alistaira; Ofanoa, Malakaia; Kerse, Ngairea; Dyall, Lornaa; Lawes, Carlene M.M.a

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Abstract

Objectives: Recent epidemiological studies have reported inverse associations between vitamin D status and blood pressure. The study aim is to determine if exposure to ultraviolet B radiation, which synthesizes vitamin D, lowers blood pressure, compared with ultraviolet A radiation.

Methods: Men and women (n = 119) with low vitamin D levels [serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/l], completed a randomized clinical trial carried out during winter. Blood pressure was measured for 12–14 h with an ambulatory monitor at baseline and 12 weeks. In between, participants received 24 whole body exposures of either ultraviolet B (n = 58) or ultraviolet A (n = 61) over 12 weeks.

Results: Mean (SD) 25(OH)D increased from 43.7 (9.7) to 92.6 (16.9) nmol/l in the ultraviolet B arm after 12 weeks, and from 45.4 (9.2) to 64.9 (11.3) nmol/l in the ultraviolet A arm. However, mean blood pressure, which was similar for the ultraviolet B and ultraviolet A at baseline (134.9/79.2 vs. 132.9/77.8 mmHg; P = 0.59 and 0.56, respectively), did not change from baseline to 12 weeks in either group. The mean change [95% confidence interval (CI)] in blood pressure over this period in the ultraviolet B group compared with the ultraviolet A group was −2.2 (−7.8, 3.3) mmHg for systolic (P = 0.42) and −2.7 (−6.5, 1.0) mmHg for diastolic (P = 0.15).

Conclusion: Exposure to ultraviolet B did not lower blood pressure. Our results suggest that if vitamin D protects against cardiovascular disease, it involves some mechanism other than blood pressure.

© 2011 Lippincott Williams & Wilkins, Inc.

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