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UVB increasing vitamin D to 34 ng did not lower blood pressure – June 2011

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

J Hypertens. 2011 Jun 30.
Scragg R, Wishart J, Stewart A, Ofanoa M, Kerse N, Dyall L, Lawes CM.
aSchool of Population Health, University of Auckland bEpsom, Auckland, New Zealand.

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.

PMID: 21720260
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Strange

  • UVA increased vitamin D levels from 18 ng to 26 ng

Not Strange

  • Increasing vitamin D levels from 17 ng to 34 ng did not change blood pressure
    • probably need at least 50 ng to make a difference

See also VitaminDWiki