HypertensionExposure to sunlight

Several studies reported increases in blood pressure with increases in latitude, latitude being a rough estimate of solar ultraviolet-B dose and vitamin D production. Peter et al1 noted the increase in blood pressure with increasing latitude in Eurasia.

Rostand2 collated the data on blood pressure and hypertension from the INTERSALT study3 and other studies and plotted them as a function of latitude from the equator. The regression fit for systolic blood pressure increased from 108 mm Hg at the equator to 125 mm Hg at 70º while that for diastolic pressure increased from 67 mm Hg at the equator to 78.5 mm Hg at 70º. The regression fit for prevalence of hypertension increased from 8% at the equator to 25% at 70º. The regression fits were highly significant (p<0.0001). While this study is considered to show a beneficial effect of solar UV irradiance and vitamin D, there are other factors related to solar radiation that also change with latitude that could explain the geographical variation4.

Blood pressure also varies with season, being higher in winter25, with temperature contributing in large measure to the seasonal variation6. It would be interesting to reexamine the regression analyses in Rostand2 in terms of mean serum 25-hydroxyvitamin D [25(OH)D] levels and mean temperatures in summer and winter.

A couple of studies have investigated changes in blood pressure with respect to artificial UV irradiance. One study found a benefit from UVB but not UVA irradiance7

However, a recent study found reduced blood pressure from UVA irradiance8. The effect was attributed to release of nitric oxide from nitrite and S-nitroso thiols in the skin. The effect lasts about an hour. This effect might explain some of the reason being in the sun is pleasurable.

Page last edited: 09 May 2011

References

  1. Peter, I. Otremski, I. Livshits, G. Geographic variation in vascular mortality in Eurasia: spatial autocorrelation analysis of mortality variables and risk factors. Ann Hum Biol. 1996 Nov-Dec; 23 (6): 471-90.
  2. Rostand, S. G. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension. 1997 Aug; 30 (2 Pt 1): 150-6.
  3. Elliott, P. Marmot, M. Dyer, A. Joossens, J. Kesteloot, H. Stamler, R. Stamler, J. Rose, G. The INTERSALT study: main results, conclusions and some implications. Clin Exp Hypertens A. 1989; 11 (5-6): 1025-34.
  4. Maverakis, E. Miyamura, Y. Bowen, M. P. Correa, G. Ono, Y. Goodarzi, H. Light, including ultraviolet. J Autoimmun. 2010 May; 34 (3): J247-57.
  5. Takenaka, T. Kojima, E. Sueyoshi, K. Sato, T. Uchida, K. Arai, J. Hoshi, H. Kato, N. Takane, H. Suzuki, H. Seasonal variations of daily changes in blood pressure among hypertensive patients with end-stage renal diseases. Clin Exp Hypertens. 2010 Jul; 32 (4): 227-33.
  6. Alperovitch, A. Lacombe, J. M. Hanon, O. Dartigues, J. F. Ritchie, K. Ducimetiere, P. Tzourio, C. Relationship between blood pressure and outdoor temperature in a large sample of elderly individuals: the Three-City study. Arch Intern Med. 2009 Jan 12; 169 (1): 75-80.
  7. Krause, R. Buhring, M. Hopfenmuller, W. Holick, M. F. Sharma, A. M. Ultraviolet B and blood pressure. Lancet. 1998 Aug 29; 352 (9129): 709-10.
  8. Oplander, C. Volkmar, C. M. Paunel-Gorgulu, A. van Faassen, E. E. Heiss, C. Kelm, M. Halmer, D. Murtz, M. Pallua, N. Suschek, C. V. Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivates. Circ Res. 2009 Nov 6; 105 (10): 1031-40.