Parkinson’s diseaseExposure to sunlight

Solar ultraviolet-B (UVB) irradiance is the most important source of vitamin D for most people. Thus, studies of sunlight exposure can give an idea of whether vitamin D reduces the risk of Parkinson’s disease (PD).

A study in Denmark found the following: 

Relying on trade grouping codes, we estimated ORs for study subjects with moderate, frequent and maximal outdoor work compared with exclusive indoor work of 0.90 (95% CI 0.78 to 1.02), 0.86 (95% CI 0.75 to 0.99) and 0.72 (95% CI 0.63 to 0.82), respectively, for Parkinson’s disease. Reduced risks were also found for Parkinson’s disease among outdoor workers based on study subjects’ job titles1.

However, not all studies find that outdoor have reduced risk of PD. An earlier study of farmers in Denmark found an increased risk of PD, likely linked to pesticide use2.

There is an increased prevalence of PD with respect to latitude in the United States34. That geographical variation was mentioned with respect to vitamin D and multiple sclerosis and prostate cancer by Schwartz5 used in developing the hypothesis that vitamin D reduced the risk of PD6. Ecological studies with respect to geographical location are a good indication of early-life and lifetime effect of solar UVB and vitamin D on disease risk; however, they are not considered definitive.

Page last edited: 03 May 2011


  1. Kenborg, L. Lassen, C. F. Ritz, B. Schernhammer, E. S. Hansen, J. Gatto, N. M. Olsen, J. H. Outdoor work and risk for Parkinson’s disease: a population-based case-control study. Occup Environ Med. 2010 Sep 30;
  2. Tüchsen, F. Jensen, A. A. Agricultural work and the risk of Parkinson’s disease in Denmark, 1981-1993. Scand J Work Environ Health. 2000 Aug.; 26 (4): 359-62.
  3. Kurtzke, J. F. Goldberg, I. D. Parkinsonism death rates by race, sex, and geography. Neurology. 1988 Oct; 38 (10): 1558-61.
  4. Lux, W. E. Kurtzke, J. F. Is Parkinson’s disease acquired? Evidence from a geographic comparison with multiple sclerosis. Neurology. 1987 Mar; 37 (3): 467-71.
  5. Schwartz, G. G. Multiple sclerosis and prostate cancer: what do their similar geographies suggest?. Neuroepidemiology. 1992; 11 (4-6): 244-54.
  6. Newmark, H. L. Newmark, J. Vitamin D and Parkinson’s disease–a hypothesis. Mov Disord. 2007 Mar 15; 22 (4): 461-8.