By Marc Sorenson, EdD. Sunlight Institute.
Regular sun exposure is one of the best ways to reduce the risk of many cancers. Although the relationship of sun exposure (and vitamin D) to the risk of prostate cancer is controversial, a study from Australia, published in 2011, showed that the less sun exposure, the greater the risk of the cancer. The researchers investigated the relationship between prostate cancer incidence and solar radiation in non-urban Australia and found an inverse association. There are many other studies that indicate a protective effect of sun exposure. One of the earliest was conducted by Dr. Esther John and her colleagues: they compared the lifetime sun exposure of 450 white men with advanced prostate cancer to that of 455 white men who did not have cancer. The men were divided into quintiles according to the amount of exposure they had received. Subjects in the highest fifth of sun exposure had only 51% of the risk of prostate cancer as did those in the lowest quintile.
Another study on cancer that corroborated these observations was entitled: Is prevention of cancer by sun Exposure more than just the effect of vitamin D? A systematic review of epidemiological studies. In their review, the authors noted that regular sun exposure correlated to a reduced risk of colorectal cancer, prostate cancer, breast cancer and non-Hodgkin’s lymphoma (NHL). However, vitamin D levels correlated to a reduced risk of colorectal, and to a lesser extent, breast cancer, but were not correlated to a significant risk reduction in prostate cancer and non-Hodgkin’s lymphoma. The authors concluded with this statement: “Particularly in prostate cancer and NHL, other sun-potentiated and vitamin D-independent pathways, such as modulation of the immune system and the circadian rhythm, and the degradation of folic acid, might play a role in reduced cancer risk as well.” These researchers did well to remind us, that as important as vitamin D is to the human body, other effects of sun exposure may be more important in some diseases. The authors could have also mentioned the effect of sun on vasodilation, mediated by the production of nitric oxide (produced by the skin after sun exposure). They could also have discussed the influence of sun on production of serotonin and endorphins, all of which may have contributed to their observations.
Other research used childhood sunburn as a measure of UVR exposure and determined that men who had sunburned as children had only about one-fifth the risk of contracting prostate cancer as those who had not sunburned. A note of caution! We are not recommending that anyone sunburn in order to prevent prostate or other types of cancer. Sunburn was used in this research to predict higher vitamin D levels, but it is not necessary to achieve those levels, since non-burning sun exposure achieves the same results. This research also demonstrated that men with lowest level of UVR exposure had more than triple the risk of prostate cancer and that onset of the disease was delayed more than four years in those who had the greatest exposure compared to those who had the least exposure. A follow-up to this study, reported that men in the lowest quartile of sunbathing were linked to a 5.33-fold greater risk of prostate cancer than those in the highest quartile. Still other research has indicated that “higher levels of cumulative exposure, adult sunbathing, childhood sunburn and regular holidays in hot climates were each independently and significantly associated with a reduced risk of this [prostate] cancer.
So men, protect your prostate by regular, non-burning sun exposure. Don’t let the Powers of Darkness frighten you away from the sun.
 Loke TW, Seyfi D, Khadra M. Prostate cancer incidence in Australia correlates inversely with solar radiation. BJU Int. 2012 Apr;109 Suppl 3:75.
 John EM, Schwartz GG, Koo J, Van Den Berg D, Ingles SA. Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer. Cancer Res 2005;65(12):5470-79.
 van der Rhee H, Coebergh JW, de Vries E. Is prevention of cancer by sun exposure more than just the effect of vitamin D? A systematic review of epidemiological studies. Eur J Cancer. 2013 Apr;49(6):1422-36.
 Moon SJ, Fryer AA, Strange RC. Ultraviolet radiation: effects on risks of prostate cancer and other internal cancers. Mutat Res 2005;571(1-2):207-19.
 Bodiwala D, Luscombe CJ, Liu S, Saxby M, French M, Jones PW, Fryer AA, Strange RC.. Prostate cancer risk and exposure to ultraviolet radiation: further support for the protective effect of sun. Cancer Lett 2003;192:145-49.