Pamela A. Popper, Ph.D., N.D.

Wellness Forum Health

Summer is almost here, and people, particularly those who live in northern climates, should spend time in the sun. Unfortunately, most people do not get enough sun and there are several reasons for this. The sunscreen industry has done a great job of selling the idea that all sun exposure is dangerous and increases the risk of skin cancer, and some medical professionals and the supplement industry have convinced people that taking vitamin D pills is a substitute for sunshine. But this is not true.

The risk of skin cancer as a result of sun exposure has been over-exaggerated. According to a World Health Organization report, only 0.1% of the total burden of disease results from excessive sun exposure. The same report stated that a much larger annual disease burden likely results from low levels of UVR exposure, since sun avoidance leads to increased risk of conditions like autoimmune diseases and cancers other than those of the skin.[1]

The most publicized benefit of sun exposure is vitamin D production, and vitamin D does play an important role in human health. For Caucasians, one half hour of sun exposure in a bathing suit results in production of between 20,000 and 30,000 IU’s of vitamin D. In darker-skinned people, 30 minutes results in production of 8,000 to 10,000 IU’s.[2] Use of sunscreens prevents the production of vitamin D.

But the benefits of sunlight go beyond production of vitamin D, and many research studies have shown this to be the case. For example, one research group discovered that while lower vitamin D levels are associated with an increased risk of type 2 diabetes,[3] vitamin D supplements did not improve insulin sensitivity for vitamin D-deficient adults at risk of developing type 2 diabetes.[4]

Another study showed that multiple sclerosis patients who had increased sun exposure had less neurodegeneration, increased gray matter volume, and greater whole brain volume than controls who took vitamin D supplements, even though those who took supplements had higher plasma vitamin D levels. The reason is that sunlight stimulates neuroendocrine and immune system functions, which vitamin D supplements do not. The researchers concluded that MS patients might be better off with lower plasma vitamin D levels from sun exposure than higher plasma vitamin D levels from supplementation.[5]

Studies show that people who do not get enough sunlight have changes in cellular defense mechanisms that can increase inflammation and the risk of autoimmune disease, and that UV radiation can reduce inflammation and can help to prevent conditions like multiple sclerosis, asthma, and cardiovascular disease.[6] Sun exposure stimulates the production of nitric oxide, a vasodilator that protects the cardiovascular system and reduces the risk of heart attacks and strokes.[7]

UV rays also deactivate viruses, including the virus that causes chickenpox and shingles. According to research Dr. Phil Rice, sun exposure is the reason why the incidence of chickenpox is lower in tropical areas. Rice analyzed 25 studies that looked at the prevalence of varicella virus in different climates and found that the only factor that consistently matched the infection rate was UV exposure.[8]

Sun exposure may even be protective against, instead of the primary cause of melanoma skin cancer. Outdoor workers have a lower risk of melanoma compared to indoor workers.[9] And an evaluation of the effects of sun exposure on patients with skin cancer showed that the risk of all-cause mortality increased 4-fold in subjects who had non-melanoma skin cancer (NMSC) and multiple myeloma as a result of avoiding sun exposure when compared to the group that had the highest amount of sun exposure.[10]

Humans need sunlight. And the reductionist approach to health that has become so common has convinced many that the benefits of sun exposure are simply vitamin D which can be easily replaced with pills. But this is not true, and a large body of evidence proves this.

Safe sun exposure is the key. We can all agree that sunburns are harmful, and actually do increase the risk of skin cancer. Start with limited exposure, enough to lightly tan but not burn, and gradually increase exposure until you can spend an hour or two in the sun. Once you’ve reached your maximum tolerable exposure, cover up or sit in the shade. Use sunscreen only for those times when you must be exposed to the sun for long periods of time without the option of covering up or access to shade. Now go outside, and enjoy the summer, the sun, and good health.

[1] Environmental Burden of Disease Series No 13. Solar Ultraviolet Radiation: Global Burden of Disease From Solar Ultraviolet Radiation http://www.who.int/uv/health/solaruvradfull_180706.pdf?ua=1

[2] Mead N. “Benefits of Sunlight: A Bright Spot for Human Health.” Environ Health Perspect 2008 Apr;116(4):A160-A167

[3] Gagnon C, Lu Z, Magliano D et al. “Serum 25-hydrovyvitamin D, calcium intake, and risk of type 2 diabetes after 5 years: results from a national, population-based prospective study (the Australian Diabetes, Obesity, and Lifestyle Study).” Diabetes Care 2011 May;34(5):1133-1138

[4] Gagnon D, Daly R, Carpenter A et al. “Effects of combined calcium and vitamin D supplementation on insulin secretion, insulin sensitivity, and B-cell function in multi-ethnic vitamin D deficient adults at risk for type 2 diabetes: a pilot randomized, placebo-controlled trial.” PLoS One 2014 Oct 9:9(10):e109607

[5] Zivadinov R, Treu C, Weinstock-Guttman B, et al. “Interdependence and contributions of sun exposure and vitamin D to MRI measures in multiple sclerosis.” J Neurol Neurosurg Psychiatry 2013 Oct;84(10):1075-1081

[6] Byrne S. “How much sunlight is enough?” Photochem Photobiol Sci 2014 Jun;13(6):841-852

[7] Oplander C, Volkmar C, Paunel-Gorgulu A et al. “Whole body UVA irradiation lowers systemic blood pressure by release of nitric oxide from intracutaneous photolabile nitric oxide derivatives.” Circ Res 2009 Nov 6:105(10):1031-1040

[8] Rice P. “Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa.” Virology Journal, 2011;8(1):189

[9] Rivers K. “Is there more than one road to melanoma?” Lancet 2004 Feb 28:363(9410):728-730

[10] Lindqvist P, Epstein E, Nielsen K, Landin-Olsson M, Ingvar C, Olsson H. “Avoidance of sun exposure as a risk factor for major causes of death: a competing risk analysis of the Melanoma in Southern Sweden cohort.”J Intern Med. Published online March 16, 2016

DOI: 10.1111/joim.12496