Your Wellness Lifestyle Starts HereHope everyone is enjoying sunny days and soaking in your Vitamin D!
Most public health messages about sunlight focus on the dangers of too much sun exposure. Dangers may be over-stated: according to a 2006 WHO report, excessive UVR exposure only accounts for 0.1% of the total global burden of disease. Plus, the definition of “excessive sun exposure” should be personalized based on skin type in consideration of particular type of UVR (season, time of day). While too much sun exposure is harmful to health, too little is also harmful: the same report states that a larger annual disease burden may result from very low levels of UVR exposure. Diseases mentioned includes major musculoskeletal and autoimmune diseases, and cancer.
We all know that the most widely known benefit of sun exposure is Vitamin D, however, there are other ignored benefits as well.
Some background: In the late 1800s, around 90% of children living in crowded and polluted cities in northern Europe developed rickets. Doctors in the U.S. and Europe promoted whole body sunbathing to resolve the issue – hospitals had sun decks for treating this and other conditions. Tuberculosis patients got better with sunlight – patients were sent to sunny places to recover. Researchers determined that the incidence of TB increased during the winter months when sun exposure was lower, decreased during the summer months with more sun exposure. Researchers observed that vitamin D levels were lower in children with TB. As awareness of sunlight’s influence on rickets and TB increased, sun became a status symbol in Western countries. Wealthy people could afford to take beach vacations and play outdoor sports. Phototherapy became a popular treatment for rheumatic conditions, diabetes, gout, chronic ulcers, wounds. Having a “tan” was considered a good thing, being pale not so much (Coco Chanel popularized having a tan as well).
Does sunlight cause skin cancer? The first reports of an association between sun exposure and skin cancer date back to late 1800s. In the 1930s, the U.S. Public Health Service started issuing warnings – avoid midday sun in summer, gradually increase sun exposure to reduce risk of sunburn. Over time, many countries adopted aggressive programs to promote sun avoidance, and the use of sunscreen anytime one is exposed to sun. Research shows that while sunscreen use continues to increase worldwide, the incidence of malignant melanoma, the condition sunscreens are supposed to prevent, is also increasing. The incidence of melanoma in U.S. has increased 50-fold in last 10 years.
Most melanomas develop on areas of the body that have the least exposure to the sun. The most common subtype of melanoma is superficial spreading melanoma, which occurs on the areas of the body with intermittent to no sun exposure such as the trunk and extremities. High continued sun exposure is related to increased survival rates in patients with early-stage melanoma. A study of 3578 patients with melanoma showed that the history of sunburn did not reduce survival; ongoing sun exposure after diagnosis was associated with better survival. (Gray-Schopfer V, Wellbrock C, Marais R. “Melanoma biology and new targeted therapy.” Nature. 2007 Feb;445(7130):851–857 Berwick M, Reiner AS, Paine S et al. “Sun Exposure and Melanoma Survival: a GEM Study.” Cancer Epidemiol Biomarkers Prev 2014 Oct;23(10):2145-215)
Non-burning exposure to sun and being engaged in outdoor occupations is associated with reduced risk of melanoma. There is no reliable evidence to support the use of sunscreens as a means for preventing melanoma.
Can sunlight save your life? Avoidance of sunlight is NOT good for your health. Studies show that exposure to sunlight reduces the risk of cancers like, intestinal, colon, breast, and colorectal. Sunlight exposure, not vitamin D supplements, reduced the risk of type 2 diabetes.
In a study of sunlight and blood pressure, oral vitamin D supplementation has no effect on endpoints like blood pressure. The skin contains significant stores of nitrogen oxides, which are converted to nitric oxide by UV radiation; sun exposure causes vasodilation and reduced blood pressure. The positive effects of sun exposure on blood pressure are independent of vitamin D levels. Skin cancer kills less than 3 per 100,000 in the U.S.; for every person who dies of skin cancer, more than 100 die of cardiovascular disease. In a study of 24 healthy volunteers – exposure to UV light was important for activating nitric oxide pathways. This may account for seasonal variations in both blood pressure and CVD.
Sunlight has a positive effect on serotonin levels and activity. Sun exposure also affects melatonin levels and circadian clocks.
Because there are so many factors associated with sunlight that are independent of vitamin D, supplements are not a substitute for sun exposure. Examples: nitric oxide, serotonin, melatonin, endorphins, anti-inflammatory molecules.
Safe sun exposure: Caucasians can produce the right amount of vitamin D by spending 15 minutes in the sun with face, arms and legs exposed 2-3 times per week between 11AM and 3PM from May-October - half this amount of time if wearing a bathing suit. People with darker skin require more time in the sun but also have lower risk of skin cancer. All people should avoid sunburn. The advice to avoid all sun exposure has been misdirected and has resulted in harm. Exposure to sunlight results in production of vitamin D. Single whole-body exposure is equivalent of taking 15,000-20,000 IU vitamin D.
Taking vitamin D supplements is not a substitute.
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