For decades we have heard about the dangers of sun exposure. Ultraviolet (UV) rays from the sun cause damage to the skin leading to premature aging and increased risks of skin cancer. With strong messages from medical organizations, many people have increased their sun protection habits, such as daily sunscreen and avoiding the sun.
Ideally, these changes have improved our health by decreasing cancer risk, but we are also blocking a major health benefit. In as little as 5-30 minutes twice a week, the sun’s UVB (a type of UV ray) rays can stimulate the Recommended Dietary Allowance of vitamin D (400-800 units.) And more and more research is showing vitamin D to be an important vitamin. Is the sun’s vitamin D benefit enough to outweigh its risks?
Vitamin D has stirred up interest in the medical community because of research that has shown that it has protective effects against heart disease, osteoporosis, and several types of cancer, including breast, prostate, and colon cancers. The benefits of vitamin D have been well researched. The debate is now about where you should get your vitamin D.
Some of the highest sources of vitamin D are fish and fish liver oils. But Americans get the majority of their vitamin D from fortified foods like milk and orange juice. Even with fortified foods, it is difficult for the majority of people to get enough vitamin D through diet alone.
Vitamin D is available in supplement form, usually in a combination pill with calcium. An effective supplement would be able to increase blood levels of vitamin D. Vitamin D3 (cholecalciferol) is a preferred source of supplemental vitamin D. However, supplements do not provide anywhere near the amount of vitamin D that the sun can provide. High amounts of vitamin D supplementation have led to dangerously high levels of calcium in the body. Sun-created vitamin D, even at significantly higher levels, does not cause these problems.
The sun is believed to provide the majority of your vitamin D supply. But even the sun’s benefits have some inconsistencies. The summer sun can create enough vitamin D within 15 minutes for people with fair skin, but it may take 6 times longer in people with darker skin.
UVB rays are also weak and can be easily blocked by clouds, smog, and glass windows. During certain times of the year, in far north and far south regions (like Washington state and Vermont), between November and February, the sun’s UVB rays do not even reach the Earth’s surface. There is far less or no production of vitamin D during these times of year.
And of course, for some, the risk of skin cancer leaves the sun out as a reasonable source for vitamin D.
The sun is by far the most efficient creator of vitamin D, but does it outweigh the harms? There is no doubt that frequent and intense sun exposure causes damage to skin cells, often starting with a painful sunburn, and potentially leading to skin cancer later on in life. Although the medical community is fairly united in sun avoidance for cancer prevention, as vitamin D evidence grows, more medical professionals are leaning toward the light.
Research will continue to try to determine exactly how much sun exposure increases risks of skin cancer and who may be at higher risk. At the same time, the growing interest in vitamin D will also prompt manufacturers to improve the efficacy of supplements. There are many factors that play into our risk of developing disease, including our environment, lifestyle habits, and genetics. You should act based on your own health and family history.
There have been no official changes to sun recommendations from organizations like the Skin Cancer Society or the American Cancer Society, but more debate will be ahead. Some organizations remain steadfast in a “don’t seek the sun” policy, but others are beginning to believe that a “no sun exposure” policy may not be the best option.
It may be best to find a balanced approach to the sun:
Talk to your doctor about your personal risk factors for skin cancer. People that have a personal or family history of skin cancer will need more sun protection than others. Your doctor may also advise you to try to increase your vitamin D levels through diet or supplement options.
American Cancer Society
Eat Right—Academy of Nutrition and Dietetics
Canadian Cancer Society
Dietitians of Canada
About vitamin D. Vitamin D Council website. Available at: http://www.vitamindcouncil.org/about-vitamin-d. Accessed May 4, 2016.
Skin cancer prevention—patient version (PDQ). National Cancer Institute website. Available at: http://www.cancer.gov/types/skin/patient/skin-prevention-pdq. Updated May 14, 2015. Accessed May 4, 2016.
Sun safety. Environmental Protection Agency website. Available at: https://www.epa.gov/sunsafety. Accessed May 4, 2016.
Vitamin D. National Institute of Health Office of Dietary Supplements website. Available at: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional. February 11, 2016. Accessed May 4, 2016.
Vitamin D deficiency in adults. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated October 5, 2016. Accessed May 4, 2016.
Vitamin D intake and supplementation. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 11, 2016. Accessed May 4, 2016.
Last reviewed May 2016 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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