Last updated on January 27, 2018
There’s no getting around the fact that damaged skin is often blamed on age and too much sun. While both are known factors for maturing our skin, the relationship between sun exposure and skin cancer is not that straightforward.
A Scandinavian study published in the Journal of the National Cancer Institute (2003) concluded that sun burns during our adolescence are the most dangerous. Yet, the same sunburn-causing UVB wavelengths received throughout your life kick off the chemical and metabolic chain reaction that produces vitamin D3.
The human body synthesizes vitamin D from the sun’s UV rays absorbed through the skin. While vitamin D receptors in the brain and body play a role in our mental health and outlook on life, it’s still unknown exactly how they operate.
Referred to as the sunshine vitamin, vitamin D not only helps keep your immune system functioning properly it also affects mood. Research shows that sunlight on skin help reverse SAD (seasonal affective disorder).
Some professors believe the connection has to do with the supplement’s energizing effects because the energy boost from vitamin D may encourage individuals to get out and socialize, get moving, eat a healthier diet and make other choices that fuel an upward spiral of positivity.
Since few foods offer enough natural sources of vitamin D, and since the body cannot make its own, it needs the sun’s help for production. Low vitamin D levels have been related to everything from poor bone health to multiple sclerosis, type 1 diabetes, rheumatoid arthritis and prostate cancer.
Early studies show that an appropriate amount of sun exposure could promote immunity against cancer. Researchers have found that higher-latitude living is associated with greater incidences of breast, colon and prostate cancers, which may be due, in part, to a lack of vitamin D.
Obesity, old age, darker skin, and excessive time spent indoors are all risk factors for low levels of vitamin D. People over the age of 70 only make about one-quarter of the amount of vitamin D as a 20-year-old who is exposed to the same amount of sunlight since the production of 7-dehydrocholesterol (the substance in the skin that converts sunlight rays to a pre-vitamin D form) declines with age. For this reason, it can be beneficial for older people to move to a sunnier climate.
A more recent study published in the Journal of Investigative Dermatology (2014) showed a connection between sun exposure and lower blood pressure. Researchers in the U.K. found that sunlight has a dilating effect on arteries which inevitably lowers blood pressure. While this report was not related to vitamin D, it was related to nitric oxide, a chemical made in the tissue of the arteries that keeps blood vessels dilated and flexible.
More studies are planned to examine the risks of skin cancer versus other sun exposure benefits, results that could affect the recommendations on sun exposure limitations. While sunlight is beneficial, it remains a cause of mortality in population studies.
The question of just how much sun exposure we need remains. Some studies suggest that getting a lot of sun at once is more dangerous than steady exposure over time. Stanford University found that to satisfy the body’s vitamin D needs, “sensible sun exposure” for five to 10 minutes per day without sunscreen is sufficient. Wearing sunscreen inhibits vitamin D3 synthesis by blocking UV rays, so brief periods of unprotected exposure, in theory, can be good for your skin.
On the other hand, doctors say it’s important not to abandon your sunscreen. New York University dermatology professor Darrel Rigel, MD says, “What isn’t theoretical are the more than 8,100 Americans who will die of melanoma this year and the 1 million Americans who will get skin cancers. The vast majority of these cancers are caused by UV exposure.”
If you are regularly in the sun for longer periods of time, then it’s important to lather up with sunscreen or wear protective clothing to avoid UV damage. Doctors also say no amount of sunlight can cause vitamin D toxicity since your body converts the excess into inert substances, however, toxicity can occur in people who over supplement (more than 10,000 units per day), as this amount is excessive and beyond safe recommendations. Federal guidelines say adults should get between 200 and 600 IU (international units) of vitamin D each day, with recommended levels increasing with age.