Reports of the death of sun protection have been greatly exaggerated.
In the past two years, dermatologists and health groups such as The Skin Cancer Foundation have been soul-searching about their core messages concerning sun protection. The reasons: recent reports that some Americans suffer from vitamin D deficiency, and that vitamin D produced in the body by solar ultraviolet (UV) exposure may help prevent prostate, colon, breast, and other cancers, as well as bone diseases.
Given these findings, the Foundation contemplated acknowledging that a few minutes of unprotected sun exposure here and there might not be such a bad thing. However, we refrained, because of more compelling proof that unprotected UV exposure ages the skin and can lead to skin cancer.
Now, an important new analysis from the Department of Dermatology, Boston University School of Medicine, proves we made the right decision.
The Debate
The authors, Deon Wolpowitz, MD, PhD, and Barbara A. Gilchrest, MD, reviewed massive research on vitamin D and sun exposure. They found that “selected epidemiologic data suggest an inverse correlation between solar UVB exposure and mortality from several cancers, including colon, breast, and prostate, and between sun exposure and the incidence of colon cancer.” In other words, in regions where people have greater sun exposure, fewer cases of colon cancer occur (presumably because of sun-induced vitamin D), and fewer deaths occur from these three cancers.
However, they pointed out that UV is an officially recognized environmental carcinogen. There has been “a near epidemic” of skin cancers, they say, with more than 1.5 million diagnosed yearly in the U.S. – and the cause of most is sun exposure.
There’s Evidence. . . and There’s Evidence
In the end, whether or not to advocate increased sun exposure for vitamin D comes down to which studies are most convincing. Drs. Wolpowitz and Gilchrest say those supporting unprotected sun exposure are of “variable quality” and merely “observational”: The data generally link mortality from colon, breast, and prostate cancer in specific regions with the amounts of UV in those regions. Such studies may be confounded by climatic factors such as pollution, variations in population genetics (such as darker- or lighter-skinned populations), and cultural or lifestyle factors (such as socioeconomic status and diet). The studies cannot directly correlate disease with individual sun exposure, and “cannot establish that solar exposure decreases incidence or mortality from these cancers.”
In contrast, research from animal studies and surveys to large population studies and human DNA studies have strongly established the connection between sun exposure and skin cancer. Sun exposure also causes wrinkles, brown spots, leathering and sagging.
Drs. Wolpowitz and Gilchrest further note that very small amounts of sun exposure provide all the vitamin D the body can manufacture. Even when you wear sunscreen, some UV reaches the skin, and this may be plenty, at least for fair-skinned individuals. “Incidental protected exposure. . . to minimal UVB radiation three times weekly generates adequate vitamin D levels by classic criteria,” they say. “Greater exposure adds nothing to vitamin D stores, while increasing DNA damage in a linear fashion.”
All evidence considered, the authors conclude, “The tradeoff of vitamin D production today for photoaging and skin cancer decades hence may have made sense millennia ago, when life expectancy was 40 years or less, but it’s a poor exchange when life expectancy has doubled, skin rejuvenation is a $35 billion/year industry, and one in three Caucasians develops skin cancer.”
We second this motion. “Skin cancer prevention messages should encourage outdoor physical activity, but it is premature to make specific recommendations for ‘sensible’ sun exposure,” says Allan C. Halpern, MD, a Vice President of The Skin Cancer Foundation and Chief, Dermatology Service, Memorial Sloan-Kettering Cancer Center, New York City. “The idea that a little sun is good for you and a lot of sun is better undermines skin cancer prevention.”
The Safer Way
Fortunately, Drs. Wolpowitz and Gilchrest point out, there are “effective and almost effortless” noncarcinogenic alternatives — vitamin D-fortified foods and/or dietary supplements. For most, just two 8-oz glasses of fortified milk or orange juice or one standard vitamin D pill is safe and sufficient. Those at high risk for vitamin D deficiency should take additional daily supplemental vitamin D (200-1000 IU) with concurrent dietary calcium.
Some experts say we should stick with the higher end of supplementation. “The skin is a target tissue for the active form of vitamin D,” notes Arnold W. Klein, MD, professor of medicine/dermatology at UCLA’s David Geffen School of Medicine. “Although the recommended dietary allowance in adults is 5 micrograms (200 IU) daily, there is mounting evidence that in the absence of sunlight exposure the requirement should be at least 15 micrograms (600 IU).”
