Lawmakers around the country are turning up the heat on the tanning bed industry, blaming the popularity of indoor tanning among young people for rising skin cancer rates. But new scientific research on the benefits of vitamin D has clouded the debate.
"We know the cause of skin cancer—too much ultraviolet light," says James Spencer, vice-chair and director of dermatologic surgery at Mount Sinai School of Medicine. "We could prevent that, and yet, the incidence of skin cancer is rising, letting us know that we're still getting too much ultraviolet light."
Indoor tanning is especially popular among teenage girls, which worries dermatologists like Spencer. "When you look at the population and who's going to indoor tanning, it's young people, teenagers, most often young women," he says. "And this is the peak of their sensitivity, this is the time when they should be avoiding this the most."
A study of the tanning behavior of white American teens, using data from the National Longitudinal Study of Adolescent Health ("Add Health") confirmed those concerns. "Fully 24 percent of the teens in our study ... used an indoor tanning facility at least once," says Catherine Demko of the Comprehensive Cancer Center at Case Western Reserve University School of Medicine and University Hospitals of Cleveland. "Females were far more likely to use it than males, and by the time girls were 18 or 19 years old, about 47 percent reported that they had used an indoor tanning facility three or more times." The study, published in the journal of Archives of Pediatrics and Adolescent Medicine, suggests that teenagers don't see tanning as potentially dangerous behavior.
While the Indoor Tanning Association warns consumers to avoid burning, "I am not satisfied with the message that burning is bad, but tanning is good," says Kevin Cooper, professor and chair of the department of dermatology at Case Western Reserve University. "There's no way you can get a tan without damaging the skin, That's what the tan is." Cooper says the message should be "that whatever color you are is OK, that's it's not necessary for you to be dark in order to be accepted."
But some researchers think if we avoid the sun, we are preventing our bodies from getting vitamin D, which our skin needs sunlight to produce. "Vitamin D has always been recognized as being very important for child bone health, and vitamin D deficiency of course causes rickets in children," says Michael Holick, professor of dermatology, medicine physiology and biophysics at Boston University Medical Center. "But we also know that vitamin D is really clinically important throughout our entire lives, not only for bone health, but for a wide variety of physiological processes."
Vitamin D together with calcium is known to protect against bone diseases including osteoporosis and osteomalacia in adults. And a growing body of evidence shows that vitamin D may also protect against diseases such as multiple sclerosis, hypertension, depression, and colon, breast and prostate cancers.
The Institute of Medicine has set 200 international units of vitamin D as the adequate allowance for adults under fifty—that's two glasses of milk a day. But research by Holick and others suggests we need five times that amount. "We think that you need 1000 international units of vitamin D a day," says Holick. " So even if you drank one or two glasses of milk a day and one or two glasses of orange juice each day, you're getting no more than 20 to 40 percent of the vitamin D requirement that truly satisfies your body's needs."
Holick and others say the best way to get that amount is moderate exposure to sunlight—"typically for a white person say in New York or in Boston that would be no more than probably 5 to 10 minutes on your arms and legs, or your face, hands and arms, two to three times a week," he says. "I then recommend that you put sunscreen on with a sun protection factor of at least 15."
The tanning industry has embraced Holick's research, leading the American Academy of Dermatology to issued a statement saying that "reports linking the health benefits of Vitamin D to unprotected sun exposure mislead the public."
"You do not need to go to the beach or the tanning parlor to raise your vitamin D—and get wrinkles and skin cancer—when you can just simply eat a balanced diet and take vitamin supplements if you want," says Spencer. "We don't really know that vitamin D prevents cancer. To say that vitamin D prevents cancer is a wild speculation. To say that ultraviolet light causes skin cancer is a fact."