Studies tout benefits of vitamin D
Despite recently publicized studies suggesting sun exposure could be a good way to maintain a healthy level of vitamin D, the American Cancer Society maintains that protecting the skin from sunlight should remain a priority.
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“There does seem to be an increasing body of evidence of the anti-cancer benefits of vitamin D,” said Joyce Gallagher Sullivan, the American Cancer Society’s vice president of communications for New England. Sullivan said the Society had already been re-evaluating its sun protection guidelines when the studies were publicized.
In April, the results of four separate studies were released, each suggesting that vitamin D may be important in preventing and treating lymphoma, and prostate, lung and colon cancer.
Dr. Edward Giovannucci, professor of nutrition and medicine at Harvard University, authored one of the studies. His findings suggest that vitamin D could help prevent 30 cancer deaths for every one caused by skin cancer. People in the Northeast have higher cancer rates than those who get more sunshine year-round – something the study suggests could be linked to vitamin D deficiency.
“All the information is rather confusing. … I think the data on the so-called effects of vitamin D from sunlight and the effects it has on cancer isn’t really solid information,” said Dr. Charles McDonald, chief of dermatology at Rhode Island Hospital and chairman of dermatology at Brown University Medical School.
While vitamin D is available in supplement form, occurs naturally in some kinds of fish and is usually added to milk, Giovannucci’s research indicates people need up to 1,500 international units of vitamin D a day to “significantly curb cancer.” The FDA says an adequate intake is 200 IU a day for people under 50 and 400 IU for those 50 to 70 and 600 IU for those over 70.
While the study, which observed large groups of people, found those with higher levels of vitamin D had lower cancer rates, McDonald said the cancer rate has been dropping steadily over the past 10 years – a decade during which people have been using sunscreen regularly at the behest of doctors who named it as a cancer-prevention method.
“If anything, the incidence of all those cancers should be rising if they’re caused by vitamin D deficiency that results from not getting enough sun,” McDonald said.
So how much sun is enough and what is too little? The studies propose 15 minutes a few times a week without sunscreen. Getting fried on the beach should always be avoided.
“There have been a number of studies done on skin cancer that have found melanoma are associated with sun-burning,” McDonald said. “We’re not telling people to stay totally out of the sun, we’re just telling them not to burn.”
The American Cancer Society still advises people to limit or avoid exposure to the sun during the midday hours and to cover as much skin with clothing as possible, to wear sunglasses to protect eyes from UV light and to use a sunscreen with a sun protection factor (SPF) of 15 or higher and apply 15 to 20 minutes before going outdoors.
Robert. A. Smith, the American Cancer Society’s director of cancer screening, said the review of sun exposure guidelines began more than two years ago.
“That said, we’ve been impressed by these data, as well as the tensions between the different professional groups related to the tradeoff between sun exposure, skin damage, and vitamin D deficiency,” Smith said. “Indeed, Dr. Giovannucci’s talk contributes to this issue by giving our own guideline deliberations a much higher profile than they otherwise would have.”
