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Experts debate clear guideline on sun exposure
Updated Thu. Mar. 9 2006 9:03 AM ET

CTV.ca News Staff

Dermatologists have long preached against unprotected sun exposure but new research is suggesting a possible change in position among some experts.

That's because vitamin D, which the skin produces naturally when exposed to the sun, could prevent certain types of cancers.

Heather Logan, director of cancer control policy at the Canadian Cancer Society told Canada AM Thursday that the need for a clear guideline on sun exposure is becoming increasingly necessary.

"There's a solid body of scientific evidence to indicate that being in the sun will increase your risk of skin cancer, cause premature aging and also cause cataracts," Logan said.

"But now there's this suggestive body of evidence that's growing, that's telling us that there might be some benefits."

She said the issue is complex because research "suggests that being out in the sun for unprotected periods of time will reduce your risk of some cancers including breast, prostate, colorectal, ovarian and non-Hodgkin's lymphoma."

What researchers have found, Logan said, is that exposing the hands and face to sunlight, without sunscreen, for just five to 10 minutes a week, will boost vitamin D levels - even on sunny days in winter.

In the summer, however, when UV levels are high, 20 seconds of sun exposure allows the body to produce 400 international units (IU) of vitamin D, which is the current recommended daily allowance in Canada and the United States for many age groups, Dr. Edward Giovannucci, a professor of epidemiology and nutrition at the Harvard School of Public Health told Canadian Press.

The dilemma, experts say, is to find a consensus on how much vitamin D is required, and the best way to get it.

"Isn't it ironic that as we've recommended sun screen to be used, that the overall cancer rate has increased?" asked Dr. Bruce Hollis of the Medical University of South Carolina, appearing on CTV News Wednesday.

In a bid to resolve the conflicting messages about sun exposure, a group of doctors and researchers are meeting in Toronto this week.

While Giovannucci pointed out that it is easy for the body to manufacture the recommended daily allowance of vitamin D, he was among several experts at Wednesday's sessions who suggested the amount was woefully insufficient.

"We generally make a lot less vitamin D from the sun than we used to, and there's not much vitamin D in foods,'' he told CP in an interview, noting that the nutrient is found naturally in cold-water fish like salmon and is added to milk.

"Cells are becoming relatively starved of the vitamin D ... and they can't really function 100 per cent properly. At least that's the hypothesis, that these lower levels of vitamin D may be increasing the risk of cancers and other conditions"

Particularly in the winter months, Giovannucci recommended that people should take vitamin D supplements, specifically the type known as D3.

"Probably 1,000 IU is a real minimum and realistically we probably need to go up to 2,000 IUs, which is the upper limit before you worry about toxic or adverse affects," he said.

Despite the evidence that vitamin D appears to have health benefits, some dermatologists remain reluctant to urge people to lie under the sun.

"What will we be telling people? Spend a little bit of time out in the sun and don't burn? It's a complicated message to give," Dr. Cheryl Rosen of Toronto Western Hospital told CTV News.

The Canadian Cancer Society, which sponsored the meeting, hopes to have a position statement advising Canadians on sun exposure guidelines mid-May.

With a report from CTV's Avis Favaro