The good, the bad and the ultraviolet.

Byline: Tim Christie The Register-Guard

Sun is bad: Unprotected exposure increases the risk of skin cancer, the most common of all cancers.

Sun is good: It's a terrific source of vitamin D, which growing evidence suggests may help prevent myriad cancers.

It's one of the conundrums of modern life: conflicting messages, often delivered by the news media, about what's good for our health.

In this case, the current consensus from researchers and doctors is that more research is needed, and in the meantime, vitamin D is best obtained through supplements and "small amounts of sun exposure," though how small is not clear.

But as summer descends haltingly on Oregon, dermatologists aren't budging from their long-held stand against unnecessary sun exposure.

"There isn't a safe amount of sun exposure," said Dr. Diane Baird, a Eugene dermatologist who has survived a half-dozen skin cancers, including melanoma. "But you got to live."

Dermatologists recommend this: Stay out of the sun from 10 a.m. to 4 p.m. If you must go out, wear a broad-brimmed hat and long sleeves, and slather on sunscreen, with an SPF rating of at least 15 (and preferably higher) every two hours. Seek shade.

Sensible advice, to be sure, but it's easy to forget or dismiss in Oregon, particularly after a dark, rain-soaked winter that leaves us vulnerable to the seductive powers of warm summer rays.

Who wants to wear long sleeves and hide in the shade when the sun comes out?

But Oregonians who find themselves tempted to bask their pasty torsos in the midday sun might first consider this disturbing statistic: Oregon has the nation's fifth-highest rate of sun-caused melanoma, the deadliest type of skin cancer.

Since 1996, Oregon's melanoma cases and melanoma deaths have been steadily increasing. In 2002, the most recent year for which statistics are available, Oregon ranked ninth in the country in the melanoma deaths.

So, sun is bad. Except when it isn't.

A growing body of evidence suggests that vitamin D can prevent cancers, particularly colon cancer, and that many people, particularly in northern climates, aren't getting enough. Vitamin D deficiency has serious health consequences for children - it can cause rickets, or soft bones - as well as for adults.

For instance, last month, a small study in the American Journal of Clinical Nutrition found that older women who took high levels of vitamin D were less likely to get cancer. Other studies have suggested that vitamin D can protect against cancer of the colon, prostate, lung, lymph nodes, and even skin cancers.

Vitamin D can be obtained through food - fatty fish such as tuna and salmon, for example - and milk, which is fortified with vitamin D. But exposure to ultraviolet rays from the sun triggers the synthesis of vitamin D in skin and is believed to be a more efficient way to obtain necessary amounts of the vitamin.

So while there's growing evidence that vitamin D can protect against cancer, there's not yet a consensus on how much vitamin D is necessary and how best to get it.

It's difficult to make recommendations on sun exposure because of variables such as the season, time of day, a person's skin color, geographical location and cloud cover.

A panel of researchers and clinicians from the United States and Canada, representing cancer, dermatology, nutrition, public health, bone health and autoimmune diseases, met last year to figure out what to tell the public about skin-cancer protection and vitamin D.

The North American Conference on UV, Vitamin D and Health warned of the risk of exposure to UV rays from the sun, and extolled the benefits of vitamin D. To minimize the health risks of sun exposure while gaining the benefits of vitamin D, the group said, "supplementation and small amounts of sun exposure are the preferred methods of obtaining vitamin D."

But they didn't define "small amounts" because of the variables of sun exposure.

"For example, it is possible that just a few minutes a day of unprotected sun exposure will increase vitamin D status, but for some, may also increase the risk of skin damage," the group said.

More research is needed before specific recommendations can be made, the group said.

Ten to 15 minutes of sun exposure at least two times per week to the face, arms, hands or back without sunscreen should provide adequate vitamin D, according to the Office of Dietary Supplements, part of the National Institutes of Health.

Dermatologists don't recommend that people seek out the sun to boost their vitamin D.

"The skin cancer risk in most of our minds outweighs the concern about not manufacturing enough vitamin D," said Dr. Neil Swanson, chairman of the Dermatology Department at Oregon Health & Science University's School of Medicine.

He said it's possible to get dosed with adequate vitamin D from the sun even while wearing the strongest sunscreens.

The main thing that Eugene dermatologist Greg Richterich stresses with his patients is to avoid prolonged, intense exposure to the sun.

"If you're going out to the mailbox, it's no big deal," he said. "You don't want to go out and expose yourself a long time to the midday sun."

In the end, it comes down to common sense, he said. "The main thing here is to use good judgment - have good sun sense," he said.

What sun-hungry Oregonians in particular need to be careful of is the cycle of burning, tanning and getting pale, Swanson said.

Baird, the Eugene skin doctor, has direct and indirect experience with the consequences of too much sun.

"Mostly what I'm treating is skin cancers, all day long," she said. "There's no question they're caused by sun exposure."

Baird said she herself has had several cases of basal cell skin cancer, which is rarely fatal and can be treated surgically. And when she was doing her residency at the University of Pittsburgh 14 years ago, one of her fellow dermatologists found melanoma, which was successfully treated.

So now, Baird puts on sunscreen every day, and if she plans to spend time in the sun, wears sun-protective clothing.

Baird attributes her susceptibility to skin cancer to her fair skin and to a sun-drenched childhood.

"I'm a redhead and I grew up in Hawaii," she said. "I've had well over my share of UV exposure."