What You Should Know About Sun Exposure

Here comes the sun, and the Beatles say it's all right.

Your dermatologist might have said just the opposite up until a few years ago, but now is likely to be a little more equivocal.

At least Dr. Laura King, who owns Patient Preferred Dermatology in Los Alamitos, Calif., isn't as strongly against the sun as she used to be.

What changed? There is recent research on vitamin D that indicates it may be a greater factor than previously thought in preventing cancer and building strong bones. And the natural way to get vitamin D is through exposure to the sun.

The conundrum: One of the best ways to get skin cancer is overexposure to that same sun.

"The question is how much should you be in the sun so that you get adequate vitamin D, weighed against the skin cancer," King said in a phone interview last week. "So it's a balancing act, I think, and you really have to do this on an individual basis.

"I think it's been estimated that for a Caucasian, 10 minutes a day of just casual sun exposure, being normally clad, is enough vitamin D," she said. But even that is in question, because of the studies that show those with the highest amount of vitamin D have less cancer and better bones.

King knows of no established guidelines for sun exposure, and guesses are further complicated by race.

"The darker you are, the less vitamin D you're going to absorb from the skin," she said.

On the other hand, those with dark skin have an advantage when it comes to skin cancer, because they also absorb fewer ultraviolet rays, which cause the damage that eventually results in the most common skin cancers -- basal cell carcinoma and squamous cell carcinoma.

As soon as you stick your head into the sunlight, these rays are going to work, and, on average, the more hours you spend in the sun, the faster you're going to see those cancers, or actinic keratosis, which is a precancerous area.

Adequate vitamin D is especially important for women, said King. "Women will get more osteopenia, a thinning of the bones, than men," she said.

There is an alternative to wrestling with the problem of how much sun.

"You can just take extra vitamin D supplements," said King.

As for those common skin cancers, you pay for those on the installment plan.

"They are both from cumulative sun exposure over several years," said King. "It's thought maybe about 30 years of sun exposure is the average for getting enough of a threshold to develop skin cancer. It's kind of like smoking. You've got to smoke for several years to get lung cancer."