By Katie Kerwin McCrimmon

Summer is officially over, but with temperatures approaching 90 degrees and bright sunny September days, you still might be able to dose up on some vitamin D.

That raises a health conundrum, however.

On the one hand, skin cancer is the most common cancer in the U.S. and dermatologists would much prefer if we stayed out of the sun altogether or remain well covered with sunscreen, hats and long sleeves during peak sun hours. New research has found that melanoma, the deadly form of skin cancer, is striking younger people — especially teen girls — in much higher numbers.

At the same time, researchers say Americans are chronically deficient in vitamin D. The name is misleading. Vitamin D is a hormone, not a vitamin, and we get it by converting UV rays into the hormone. Vitamin D is crucial to bone health and may have all sorts of other benefits from preventing some types of cancer to thwarting infections.

With seemingly incongruent advice to stay out of the sun because it causes skin cancer while finding ways to get adequate vitamin D, what do doctors advise?

Skin cancer experts are adamant. They say UV radiation is a known carcinogen, and potential harm from sun exposure is too great to risk spending time outdoors without sunscreen. People who need vitamin D should get it through fortified foods or supplements.

But vitamin D experts say that some individuals may decide to load up on vitamin D by spending very short periods of time outside on sunny days without sunscreen since sunlight gives much bigger boosts of vitamin D than people can get through food or supplements.

“I’m not personally making this recommendation, but the amount of vitamin D that a light-skinned individual in the summer in Colorado would get wearing short sleeves for about 10 to 15 minutes would be as much vitamin D as you’d get in 30 glasses of (fortified) milk,” said Dr. Adit Ginde, an emergency room physician at University of Colorado Hospital and an associate professor of emergency medicine at the University of Colorado School of Medicine.

“The darker your skin tone, the more likely you are to need vitamin D,” Ginde said.

“It’s a personal decision. If you want to raise your vitamin D levels and you want 0 risk, taking a supplement is probably the safest way to do that,” he said.

For those who want some vitamin D through minimal sun exposure, Ginde said you’d never want to stay out to the point of getting a sunburn. Rather, you’d absorb some rays for less than half the time it would take to get any kind of burn.

The complication is that individuals are so different. Some people have a greater risk of getting skin cancer, so they should be very cautious. Skin tones vary, as do exposure levels depending on the latitude. In Colorado, it’s very difficult to get any exposure to vitamin D in the winter and you don’t absorb much during off-peak hours.

Ginde was the lead researcher of a 2009 study that found that three out of four people are deficient in vitamin D and that deficiency levels are growing.

Deficiencies among African-Americans and Hispanics are particularly high, according to the study, which was published in the Archives of Internal Medicine.

Ginde is completing a study now on the role that vitamin D might play in preventing infection. He can’t share those results yet, but said researchers may find that lower vitamin D levels in the winter may make people more vulnerable to colds, the flu and respiratory infections.

The optimal level of vitamin D in the blood ranges from about 30 to 40 nanograms per milliliter, he said.

Ginde and his fellow researchers found a marked increase in people who were deficient. The population of people who were severely deficient with levels of less than 10 nanograms per milliliter had gone up from 2 to 6 percent when the researchers compared vitamin D levels in people in the late ’80s and early ’90s compared to those tested between 2001 and 2004.

Since Ginde’s study, the Institute of Medicine issued new guidelines ecommending 600 IUs per day for adults ages 70 and younger and 800 IUs per day for those 71 and older. Those recommendations were controversial as soon as they came out in 2010 and some researchers have said people should be getting much more vitamin D.

“It’s clear that the rates of deficiency are high and increasing,” Ginde said. “Increased sunscreen (use) has some part of it, but also becoming a more indoor population has played a big role.”

Ginde said that 80 to 90 percent of vitamin D intake is related to UV exposure and that outdoor exposure is the “primary determinant of vitamin D levels in people.”

If most of the exposure to vitamin D happens outdoors, that brings back the concerns about skin cancer.

Melanoma surged into the news recently when former President Jimmy Carter revealed that he had been diagnosed with melanoma that had spread to his brain.

While Carter is 90, researchers at a New York cancer center have found staggering increases in melanoma rates among young patients.

Researchers at the Roswell Park Cancer Institute in Buffalo, N.Y., earlier this summer unveiled a study that found that the number of cases of melanoma in children, adolescents and young adults increased by 253 percent from 1973 to 2011. Survival rates linked to much better treatments for melanoma have also increased.

But the disease still can be deadly or require extensive, costly treatments. Young people who get it are shocked to have cancer at such an early age. In particular, melanoma cases have shot up among young women. Risky behavior including the use of tanning beds is a likely culprit for the increase in cases among younger women.

Dr. Demytra Mitsis, a fellow at Roswell Park and lead author of the study, said she often meets young patients who wish they could turn the clock back.

“They say, ‘I thought I was invincible. If I could go back and talk to my 16-year-old self, I would do things differently.’ It’s hard for them to understand that something like this can happen,” said Mitsis.

For her study, she analyzed data from 35,726 people who had gotten melanoma between 1973 and 2011. Before 1980, females represented 57 percent of cases. That percentage rose to 65 percent from 2001 to 2011.

While survival rates have improved, about 7 to 10 percent of people diagnosed with melanoma will die, Mitsis said.

Dr. Ilene Rothman, chair of the dermatology department and Mitsis’ colleague at Roswell Park, said she used to see one or two patients a month with melanoma.

“Now we’re seeing them all the time. One American dies from melanoma every hour. It’s still quite common and quite serious,” Rothman said.

“Skin cancer is the most common (cancer) in the U.S. One in five Americans gets some kind of skin cancer. One in 58 gets melanoma,” Rothman said.

Rothman said vitamin D is very important to bone health. Other potential benefits haven’t been proven yet, so she sees no conflict between the need to get vitamin D and the importance of preventing skin cancer.

“There are excellent sources of vitamin D that don’t cause skin cancer. Any UV exposure — whether it’s from the sun or tanning beds — can cause cancer. We already know that. We can get vitamin D from our diet, from fatty fishes like salmon and tuna. And supplements are readily available.

“I do not recommend that people get their vitamin D from the sun,” Rothman said.

She said the jury is out on exactly how much extra vitamin D people should take. Rothman recommends getting your levels checked, then mapping out a plan with your doctor.

And she says skin cancer can be prevented.

About 24 states have some kind of ban for tanning beds for teens. (Colorado does not.)

Adults and young people need to use sunscreen properly and more often. The U.S. Centers for Disease Control and Prevention found that only about 30 percent of women and 15 percent of men regularly use sunscreen.

“It’s abysmally low,” Rothman said.

Even when people use sunscreen, they often don’t put it on properly or forget to reapply it.

“You need water-resistant sunscreen if you’re active, and try to avoid the middle of the day. Seek shade. Wear hats. Think of enjoying yourself outside, but not trying to get a tan,” Rothman said.

The non-melanoma skin cancers are directly linked to sun exposure. Causes for melanoma are more complex.

“We can’t say for sure, but many patients recall those blistering burns as children,” Mitsis said. “They could have actually prevented this. It can be very frustrating for patients.”(Click here to see the video Dear 16-year-old me.)

“There are a lot of factors we can’t do anything about. We can’t change our genetics. One thing we can change is our behavior,” Rothman said.

Telling young people that they might someday have cancer doesn’t always resonate. But teens who want to be beautiful sometimes heed warnings if they hear that sun exposure could make their skin look bad.

Colorado has a higher rate of melanoma than the U.S. average, but surprisingly some northern states have higher rates. Colorado’s rate is 21.6 per 100,000 people compared to the U.S. average of 19.7. By comparison, Vermont has a rate of 28.1 while in Minnesota the rate is 27.5 per 100,000 people.

For Ginde, the vitamin D expert, health choices are always about tradeoffs.

“Certainly by using sunscreen all the time, you increase your risk of vitamin D deficiency and you have some protection from skin cancer,” he said. “Perhaps for an individual, there’s some middle ground.”