Suncream in Your Coffee?

Caffeine may prevent skin cancer in mice, study shows

MONDAY, Aug. 26, 2002 (HealthDayNews) -- If the perfect tan is the color of light coffee, there may be a good reason.

Caffeine, it seems, may offer protection against skin cancer -- at least in lab animals.

Experts said it's too soon to say if the work has any relevance for humans. However, since caffeine is the stimulant of choice for most of the world, the study is undoubtedly going to make coffee, tea, and cola drinkers take note. A report on the findings appears this week in the Proceedings of the National Academy of Sciences.

The work was conducted by researchers at Rutgers University in Piscataway, N.J., who looked at two constituents of green tea: caffeine and another molecule called EGCG (mercifully short for epigallocatechin gallate).

When applied topically for 18 weeks to hairless mice previously exposed to UVB radiation -- which causes skin cancer -- the two compounds sped up the death of abnormal tissue and tumor cells, while sparing normal cells.

"We wanted to see if it had a biological effect independent of inhibiting UVB directly, which is how sunblock works," said Allan Conney, a Rutgers cancer specialist and a co-author of the study. "It's a biological effect that we're seeing as opposed to a physical effect."

Caffeine appeared to be somewhat more effective than EGCG at eliminating carcinoma cancer cells, eradicating 72 percent vs. 66 percent for the other substance. But it was less potent at inducing death in abnormal (but not necessarily cancerous) skin cells than the other molecule. Still, it's a more stable chemical, which bodes better for an eventual lotion should one arrive.

Conney said previous studies, including his own, have suggested that oral caffeine may also protect against skin cancer. However, in animal work the doses that have to be administered to produce such an effect are about 50 percent higher than what humans typically ingest.

As a result, at least for skin cancer, Conney feels a topical solution with the stimulant would work best. He and his colleagues hope to test a caffeine lotion on people at high risk of skin cancer, such as those with a history of the lesions. "Caffeine is terrific in mice, but we would like to know if it works in people," he said.

Conney's group is also concerned about potential side effects from the substance, although the mice in the latest study seemed to tolerate it well.

But hold on before you reach for that java. A second study in the journal, by researchers in Colorado and New Mexico, showed that mammoth doses of caffeine retard a cell's ability to repair genetic damage caused by cancerous particle radiation.

A research team led by Theodore Puck of the Eleanor Roosevelt Institute in Denver found that oral doses of caffeine hinder the ability of hamster cells in a lab dish to repair DNA damage caused by toxic radon gas. Radon, which is naturally occurring, is a relatively common hazard in homes with basements and is believed to cause many cases of lung cancer in this country. It emits alpha-particles, which can scramble a cell's genes if it strikes them directly.

Harry Crissman, a cell biologist at Los Alamos National Laboratory and a co-author of the paper, said his study doesn't necessarily indict caffeine, which has long been used by researchers as a way to inhibit DNA repair. In fact, he said, it may agree with the New Jersey findings in that caffeine permits the suicide of injured cells -- a beneficial process when it comes to preventing cancer. "If they're partially repaired, enough that maybe they can survive [with mutations], it's better to kill them off," Crissman said.

What To Do

To find out more about the health effects of caffeine, visit the University of Illinois or the National Toxicology Program.

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