The sun-protective effect of this caffeine-exercise combination is still no excuse to skimp on the sunscreen. But researchers say the two may work together to prevent skin cancer better than either element alone.
"We need to dig deeper into how the combination of caffeine and exercise is exerting its influence at the cellular and molecular levels, identifying the underlying mechanisms," says researcher Allan Conney, director of Rutgers University's Cullman Laboratory, in a news release. "With an understanding of these mechanisms we can then take this to the next level, going beyond mice in the lab to human trials.
"With the stronger levels of UVB radiation evident today and an upward trend in the incidence of skin cancer among Americans, there is a premium on finding novel ways to protect our bodies from sun damage."
Caffeine, Exercise, and Skin Cancer
The study compared the effects of caffeine, exercise, and the combination of both in groups of hairless mice whose exposed skin is prone to skin cancer.
One group of mice drank the human equivalent of one or two cups of coffee a day in the form of caffeinated water. Another group voluntarily ran on an exercise wheel, and a third drank and ran.
All of the mice were exposed to UV radiation from lamps that damaged their skin cells.
Some of the damaged (precancerous) skin cells died naturally through apoptosis -- the process that occurs when the body orders damaged cells to die. But the rate of cell death among the precancerous cells was highest in the group that drank caffeine and exercised.
"If apoptosis takes place in a sun-damaged cell, its progress toward cancer will be aborted," says Conney. "The most dramatic and obvious difference between the groups came from the caffeine-drinking runners, a difference that can likely be attributed to some kind of synergy."
Researchers say previous studies have linked increased exercise or caffeine consumption with a lower risk of certain types of cancer, but the mechanisms behind this protective effect of the two working together are still somewhat of a mystery.
The results of the study appear in the Proceedings of the National Academy of Sciences.
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