We've long been advised to exercise regularly and cut back on caffeine. But a new study finds that a combination of the two might just make our skin more resilient to cancer.

Researchers from Rutgers University have found that in mice, the combination of exercise and caffeine helped to protect the skin by increasing destruction of precancerous cells that had been damaged by the sun.

The studies appear in the July 31 Proceedings of the National Academy of Sciences (PNAS).

The researchers used groups of hairless mice, whose exposed skin is vulnerable to the sun. One group drank caffeinated water (the human equivalent of one or two cups of coffee a day); another group was offered a running wheel on which to run; while a third group both drank and ran. A fourth group, which served as a control, didn't run and didn't drink any caffeine.

All of the mice were exposed to lamps that generated UVB radiation that damaged the DNA in their skin cells.

The caffeine drinkers and exercisers showed an increase over the control group in "apoptosis," a mechanism in the body that tells cells with badly damaged DNA to self-destruct.

  • The caffeine drinkers showed an approximately 95 per cent increase in apoptosis;
  • The exercisers showed a 120 per cent increase,
  • Meanwhile, the caffeine drinking and exercising mice showed a nearly 400 per cent increase.

"If apoptosis takes place in a sun-damaged cell, its progress toward cancer will be aborted," said Allan Conney, director of Rutgers' Cullman Laboratory and one of the paper's authors.

The authors acknowledge that the mechanisms of the protective effect of caffeine and exercise is still unclear. And the finding still needs to be tested on humans.

"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," said Conney.