Coffee plus exercise could have health benefitsBut experiment only conducted on mice so far

31 July 2007

Coffee and exercise may combine to guard against the dangerous effects of too much sun, new research suggests.

Separately, both caffeine and exercise help to prevent skin cancer, animal tests have shown. But together they work 'synergistically' to produce a much more powerful effect, say scientists.

The coffee-workout recipe appears to kill off pre-cancerous skin cells damaged by ultraviolet rays from the sun.

If they are allowed to survive, these cells can go on to produce malignant skin cancers.

UVB radiation

US scientists at the State University of New Jersey in New Brunswick exposed different groups of hairless mice to lamps that generated ultraviolet-B (UVB) radiation.

One group drank amounts of caffeinated water which were the equivalent in human terms of one or two cups of coffee a day.

Another group was allowed to exercise on a running wheel, while a third group both drank caffeinated water and ran.

A fourth comparison 'control' group did not run and was not given any caffeine.

The scientists carried out tests looking for evidence of programmed cell death, or apoptosis, the process by which DNA-damaged cells commit suicide and avoid cancer.

Compared with the control animals, mice exposed to caffeine but not able to exercise showed a 95 per cent increase in UVB-induced apoptosis.

Caffeine and running

A 120 per cent increase in programmed cell death was seen in mice which took exercise but were not given caffeine. However, combining caffeine and exercise produced an almost four-fold increase in UVB-induced apoptosis.

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

'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.'

The researchers, who reported their findings in the journal Proceedings of the National Academy of Sciences, suggested several biochemical mechanisms that might be responsible for the effect. But they admitted that the synergistic interplay between caffeine and exercise was a mystery which needed more exploration.

More than 8,000 cases of malignant melanoma, the most dangerous form of skin cancer, are diagnosed in the UK each year, leading to almost 2,000 deaths.

At least 75,000 cases of non-melanoma skin cancer, a much milder and less harmful disease, occur each year in the UK.

Fastest growing cancer

Rates of skin cancer in the UK have quadrupled for men and tripled for women in the past 25 years. The disease is the fastest growing cancer in the UK, partly because more people are taking sunshine holidays abroad.

Dr Alison Ross, science information officer at the charity Cancer Research UK, said: 'This study was carried out in mice so there will need to be more research in this area to see if there is a similar effect in humans.

'Drinking a cup of coffee before going out jogging is definitely not a substitute for adequate sun protection - and those who are fair-skinned should take extra care.'

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