Applying caffeine to the skin in sunny weather may protect against a type of skin cancer, US researchers hope.
Experiments on mice, reported in the Proceedings of the National Academy of Sciences , suggest that caffeine prevents UV damage. Tumours took longer to develop and there were fewer of them, the study reports.
But other experts warned there could be an adverse affect on other cancers by using caffeine in this way.
The researchers did not apply caffeine to the mice, instead they genetically modified the animals.
Caffeine is known to interfere with a protein involved in detecting DNA damage called ATR. Scientists modified the mice so they did not produce any ATR in the skin.