Caffeinated suncream gives protection a boost

A new study has found that caffeine could help to block cancer formation in UV-sensitive mice by increasing the likelihood of damaged cells dying after sun exposure. The findings suggest caffeine could help protect against skin cancer by promoting the death of cells with damaged DNA.

'This study suggests the possibility that caffeine, possibly [applied to the skin], would have an inhibitory effect on sunlight-induced skin cancer', said Professor Allan Conney from Rutgers University in the USA who was involved in the study.

Several studies have previously found that drinking caffeinated drinks could help protect against various types of cancer, including UV-associated skin cancers. The current research helps explain why this appears to be so.

One of the known functions of caffeine is to suppress a protein called ataxia telangiectasia and Rad3-related (ATR). ATR is part of a mechanism that senses DNA damaged by, for example, UV light, and triggers DNA repair. If caffeine inhibits ATR, the study suggests this will encourage the damaged cells to self-destruct, preventing them from spreading or becoming cancerous.

The scientists developed genetically modified mice that were sensitive to UV light and produced little ATR. After 19 weeks of chronic exposure to UV, these mice had 69 percent fewer tumours than normal mice. Also, the tumours that did form seemed to be less invasive in the mice without ATR in the skin. By the end of the study, however, all mice had developed a common form of skin cancer, squamous-cell carcinoma.

The caffeine molecule itself can directly block some UV rays. 'Therefore adding it to sunscreens may make sense for two reasons - it's directly a sunscreen, and completely independently, it has this effect on ATR', said Dr Paul Nghiem, who led the research

However, Professor Dorothy Bennett from St George's, University of London, warned that there is still work to be done before caffeine should be added to sunscreens. 'One might want to check there is no adverse effect of caffeine on the incidence of other cancers, especially melanoma, which kills over four times as many people as [squamous-cell carcinoma]', she said.

The study was published in the journal Proceedings of the National Academy of Sciences.