Indian scientists say coffee protects mice from radiation and could work the same way in humans.
Researchers at India's Bhabha Atomic Research Centre (BARC) discovered mice injected with caffeine survived high doses of normally lethal radiation.
Although the study was limited to animals, Kachadpillill George, the head of the research team, believes the findings could have implications for humans.
"It does suggest that coffee might have some beneficial effects in protecting against radiation," he told New Scientist magazine.
But British radiation expert Peter O'Neill, of the Medical Research Council's Radiation and Stability Unit in Oxfordshire, said it would take huge amounts of coffee to protect human cells from radiation damage.
Mr George and his team injected 471 mice with caffeine and exposed them to rays of gamma radiation, enough to kill most mice.
But 25 days later, 70 per cent of the mice that received 80 milligrams of caffeine per kilogram of body weight were still alive.
In contrast, all 196 mice which had been exposed to the same radiation but had not been given any caffeine died.
The researchers said the caffeine reacts with hydroxyl radicals produced by the radiation.
This could stop the radicals from damaging cells and prevent body functions from failing.
"George suggests that a better understanding of the protection offered by caffeine might lead to improvements in the way radiation is used to treat cancer," the magazine said.