Cancer Research UK is playing down reports that a combination of exercise and coffee can protect people against developing skin cancer.
Scientists at the State University of New Jersey, USA looked at the effects caffeine and exercise had on skin cell growth in mice.
They found that mice who used an exercise wheel and drank two to three cups of coffee a day had a greater level of cell death, which is thought to prevent the development of tumours.
Study author Allan Conney, commented: "We need to dig deeper into how the combination of caffeine and exercise is exerting its influence at the cellular and molecular levels, identifying the underlying mechanisms.
"With an understanding of these mechanisms we can then take this to the next level, going beyond mice in the lab to human trials."
But Dr Alison Ross, science information officer at Cancer Research UK, is not so sure that the research is relevant to humans.
"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," she says.
"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."