Japanese researchers have found that applying high quality olive oil to the skin after sunbathing reduces the risk of developing tumours.
The theory was tested on genetically modified hairless mice.
The researchers found that high-grade, virgin olive oil smeared on the skin delayed the appearance of tumours and reduced their size.
The researchers led by Dr Masamitsu Ichihashi of Kobe University School of Medicine placed the mice under a sunlamp three times a week.
Five minutes after each session a some of the mice were painted either with regular or extra virgin olive oil. The rest were left unoiled.
After 18 weeks, the mice not treated with olive oil started to grow tumours.
Mice treated with regular olive oil fared little better.
But those daubed with virgin olive oil took an extra six weeks to show any sign of cancer.
Smaller tumours
Their tumours were smaller, less frequent, and there was less DNA damage to skin cells.
Olive oil is rich in antioxidants, which are thought to counteract the harmful effects of ultra violet radiation.
UV triggers the production of free radicals, destructive molecules which damage DNA.
Antioxidants, such as vitamin E, mop up free radicals and help to neutralise them.
Olive oil is not a sunscreen - it does not stop UV rays penetrating the skin.
Imperial Cancer Research Fund skin specialist Dr Julia Newston-Bishop said: "A number of groups have shown that you can to some extent reduce the damage caused by sunlight by with compounds that quash the effects of free radicals.
"I've never heard of olive oil being used in this way before, but there does some to be some common sense to it.
"You could argue that olive oil won't do you any harm anyway, and it's a nice moisturiser. But I wouldn't want people to get the impression that if they sunbathe and paint their skin with olive oil they will be OK."
Dr Kate Law, head of clinical programmes for the Cancer Research Campaign, it was impossible to draw firm conclusions from a short-term study on animals.
She said: "People want to go out in the sun, and any story that makes them feel they can retrieve some of the damage done to their skin will go down well.
"But to suggest you can go out in the sun and frazzle, and then undo some of the damage using olive oil does not seem terribly scientific to me."