One large glass of wine a day could contain enough of a tumour-fighting compound to prevent bowel cancer, research has suggested.
The plant chemical, resveratrol, is found in the skins of grapes and concentrated in red wine.
Scientists have long known that resveratrol has anti-cancer properties, as well as effects that might benefit diabetes and heart disease patients. But a question mark remains over what dose of the compound it is best to take.
The new research suggests that for fighting bowel cancer it is very small - around five milligrams per day. That is about the amount of resveratrol typically found in one large glass of red wine, or two small glasses.
Scientists conducted tests on laboratory mice which showed that a dose of resveratrol in their food equivalent to five milligrams in humans halved the growth of bowel tumours. The low dose proved more potent than a much higher one of one gram.
Lead researcher Professor Karen Brown, from the University of Leicester, said: "Everybody thinks that more is better but we found that the low dose was more effective than the high one. We were amazed that it had any effect at all, and even more surprised by the effectiveness of the low dose."
Prof Brown will present her findings at Resveratrol 2012, a conference dedicated to resveratrol research which is starting at the university.
Previous studies have shown that even tiny amounts of the compound can reach target tissues in humans. However, cancer trials involving resveratrol supplements have proved disappointing. There is some evidence that very high doses of resveratrol may interfere with certain medicines.
"We're still trying to understand the mechanism behind the way resveratrol works and see if it translates to human tissues and cells," said Prof Brown, whose team hopes to conduct a trial in two years looking at the impact of carefully measured doses of resveratrol on patients at high risk of bowel cancer.
"It's a fascinating compound because it does so much," Prof Brown added. "We're now at a really exciting stage of research on resveratrol, but we need to nail down what mechanisms are important at the right concentrations."