One large glass of wine a day could contain enough of a tumour-fighting compound to prevent bowel cancer, research suggests.
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 to fight bowel cancer, only a small amount of the compound is required - 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 starting at the university today.
Find out what you can do to help prevent yourself against bowel cancer.
Try to do 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes on at least five days each week.
Drink alcohol in moderation - no more than two to three units a day for women and three to four units a day for men.
Getting enough vitamin D may reduce your risk of developing a number of cancers, including bowel cancer - although more research needs to be done to be certain. Vitamin D is produced naturally by your body when your skin is exposed to sunlight and can also be obtained from some foods, such as oily fish.
Smokers are 25% more likely to die from bowel cancer than people who had never smoked. If you smoke - quit now.
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.
"People do take it as a supplement, but there's no clinical evidence that this is of any benefit," said Prof Brown.
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.
Her 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."