They say that drinking beer may contribute to a reduction in the risk of cancer susceptibility in humans too.
The team from Japan's Kirin Brewery carried out a 42-week experiment on 344 male Fischer rats with chemically induced colon cancer.
Intake of beer decreased tumour incidence by 22 per cent and decreased the number of neoplastic lesions, including adenocarcinomas and adenomas (benign and malignant tumours), by 44 per cent, they report in the International Journal of Cancer (vol 108, issue 3, pp404 - 411).
In initial experiments the researchers show that the efficacy in inhibition of cancer varied with the brand of beer. Rats treated with freeze-dried beer saw significant protection but there was no association with ethanol, suggesting that non-volatile components of beer are responsible for the reduction, said the researchers.
Groups of rats treated with hot water extract of malt, especially with extracts of coloured malts, significantly reduced cancerous lesions but no reduction was observed by feeding with hops extract.
Beer has previously been found to be high in antioxidants, with one study suggesting that it could be just as good for health as the much-reported benefits of red wine.
Cancer of the colon or rectum is the second deadliest form of cancer but is also considered one of the most preventable types of cancer, as there are several dietary factors that appear to play a protective role against the disease.