The findings are based on a population study of over 29,000 Danish men and women aged between 23 and 95. Their weekly intake of beer, wine, and spirits was assessed, as were other factors likely to influence bowel cancer risk, such as how much they smoked, weighed, and took regular exercise.
Men were more likely than women to be heavy drinkers, and heavy drinkers were more likely to be smokers and to weigh more than light drinkers.
During a monitoring period of almost 15 years, 411 cases of colon cancer and 202 cases of rectal cancer were reported among those studied. Alcohol seemed to have little influence over the risk of colon cancer, but there was a clear association between rectal cancer risk and the amount of alcohol consumed. Those drinking more than 41 units of alcohol a week had twice the risk of developing the disease as non-drinkers.
But the type of alcohol consumed had a significant bearing on rectal cancer risk. Those who drank 14 or more units of beer or spirits a week were over 3.5 times as likely to develop rectal cancer as non-drinkers. Yet those who drank the same total amount of alcohol, but who included around a third or more of wine in their intake were less than twice as likely to develop the disease.
The authors point out that wine drinkers tended to be better educated and to take more exercise than beer or spirit drinkers, so there may be other healthier lifestyle factors at play.
There are no obvious reasons why alcohol should apparently be more damaging to the rectum than the colon, say the authors, but the reasons why wine seems to exert its protective effect most likely lie in resveratrol, which is found in both grapes and wine. Previous research indicates that this chemical damps down the cellular processes involved in the promotion and growth of cancerous cells.
Gut 2003; 52: 861-7
Journal
Gut