A pint of beer or a glass of wine a day can protect against gallstones, scientists have found.
Drinking two units a day reduces the risk of developing the painful stones by a third.
It had long been known that moderate drinking can reduce the chances of gallstone formation, but this is the first study to show how much was required. It is the latest evidence that consumption of small amounts of alcohol can be beneficial to your health. Other studies have linked it to lower rates of heart attack or stroke.
Dr Andrew Hart, from the University of East Anglia, said the new study may now allow doctors to offer specific guidance on avoiding the formation or growth of gallstones, without introducing the risk of excessive alcohol consumption.
His team examined the dietary habits of 25,639 people with questionnaires over a 10-year period, during which time 267 patients developed gallstones. Results showed that those who consumed two units of alcohol per day had a one-third reduction in their risk of developing gallstones. Two units is equal to a pint of beer, a medium-sized glass of wine, or a double shot of whisky.
For every unit of alcohol consumed per week the chances of developing a gallstone decreased by three per cent.
Dr Hart, senior lecturer in gastroenterology at UEA's school of medicine, health policy and practice, in Norwich, said the findings were an important step towards finding a way to stop the formation of gallstones.