Women who drink moderate amounts of alcohol are less likely to get rheumatoid arthritis than those who do not drink, research suggests.
Drinking more than three glasses a week for at least 10 years halves the risk of rheumatoid arthritis, researchers found.
The study of more than 34,000 Swedish women found the risk among those who drank more than three glasses of alcohol per week in 1987 and 1997 was 52% lower than those who were never drank.
The researchers gathered detailed information on alcohol consumption, diet, smoking history, physical activity and education level between 1987 and 1997.
Between January 2003 and December 2009, when the participants were aged between 54 and 89, 197 new cases of rheumatoid arthritis were registered.
The authors of the research, published on bmj.com, concluded that alcohol may be a "protective factor" for rheumatoid arthritis.
"The results of this study indicate that moderate consumption of alcohol may reduce the risk of developing rheumatoid arthritis among women," they report.
"These results are in accordance with the inverse association between moderate alcohol consumption and risk of cardiovascular disease and add to the evidence that moderate alcohol consumption is not harmful and can be protective against such a chronic disease as rheumatoid arthritis.
"However, the effect of higher doses of alcohol on the risk of rheumatoid arthritis remains unknown."
Rheumatoid arthritis is a chronic inflammatory joint disorder that usually develops between the ages of 40 and 50.
About 1% of the world's population is affected - women three times more often than men.
Professor Alan Silman, Arthritis Research UK medical director, said: "This is a very interesting study that shows that compared to people who drink absolutely no alcohol, people who drink very modest amounts - two to four glasses of alcohol a week - have a degree of protection against developing rheumatoid arthritis.
"Small amounts of alcohol are also known to be beneficial in reducing the risk of other conditions such as heart disease, also an inflammatory disease, so the study is also telling us something about the mechanism of inflammation.
"However, it's important to stress that the paper isn't saying that excessive amounts of alcohol are good for you. And it must be remembered that drinking alcohol in excess can be especially dangerous in rheumatoid arthritis patients who are taking some anti-rheumatoid drugs that may cause liver damage, and anti-inflammatory painkillers which can lead to gastro-intestinal problems, which can be exacerbated by alcohol."