Lower levels of both obesity and "bad" cholesterol may also be a benefit of having the odd glass of red, after an experiment on more than 900 twins showed an increase in gut microbiota diversity - a sign of gut health - compared to those who drank other types of alcohol, the new study showed.

The scientists looked into the effects of beer, cider, red wine, white wine and spirits on the gut microbiome, the micro-organisms found in digestive tracts.

They found that the gut microbiome of red wine drinkers was more diverse compared to those who had other drinks, which researchers speculate could be due to a higher amount of defence chemicals called polyphenol that act as an antioxidant.

"While we have long known of the unexplained benefits of red wine on heart health, this study shows that moderate red wine consumption is associated with greater diversity and a healthier gut microbiota that partly explain its long-debated beneficial effects on health," Dr Caroline Le Roy, first author of the findings, said.

Results from the 916 UK female twins who participated in the research also matched up to three other groups tested in the UK, the US and the Netherlands.

However, professionals have also warned that the positives should still be weighed up against the negative impacts of alcohol.

"No doctor would recommend drinking on medical grounds, as any potential benefits of red wine polyphenols should be considered alongside alcohol's links to over 200 health conditions, including heart disease and cancers as identified in the Chief Medical Officer's guidelines review," Dr Sadie Boniface, research co-ordinator at the Institute of Alcohol Studies, said.

"Polyphenols are also available from a range of other foods besides red wine."

But scientists behind the paper, published in the journal Gastroenterology, say that if people should choose any alcohol, red wine should be the one to go for if consumed in moderation.

Professor Tim Spector, lead author from King's College London, said it was one of the largest-ever studies to explore the effects of red wine in the guts of nearly 3,000 people in three different countries and "provides insights that the high levels of polyphenols in the grape skin could be responsible for much of the controversial health benefits, when used in moderation".

Australian Associated Press