Having one large glass of wine a day in middle age raises the risk of a stroke, warn researchers.

A study of almost 12,000 twins followed for four decades found that ‘heavy drinkers’ – defined as those having 250ml of wine a day – had a stroke risk one-third higher than those having less than 60ml a day.

People in their 50s and 60s who were heavy drinkers had a stroke five years earlier as a result.

Traditional factors associated with stroke, such as high blood pressure and diabetes, became more important only around the age of 75.

One drink or unit is normally defined as containing 8g of alcohol, equivalent to about one small (125ml) glass of wine, just over half a pint of beer and less than one shot of spirits such as whisky or vodka.

A medium (175ml) glass of wine contains around two units and a large (250ml) glass contains three units. Red wines often have a higher alcohol content.

Past research has shown that alcohol affects stroke risk, but this study – published in the American Heart Association journal Stroke – is the first to pinpoint differences with age.