The study did not differentiate between different coffee drinks. Photo: Getty Drinking more than four cups of coffee a day increases the chances of a stroke by a third, while frequent fizzy drinks double the risk, new Irish research has revealed. But consuming water and black or green tea may act to lower stroke risk.

Downing more than four cups of coffee a day led to a 37pc higher risk. The findings have emerged in global research studies co-led by the University of Galway, in collaboration with McMaster University, Canada, and an international network of stroke researchers. Coffee contains caffeine which may increase blood pressure, a risk factor for stroke, but the study did not examine different types of coffee.

Fizzy drinks, including both sugar-sweetened and artificially sweetened, such as diet or zero sugar, were linked with a 22pc increased chance of stroke. It rose sharply with two or more of these drinks a day. The link between fizzy drinks and chance of stroke was greatest in Eastern and Central Europe, the Middle East, Africa and South America.

Researchers said many products ­marketed as fruit juice are made from concentrates and contain added ­sugars and preservatives, which may offset the benefits usually linked with fresh fruit, and actually increase the risk of stroke. Juice drinks were associated with a 37pc increased risk of stroke due to bleeding. The risk triples with two of these drinks a day and women were found to be more vulnerable.

However, drinking.