London - Drinking four cups of tea a day can reduce the risk of a stroke by more than a fifth, research has found.

But less than that does not have a beneficial effect, say scientists.

Previous studies have shown the protective effects of green tea on the brain, but the latest research focused on black tea – the kind mostly drunk in the UK.

It contains components called flavonoids which researchers say have cardiovascular benefits.

Scientists at the Karolinska Institute in Stockholm studied 74,961 Swedish adults, who were in good health when they signed up, for ten years from 1997.

During the study period, just over 4,000 of the volunteers suffered a stroke.

Most of these were ischaemic – where a blood clot blocks off the brain’s blood supply – the cause of around 85 percent of strokes.

In that time their tea-drinking habits were also monitored.

Once they allowed for other risk factors, such as smoking or high blood pressure, researchers found that at least four cups every day lowered the chances of a brain blood clot by 21 per cent.

Strokes kill around 200 people a day in the UK and leave many more disabled. - Daily Mai