The caffeine in the drinks can induce a 'healthy' rise in blood pressure that counteracts a drop after a meal - something that becomes more pronounced as people age.

Despite concerns about the effects of excess amounts of caffeine, it has been found that the higher the caffeine level, the lower the risk.

A new study has shown that people who drink four or more caffeinated drinks daily have a 53% lower risk of death from heart disease, compared to those who drink less than half a cup a day. Those who have two to four caffeinated drinks a day have a 32% lower risk.

But the protective effect was not seen in people with very high blood pressure or in those under 65.

The findings, published in the American Journal of Clinical Nutrition, are likely to re-ignite the debate about whether coffee is safe.

Antioxidants
Some studies claim that drinking between one and three cups a day reduces the risk of heart disease and stroke, due to the antioxidants rather than caffeine. Others suggest coffee could reduce the risk of diabetes.

The lasted study was carried out by Dr James Greenburg and colleagues at the City University of New York.

"The association was dose-related and it was a substantial effect," he said, but warned one study found drinking coffee increased the risk in younger subjects.

A past study also found that drinking four or more cups of tea daily could be more beneficial than drinking water. Scientists have said that tea not only rehydrates you as well as water does, but it can also protect against heart disease and cancer.

Some studies suggest caffeine in tea can help concentration and improve one's mood.

The major component of tea is a group of antioxidants called flavonoids, which help prevent cell damage. Tea is a natural source of flavonoids - there is eight times the antioxidant capacity of one apple in three cups of tea.