People who drink black tea are less likely to develop type 2 diabetes, say researchers.

A new analysis of data from 50 countries found that the nations who drank the most black tea also suffered the lowest levels of the metabolic syndrome.

Further the study, published in the British Medical Journal, found that high tea consumption was related to lower levels of obesity.

Scientists believe that the fermentation process, which turns green tea black, could also cause the production of complex health-giving ‘flavonoids.’

They analysed consumption of black tea and the prevalence of various diseases, including type-2 diabetes.

Ireland drank the most black tea, with each person consuming 2kg each a year, according to sales data. Britain and Turkey were close behind, with all three countries found to have lower levels of diabetes than others where consumption was low, including Brazil, Morocco and Mexico.

However, tea drinking did not appear to have a strong association with any other diseases studied, according to the study led by Dr Ariel Beresniak from Data Mining International, in Geneva, Switzerland.