Drinking plenty of tea – at least four cups a day – can help reduce the risk of developing type 2 diabetes, research has found.
Chinese academics behind the findings say that four or more cups of tea daily can lower the risk by 17% over 10 years. “Our results are exciting because they suggest that people can do something as simple as drinking four cups of tea a day to potentially lessen their risk of developing type 2 diabetes,” said Xiaying Li from the Wuhan University of Science and Technology in China, the lead author.
The protective effect may be even greater if people put milk in their tea, Li said. Although she and her seven co-authors did not investigate the effect of milk in tea as part of their work, previous studies have shown that dairy products can also have an anti-diabetic effect.
“I think the milk would make the effect of tea on diabetes stronger. That is, tea would be more effective with milk in,” Li said.
She will present the findings on Sunday at the European Association for the Study of Diabetes’s annual meeting, in Stockholm, Sweden.
The researchers undertook a meta-analysis of 19 previous studies into tea drinking and diabetes which involved almost 1.1 million adults in eight countries in America, Asia or Europe, including one conducted in the UK. They found a “significant linear association” between drinking black, green or Oolong tea – a traditional Chinese tea – and a reduced risk of becoming diabetic.
Compared to non-tea drinkers, people who drank one, two or three cups a day had a 4% reduced risk –but those who consumed four or more cups daily were at 17% less risk. The effect was consistent across both sexes.
Asked why tea might protect against diabetes, Li said: “It is possible that particular components in tea, such as polyphenols, may reduce blood glucose levels, but a sufficient amount of these bioactive compounds may be needed to be effective.”
About 4 million Britons have been diagnosed with diabetes. Of those, about 90% have type 2, which is associated with unhealthy lifestyles, especially being overweight. The others have type 1, an autoimmune condition that is not associated with lifestyle and is usually diagnosed in childhood. Although the findings have not appeared in a medical journal they were peer reviewed by the Stockholm conference organisers.
Li said that while the findings are observational and do not prove that tea drinking causes the lower risk of type 2 diabetes, they believe it is likely to contribute.