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Black tea linked to lower diabetes risk

By Salynn Boyles
WebMD UK Health News
Medically Reviewed by Dr Farah Ahmed
man drinking tea

8th November 2012 - Drinking black tea may help protect against type 2 diabetes, but further studies are needed to confirm an association.

When researchers analysed data from 50 countries, they found that the rate of diabetes was lowest in countries where people drank the most black tea.

Rising diabetes rates

Type 2 diabetes rates have skyrocketed worldwide in recent decades. It is projected that by 2030 there will be over 900 million people across the globe with diabetes or with a high risk for developing it. Between 2006 and 2011, the number of people diagnosed with diabetes in England increased from 1.9 million to 2.5 million.

When researchers used a mathematical model to estimate the impact of drinking black tea on a number of health conditions, they found a link to just one - diabetes.

Tea drinking nations

Of the countries included in the analysis, black tea drinking was highest in Ireland, the UK and Turkey. It was lowest in South Korea, Brazil and China.

Researcher Dr Ariel Beresniak of the mathematical research group Data Mining International in Geneva, Switzerland, says the study shows a consistent relationship between black tea drinking and the risk of type 2 diabetes. However, this study does not prove a cause and effect relationship.

Black tea may protect against diabetes, Dr Beresniak says, but more research is needed to prove this.

"You certainly can't say that on the basis of this study alone, but the findings are consistent with previous studies that have also suggested a link," he says.

The new study was published today in the journal BMJ Open.

Role of green tea and white tea

Studies have also linked green tea and white tea to a lower risk of diabetes, but Dr Beresniak and colleagues were not able to examine this association.

Black tea is more highly fermented and, as the name suggests, darker than green or white tea.

The fermentation process turns simple flavonoid compounds called catechins in green tea into complex compounds called theaflavins and thearubigins.

Dr Beresniak says if black tea is shown in future research to actually lower diabetes risk, the fermentation process may explain why.

Experts have serious doubts about the claims being made in the research.

Dr Matthew Hobbs, head of research at Diabetes UK says in a statement: "This study doesn’t show that drinking tea reduces the risk of developing type 2 diabetes. There are many other important differences between populations which mean that this study tells us nothing about the risk of an individual developing the condition."

Additional BootsWebMD reporting by Peter Russell.

Reviewed on November 08, 2012

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