Diabetes, longevity: regular consumption of dark tea maybe good for you

Green tea gets plaudits in scientific studies for health benefits, but it's far from the only tea that is getting attention in this area.


One of the most widely consumed beverages in the world, along with water and coffee, tea is often singled out for its soothing, anti-stress and health-protecting properties.

Some of these have already been the subject of much research, in particular on well-being and cognitive functions, but what’s now attracting scientific interest is its impact on diabetes.

A new study by researchers at the University of Adelaide, Australia, and Southeast University, China, reveals daily consumption of dark tea also known as fermented tea or post-fermented tea may help control blood sugar levels and reduce the risk of diabetes.

Presented at the annual meeting of the European Association for the Study of Diabetes (EASD), taking place from October 2-6 in Hamburg, Germany, the study involved 1,923 adults aged between 20 and 80 from eight Chinese provinces.

Of the participants, 436 had diabetes, 352 had prediabetes (blood sugar levels higher than normal but not high enough to be considered diabetes), and 1,135 had normal blood sugar levels.

The researchers asked them about the frequency of their tea consumption, as well as the type of tea consumed, and then studied a potential association with various parameters such as glucose excretion in urine, insulin resistance, and glycemic status.

Better blood sugar control

“Our findings hint at the protective effects of habitual tea drinking on blood sugar management via increased glucose excretion in urine, improved insulin resistance and thus better control of blood sugar.

“These benefits were most pronounced among daily dark tea drinkers,” explained Professor Tongzhi Wu of the University of Adelaide – and co-lead author of the study – in a Press Release.

The researchers say this phenomenon could be linked not only to the way dark teas, such as pu’er cha, is produced, “which involves microbial fermentation”, but also to the presence of antioxidants and anti-inflammatories.

The study reports daily tea consumption was associated with a 15% reduction in the risk of pre-diabetes, and a 28% reduction in the risk of type 2 diabetes, irrespective of the type of tea consumed.

And the relationship was even more significant with dark tea (53% reduction in the risk of pre-diabetes and 47% in the risk of type 2 diabetes).

“Our findings suggest drinking dark tea every day has the potential to lessen type 2 diabetes risk and progression through better blood sugar control.

“When you look at all the various biomarkers associated with habitual drinking of dark tea, it may be one simple step people can easily take to improve their diet and health,” concludes Professor Zilin Sun, who was a co-lead on this research.

Boost to longevity

This is not the only study to extol the health benefits of tea. Just over a year ago, researchers at the US National Institutes of Health (NIH) looked at the effects of black tea consumption on all-cause mortality in the UK.

They found that participants drinking two or more cups of black tea a day were 9% to 13% less likely to die than those who drank no tea at all.

“The associations were observed regardless of whether participants also drank coffee, added milk or sugar to their tea, their preferred tea temperature, or genetic variants related to caffeine metabolism.

According to the authors, their findings suggest that tea, even at higher levels of intake, can be part of a healthy diet,” noted the Press Release published when that research was first published.

NOW READ: 4 reasons why eating chocolate is healthy for you, according to science

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