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October 09, 2023

Drinking dark tea each day may reduce the risk of type 2 diabetes, study finds

The fermented drink appears to help people better manage their blood sugar levels, new research shows

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Dark Tea Diabetes Study Drew Jemmet/Unsplash

Drinking one cup of dark tea per day may help reduce the risk of type 2 diabetes by helping control blood sugar levels, according to a recent study.

Habitual tea drinking is linked to an array of health benefits. Studies have suggested that a daily cup of hot tea reduces the risk of cardiovascular disease, stroke, type 2 diabetes and premature death.

New research, released earlier this month, adds to this evidence. It suggests that consuming a cup of dark tea every day helps people better manage their blood sugar levels, reducing the risk of type 2 diabetes.

Adults who drank at least one cup of dark tea every day had a 47% lower risk of developing type 2 diabetes and a 53% lower risk of being diagnosed with prediabetes than people who never drank tea. But drinking any kind of tea proved beneficial, too. Tea drinkers were 28% less likely to be diagnosed with type 2 diabetes and 15% less likely to be diagnosed with prediabetes.

Dark tea, which differs from black tea, undergoes a microbial fermentation process that gives it a unique flavor and function. The researchers said this process may result in antioxidant and anti-inflammatory effects that improve insulin sensitivity and the performance of beta cells in the pancreas, which produces insulin. Insulin helps the body convert blood sugar to energy.

The most common type of dark tea is Pu-erh, which is made in China and is available online and in some shops in the U.S. In addition to its potential for reducing type 2 diabetes risk, Pu-erh and other types of dark tea have been linked to improved indigestion, lower cholesterol and weight loss support

The latest study included 1,923 adults in China. Some of them didn't drink tea at all; others exclusively drank black, green or dark tea. The researchers found that habitual tea consumption – and particularly dark tea – was linked to increased sugar excretion and reduced insulin resistance. 

Excreting high amounts of sugar in the urine is often an indicator that the body is maintaining healthy blood sugar levels, Dr. Tongzhi Wu, the study's co-author and an associate professor at the University of Adelaide in Australia, told Everyday Health. By contrast, insulin resistance is an indicator that the body is struggling to manage blood sugars. 

"The substantial health benefits of tea ... have been reported in several studies over recent years, but the mechanisms underlying these benefits has been unclear," Wu said. "Our findings hint at the protective effects of habitual tea drinking on blood sugar management via increased (sugar) excretion in urine, improved insulin resistance and thus better control of blood sugar. These benefits were most pronounced among daily dark tea drinkers." 

The research is not definitive, Wu said. The scientists are conducting more research on the potential benefits that dark tea has on blood sugar control, including among people who already have type 2 diabetes.

Though drinking a cup of dark tea each day may help control blood sugar levels, it's important to look at a person's entire diet to determine how best to reduce the risk of diabetes and other serious ailments. Mayo Clinic recommends maintaining a healthy weight, being physically active, and eating plant-healthy foods and heathy fats like nuts and seeds.

But there are many benefits of tea, according to previous research. 

One study found that people who drink at least two cups of black tea each day are 9% to 13% less likely to die an early death. Studies have shown that chamomile tea is an effective calming agent that can aid sleep, while ginger tea may reduce chronic inflammation and improve gut health. Ginseng has been associated with increased energy and sharper cognitive function, while peppermint tea may reduce the severity of nausea and vomiting

Kombucha, another kind of fermented tea, also also help reduce blood sugar levels in people with type 2 diabetes. Green tea extract, which is rich in antioxidants, can accelerate weight loss, improve blood pressure regulation and improve the symptoms of metabolic syndrome, according to previous studies.

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