A cup of tea can help keep you young.

A cup of tea can help keep you young.

Thanks to The Times, tea lovers can now be re-assured that their daily cups of tea are doing something great for them from the inside.

Want to be healthier and live longer? One way of doing this, scientists say, could be as simple as having a nice cup of tea. In the UK we drink an estimated 100 million cups of tea a day — 36 billion a year — and while fashionable green tea and matcha are growing in popularity, it is black tea that remains the most popular. Researchers have long known that tea drinking is good for us, but the latest study on its benefits published in The Lancet suggests that three cups of tea a day could slow down biological ageing and extend your life.

For the study, scientists at Sichuan University analysed the tea-drinking habits of 7,931 adults living in China and 5,998 people from the UK. Participants were asked for details about their tea preferences — whether they drank black or green tea, and how frequently. Assessments of biomarkers such as blood pressure, cholesterol and body fat were taken to determine their biological age — an estimate of how well they are ageing at a cellular level as opposed to their chronological age. Daily drinkers of black and green tea showed signs of slower biological ageing, and among those consuming three cups a day the benefits were marked. “The exposure-response relationship suggested that consuming around three cups of tea, or 6-8g of tea leaves per day, may offer the most evident anti-ageing benefits,” the researchers wrote. “Moderate tea consumption exhibited the strongest anti-ageing benefits among consistent tea drinkers.”

Although they were not comparing the anti-ageing effects of different types of tea, the researchers did state that they found no “substantial differences” in effects on the tea drinkers in the UK, where black tea is the preferred choice, and those in China, who more commonly drink other varieties. However, people who stopped drinking tea appeared to show an acceleration in biological ageing, the study found.

Alex Ruani, a researcher in nutrition science at University College London, says the findings corroborate what other scientists have discovered. “Black and green tea are by far the richest source of flavan-3-ols, a subgroup of the healthy plant compounds found in many foods, which can lower the chances of diet-related problems such as heart disease, stroke and type 2 diabetes,” Ruani says. “These compounds work in various ways, such as improving blood pressure, blood flow, cholesterol and even blood sugar levels, but they also help to safeguard our cells from ageing-related damage.”

While there is no official recommendation for optimal flavanol intake in the UK, it is set at 400-600mg of flavan-3-ols daily in the US. “We can meet that by having two to four cups of black tea a day, which coincides with the recommendations of the new Lancet study,” Ruani says.

The black tea that is so popular in the UK — Assam, Ceylon, Darjeeling, Earl Grey, Kenyan, and blends such as English breakfast tea — is made from the dried leaf of the plant Camellia sinensis. The distinctive flavour comes from the drying process, which produces higher levels of beneficial plant substances known as thearubigins, which give black tea its colour and which have been linked to health benefits including reduced inflammation and improved digestion.

“Beneficial antioxidants called theaflavins are only found in black tea,” says Dr Michelle Braude, a nutritionist and the author of The Food Effect Diet. “These theaflavins can protect fat cells from damage by free radicals, may support your body’s natural antioxidant production and are protective to the heart and blood vessels.” Studies have shown that theaflavins significantly reduce cholesterol and blood sugar.

Nutritionists estimate that three cups of ordinary black tea provide about the same level of antioxidants as six apples do. “It is also a useful source of the minerals potassium and manganese,” says the specialist dietician Priya Tew, a spokeswoman for the British Dietetic Association. “And there is some evidence that black tea can have positive effects on the gut microbiome, increasing levels of beneficial microbes in the gut.”

The findings reported in The Lancet come hot on the heels of a review of 33 studies published in the journal Nutrition and Food Technology that showed how drinking tea of any type, including regular black tea, can help to regulate stress, anxiety and sleep disturbances — things that can make you age quicker. “We know that stress and anxiety can disrupt sleep, and sleep deprivation increases levels of anxiety and stress, so it’s likely that any intervention that addresses one of these triggers will lead to improvements in all three areas,” the review’s co-author Dr Tim Bond, a research chemist, says. “What makes tea so interesting is that it seems to have an impact on all three.”

Bond and his fellow researchers found no evidence for the belief that because it contains caffeine drinking tea might disrupt sleep. “While tea contains enough caffeine to provide a mental boost, there is evidence that it does not negatively impact sleep in the same way as coffee, which depending on the type and brewing time has about twice the amount of caffeine,” Bond says. One UK study found that adults who drank black tea regularly for six weeks had lower levels of the stress hormone cortisol than those given a solution containing nutrients similar to those in tea. Even inhaling the aroma of black tea lowered the stress levels of participants asked to sit a maths test for a paper published in the Journal of Physiological Anthropology.

Of course, adding sugar to your tea is not good for your health or your waistline, but adding a little cow’s milk provides bone-boosting calcium. If you prefer plant-based milks, they come with a bonus. “It does seem from a paper in The Journal of Nutrition that the effects of beneficial plant compounds can be boosted by 55-70 per cent when you top up your cuppa with soy or rice milk,” Ruani says. “More of the healthful flavan-3-ols make it to the colon, where they’re transformed into beneficial bacteria.”

Ultimately, the nutritionist Eli Brecher says, tea is something we should be drinking plenty of. “The antioxidants and compounds in black tea are similar to those found in fruit and vegetables, and are associated with so many benefits for combating diseases of age, including heart disease, high blood pressure, high cholesterol and even obesity,” Brecher says. “We should all put the kettle on more often.”

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