Participants who stopped drinking tea appeared to show an increase in ageing.
Drinking three cups of tea a day could extend your life, according to a study published in The Lancet Regional Health - Western Pacific. Researchers from Sichuan University in Chengdu, China, surveyed 5,998 British people aged 37 to 73 in addition to 7,931 people in China between the ages 30 and 79 regarding their tea-drinking habits. They found that consistent tea drinkers showed signs of slower ageing. Most of those people were male, ate a healthier diet, consumed alcohol and were less likely to experience anxiety and insomnia.
For the study, participants were asked whether they drank black, green, yellow or traditional Chinese oolong tea, as well as how many cups of it they drank daily. Researchers then calculated each participant's biological age by compiling their body fat percentage, cholesterol and blood pressure.
"The relationship suggested that consuming around three cups of tea, or 6 to 8 grams of tea leaves per day, may offer the most evident anti-ageing benefits," the authors wrote, as per Newsweek. "Moderate tea consumption exhibited the strongest anti-ageing benefits among consistent tea drinkers," they concluded.
However, the researchers noted that the study was merely "observational," so they couldn't prove if drinking tea slowed biological ageing. Participants who stopped drinking tea appeared to show an increase in ageing, the study found.
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Authors believe that polyphenols, a bioactive substance in tea "modulate gut bacteria," might play a role in regulating the immune system, metabolism and cognitive function. They also noted that flavonoids, "a kind of polyphenol that is rich in tea", can extend life expectancy in worms, fleas and mice.
"Studies are accumulating that tea consumption may protect against age-related diseases, such as cardiovascular diseases, diabetes mellitus, dementia and some types of cancer, and that tea consumption was associated with lower mortality risk," the study authors said. Given the evidence, it was "plausible" that tea consumption could delay the biological ageing process in humans, they added.
Notably, researchers did not study whether one specific type of tea was better with anti-ageing than another, although they found no "substantial differences" between the tea drinkers in China versus the UK. The temperature of the tea also made no difference. The study authors noted they didn't ask people the size of the teacups they consumed.