Now might be a good time to brew another cup of tea.
Researchers studying the impact of tea found that drinking four or more cups of black, green or oolong tea every day was linked to a 17% lower risk of developing type 2 diabetes over the course of a decade.
“Our results are exciting because they suggest that people can do something as simple as drinking four cups of tea a day to potentially lessen their risk of developing type 2 diabetes,” said lead study author Xiaying Li, from Wuhan University of Science and Technology in China.
Li's team did a meta-analysis of 19 studies that included more than 1 million adults from eight countries.
First, they studied nearly 5,200 adults with no history of type 2 diabetes and an average age of 42 who were recruited in 1997 and followed until 2009 in the China Health and Nutrition Survey.
Study participants answered food and drink frequency questionnaires and provided information on lifestyle factors such as regular exercise, smoking and alcohol consumption. About 46% of participants reported drinking tea. About 10% (522 people) developed type 2 diabetes by the end of the study.
The investigators adjusted for known links to diabetes, finding that in this study results were similar for tea drinkers and those who didn't drink tea.
The research team then did a systematic review of all studies investigating tea drinking and the risk of type 2 diabetes in adults up to September 2021.
The team looked at three types of tea and the frequency of the cups, including less than one cup per day, one to three cups per day, and four or more cups per day. They also considered gender and whether participants were in Europe, the United States or Asia.
This time, the researchers found that with each cup consumed, tea drinkers reduced their risk of type 2 diabetes by 1%. Compared to people who didn't drink tea, adults who drank one to three cups daily reduced their risk by 4%. Those who consumed at least four cups a day reduce their risk by 17%.
This happened regardless of location, gender or type of tea.
The findings will be presented this week at the European Association for the Study of Diabetes (EASD) annual meeting, in Stockholm. Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
“While more research needs to be done to determine the exact dosage and mechanisms behind these observations, our findings suggest that drinking tea is beneficial in reducing the risk of type 2 diabetes, but only at high doses (at least 4 cups a day),” Li said in a meeting news release.
“It is possible that particular components in tea, such as polyphenols, may reduce blood glucose levels, but a sufficient amount of these bioactive compounds may be needed to be effective. It may also explain why we did not find an association between tea drinking and type 2 diabetes in our cohort study, because we did not look at higher tea consumption,” Li added.
Study limitations include relying on self-reports of amounts of tea consumed. It is also possible that other lifestyle or physiological factors affected the results.
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SOURCE: European Association for the Study of Diabetes, news release, Sept. 17, 2022