Summary: Drinking four or more cups of black, green or oolong tea a day was associated with a 17% lower risk of developing type 2 diabetes.
Font: diabetology
A systematic review and meta-analysis of 19 cohort studies involving more than 1 million adults from eight countries reveals that moderate consumption of black, green or oolong tea is associated with a lower risk of developing type 2 diabetes.
The findings, which were presented at this year’s European Association for the Study of Diabetes (EASD) annual meeting in Stockholm, Sweden (September 19-23), suggest that drinking at least four cups of tea a day is associated with a 17% lower risk of T2D over an average 10-year period.
“Our results are exciting because they suggest that people can do something as simple as drinking four cups of tea a day to potentially reduce the risk of developing type 2 diabetes,” says senior author Xiaying Li of the Wuhan University of Science and Technology. in China.
While it has long been known that drinking tea regularly can be beneficial to health due to the various antioxidant, anti-inflammatory, and anti-cancer compounds it contains, the relationship between tea consumption and T2D risk has been less clear. To date, published meta-analyses and cohort studies have reported inconsistent findings.
To address this uncertainty, the researchers conducted a cohort study and dose-response meta-analysis to better define the relationship between tea consumption and future risk of T2DM.
First, they studied 5,199 adults (2,583 men, 2,616 women) with no history of T2D (mean age 42) from the China Health and Nutrition Survey (CHNS), who were recruited in 1997 and followed up to 2009. The CHNS is a prospective multicenter study that analyzes the economy, sociological problems and the health of residents of nine provinces.
Initially, the participants completed a food and beverage frequency questionnaire and provided information on lifestyle factors such as regular exercise, smoking and alcohol consumption. Overall, 2,379 (46%) participants reported drinking tea, and at the end of the study, 522 (10%) participants had developed T2D.
After adjusting for factors known to be associated with an increased risk of T2D, such as age, gender and physical inactivity, the researchers found that tea drinkers had a similar risk of developing T2D compared to non-drinkers . And the results did not change significantly when analyzed by age and sex, or when participants who developed diabetes during the first 3 years of follow-up were excluded.
In the next step of the study, the researchers conducted a systematic review of all cohort studies investigating tea consumption and T2D risk in adults (aged 18 years and older) up to September 2021. In total, 19 studies from cohorts with 1,076,311 participants from eight countries [1] were included in the dose-response meta-analysis.
They explored the potential impact of different types of tea (green tea, oolong tea, and black tea), frequency of tea consumption (less than 1 cup/day, 1-3 cups/day, and 4 or more cups/day), gender (male and female), and the location of the study (Europe and America, or Asia), on the risk of T2D.
Overall, the meta-analysis found a linear association between tea consumption and type 2 diabetes risk, with each cup of tea consumed per day reducing the risk of developing type 2 diabetes by around 1%.
Compared to adults who did not drink tea, those who drank 1 to 3 cups a day reduced their T2D risk by 4%, while those who drank at least 4 cups a day reduced their risk by 17%.
The associations were seen regardless of the type of tea the participants drank, whether they were male or female, or where they lived, suggesting that it may be the amount of tea consumed, rather than any other factor, that plays a role.
“While more research is needed 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 in high doses (at least 4 cups a day). )”. Li says.
She adds: “It is possible that certain components of tea, such as polyphenols, can lower blood glucose levels, but sufficient amounts of these bioactive compounds may be needed for them to be effective. It may also explain why we didn’t find an association between tea consumption and type 2 diabetes in our cohort study, because we didn’t see higher tea consumption.”
Oolong tea is a traditional Chinese tea that is made from the same plant that is used to make green and black teas. The difference is how the tea is processed: green tea is not allowed to oxidize heavily, black tea is allowed to oxidize until it turns black, and oolong tea is partially oxidized.
Despite the important findings, the authors note that the study is observational and cannot prove that drinking tea reduces the risk of T2D, but suggests that it likely contributes.
And the researchers note several caveats, including that they were based on subjective assessments of amounts of tea consumed and cannot rule out the possibility that residual confounding by other physiological and lifestyle factors may have affected the results.
About this diabetes research news
Author: Judy Naylor
Font: diabetology
Contact: Judy Naylor – Diabetology
Image: The image is in the public domain.
original research: The findings will be presented at the annual meeting of the European Association for the Study of Diabetes.
