A systematic review and meta-analysis of 19 cohort studies including more than 1 million adults from eight countries found that moderate consumption of black, green, or oolong tea is associated with a lower risk of infection. The development of type 2 diabetes.
The results, presented at this year’s European Association for the Study of Diabetes (EASD) annual meeting in Stockholm, Sweden (September 19-23), indicate that drinking at least four cups of tea per day is associated with a 17% lower risk. of T2D over a period of 10 years on average.
Our findings are exciting because they suggest that people can do something as simple as drinking four cups of tea a day to reduce their likelihood of developing type 2 diabetes.”
Xiaying Li, lead author, Wuhan University of Science and Technology, China
While it has long been known that drinking tea regularly may be beneficial to health due to the various antioxidants and anti-inflammatory and anti-cancer compounds that tea contains, the relationship between tea drinking and the risk of T2D is less clear. To date, published cohort studies and meta-analyses have reported inconsistent results.
To address this uncertainty, the researchers conducted a cohort study and dose-response meta-analysis to better determine the relationship between tea consumption and future T2DM risk.
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 until 2009. Study looks at economics and issues Social and health of the population of nine provinces.
Initially, participants filled out a food and drink 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 by 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 as compared to non-drinkers. The results did not change significantly when analyzed by age and gender, or when excluding participants who developed diabetes during the first three years of follow-up.
In the next step of the study, the researchers performed a systematic review of all cohort studies looking at tea drinking and the risk of T2D in adults (aged 18 years or older) through September 2021. Overall, 19 cohort studies included 1,076,311 Participants from eight countries 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 drinking (less than 1 cup per day, 1-3 cups per day, 4 or more cups per day), gender (male and female). ), and study location (Europe, America, or Asia), on the risk of T2D.
Overall, the meta-analysis found a linear association between tea drinking and T2D risk, with each daily cup of tea reducing the risk of T2D by about 1%.
Compared with adults who did not drink tea, those who drank 1-3 cups per day reduced their risk of T2D by 4%, while those who drank at least 4 cups per day reduced their risk by 17%.
Associations were observed regardless of what type of tea participants drank, whether they were male or female, or where they lived, suggesting that it was the amount of tea consumed, and not any other factor, that played a major role.
“While more research is needed to determine the exact dosage and mechanisms underlying 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 per day),” tell me.
She adds: “It is possible that certain components in tea, such as polyphenols, may reduce blood glucose levels, but enough of these bioactive compounds may be needed to be effective. It may also explain why there is no association between drinking tea and diabetes. type 2 in our cohort study, because we did not look at increased tea consumption.”
Oolong tea is a traditional Chinese tea made from the same plant used to make green and black tea. The difference lies in how the tea is processed; Green tea is not allowed to oxidize much, 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 they do suggest that it likely contributes to it.
The researchers point to several caveats, including that they relied on subjective assessments of the amounts of tea consumed and cannot rule out the possibility that residual confounding due to lifestyle and other physiological factors may have affected the results.