According to a systematic review and meta-analysis of 19 cohort studies including more than 1 million adults from eight different countries, moderate use of black, green, or oolong tea is linked to a decreased risk of developing type2 diabetes. Findings were presented at the European Association for the Study of Diabetes (EASD) Annual Meeting this year in Stockholm, Sweden. They show that drinking at least four cups of tea per day is associated with a 17% decreased risk of type 2 diabetes (T2D) over an average of 10 years (19-23 September).
Our findings are exciting because they suggest that people can potentially reduce their risk of developing type 2 diabetes by doing something as simple as drinking four cups of tea each day, according to lead author Xiaying Li of Wuhan University of Science and Technology in China.
It has long been recognized that drinking tea often may be healthful due to the multiple antioxidants, anti-inflammatory, and anticarcinogenic components it contains, but the relationship between tea consumption and the risk of T2D has been less clear. The published cohort studies and meta-analyses have produced contradictory findings.
Researchers conducted a cohort study and dose-response meta-analysis to better understand the relationship between tea consumption and the risk of developing T2DM in the future. The researchers started by examining 5,199 participants from the China Health and Nutrition Survey (CHNS), who were enlisted in 1997 and followed up with by 2009 and had no prior history of T2D. Of these, 2583 males and 2616 women made up the sample, with an average age of 42. The CHNS is a multicentre prospective study that looks at residents’ physical and mental health as well as their socioeconomic circumstances in nine different provinces.
To learn more about the association between tea drinking and the risk of T2DM in the future, researchers carried out a cohort study and a dose-response meta-analysis. Starting with 5,199 individuals who had no prior history of T2D and were recruited for the China Health and Nutrition Survey (CHNS) in 1997 and followed up within 2009, the researchers looked at them. The sample, which consisted of 2616 women and 2583 men, had an average age of 42. The CHNS is a multicenter prospective study that examines inhabitants’ socioeconomic situations, physical and mental health, and nine distinct provinces.
Then, up until September 2021, the researchers carried out a systematic review of all cohort studies exploring the connection between tea drinking and the risk of T2D in individuals (aged 18 or older). 19 cohort studies totaling 1,076,311 people from eight different countries made up the dose-response meta-analysis. As well as gender (male and female), research region (Europe and America, or Asia), and tea drinking habits (less than one cup per day, one to three cups per day, and four or more cups per day), they looked into the potential effects on the risk of T2D.
The meta-analysis found a linear association between tea consumption and T2D risk, with each daily cup of tea reducing risk by roughly 1%. Adults who drank between one and three cups of tea daily had a 4% lower risk of T2D than those who didn’t, while those who drank at least four cups daily had a 17% lower risk.
No matter the sort of tea people drank, whether they identified as male or female, or where they lived, connections were still there, suggesting that the amount of tea consumed may be more significant than any other element in explaining the associations. According to our findings, drinking tea can help reduce the risk of type 2 diabetes, but only in big doses (at least 4 cups per day), adds Li. To determine the specific dosage and processes behind these discoveries, more study is necessary.
She continues, “It is plausible that specific tea constituents, like polyphenols, may lower blood glucose levels, but it may need a significant quantity of these bioactive substances to be effective. It may also be the reason why, despite looking at higher tea intake, we did not discover a link between type 2 diabetes and tea drinking in our cohort analysis.
Oolong tea, a classic Chinese brew, is also made from the same plant that yields green and black teas. Oolong tea is partially oxidized while black tea is allowed to totally oxidize; this difference is due to the processing procedure. Green tea is not permitted to significantly oxidise. Despite the significant results, the authors note that because the study was observational, they cannot prove with certainty that drinking tea lowers the incidence of T2D, but rather that it probably does.
The study’s authors also note several caveats, including the fact that they relied on estimates of tea consumption that were made subjectively and that they cannot completely rule out the possibility that residual confounding from other lifestyle and physiological factors may have affected the results.