Tea use may reduce the chance of developing type 2 diabetes

Tea use may reduce the chance of developing type 2 diabetes, according to a study.

The moderate use of black, green, or oolong tea is linked to a lower risk of developing type 2 diabetes, according to a systematic review and meta-analysis of 19 cohort studies involving more than 1 million adults from eight different countries.

According to a systematic review and meta-analysis of 19 cohort studies encompassing more than 1 million adults from eight different nations and more than 1 million black, green, or oolong tea drinkers, there is a link between moderate tea consumption and a reduced risk of developing type 2 diabetes. According to studies presented at this year’s European Association for the Study of Diabetes (EASD) Annual Meeting in Stockholm, Sweden, 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 ten years (19-23 September).

“Our results are exciting because they show that people can do something as straightforward as drink four cups of tea a day to potentially lessen their risk of developing type 2 diabetes,” says principal 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 dose-response meta-analysis and a cohort study to better understand the relationship between tea consumption and the risk of developing type 2 diabetes in the future. First, they looked at 5,199 participants from the China Health and Nutrition Survey (CHNS) who were enlisted in 1997 and followed up within 2009 and had no prior history of T2D. These participants were 2583 males and 2616 women, with an average age of 42. The CHNS is a multicenter prospective study that looks at the socioeconomic circumstances and the physical and mental health of people in nine provinces.

In the beginning, participants filled out a questionnaire about their eating and drinking habits and provided information on their lifestyle habits, such as how often they exercised, smoked, and drank. Overall, 2,379 (46%) participants reported drinking tea, and 522 (10%) participants had T2D by the trial’s end. After adjusting for factors including age, sex, and physical inactivity that are known to be associated with a greater risk of T2D, researchers found that tea drinkers and non-drinkers had comparable odds of developing type 2 diabetes (T2D). Additionally, the results were not significantly changed when individuals who developed diabetes within the first three years of follow-up were excluded or the results were divided by age and sex.

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.

“It is likely that some components of tea, such as polyphenols, may lower blood glucose levels, but it may require a large amount of these bioactive compounds to be effective,” she explains. It might also be the reason why, despite examining higher tea use, our cohort analysis did not find any evidence of a connection between type 2 diabetes and tea consumption.

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.