Drinking tea linked to reduced risk of type 2 diabetes

New research presented at the 2022 European Association for the Study of Diabetes (EASD) Annual Meeting has analyzed data from nearly 20 studies encompassing one million adults and found a link between drinking tea and a reduced risk of type 2 diabetes. But it all depends on how much tea you drink.

Over the years plenty of research has accumulated citing the potential health benefits of tea, from improving cardiovascular health to reducing the risk of cancer. This new research set out to try and clarify one particularly uncertain topic – the relationship between tea drinking and the risk of type 2 diabetes.

A two-part review of pre-existing research was conducted. The first stage was a cohort study looking at data from more than 5,000 adults followed who were for 12 years. Around half the cohort reported drinking tea, but by the end of the follow-up period there were similar rates of type 2 diabetes in both tea drinkers and non-drinkers.

So the next part of the research set out to explore whether there was a dose-response aspect to tea drinking and diabetes. Looking at 19 studies with detailed data on tea-drinking frequency the researchers discovered the risk of type 2 diabetes declined relative to the amount of tea a person was regularly drinking.

While people who drank one to three cups of tea per day were 4% less likely to develop diabetes compared to non-drinkers, those consuming at least four cups a day reduced their risk of diabetes by 17%.

Lead author on the research Xiaying Li said the diabetes risk reduction was observed even after accounting for gender, geographical location and type of tea consumed. Li said this suggests something in tea may be specifically reducing a person’s risk of diabetes.

“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,” speculated Li. “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.”

Of course, these findings come with plenty of caveats. The research is not yet peer-reviewed or published in a journal, and it’s based on self-reported dietary questionnaires, which can’t track in detail long-term food habits. Plus, the data offers no insight into the varieties of ways people drink tea. For example, does drinking tea with or without milk influence diabetes risk?

Speaking to The Guardian, Li speculated milk in tea could enhance the health benefits of tea. However, a 2002 study found milk can actually decrease the insulin-enhancing activity of tea, suggesting the dairy product may counteract the diabetes-preventing benefits of tea.

“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)”, concluded Li.

Source: Diabetologia