According to a systematic review and meta-analysis of 19 cohort studies, moderate use of black, green, or oolong tea is associated with a lower risk of acquiring type 2 diabetes. The study involved over one million adults from eight different countries. The findings, presented at this year’s European Association for the Study of Diabetes (EASD) Annual Meeting in Stockholm, Sweden, indicate that having at least four cups of tea per day is linked to a 17 per cent lower risk of type 2 diabetes over an average of ten years.
The main author of the study, Xiaying Li of Wuhan University of Science and Technology in China, said, “Our results are intriguing because they imply that people can do something as easy as drinking four cups of tea a day to potentially lower their chance of acquiring type 2 diabetes.” Because of the numerous antioxidant, anti-inflammatory, and anti-carcinogenic components present in the beverage, it has long been known that drinking tea frequently may be healthy, but the link between tea consumption and type 2 diabetes has been less obvious.
The meta-analysis discovered a linear relationship between tea consumption and type 2 diabetes risk, with each daily cup of tea lowering risk by about one per cent. Adults who drank 1-3 cups of tea per day had a four per cent lower risk of the disease than those who didn’t, while those who drank at least four cups per day had a 17 per cent lower risk.
Li said, “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.”
The same plant that is used to produce green and black teas is also used to manufacture oolong tea, a traditional Chinese beverage. The processing method makes a difference; oolong tea is partially oxidised whereas black tea is permitted to fully oxidise. Green tea is not allowed to oxidise substantially.
