Drinking three or more cups of tea or coffee per day lowers the risk of developing type 2 diabetes by about forty percent. This has been stated in an article by epidemiologists from the University Medical Center (UMC) Utrecht in the journal Diabetologia published in December 2009. They analyzed the lifestyle of almost 40,000 people for a period of ten years.
The protective effect of coffee and tea has emerged from an analysis of lifestyle and nutrition that was estimated through questionnaires. The researchers followed the people for ten years after examining their lifestyle. After ten years, slightly more than 900 of the 40,000 people studied had developed type 2 diabetes. The study shows that people who drink three cups of coffee or tea a day have less risk of developing type 2 diabetes than those people who drink none or only one cup a day. They have approximately forty percent less risk of developing the disease. However, there is no point in drinking many more than three cups a day as this does not increase the protective effect. The epidemiologists used data from the European Prospective Investigation into Cancer (EPIC-NL) population studies. Taken over a period of ten years, the participants in these studies showed a 2.4 percent risk of developing type 2 diabetes.
The first author of the article is epidemiologist Susan van Dieren. “It has been previously shown that coffee has a protective function on type 2 diabetes, but this was not at all clear regarding tea. In our study we saw a lowered risk of type 2 diabetes when people drink from three cups upwards of either coffee or tea a day.
Incidentally, coffee drinkers turned out to have very different lifestyles from tea drinkers. Tea drinkers are associated with a high level of education, do more physical activity, drink less alcohol, smoke less and are less overweight. But the exact opposite is true for people who drink a lot of coffee. In general, they live far more unhealthy lives.
It is not clear why exactly coffee and tea protect against diabetes. The effect does not appear to be due to the effects of caffeine, salts or blood pressure. However, coffee and tea do contain antioxidants which suggests that they may be able to inhibit the development of diabetes. But this connection is controversial.
In the Netherlands, about 740,000 people suffer from diabetes and 90 percent of these people have type 2 diabetes.
Some risk factors that are known to be associated with the development of type 2 diabetes are: overweight, high blood pressure and a high cholesterol level. When these risk factors are accompanied by a lifestyle that includes an unhealthy diet and too little physical exercise, the risk of developing the disease is even higher.
Epidemiologists at UMC Utrecht conducted the research together with the National Institute for Public Health and the Environment (RIVM). The article has been published online.