A new study published in PLOS Medicine suggests that drinking moderate amounts of tea or coffee daily may lower your chances of having a stroke or developing dementia.
The study looked at the tea and coffee drinking habits of 365,682 adults between the ages of 50 and 74. Each participant answered questions on how much tea or coffee they consumed each day, and then the research team tracked each participant’s health for over 10 years.
At the end of the study, there were 5,079 cases of dementia and 10,053 cases of stroke, according to hospital records. Looking at the data, it became evident that those who drank either two to three cups of coffee, three to five cups of tea, or a combination of four to six cups of coffee and tea, were the least likely to have developed dementia or to have experienced a stroke.
Compared to those who do not drink either beverage, coffee and tea drinkers had a 28 percent lower risk of dementia and a 32 percent lower risk of stroke.
“Our findings suggested that moderate consumption of coffee and tea separately or in combination were associated with lower risk of stroke and dementia,” the authors write. However, the researchers also acknowledge that their work does not establish a causal link.
Lee H. Schwamm, chair of the American Stroke Association Advisory Committee and chair in Vascular Neurology at Massachusetts General Hospital told CNN that they “cannot impute causality, and say ‘drinking more coffee or tea is good for your brain… [they] can only say… people who reported moderate coffee/tea drinking were less likely to have a stroke or dementia occur in the 10 years of follow-up.”
Other limitations of the study that the team acknowledges are that they only took self-reported coffee and tea consumption data at the commencement of the study, so if people’s drinking habits were changed at all during the study period, this data was left out.
Also, people may have different definitions of a “cup” of coffee and may also misremember how much they consumed. The participants in the group were also not very diverse, being mostly white and from “less socioeconomically deprived areas” of the United Kingdom.
Also, it’s important to note that the links between coffee and tea drinking and the reduced risk of stroke and dementia are limited to moderate drinking. “After a certain level of consumption, the risk started to increase again until it became higher than the risk to people who drank none,” Kevin McConway, a statistician at the Open University in England, told The Guardian. “Once the coffee consumption got to seven or eight cups a day, the stroke risk was greater than for people who drank no coffee, and quite a lot higher than for those who drank two to three cups a day.”