Drinking coffee or tea may be associated with a lower risk of stroke and dementia, according to the largest study of its kind.
Stroke causes 10% of deaths globally, while dementia is one of the world’s biggest health challenges – 130 million are expected to live with it by 2050.
In the research, 365,000 people aged between 50 and 74 were followed for more than a decade. At the outset, participants involved in the UK Biobank survey reported for themselves how much coffee and tea they drank. During the research period, 5,079 of them developed dementia and 10,053 had at least one stroke.
Researchers found that people who drank two to three cups of coffee or three to five cups of tea a day, or a combination of four to six cups of coffee and tea, had the lowest risk of stroke or dementia.
Those who drank two to three cups of coffee and two to three cups of tea daily had a 32% lower risk of stroke. These people had a 28% lower risk of dementia compared to those who did not drink tea or coffee.
The research, conducted by Yuan Zhang and colleagues from Tianjin Medical University, China, suggests that drinking coffee alone or in combination with tea is also associated with lower risk of dementia after stroke.
The authors wrote in the journal Plos Medicine, saying, “Our results suggested that moderate consumption of coffee and tea separately or in combination was associated with lower risk of stroke and dementia.”
However, the researchers warned that the UK biobank reflects a relatively healthy sample in relation to the general population, which could limit the possibility of generalizing these contexts. While it is possible that coffee and tea may be protective against stroke, dementia and dementia after stroke, the researchers say causality cannot be inferred from the associations.
Prof Tara Spiers-Jones, Program Director at the UK Dementia Research Institute and Deputy Director of the Center for Discovery Brain Sciences at the University of Edinburgh, who was not involved in the research, described it as “interesting” and “robustly conducted”, but stressed that more work is being done to fully understand the potential biological links between tea and coffee and the risk of stroke and dementia.
Professor Kevin McConway, an emeritus professor of applied statistics at Open University, who is also not involved in the study, said it showed that correlations between stroke and dementia risk did not increase or decrease uniformly with tea and coffee drinking.
“Instead, what generally happened was that the risk of stroke or dementia was lower in people who drank reasonably small amounts of coffee or tea compared to those who drank nothing at all, but that the risk after a certain consumption began to increase. again, until it became higher than the risk of people not drinking anything.
“When coffee consumption rose up to seven or eight cups a day, the risk of stroke was greater than for people who did not drink coffee, and a whole lot higher than for those who drank two or three cups a day.”
Dr. Rosa Sancho, head of research at Alzheimer’s Research UK, said: “For most of us, our risk of dementia depends on the complex interplay between our age, genetics and lifestyle. Understanding which aspects of our lifestyle have the greatest impact on our brain health is the key to enabling people to make informed decisions about their lives. “