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Is there a link between coffee and tea and a lower risk of stroke and dementia?

coffee and tea drinking
A new study investigates the relationship between coffee and tea consumption and stroke and dementia.
  • Coffee and tea are widely consumed beverages across the world, and stroke and dementia affect millions of people.
  • A recent study looked at the link between coffee and tea intake and stroke, dementia, and post-stroke dementia.
  • The investigators discovered a shaky link between the use of these beverages and the risk of dementia and stroke.

Researchers find in a recent study that drinking coffee, tea, or both reduces the risk of dementia or stroke.

However, the study, which was published in the journal PLOS Medicine, did not show that coffee and tea reduce risk directly. To determine if the link is causative, scientists will need to do further study.

Although previous studies have looked at the links between coffee, tea, stroke, and dementia, the authors of the current study stress that “significant dispute” still exists.

“Little is known regarding the relationship between the mix of tea and coffee and the risk of stroke, dementia, and poststroke dementia,” they add. The new study contributes to closing this gap.

Stroke and dementia

According to the World Health Organization (WHO), dementia affects over 55 million people worldwide and is the seventh leading cause of death.

Dementia is a term used to describe a group of symptoms that are all characterized by increasing cognitive deterioration. The elderly are the people who are most affected.

Alzheimer’s disease is the most prevalent kind of dementia, according to the Centers for Disease Control and Prevention (CDC).

Stroke is another top cause of mortality, according to the CDC. Every year, more than 795,000 people in the United States have a stroke.

When the blood supply to the brain is cut off or a blood artery in the brain breaks, a stroke ensues. This results in the death or injury of brain tissue.

Around 60% of the risk and preventative variables for stroke and dementia are the same. Dementia is also a risk factor for people who have had a stroke. One-third of dementia cases may be avoided, according to researchers, if people were prevented from having a stroke.

Given the high frequency of dementia and stroke, experts are eager to learn more about the variables that increase risk.

Consumption of tea and coffee is one such lifestyle component. Because many people drink tea or coffee on a daily basis across the world, even a minor potential effect might have a large population-level impact.

The authors of the current study point out that some studies has linked consuming more tea or coffee to a lower risk of dementia. However, there has been little study done to see if a mix of tea and coffee has the same impact.

Furthermore, the authors of the study note out that research on whether coffee and tea intake is linked to a lower risk of stroke has produced mixed results.

As a result, the researchers investigated the link between tea, coffee, and a mix of tea and coffee intake with the risk of dementia and stroke.

Over 350,000 people took part

The researchers used information from the UK Biobank, a database that has precise medical and genetic information on 500,000 people in the UK.

They used information from 365,682 individuals who were recruited between 2006 and 2010. Until 2020, the researchers followed their medical records.

When people signed up for the research, they self-reported how much tea or coffee they drank on a daily basis. The researchers next looked at how many people had a stroke or developed dementia during the course of the study.

They also took into account a number of other characteristics that might increase the risk of dementia or stroke. Sex, age, ethnicity, educational attainment, income, BMI, smoking status, alcohol use, physical activity, eating patterns, specific biomarkers, and a history of cancer, diabetes, cardiovascular disease, and hypertension were among the factors considered.

Reduced danger

Over the course of the trial, 5,079 people got dementia and 10,053 suffered a stroke.

The researchers matched this information to the amount of tea, coffee, or a mix of tea and coffee drank by subjects.

People who consumed 2–3 cups of coffee, 3–5 cups of tea, or 4–6 cups of tea and coffee per day had the lowest risk of dementia and stroke, according to the study.

When compared to those who did not consume tea or coffee, those who drank 2–3 cups of tea and 2–3 cups of coffee per day were 32 percent less likely to have a stroke and 28 percent less likely to acquire dementia.

Association, not causation

Importantly, while the study discovered a link between tea and coffee intake and a lower risk of dementia or stroke, this does not suggest that tea and coffee consumption caused the lower risk.

Professor Paul Matthews, O.B.E., M.D., Ph.D., center director at the U.K. Dementia Research Institute at Imperial College London and member of the U.K. Biobank steering group, talked with Medical News Today. Professor Matthews was not a participant in the research.

Other factors not taken into consideration, he noted, might influence the lower risk of dementia and stroke among tea and coffee consumers.

“This study found a weak link between coffee and tea intake and a reduced risk of stroke or dementia in old age.” The findings are intriguing since tea and coffee are high in polyphenols, which may aid in the prevention of age-related disorders.”

“However, the study cannot be interpreted as even suggesting that tea or coffee actually have a beneficial, protective effect.”

– Prof. Paul Matthews

Unknown unknowns

Professor Matthews stated, “It is based on comparisons of persons in [the] U.K. Biobank who consume tea and coffee with those who do not.” “There are several differences between these groups. Tea and coffee users, for example, are more likely to have a university diploma and a better salary.”

“While the authors have used statistical approaches to address some of the documented discrepancies, they are unable to account for those that they have not detected, or the ‘unknown unknowns.'”

“While the findings is interesting, it should not lead to changes in coffee or tea intake for health reasons,” Professor Matthews recommended.

This viewpoint was shared by Patrick Kehoe, Ph.D., professor of translational dementia research at Bristol Medical School in the United Kingdom, who was not engaged in the study.

“There has been earlier evidence of how coffee intake was connected with increased lung cancer risk,” Professor Kehoe told MNT.

“However, what emerged […] as a result of […] the timing of some of these research was that smoking and tobacco may have been a hidden component in those instances where people used to smoke with their social coffee, and in public locations where smoking is now more outlawed.”

“In this situation, things have progressed socially and [in terms of health], and there are now parts of tea [and] coffee use that might [explain] why there are beneficial effects.”

“For example, higher levels of socializing, which is considered to guard against dementia, [and] exercise, which is good for the heart and mind, are linked to getting out to meet people, and might all be contextual factors driving these figures.” “This might involve less smoking today as well, which has a mixed past in terms of dementia risk but would surely not have been beneficial in terms of cardiovascular hazards and stroke risk,” Professor Kehoe added.