Coffee and Tea Linked to Lower Risk of Stroke and Dementia in 11-Year Study – Gizmodo

A waitress pours tea at a cafe.

Photo: Christopher Furlong (Getty Images)

New research out this week suggests that a tea or coffee habit in your later years could help your brain stay in tip-top shape. The study found that healthy older adults in the UK who regularly drank coffee and/or tea were less likely to develop stroke and dementia over an 11-year period than those who drank neither. Though these findings can’t confirm a cause-and-effect link, they are the latest to indicate that these brewed drinks have some health benefits.

Dementia is a progressive and currently incurable loss of cognitive function that becomes more common as we age. It’s poised to be an ever larger health problem in the future, thanks to people living longer. Strokes, which happen when blood flow in the brain is interrupted, account for about 10% of deaths globally every year. Stroke survivors can also be left with many lingering complications, including dementia. So any possible way to reduce the odds of developing these debilitating diseases would be a boon.

While tea has long been considered a healthy beverage, coffee has been more controversial. Lately, however, it’s become clear that coffee isn’t the devil’s drink and that it may even do some good. Recent studies have suggested that regular coffee consumption is linked to a lower risk of cardiovascular disease, certain cancers, and early death in general. But according to the authors of this new study, published Tuesday in PLOS Medicine, there remains a debate over the benefits, if any, that coffee and tea may have in reducing the risk of stroke and dementia.

The researchers, based in China, looked at data from the UK Biobank, a long-running research project that’s been tracking the health of volunteers in the United Kingdom since the mid-2000s. They specifically focused on 365,682 people between the ages of 50 and 74 with no pre-existing stroke or dementia, who had been followed for a median length of 11.4 years, up till 2020. At the start of the study, the participants were asked how often they drank coffee and/or tea.

Overall, there were 5,079 cases of dementia and 10,053 cases of stroke diagnosed during that time, based on hospital records. And across different groups of reported coffee and tea consumption, those who said they drank either two to three cups of coffee a day, three to five cups of tea a day, or a combination of four to six cups of coffee and tea were the least likely to develop either dementia or stroke. Compared to non-consumers, these individuals had a 28% lower risk of dementia and a 32% lower risk of stroke.

Other studies have found a relationship between tea and coffee consumption and lower stroke/dementia risk. But the authors say theirs is one of the first to account for those who regularly drink both tea and coffee, as opposed to one or the other.

“Our findings suggested that moderate consumption of coffee and tea separately or in combination were associated with lower risk of stroke and dementia,” they wrote.

These sorts of observational studies can’t be used to prove causation, the authors caution. They also note that UK Biobank volunteers tend to be in good shape, which could mean the findings would be less applicable to the general population. The study only looked at a snapshot of people’s diets, meaning we can’t be sure that people in the study remained coffee/tea drinkers or abstainers the entire time. But the findings do add to the growing pile of research showing a positive effect on stroke risk from these drinks.

Other studies have suggested that coffee and tea can improve the overall functioning of our blood vessels, which may explain why these drinks seemed to lower risk of ischemic strokes specifically, rather than hemorrhagic strokes. Ischemic strokes are caused by blood clot blockages, while hemorrhagic strokes are the result of vessels breaking and bleeding out into the brain (about 80% of strokes are ischemic). Still, there might be other protective factors that should be investigated in future studies, such as the antioxidant benefits of caffeine, the authors say. More research is also needed to know whether it’s really possible to prevent cases of stroke and dementia by telling people to start drinking coffee and tea if they aren’t already regular drinkers.

“Our findings support an association between moderate coffee and tea consumption and risk of stroke and dementia. However, whether the provision of such information can improve stroke and dementia outcomes remains to be determined,” the study authors wrote.

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