Coffee contains caffeine and is a rich source of antioxidants and other bioactive compounds. Tea containing caffeine, catechin polyphenols, and flavonoids has also been reported to play neuroprotective roles, such as antioxidative stress, anti-inflammation, inhibition of amyloid-beta aggregation, and an antiapoptotic effect.
While previous studies have revealed the involvement of coffee and tea in the development of stroke and dementia, little is known about the association between the combination of coffee and tea and the risk of stroke, dementia, and post-stroke dementia.
Researchers from Tianjin Medical University in Tianjin aimed to investigate the associations of coffee and tea separately and in combination with the risk of developing stroke and dementia.
They studied healthy individuals aged 50-74 from the UK Biobank. Participants were recruited between 2006 and 2010 and followed until 2020. At the outset participants self-reported their coffee and tea intake. Over the study period, 5,079 participants developed dementia and 10,053 experienced at least one stroke.
People who drank 2-3 cups of coffee or 3-5 cups of tea per day, or a combination of 4–6 cups of coffee and tea had the lowest incidence of stroke or dementia. Individuals who drank 2-3 cups of coffee and 2-3 cups of tea daily had a 32% lower risk of stroke and a 28% lower risk of dementia compared with those who drank neither coffee nor tea. Intake of coffee alone or in combination with tea was also associated with lower risk of post-stroke dementia.
Strokes are life-threatening events which cause 10 percent of deaths globally. Dementia is a general term for symptoms related to decline in brain function and is a global health concern with a high economic and social burden. Post-stroke dementia is a condition where symptoms of dementia occur after a stroke.
The UK Biobank reflects a relatively healthy sample relative to the general population which could restrict the ability to generalize these associations. Also, relatively few people developed dementia or stroke which can make it difficult to extrapolate rates accurately to larger populations. While it’s also possible that coffee and tea consumption might be protective against stroke, dementia and post-stroke dementia, this causality cannot be inferred from the associations.
“We found that drinking coffee and tea separately or in combination were associated with lower risk of stroke and dementia,” the study’s authors concluded. “Moreover, drinking coffee alone or in combination with tea was associated with lower risk of post-stroke dementia. 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.”
From a public health perspective, they added, because regular tea and coffee drinkers comprise such a large proportion of the population and because these beverages tend to be consumed habitually throughout adult life, ‘even small potential health benefits or risks associated with tea and coffee intake may have important public health implications’. Further clinical trials on lifestyle interventions, they said, will be necessary to assess whether the observed associations are causal.
Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank