Summary: People who drink between 4 – 6 cups of coffee or tea per day have a lower risk of stroke and dementia, researchers report. Drinking coffee alone, or in combination with tea, was associated with lower risk of post-stroke dementia.
Drinking coffee or tea may be associated with a lower risk of stroke and dementia, according to a study of healthy individuals aged 50-74 published in PLOS Medicine. Drinking coffee was also associated with a 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.
Yuan Zhang and colleagues from Tianjin Medical University, Tianjin, China studied 365,682 participants from the UK Biobank, who were recruited between 2006 and 2010 and followed them 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 (HR, 0.68, 95% CI, 0.59-0.79; P <0.001) and a 28% lower risk of dementia (HR, 0.72, 95% CI, 0.59-0.89; P =0.002) 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.
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. Finally, while it’s possible that coffee and tea consumption might be protective against stroke, dementia and post-stroke dementia, this causality cannot be inferred from the associations.
The authors add, “Our findings suggested that moderate consumption of coffee and tea separately or in combination were associated with lower risk of stroke and dementia.”
Previous studies have revealed the involvement of coffee and tea in the development of stroke and dementia. However, little is known about the association between the combination of coffee and tea and the risk of stroke, dementia, and poststroke dementia. Therefore, we aimed to investigate the associations of coffee and tea separately and in combination with the risk of developing stroke and dementia.
Methods and findings
This prospective cohort study included 365,682 participants (50 to 74 years old) from the UK Biobank. Participants joined the study from 2006 to 2010 and were followed up until 2020.
We used Cox proportional hazards models to estimate the associations between coffee/tea consumption and incident stroke and dementia, adjusting for sex, age, ethnicity, qualification, income, body mass index (BMI), physical activity, alcohol status, smoking status, diet pattern, consumption of sugar-sweetened beverages, high-density lipoprotein (HDL), low-density lipoprotein (LDL), history of cancer, history of diabetes, history of cardiovascular arterial disease (CAD), and hypertension. Coffee and tea consumption was assessed at baseline.
During a median follow-up of 11.4 years for new onset disease, 5,079 participants developed dementia, and 10,053 participants developed stroke. The associations of coffee and tea with stroke and dementia were nonlinear (P for nonlinear <0.01), and coffee intake of 2 to 3 cups/d or tea intake of 3 to 5 cups/d or their combination intake of 4 to 6 cups/d were linked with the lowest hazard ratio (HR) of incident stroke and dementia.
Compared with those who did not drink tea and coffee, drinking 2 to 3 cups of coffee and 2 to 3 cups of tea per day was associated with a 32% (HR 0.68, 95% CI, 0.59 to 0.79; P < 0.001) lower risk of stroke and a 28% (HR, 0.72, 95% CI, 0.59 to 0.89; P = 0.002) lower risk of dementia. Moreover, the combination of coffee and tea consumption was associated with lower risk of ischemic stroke and vascular dementia. Additionally, the combination of tea and coffee was associated with a lower risk of poststroke dementia, with the lowest risk of incident poststroke dementia at a daily consumption level of 3 to 6 cups of coffee and tea (HR, 0.52, 95% CI, 0.32 to 0.83; P = 0.007).
The main limitations were that coffee and tea intake was self-reported at baseline and may not reflect long-term consumption patterns, unmeasured confounders in observational studies may result in biased effect estimates, and UK Biobank participants are not representative of the whole United Kingdom population.
We found that drinking coffee and tea separately or in combination were associated with lower risk of stroke and dementia. Intake of coffee alone or in combination with tea was associated with lower risk of poststroke dementia.