Stroke and dementia are serious health concerns that lead to significant health and socio-economic burdens around the world. The involvement of coffee and tea in causing strokes and dementia has been reported by many studies in the past. However, the association between coffee and tea consumption and the risk of stroke, dementia, and poststroke dementia is not well understood.
Recently, a group of researchers from Tianjin Medical University investigated the impact of coffee and tea separately and in combination on the risk of stroke and dementia.
Study: Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. Image Credit: YaiSiriChai / Shutterstock.com
About the study
The current prospective cohort study included 365,682 participants from the United Kingdom Biobank who were between 50 to 74 years old. Participants joined the study from 2006 to 2010 and were followed up until 2020.
Cox proportional hazards models were used to estimate the associations between coffee/tea consumption and the rates of stroke and dementia after adjusting for age, sex, ethnicity, income, qualification, body mass index (BMI), alcohol and smoking status, physical activity, diet habits, high- and low-density lipoproteins (HDL and LDL), consumption of sugary beverages, and history of cancer, diabetes, cardiovascular arterial disease (CAD), and hypertension.
Key findings
Consumption of coffee and tea was assessed at baseline. A median follow-up of 11.4 years for new-onset disease revealed that 10,053 participants developed stroke and 5,079 participants developed dementia.
Coffee and tea showed nonlinear associations with stroke and dementia. More specifically, coffee intake of two to three cups/day or tea intake of three to five cups/day or a combined intake of four to six cups/day were linked with the lowest hazard ratio (HR) of stroke and dementia.
As compared to individuals who did not drink coffee or tea, those who drank two to three cups of coffee and two to three cups of tea per day had a 32% reduced risk of stroke and a 28% reduced risk of dementia. Moreover, the combined consumption of coffee and tea was linked to a lower risk of ischemic stroke and vascular dementia.
The combined consumption of the beverages was also associated with a lower risk of poststroke dementia, with the lowest risk seen in individuals consuming three to six cups of coffee and tea daily.
Underlying mechanisms of the protective role of coffee and tea
Several mechanisms may explain the apparent protective effect of coffee and tea intake on stroke and dementia. Coffee contains caffeine, phenolics, and other bioactive compounds that have beneficial health effects. Similarly, tea consists of caffeine, flavonoids, and catechin polyphenols, all of which have been shown to have neuroprotective functions including anti-inflammation, antioxidative stress, inhibition of amyloid-beta aggregation, and anti-apoptosis.
The combined protective role of these two beverages may be due to the combined benefit of different antioxidants and other beneficial biological contents in these beverages. The polyphenols in coffee and tea contain hydroxycinnamic acids and catechins, which have potential benefits such as enhancing endothelial function, anti-inflammation, and insulin resistance.
These factors may have a combined protective effect on the pathogenesis of stroke and dementia. Coffee and tea intake may also jointly modulate cytokine activation.
Implications and limitations
The findings of the study reveal a potentially beneficial relationship between tea and coffee consumption and the risk of dementia, stroke, and poststroke dementia. Clinicians focusing on the prevention and treatment of stroke, dementia, and poststroke dementia may find these observations interesting and helpful.
The limitations of the study were that coffee and tea consumption was self-reported at the beginning of the study and may not be an accurate reflection of long-term intake patterns. Also, unmeasured confounders in observational studies may lead to biased effect estimates. Moreover, all participants were from the U.K. Biobank, which is representative of the whole population of the United Kingdom.
Conclusions
The findings of the current showed that drinking tea and coffee separately or in combination were linked to a lower risk of stroke and dementia. Coffee intake alone or in combination with tea was associated with a reduced risk of poststroke dementia.
Although the findings demonstrate an association between coffee and tea consumption and stroke and dementia risk, more studies are needed to determine if this information can help improve stroke and dementia outcomes in the clinical setting. More clinical trials on lifestyle interventions are needed to clarify if the observed associations between coffee/tea consumption and the risk of stroke and dementia are causal.
The impact of changes in tea and coffee consumption over time on the risk of stroke and dementia also needs to be investigated further.
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