Drinking coffee, tea or both may help lower the risk of stroke and dementia according to a recent study in PLOS Medicine. Participants who drink moderate amounts coffee alone or both coffee and tea were found to have a lower post stroke dementia risk.
Because stroke doubles the chance of dementia, and because many incidences of stroke are preventable, the researchers wanted to take a different look at the benefit of coffee and/or tea consumption on lowering risk. Both beverages contain compounds with antioxidant and anti-inflammatory properties. Previous studies have looked at the benefits of coffee and tea separately in dementia and stroke prevention. However, the researchers for the current study wanted to look at coffee and tea in combination.
The researchers used data from the UK Biobank. A questionnaire taken by UK Biobank participants assessed coffee and tea intake. The amount of coffee and tea consumption was divided into categories that ranged from 0 to 4 or more cups per day. In addition to coffee/tea data, the researchers used hospital records to analyze stroke, Alzheimer disease, and dementia diagnoses. After applying inclusion and exclusion criteria, the study included 13,352 participants.
The researchers found both coffee and tea intake were associated with a lower risk of stroke. As intake increased, the risk of ischemic stroke decreased but not hemorrhagic stroke.
Compared with those who did not drink tea and coffee, hazard ratios of drinking 2 to 3 cups of coffee and 2 to 3 cups of tea per day were 0.68 (95% CI, 0.59 to 0.79; P < .001) and 0.62 (95% CI, 0.51 to 0.75; P < .001) for stroke and ischemic stroke, respectively.
Drinking coffee, tea, or a combination was associated with a lower risk of dementia and vascular dementia but not Alzheimer disease. Compared with participants who only drank either coffee or tea, participants who drank both coffee and tea were associated with a lower risk of stroke (HR, 0.89; 95% CI, 0.86 to 0.93; P < .001), ischemic stroke (HR, 0.89; 95% CI, 0.84 to 0.94; P < .001), dementia (HR, 0.92; 95% CI, 0.87 to 0.98; P = .001), and vascular dementia (HR, 0.82; 95% CI, 0.72 to 0.92; P < .001). The combination of coffee and tea was also associated with lower post-stroke dementia risk.
The researchers note that participants self-reported coffee and tea intake at baseline, which may not reflect consumption over time. The self-report nature may also impact accuracy. The researchers also state UK Biobank participants tend to be “more health conscious” than nonparticipants which may introduce selection bias.
Our findings support an association between moderate coffee and tea consumption and risk of stroke and dementia,” the researchers conclude. “However, whether the provision of such information can improve stroke and dementia outcomes remains to be determined.”
Zhang Y, Yang H, Li S, Li WD, Wang Y. Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. PLoS Med 18(11): e1003830. doi:10.1371/journal.pmed.1003830