Could your daily coffee or tea habit influence your heart rhythm? A 13-year study involving nearly half a million UK adults examines how different consumption levels relate to atrial fibrillation risk, raising fresh questions about two of the world's most popular beverages.
Study: Association of coffee and tea consumption with the risk of atrial fibrillation: a prospective cohort study from the UK Biobank. Image Credit: Natali 44 / Shutterstock
In a recent study published in the journal Food & Nutrition Research, researchers investigated associations between tea and coffee intake and the risk of atrial fibrillation (AF). The findings linked coffee consumption to a modestly lower AF risk, particularly at 2–3 cups daily, while tea results were less consistent.
AF is the most common arrhythmia, affecting about 33 million individuals worldwide. AF-related morbidity and mortality have also substantially increased. Because AF places a considerable burden on healthcare systems, researchers are examining modifiable risk factors and ways to prevent the condition. Several dietary components have been suggested to reduce AF risk. Caffeine is a naturally occurring stimulant long suspected of exerting negative cardiovascular effects.
Evidence suggests that moderate intake of caffeinated beverages, especially tea and coffee (the primary sources of caffeine consumption), is safe and may even confer cardiovascular benefits. Yet the associations between tea and coffee consumption and AF are unclear. Meta-analyses have yielded inconsistent results, with some studies finding a lower risk of AF with moderate coffee intake and others reporting a higher risk of AF or no association.
About the study
In the present study, researchers from Zhengzhou University, its First Affiliated Hospital, and Peking University in China examined the relationship of tea and coffee consumption with AF risk in a large prospective cohort. They analyzed data from the United Kingdom Biobank (UKB) cohort of over 500,000 adults. Participants with AF at baseline and those without information on tea and coffee consumption were excluded. A touchscreen questionnaire was administered at baseline to assess tea and coffee intake, including decaffeinated coffee and black and green tea.
Intake was stratified into four categories: no intake, 0.5–1 cup, 2–3 cups, and ≥ 4 cups per day. The study's outcome was incident AF identified from self-reports, hospital and primary care data, or death records. The researchers examined how beverage intake related to subsequent AF diagnoses. The analyses accounted for sex, age, ethnicity, physical activity, education, smoking status, alcohol intake, body mass index (BMI), income, and Townsend Deprivation Index. Statistical methods were used to account for missing participant information.
The researchers examined how AF risk varied with tea and coffee consumption. They also assessed whether the associations differed by age, sex, smoking status, and BMI. Sensitivity analyses excluded participants with existing cardiovascular disease, early AF diagnoses, or missing covariate data. Additional models accounted for hypertension, diabetes, sleep apnea, coronary artery disease, and relevant medications.
Findings
The study included 495,269 UKB participants, with an average age of 57 years. Most participants were female (54.6%) and White (94.4%). Over a median follow-up of 13 years, 37,261 individuals developed AF. About 22% of participants did not consume coffee, while 31% drank 2–3 cups daily.
Approximately 15% of participants did not consume tea, whereas 44% drank at least four cups daily. Beverage consumption also varied with participants’ demographic and lifestyle characteristics. After adjustment for these and other factors, coffee drinkers had an estimated AF risk 7% to 11% lower than non-consumers. The largest difference was observed at 2–3 cups per day.
For tea, intake was associated with a 5% lower risk of AF among those consuming 2–3 cups/day. The estimated associations were smaller at other intake levels, and the authors advised caution in interpreting the tea results. AF risk did not decrease steadily with increasing consumption; estimates were lowest at 2–3 cups daily for both beverages. The associations did not differ significantly by age, sex, smoking status, or BMI. Sensitivity analyses generally supported the findings, but the coffee associations weakened among participants drinking 0.5–1 or at least four cups per day after excluding those with existing cardiovascular disease.
Conclusions
Overall, coffee consumption was associated with lower AF risk across intake frequencies. Meanwhile, the association for tea was strongest at 2–3 cups/day, with less certain findings at other intake levels. Because this was an observational study, the findings cannot establish that drinking coffee or tea prevents AF. The study's limitations include self-reported intake data, assessment of consumption only at baseline, no caffeine quantification, and potential residual confounding.
Coffee and tea were also analyzed in separate models without adjusting for each other. Cup size, beverage preparation practices, brewing method, and beverage strength were not standardized, and the study was conducted in the UKB cohort, which limits generalizability. Coffee intake included decaffeinated varieties, so the results cannot be attributed to caffeine itself. Further research is needed to validate these results in diverse populations and elucidate the underlying mechanisms.
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