Summary: New international analyses of the INTERSTROKE study find that frequent consumption of carbonated (fizzy) drinks and many commercially produced fruit drinks is linked with a higher risk of stroke. Across nearly 27,000 participants in 27 countries, carbonated beverages were associated with a roughly 22% higher chance of stroke, while fruit drinks were linked with an increased risk of intracranial hemorrhage. High coffee intake (more than four cups daily) was also associated with higher stroke odds, whereas regular tea drinking was generally associated with a lower stroke risk.
These results, co-led by researchers at the University of Galway in collaboration with McMaster University and an international network of stroke investigators, emphasize choosing healthier beverages—particularly replacing sugary or carbonated drinks with water—to help reduce stroke risk.
Key findings:
- Carbonated drinks (both sugar-sweetened and artificially sweetened) were associated with a 22% increase in stroke risk, with risk rising significantly at two or more servings per day.
- Fruit drinks and many commercial juices—often produced from concentrate and containing added sugars and preservatives—were linked with a 37% higher chance of intracranial hemorrhage; two servings per day were associated with a substantially higher risk.
- Drinking more than four cups of coffee daily was associated with a 37% higher chance of stroke; lower coffee intakes showed no association with increased stroke risk.
- Tea consumption was associated with an 18–29% lower chance of stroke in many analyses; black tea (3–4 cups daily) and green tea (3–4 cups daily) showed notable protective associations. Adding milk appeared to negate the benefit in some groups.
- Drinking more than seven cups of water per day was linked with reduced odds of ischemic stroke.
Source: University of Galway
Study context
Stroke occurs when blood flow to part of the brain is interrupted, causing brain cell damage. It can be ischemic (typically from a clot) or intracerebral hemorrhage (bleeding into brain tissue). INTERSTROKE is a large international matched case-control study of first stroke that included nearly 27,000 participants from 27 countries, including roughly 13,500 individuals who experienced a first stroke. The study population spans diverse geographic and ethnic backgrounds and a wide range of cardiovascular risk profiles.
Carbonated beverages, fruit drinks and water
Analyses comparing cases and controls showed a consistent relationship between carbonated beverage intake and ischemic stroke, with a clear dose-response effect: more frequent consumption corresponded to higher odds of stroke. The association varied by region and was most pronounced in parts of Eastern and Central Europe, the Middle East, Africa, and South America.
Fruit drinks and many bottled juices—often not equivalent to freshly squeezed juice—were associated with increased odds of intracerebral hemorrhage. The study highlights differences between fresh fruit juice and processed fruit drinks made from concentrate with added sugars and preservatives, which may offset any benefits of fruit-derived nutrients.
Conversely, very high water intake (>7 cups/day) was associated with reduced odds of ischemic stroke after adjustment for other risk factors.
Tea and coffee
In separate analyses of tea and coffee consumption, low to moderate coffee intake showed no association with stroke, while high intake (>4 cups/day) was linked with increased odds of all stroke and ischemic stroke. Tea intake was associated with lower odds of stroke overall, with strongest associations for 3–4 cups of black tea and for 3–4 cups of green tea. The potential benefit of tea appeared reduced or absent among those who added milk, suggesting milk may interfere with some antioxidant effects. Geographic differences were observed: tea correlated with lower stroke odds in regions such as China and parts of South America, but not uniformly across all regions.
Clinical and public-health implications
Lead investigators note that while hypertension remains the most important modifiable risk factor for stroke, beverage choices represent a potentially actionable lifestyle factor. The findings support minimizing or avoiding carbonated drinks and processed fruit drinks, limiting very high coffee intake, favoring tea in moderation (without milk where possible), and encouraging adequate water consumption as part of broader stroke-prevention strategies.
About this diet and stroke research news
Author: Sheila Gorham
Source: University of Galway
Contact: Sheila Gorham – University of Galway
Image: The image is credited to Neuroscience News
Publications: Results on carbonated beverages, fruit drinks and water were published in the Journal of Stroke. Findings on tea and coffee were published in the International Journal of Stroke.
Abstract — Carbonated Beverage, Fruit Drink, and Water Consumption and Risk of Acute Stroke: the INTERSTROKE Case-Control Study
Background: Cold beverage intake (carbonated drinks, fruit drinks, and water) may be important population-level exposures relevant to stroke risk and prevention. Methods: INTERSTROKE is an international matched case-control study of first stroke. Participants reported beverage intake using food frequency questionnaires or were asked about daily water cups. Multivariable conditional logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for associations with stroke. Results: The analysis included 13,462 cases and 13,488 controls (mean age 61.7 years; 59.6% male). After adjustment, carbonated beverages were associated with ischemic stroke and, at certain consumption levels, with intracerebral hemorrhage. Fruit drinks were associated with higher odds of intracerebral hemorrhage. High water intake (>7 cups/day) was associated with lower odds of ischemic stroke. Associations varied by geographic region. Conclusion: Carbonated beverages and many fruit drinks were linked with higher odds of stroke subtypes, while high water consumption was associated with lower odds of ischemic stroke; findings support minimizing carbonated and processed fruit drinks and encouraging adequate water intake.
Abstract — Tea and coffee consumption and risk of acute stroke: The INTERSTROKE Study
Background: Tea and coffee are widely consumed and may influence stroke risk. Aims: To explore global associations between tea/coffee intake and stroke. Methods: INTERSTROKE participants reported daily cups of coffee, green tea, black tea, and other teas. Multivariable analyses estimated odds of stroke by intake. Results: Among 13,462 cases and 13,488 controls, high coffee consumption (>4 cups/day) was associated with higher odds of all stroke and ischemic stroke, while low–moderate coffee showed no association. Tea consumption was associated with lower odds of stroke, with stronger associations for 3–4 cups of black or green tea; adding milk appeared to attenuate benefit. Conclusions: These associations suggest avoiding very high coffee intake (≥5 cups/day) and that moderate tea consumption may be linked with lower stroke risk, though regional differences exist.