New global research co-led by the University of Galway, in collaboration with McMaster University Canada and an international network of stroke researchers, has revealed that regular consumption of fizzy drinks or fruit juice is linked with an increased risk of stroke, as is drinking more than four cups of coffee per day. These findings are part of the INTERSTROKE research project, with results published in the Journal of Stroke and the International Journal of Stroke. The research involved nearly 27,000 participants across 27 countries, including almost 13,500 who experienced their first stroke. This diverse cohort included individuals from various geographical and ethnic backgrounds and with different cardiovascular risk profiles from countries including Ireland and the UK.
The research highlighted significant risks associated with certain beverages. Consumption of fizzy drinks, including sugar-sweetened and artificially sweetened varieties, was connected to a 22% increase in stroke risk, which sharply rose with the intake of two or more such drinks daily. This association was influential in Eastern/Central Europe, the Middle East, Africa, and South America. The study also pointed out that many commercially available fruit juices, often made from concentrates with added sugars and preservatives, might negate the benefits of fresh fruit and even heighten stroke risk.
In terms of fruit juice consumption, the data showed a 37% increased risk of stroke due to bleeding (intracranial haemorrhage) with regular consumption of such drinks, with the risk tripling when consuming two drinks daily. Women exhibited the highest increase in stroke risk due to bleeding associated with these beverages. In contrast, drinking more than seven cups of water daily was linked to reduced odds of stroke caused by a clot, emphasising the benefits of simple water intake over sugary or caffeinated drinks.
The study also explored the effects of coffee and tea consumption on stroke risk. It found that drinking more than four cups of coffee daily raised the risk of stroke by 37%, although lower coffee consumption did not pose the same risk. Conversely, tea drinking was generally associated with a reduced risk of stroke, showing an 18-20% decrease in risk. Drinking 3-4 cups per day of black tea, including varieties like Breakfast and Earl Grey (but not green or herbal teas), was linked with a 29% lower risk of stroke.
However, the beneficial effects of tea could be nullified by adding milk, as this could inhibit the antioxidants in tea that contribute to its protective effects against stroke. The research also highlighted significant geographical differences in how tea consumption affected stroke risk, with a reduced risk noted in regions like China and South America. In contrast, a higher risk was observed in South Asia.
Lead researcher Professor Andrew Smyth, Clinical Epidemiology at the University of Galway and Consultant Physician at Galway University Hospitals, advises caution with fruit and fizzy beverages. He recommends avoiding or minimising consumption of such drinks and suggests switching to water to mitigate stroke risk. Smyth’s findings stress the importance of understanding the health implications of our beverage choices, enlightening us about the significant impact these choices can have on our cardiovascular health.
More information: Andrew Smyth et al, Carbonated Beverage, Fruit Drink, and Water Consumption and Risk of Acute Stroke: the INTERSTROKE Case-Control Study, Journal of Stroke. DOI: 10.5853/jos.2024.01543
Journal information: Journal of Stroke Provided by University of Galway
