Researchers were intrigued by the inconclusive link in studies so far regarding blood pressure and tea intake, so they analyzed 25 randomized controlled trials—the gold standard of scientific research—to further explore on the association.
They found that in the short term, tea didn’t seem to make a difference for blood pressure. But long-term tea intake did have a significant impact. After 12 weeks of drinking tea, blood pressure was lower by 2.6 mmHg systolic and 2.2 mmHg diastolic. Green tea had the most significant results, while black tea performed the next best.
Those might not seem like big numbers, but small changes in blood pressure can have a significant impact on health, the study authors write. Reducing systolic blood pressure by 2.6 mmHg “would be expected to reduce stroke risk by 8%, coronary artery disease mortality by 5% and all-cause mortality by 4% at a population level,” they write.
Tea is thought to offer endothelial protection by helping blood vessels relax, allowing blood to flow more freely. It’s a high source of antioxidants that have been linked to better cardiovascular health.
The researchers weren’t able to pinpoint the optimal number of cups to drink to get the benefit, but other studies have shown protective effects at 3-4 daily cups. The researchers said they didn’t see a difference in caffeinated tea vs. decaf.
“These are profound effects and must be considered seriously in terms of the potential for dietary modification to modulate the risk of CVD [cardiovascular disease],” the authors write.