A large Chinese study suggests a possible benefit, but British heart experts say other factors may explain the finding and that no “optimal dose” has been established.
Chinese researchers publishing in the Journal of Internal Medicine say regular tea drinkers had up to an 11% lower risk of vascular disease. The study followed 485,934 adults in China for a median of 9.05 years and recorded 14,863 cases. The authors hope the work could one day help identify an “optimal dose” for tea drinkers. British heart experts have urged the public to treat the result with caution, saying other factors may have helped participants stay free of disease.
What the study found
Vascular disease is caused by inflammation and weakness of the veins and arteries. The study covered several categories of vascular outcome, including cardiovascular disease, cerebrovascular disease, pulmonary heart disease and peripheral artery disease. The 11% figure therefore reflects an association with a group of conditions, not a separately demonstrated reduction in heart attacks or strokes.
Other findings, according to the research notes:
- Type of tea: Black tea had more consistently favourable associations than green tea. The study did not show that black tea is inherently healthier, or that switching will prevent illness.
- Temperature: Moderate-strength tea was linked to the lowest risk, and tea described as burning hot was linked to a higher risk. This does not show that hot tea causes vascular disease, and the finding needs confirmation.
- Amount: The lowest estimated risk was at six to eight cups a day. This is an observational estimate, not a recommended intake. It was identified among weekly tea drinkers whose typical intake averaged about 2.78 cups a day, so it should not be read as a proven prescription.
- Lifestyle: The lowest observed risk was among people who drank tea regularly, did not smoke and were physically active. The researchers did not show that tea alone was responsible, as avoiding smoking and exercise matter independently for cardiovascular health.
Caution from scientists
Dr Charalampos Rallis, a genetics and cell biology researcher at Queen Mary University of London, raised several concerns, according to the Science Media Centre. He said the statistical model was not fully adjusted for differences in diet and income, and that the researchers made many comparisons, so individual results need careful interpretation. He said the findings on black tea and drinking temperature should be treated as exploratory. The 11% reduction is also a relative figure and not an 11-percentage-point fall. Differences between tea drinkers and non-drinkers could partly explain the results.
What UK studies show
A 2025 study of 177,810 UK Biobank participants found that unsweetened tea was associated with lower cardiovascular disease risk, with the lowest estimated risk at zero to two drinks a day. It followed people for a median of 12.7 years and recorded 15,003 cases. The studies differ in participants, definitions of quantity, outcomes and methods, so their ranges are not interchangeable. Taken together, they show that researchers have not established a universal best daily amount.
A June 2026 paper in the European Journal of Nutrition looked at 167,142 UK Biobank participants. It found that unsweetened tea was associated with reduced cardiovascular risk across several drinking categories. People who drank more than five sweetened teas a day had a 13% higher relative risk than non-drinkers. That does not show that sugar was responsible.
