Tea and heart health: study of 486,000 adults links habit to lower risk

People who drink tea regularly showed an 11% lower risk of conditions affecting the heart and blood vessels compared with non-drinkers, according to a large study of adults in China published in the Journal of Internal Medicine. The same research found that tea consumed “burning hot” was tied to a higher risk.

The study followed 485,934 adults over a median of 9.05 years. Across that period, the researchers recorded 14,863 cases of vascular disease.

Four conditions studied

The diseases examined were cardiovascular disease, cerebrovascular disease, which concerns the vessels feeding the brain, pulmonary heart disease and peripheral artery disease. All four disrupt blood circulation, which carries oxygen and nutrients to the body’s organs and tissues.

The link appeared to depend on quantity. Among participants who drank tea at least once a week, the lowest estimated risk came at about six to eight cups a day.

That figure is not a recommendation. Because the study was observational, it could only show a connection linking tea habits to health outcomes, without proving that tea itself caused the difference.

Black tea, moderate strength

Black tea was linked more consistently with lower vascular risk than green tea. Both come from the plant Camellia sinensis: black tea usually undergoes extensive oxidation during processing, whereas green tea processing keeps oxidation to a minimum.

Tea contains polyphenols, plant compounds studied for their antioxidant properties and their possible role in how blood vessels function. The research left open the question of whether these compounds explain the gap between the two varieties.

Strength also mattered. Participants drinking tea of moderate strength showed the lowest associated risk, meaning stronger brews were not necessarily tied to greater benefit.

Risk with “burning hot” tea

Drinking tea described as “burning hot” was associated with increased vascular risk, reversing the general pattern. The study did not identify the biological mechanism behind this, nor did it pin down any particular threshold above which tea turns risky, and the result does not prove that very hot tea causes vascular disease.

Smoking and exercise

The researchers also looked at tea alongside smoking and physical activity. The lowest risk was found among people who drank tea habitually, did not currently smoke and were highly active.

“Joint analyses showed that tea consumption, smoking status and physical activity were collectively associated with vascular risk, with the favorable combination of habitual tea consumption, non-current smoking and high physical activity associated with the lowest risk.”

The authors, whose team includes Zichen Ye and Liming Li, wrote that conclusion in the paper. More work remains to be done before scientists can say whether tea itself changes disease risk.