Regular tea drinking linked to 11% lower vascular disease risk in Chinese study

What the study measured

A study published in the Journal of Internal Medicine followed 485,934 adults in China over a typical nine-year period, and 14,863 cases of vascular disease were recorded during that time. The study's definition of vascular disease covers heart disease, cerebrovascular disease, pulmonary heart disease and peripheral artery disease. Researchers led by Yu Jiang adjusted their analysis for age, sex, smoking, physical activity, alcohol consumption and several medical histories. People who drank tea at least three days a week had an estimated 11% lower risk of vascular disease than people who did not drink it regularly. The study is observational, so it shows an association rather than proof that tea itself caused the lower risk.

Which conditions showed the strongest link

La Razón reports that the estimated risk of ischemic heart disease was 10.3% lower among regular tea drinkers, while the risk of cerebrovascular disease was 19.1% lower. The largest reported gap concerned ischemic stroke, at 36.6% lower. The same report notes that not every category produced statistically significant results, so the pattern was not uniform across all vascular diseases. The figures for the three conditions are set out below.

Temperature and tea type

Temperature appeared to change the picture. Participants who described their tea as burning hot had a higher risk of vascular disease, and one report put that increase at 16%. Moderate-strength tea was associated with lower risk. On variety, the sources diverge: N-tv says the protective effect of green tea was clearly greater than that of black tea, while La Razón says black tea showed more consistent inverse associations across the conditions studied. La Razón adds that the study does not show black tea is necessarily better than green, because differences between the people who drank each kind could shape the results.

Dose and lifestyle factors

The lowest estimated risk appeared at roughly six to eight cups a day among weekly tea drinkers, who averaged 2.78 cups a day. Tea drinking combined with not smoking and regular exercise was associated with the lowest overall risk. The researchers described the pairing of regular tea intake, not smoking and high physical activity as the most favourable combination. The study did not establish a recommended daily amount, and UK experts said further work is needed before any dose advice can be given.

Expert caution

Dell Stanford, senior dietitian at the British Heart Foundation, said the study adds to evidence linking tea with better cardiovascular health but does not show that a daily cup protects the heart.

But this doesn't prove that a daily cuppa protects your heart.

Stanford also pointed to the single measurement of tea intake and the lack of standardised cup sizes. She noted that the research was carried out in China, so further evidence is needed before the findings are assumed to apply to people in the UK.

There's no single food or drink that will transform our heart health; our overall diet and lifestyle matter much more.

Stanford also said the observational design means other differences in diet and lifestyle could help explain the findings.