Drinking tea regularly is linked to an 11% lower risk of vascular disease

Tea is the most consumed beverage in the world after water, and the question of whether it helps or does nothing for the heart has been argued over small studies for decades. A new analysis of one of the largest health cohorts ever assembled gives a clearer answer than most of what came before it, with a twist that has nothing to do with what kind of tea anyone drinks.

The study

Researchers led by Zichen Ye at the Chinese Academy of Medical Sciences and Peking Union Medical College, working with the China Kadoorie Biobank Collaborative Group, followed 485,934 adults in China for a median of 9.05 years. Over that period, 14,863 participants developed a vascular disease event: coronary heart disease, cerebrovascular disease (including stroke), pulmonary heart disease or peripheral artery disease. The study, "Habitual tea consumption is associated with lower cardiovascular disease risk," was published in the Journal of Internal Medicine.

The finding

People who drank tea habitually had an 11% lower risk of developing vascular disease than those who did not, a hazard ratio of 0.888 (95% CI 0.857 to 0.921). Among participants who drank tea at least weekly, average intake was about 2.78 cups a day, and the lowest estimated risk in the cohort fell around six to eight cups a day. That is a description of where risk was lowest in this particular population, not a target the study recommends adopting from scratch.

Two qualifiers narrowed the finding. The inverse association was not clearly seen for hemorrhagic stroke or pulmonary heart disease specifically, only for the vascular disease category as a whole and some of its components. And the benefit depended on how the tea was drunk, not just whether it was drunk at all.

Type, strength and temperature

Three details inside the data stand out:

• Type. Black tea showed a more consistent inverse association with vascular disease than green tea in this cohort.
• Strength. Moderate-strength tea was linked to lower risk than either very weak or very strong brews.
• Temperature. Tea drunk "burning hot" was linked to higher risk, a hazard ratio of 1.160, the opposite direction from the overall benefit. Tea at room or warm, non-scalding temperature was linked to lower risk instead.

The combination of regular tea drinking with not smoking and staying physically active was associated with the lowest vascular disease risk of any group the researchers reported, though the specific size of that combined effect was not available in the coverage of this study and is not repeated here.

What this design can and cannot tell you

This is an observational cohort, not a trial where people were assigned to drink more or less tea. Tea drinkers and non-drinkers differ in diet, income, education and other habits that a questionnaire cannot fully capture, and any of those differences could account for part of the association. Tea consumption and temperature were based on what participants reported about their own habits, measured at the start of the study, which is a cruder measure than tracking what people actually drink over nine years.

None of that erases the finding. A sample of nearly half a million people followed for nine years, with a result that holds up across a dose pattern (more tea, lower risk, up to a point) and a plausible mechanism-adjacent detail (temperature matters independent of amount), is a stronger basis than a small trial. But "linked to" is the right description, not "prevents" or "protects," and the population was entirely Chinese adults, whose tea-drinking habits differ from a typical American or European one.

How different tea habits compare

What the study measured, and did not measure, matters for reading this honestly. Ordered roughly by how directly each pattern maps onto what the researchers reported:

• Plain black tea, moderate strength, hot but not scalding: the profile most consistent with the lower-risk finding in this cohort
• Plain black tea, weak or oversteeped/very strong: still black tea, but outside the moderate-strength band linked to the lowest risk
• Green tea, moderate strength: tea, but with a less consistent inverse association than black tea in this particular cohort
• Tea drunk "burning hot," any type: the one pattern linked to higher risk rather than lower, independent of tea type
• Six to eight cups a day, among people who already drink tea weekly: where the lowest estimated risk fell in this cohort, not a target to start from zero
• Oolong tea: not separately broken out in the coverage of this study; chemically closer to black and green tea than to herbal tisanes
• White tea: not separately broken out in the coverage of this study
• Matcha (whisked whole-leaf green tea): not separately studied here; nutritionally closer to green tea than to brewed black tea
• Chai, brewed with milk and spices: milk and added spices were not accounted for in this analysis
• Tea with sugar added: not separately analyzed; added sugar carries its own, separately documented risks
• Tea with milk added: not separately analyzed in this cohort
• Decaffeinated tea: not separately broken out; the study did not isolate caffeine as the mechanism
• Herbal tea or tisane (chamomile, peppermint, rooibos): botanically not tea at all, and not covered by this study, which looked at tea from the Camellia sinensis plant
• Unsweetened iced tea, brewed and cooled: closer to the moderate-temperature pattern linked to lower risk than to the hot pattern, though not separately reported
• Bottled sweetened iced tea: the added sugar in most bottled versions is not accounted for in this analysis and works against the overall pattern documented elsewhere on sugar
• Instant iced tea mix: typically includes added sugar; not the beverage this cohort measured

Is there a recommended amount?

Tea has no RDA, AI or upper limit, because it is a beverage, not an essential nutrient. The six-to-eight-cups-a-day figure describes where risk was lowest among people in this cohort who already drank tea regularly, not a dose the study tested by assignment or a target the researchers recommend adopting. Going from zero cups to eight is not what this study measured, and the result should not be read as a reason to start.

Too little, and too much

Too little is not a real category here. Tea has no biological requirement, so not drinking it is not a deficiency of anything.

Too much runs through caffeine more than through tea itself. Black and green tea both carry meaningful caffeine, and high intake late in the day can quietly cut deep sleep even when it does not feel like it. Tea also contains tannins that measurably reduce iron absorption when drunk with a meal, which matters more for people already running low on iron. And per this study specifically, drinking tea scalding hot was linked to higher vascular disease risk, not lower, so how hot it is drunk is worth as much attention as how much is drunk.

Tracking it in AIM

Tea is not one of the fourteen nutrients AIM tracks as standard, and this study does not hand down a number to chase. What is worth tracking, if this is a habit worth watching, is simply how much is drunk: add "tea" as a custom metric in cups, with no target set, or a personal range if the six-to-eight-cup pattern is one worth watching for yourself. Any custom nutrient works the same way.

Estimates from a photograph carry real uncertainty for micronutrients, because content varies with soil, cultivar, storage and cooking in ways no image contains. A cup of tea is easier to log reliably than most foods are, since it is closer to a count than an estimate, but temperature and steep strength, the two details this study flagged as mattering most, are not something a photograph can capture at all.