The guide

Is tea healthy? What the studies found

By GyroscopeUpdated November 15, 20269 sources

Yes. In the UK Biobank, 498,043 adults were followed for about 11 years, and people who drank two or more cups of tea a day had a 9 to 13% lower risk of dying than people who drank none. Across 96 meta-analyses, tea went with benefit far more often than harm. The one clear risk is drinking it very hot.

Tea gets less attention than coffee, partly because it’s milder. A cup of black tea has about half the caffeine of a cup of coffee, and green tea about a third. People tend to think of it as either a weak coffee or a health tonic. The studies put it somewhere more ordinary and more useful: a daily drink that goes with a longer life, at a dose that’s easy on your sleep.

What the big studies found

The UK Biobank result is the best one for American and British tea drinkers, since 89% of the tea drinkers in it had black tea. The lower risk started at two cups a day and stayed about the same up to 10 cups or more. It showed up for deaths from heart disease and stroke too, and it held whether people also drank coffee or not, whether they added milk or sugar, and whatever their genes said about clearing caffeine. Three in four tea drinkers added milk and about one in eight added sugar.

The researchers didn’t measure cup size or how strong the tea was, and like the coffee studies, this one watched people instead of assigning them tea. It can’t prove the tea caused the lower risk.

A 2019 umbrella review pulled together 96 meta-analyses covering 40 health outcomes. It found lower risks of dying, of dying from heart disease, of coronary artery disease, of stroke and of type 2 diabetes with each extra two to three cups a day. It also found lower risks for several cancers and for bone, brain and pregnancy outcomes.

For cancer, a 2020 review was stricter. Of 25 cancer types, only the lower risk of mouth cancer in tea drinkers was backed by convincing evidence, about 38% lower odds. The rest were weaker.

The one risk: very hot tea

The 2019 review found a harmful link for cancers of the esophagus and stomach when tea was drunk hotter than about 55 to 60°C (131 to 140°F). The World Health Organization’s cancer agency came to the same conclusion in 2016 about any drink above 65°C (149°F). Studies in China, Iran, Turkey and South America, where tea or maté is often drunk at about 70°C, found the risk rose with the temperature. The agency’s director said “it is the temperature, rather than the drinks themselves” that appears to be responsible.

A fresh cup of tea, straight off the boil, is the moment to wait. A few minutes on the counter takes it out of the range.

Green tea and blood pressure

For blood pressure there are real trials, where people were given green tea or a placebo. A 2020 review of 24 trials with 1,697 people found green tea lowered blood pressure by about 1 point on top and 1 on the bottom (1.17/1.24 mmHg). An earlier review of 13 trials found about 2 points (2.08/1.71 mmHg), more in people whose top number started at 130 or above, and a small drop in LDL cholesterol, about 6 mg/dL (0.16 mmol/L).

That’s a small effect next to the things that move blood pressure most, which bloodpressure.guide ranks.

How much caffeine is in your tea?

Matcha is the exception. You drink the whole leaf, ground, so a strong bowl can match a cup of coffee. How much caffeine is in matcha? has the lab numbers, and how much caffeine is in tea? has the rest.

Tea after dinner

Because a cup has less caffeine, tea fits later in the day than coffee does. A black tea at 8pm still leaves about 34 mg in you at 11pm, the same as a can of Coke, and a green tea about 21 mg.

8pm

34 mg is still in you when you fall asleep at 11pm after a black tea at 8pm, about a can of Coke. On our lines that’s low.

On our lines that’s low, under 40 mg. If you’re sensitive, green tea or decaf tea are smaller still. Can I drink tea at night? goes through each kind.

Tea or coffee?

Both come out well in the big studies. Coffee has the longer list of results, mostly because more people have studied it, and tea has the gentler caffeine. If coffee keeps you up or makes you jittery, tea gives you most of the same habit at half the dose. Is coffee healthy? has the coffee side, and where the real risks are covers what you add to either one.