Tea and Heart Health Come Down to How Hot Your Cup Is

Tea has a long-standing reputation as a virtuous hot drink, linked over the years to a lower risk of heart disease, stroke, and dementia. A large new study suggests the benefit may depend on something most people never think about, which is how hot the cup is when it reaches your lips.

The study, published on October 21 in the Journal of Internal Medicine and explained for CNN by emergency physician Dr. Leana Wen, adds a useful twist to what we know about tea and heart health. Regular tea drinkers had a lower risk of heart and blood vessel disease, while people who drank their tea burning hot had a higher risk than people who rarely drank it at all.

Key takeaways

Researchers analyzed data from more than 485,000 adults in China, aged 30 to 79, followed for about nine years.

People who drank tea at least three days a week had about an 11 percent lower risk of heart and blood vessel disease than those who drank it less often.

People who drank their tea burning hot had about a 16 percent higher risk than people who did not regularly drink tea.

Temperature was self-reported, so the study shows a link and cannot prove that hot tea harms the heart.

Letting tea cool to a comfortable sipping temperature is the simplest takeaway for anyone who already enjoys it.

What did the tea study find?

The tea study drew on the China Kadoorie Biobank, a long-running project that asked participants how often they drank tea, what type they preferred, how strong they brewed it, and how hot they drank it. Over about nine years, researchers recorded more than 14,800 cases of diseases affecting the heart and blood vessels, including heart attacks, strokes, and peripheral artery disease, a narrowing of the arteries that supply blood to the arms and legs.

People who drank tea at least three days a week had a roughly 11 percent lower risk than those who drank it less often, even after the researchers accounted for age, smoking, physical activity, body weight, and existing medical conditions. Moderate-strength tea was linked to lower risk, and black tea was associated with lower risk across more types of heart and blood vessel disease than green tea, though green tea also showed benefits.

Why might scalding tea be different?

The most surprising result was about temperature. People who said they drank scalding tea, described in the study as burning hot, had a 16 percent higher risk of heart and blood vessel disease than people who did not regularly drink tea. By contrast, people who drank tea at room temperature or hot, but not scalding, had about a 17 percent lower risk than non-drinkers.

Wen pointed out important caveats. Participants reported their own preferred temperature, and one person's burning hot can be quite different from another's, while people who like scalding drinks may also differ in diet or lifestyle in ways the researchers could not fully measure. So the study does not prove that hot tea damages your heart.

How could tea protect your blood vessels?

Part of the link between tea and heart health may come from what is in the leaves. Wen explained that tea contains natural compounds called polyphenols, including flavonoids, which have antioxidant and anti-inflammatory properties. These compounds may help protect the cells that line your blood vessels and help your arteries relax and widen, which can lower blood pressure and ease the strain on your heart. Our guide to why your blood pressure numbers keep changing explains how those everyday shifts add up.

There may also be an indirect benefit when unsweetened tea replaces pop, juice, or other sugary drinks. That swap alone cuts a meaningful amount of sugar from many people's days.

Should you aim for six to eight cups a day?

Among people who drank tea at least weekly, the lowest estimated risk appeared at about six to eight cups a day, with risk rising again at very high amounts. Wen cautioned against treating that as a target, since the researchers did not use a standard cup size, the numbers relied on self-reporting, and the authors warned against reading it as a recommended intake.

Caffeine is the other reason to go easy. A 240 mL cup of black tea typically contains about 30 to 50 mg of caffeine, and green tea usually less, while Health Canada suggests that most healthy adults keep their total caffeine below 400 mg a day. If tea or coffee leaves your heart fluttering, our guide to heart palpitations and what they mean is worth a read.

What can you do with your next cup?

If you already love tea, there is no reason to change brands or switch from green to black, and Wen said both can be part of a heart-healthy diet, especially without added sugar. These simple habits make your next cup a better one.

Let it cool. Wait until you can sip comfortably, which avoids burns, and Wen noted that repeatedly drinking very hot drinks has also been linked to a higher risk of cancer of the esophagus.

Skip the sugar where you can. Unsweetened tea keeps the possible benefit without the extra sugar.

Watch your total caffeine. Add up your coffee, tea, energy drinks, and pop, especially if you notice poor sleep, anxiety, or a racing heart.

Do not start just for your heart. If you do not drink tea, regular physical activity, not smoking, eating well, and keeping your blood pressure and cholesterol in check remain the proven ways to protect your heart.

Frequently asked questions

Is tea good for your heart?

Research on tea and heart health has linked regular tea drinking with a lower risk of heart and blood vessel disease. The newest study, of more than 485,000 adults, found about an 11 percent lower risk among people who drank tea at least three days a week. This kind of study can only show a link, and temperature appears to matter.

How hot is too hot for tea?

The study relied on people describing their tea as burning hot, so it did not set an exact temperature. A practical rule is to wait until you can sip comfortably without any sting. Very hot drinks have also been linked to a higher risk of cancer of the esophagus, which is another reason to let your cup cool.

Is black tea or green tea better for your heart?

In this study, black tea was linked to a lower risk across more types of heart and blood vessel disease than green tea, though green tea also showed benefits. Dr. Leana Wen said both can be part of a heart-healthy diet, especially without added sugar, so the best choice is the tea you actually enjoy.

Your next step

Your tea habit is only one piece of the picture, and your blood pressure and cholesterol tell the rest of the story. The Medimap Health Hub has more on heart health, and you can book a visit at a walk-in clinic near you to get both numbers checked.

Disclaimer: This article is for general information only and is not medical advice. It does not replace a conversation with a doctor or other qualified health professional who knows your history. If you think you are having a medical emergency, call 911 or go to the nearest emergency department.