Green Tea and Cardiovascular Health: Insights from a New Study

My mornings feel incomplete without sipping a couple of soothing yet revitalizing cups of green tea. It’s not just a comforting ritual; tea brings along a range of health benefits that people have long appreciated. There’s talk of it potentially lowering the risks of heart disease, stroke, and even dementia. Recently, a study came out in the Journal of Internal Medicine, suggesting that the way we prepare and enjoy our tea might also play a role in our heart health.

Over nearly nine years, researchers tracked more than 14,800 instances of cardiovascular-related conditions like heart attacks and strokes among participants. They were keen on documenting diseases linked to the heart and blood vessels—things like peripheral artery disease, which narrows arteries that supply blood to the limbs.

The study focused on over 485,000 Chinese adults aged 30 to 79. Participants shared details about their tea-drinking habits: how often they enjoyed tea, the types they preferred, brew strength, and preferred drinking temperature.

To break down the findings and their implications, I chatted with CNN wellness expert Dr. Leana Wen, who has a background in emergency medicine and public health.

CNN: What findings did this study reveal regarding tea consumption and cardiovascular disease?

Dr. Leana Wen: A significant takeaway was that those who drank tea at least three times a week experienced about an 11% reduction in their cardiovascular disease risk, even after considering variables like age, smoking status, physical activity, and existing health issues. Interestingly, nonsmokers who regularly consumed tea and maintained high activity levels had the lowest heart risks.

What’s also notable is that moderate-strength tea was linked to lower risk levels, and black tea appeared to offer more robust cardiovascular protective measures compared to green tea. Strangely enough, those who preferred their tea at “burning hot” temperatures had a 16% higher chance of vascular disease than those who drank it at cooler temperatures. It turns out that sipping tea at room temperature or hot—but not scalding—was actually associated with reduced risks.

However, a limitation of this study is that participants self-reported their preferred drinking temperatures. What might be considered “burning hot” varies significantly from one person to another. It’s also possible that individuals who prefer very hot tea could have different lifestyle patterns that impact their heart health, but researchers couldn’t fully investigate that.

CNN: How does drinking tea benefit heart health?

Wen: Tea contains natural compounds known as polyphenols, particularly flavonoids, which have antioxidant and anti-inflammatory properties. These may help protect the cells in blood vessels and enhance the arteries’ ability to relax and expand, ultimately lowering blood pressure and reducing stress on the heart.

Several studies indicate that consuming tea can lead to modest improvements in blood pressure and cholesterol levels, which may explain why regular tea drinkers tend to have lower rates of serious heart issues.

There might even be indirect benefits when people opt for unsweetened tea instead of sugary drinks, such as sodas or juice. Swapping high-sugar beverages for unsweetened tea can help with managing weight and improving metabolic health, thereby potentially lowering cardiovascular disease risks.

CNN: Does the type of tea matter—like black versus green tea?

Wen: Both black and green teas originate from the same plant, Camellia sinensis, but the processing methods create variations in their polyphenol compositions. Previous studies have shown positive outcomes from both, but this study found that black tea consistently correlates with reduced cardiovascular risks, although green tea still presents benefits.

I wouldn’t suggest that someone switch from green tea to black tea or vice versa. Both can fit well into a heart-healthy lifestyle, particularly if enjoyed without added sugars.

CNN: How much tea should one drink? Can there be too much?

Wen: For those drinking tea regularly, the sweet spot for minimizing vascular disease risk seems to be around six to eight cups a day. However, risks tend to rise when consumption surpasses this range.

That said, it’s important not to interpret this as a specific goal for everyone. Researchers didn’t standardize cup sizes, and responses depended on self-reported consumption, so caution is necessary. The authors caution against labeling this finding as an optimal target.

Another point to keep in mind is that tea does contain caffeine. An 8-ounce cup of black tea typically has about 30 to 50 milligrams of caffeine, while green tea usually holds a bit less but isn’t entirely caffeine-free unless specified. The FDA suggests that up to 400 milligrams of caffeine daily is generally considered safe, but pregnant individuals are advised to limit intake to around 200 milligrams, and children should avoid caffeinated beverages.

CNN: What advice do you have for people who already drink tea or are considering adding it to their diets?

Wen: It’s wise to steer clear of tea that’s hot enough to burn your mouth or throat. Regularly consuming very hot drinks has been linked to an increased risk of esophageal cancer. Letting your tea cool to a comfortable sipping temperature can help avert burns and could preserve its heart-healthy advantages.

People can choose unsweetened black, green, or other teas based on their preferences, but they should be mindful of their overall caffeine consumption, especially if they struggle with sleep issues, anxiety, or palpitations.

If you’re not a tea drinker already, don’t feel pressured to start. There are plenty of proven ways to lower your chances of cardiovascular disease, such as staying active, avoiding tobacco, controlling blood pressure and cholesterol, and maintaining a balanced diet.