8 Teas That Can Help or Harm Your Heart

“Black tea has cardio-protective benefits that can improve blood vessel function and blood flow,” says Mintz.

He also notes this is due to polyphenols and flavonoids, antioxidants found in plants like tea lives, which research suggests can help prevent cell damage, reduce inflammation, and improve cholesterol levels.

Results of a study testing the effects of black tea on rats, published in March 2018 in Lipids in Health and Disease Preventive Medicine, indicated that rats in the test group that ingested a theaflavin-based solution, another antioxidant polyphenol found in black tea, and saw a 10.39 percent reduction in cholesterol, 10.84 percent reduction in LDL cholesterol, and 6.6 percent reduction in triglycerides.

However, less caffeine does not mean there are no harmful effects associated with black tea. Black tea has the highest amount of caffeine out of any type of tea, with an 8-ounce cup containing 47 milligrams (mg) of caffeine depending on how long it’s brewed, notes Mayo Clinic.

While black tea has less caffeine than coffee, the caffeine level varies depending on the tea, brand, processed, and how long it steeps. People with heart problems and those who are breastfeeding or pregnant should not consume more than 200 mg of caffeine daily, or roughly four cups of black tea daily.

Derocha says that the tannins, a class of polyphenol, may also give people an upset stomach, among other potential side effects.

“Tannins in black tea can also decrease iron absorption from plant-based foods,” Derocha explains. “That's why there's tea time. You’re not supposed to have tea with your meals for a reason.”

Finally, Derocha says that black tea can interfere with mental health drugs, and you should speak to your doctor if you are taking medication or trying a new tea.

For your heart health, it pays to go green.

Powerful antioxidants in green tea — especially one called epigallocatechin gallate, or EGCG — can help prevent atherosclerosis and plaque buildup in the arteries.

“Because green tea is a steamed tea leaf and not as processed as black or oolong, you’re going to get a little more of the tea leaves health benefits,” says Derocha. “Steam tea leaves have a higher concentration of EGCG, an antioxidant that helps prevent plaque buildup in our arteries.”

And drinking green tea is also associated with a lower risk of cardiovascular diseases, especially in habitual tea drinkers, according to a review published in May 2022 in Food Science and Human Wellness.

The benefits of green tea led researchers to declare that “tea drinkers live longer” in a study published in January 2020 in the European Society of Cardiology. After surveying 101,000 participants in China, scientists found drinking green tea was linked with approximately 25 percent lower risk of living with heart disease or after a stroke, the chance of dying from heart disease and stroke, and general death. Participants were split between two groups: habitual tea drinkers (three times or more a week) or not.

However, it’s worth noting that these benefits are strongest with habitual tea drinkers, and more so for those drinking more than one cup of green tea a day.

This might not be doable for everyone. Derocha says that people with caffeine sensitivity should watch how much green tea they drink, just like black tea. An 8-ounce cup of green tea gives you 28 mg of caffeine depending on how long it’s brewed, notes Mayo Clinic.

White tea is harvested from the young buds of the tea plant and only briefly processed.

“White tea has the most potent anti-cancer properties compared with some of the more processed teas like black tea or oolong,” says Derocha. “It also has catechins, a polyphenol that can protect us from cell damage, whether that be aging or from a chronic condition.”

A study published in Food Chemistry found that white tea may protect the DNA of normal cells against cell damage from colon cancer, acting as a potential chemotherapeutic agent by inhibiting colon cancer cells.

Regarding heart health, research is limited. Mintz says that while white tea does have antioxidant effects, there aren’t any specific studies exploring the link between the two.

Also, check with your doctor if you’re taking a blood thinner like warfarin (Coumadin) or are sensitive to caffeine. White tea does contain caffeine, which can speed your heart rate or increase your risk for high blood pressure.

Oolong tea is crushed tea leaves that have been oxidized for a period of time and then heated to stop the process.

A clinical study published in the British Journal of Nutrition found that oolong tea may help lower cholesterol levels in the study population from Shantou, China. While the results showed that oolong tea was able to increase HDL cholesterol, it was inconsistent with previous studies.

Derocha cautions that oolong has a laxative effect and to be wary about what that can do to the body.

“It’s not a weight loss cure or supplement,” says Derocha. “That’s not how you want to sell anything because it could be dangerous for people.”

If you’re unsure how oolong tea will affect you, Derocha recommends speaking with a doctor. Like other teas, it can contradict medications like blood thinners.

This herbal tea is notorious for helping people sleep at night because it contains flavanoids, per research.

“Flavanoids help us relax and sleep, and it can also help reduce menstrual cramping and pain,” says Derocha. Sleep is also one of the best tools for dealing with inflammation or healing from an injury, she notes.

Sleep is also vital to heart health, according to the American Heart Association’s recent Life’s "Essential 8" fact sheet measuring a person’s cardiovascular health.

Getting restful sleep is necessary too. A study published in March 2021 in the Journal of the American Heart Association found that poor sleep quality was associated with increased risk of major cardiovascular diseases.

Sometimes the tea works so well that doctors tell patients not to drink chamomile before surgery because it can cause them to be too relaxed and have an adverse effect with anesthesia, says Derocha.

Patients with a coronary artery stent or who are taking aspirin or warfarin blood thinners should consult their doctor before drinking chamomile tea because it may increase the risk for internal bleeding.

“Just like with black tea, pharmacists and doctors want to know what herbal teas you drink,” says Derocha. “Just so they know in case your medication isn’t working.”

Though ginseng has not been officially evaluated by the U.S. Food and Drug Administration (FDA), drinking it may potentially give a boost to your heart. A review in the Journal of Ginseng Research found that ginseng could help with cardiovascular function like increasing blood circulation, but ultimately, more studies need to be done.

“Ginseng is trickier because it can come in tea or capsule form,” says Derocha. “But ginseng is known to help improve overall health by boosting our immune system.”

While ginseng is more popular in Asian counties, it is used as a dietary supplement in the United States for everything from overall health to erectile dysfunction.

A systemic review published in March 2019 in the EPMA Journal found that ginseng supplements may be linked to increased bleeding. However, the results are inconsistent to each other, nor does it exhibit the same qualities as a blood thinner medication.

Derocha warns that ginseng supplements are sometimes touted as “miracle capsules” but with little proof of doing anything miraculous or with the approval of the FDA. If you want ginseng, it is best as tea.

As with most teas, talk to your doctor if you’re taking blood thinners like warfarin or anti-platelet drugs such as clopidogrel (Plavix).

You may have heard that St. John’s wort can help treat symptoms of depression, but be wary of drinking this tea if you have a heart condition.

For those who take digoxin or ivabradine, taking St. John's wort can reduce these drugs' effects, according to the National Center for Complementary and Integrative Health.

The organization also notes that while there has been extensive research on St. John’s wort for depression, the interactions with some medications can be life-threatening.

Derocha says she would rather you drink ginseng tea instead if you are looking for a herbal tea. Black and green tea are also still the best option for heart health.

Red tea is a South African herb that is fermented. While, like chamomile tea, it has plant flavonoids with cancer-fighting properties, medical studies have been limited.

A clinical study of 40 people published in the Journal of Ethnopharmacology found that consuming six cups of rooibos tea daily for six weeks decreased LDL cholesterol and boosted HDL cholesterol. Still, the same effects were not seen in healthy people.

But that doesn’t mean we shouldn’t drink it, notes Derocha.

“We talk about [eating] a rainbow of color with fruits and vegetables and getting a little bit of color from everything because there's a variety of nutrition that you'll get,” she says. “I feel the same way about tea. I think we should have red, black, white, and green tea because you'll get different perks.”