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Most of us have reached for a mug of hot tea in the hopes of easing a sore throat or staving off the common cold.
The concept of tea as medicine is nothing new. “The Chinese have been using this method for centuries to reduce ailments and improve the immune system,” says Paulina Lee, RD, a Houston-based registered dietitian who uses Western medical practices and alternative and integrative therapies to help clients address the root causes of their health concerns.
Despite the widespread use of tea for immunity, there is little hard scientific evidence to prove that tea offers this type of perk. Read on to learn what we’ve discovered about how tea may — or may not — keep your immune system on point.
How Tea May Support Your Immune Health
The bulk of tea’s immune and overall health benefits are tied to a group of antioxidants known as polyphenols. “A significant amount of epidemiological data has shown that a diet rich in polyphenols is protective against chronic health conditions such as cardiovascular disease and type 2 diabetes,” says Megan Meyer, PhD, the Durham, North Carolina–based senior director of science communications for the International Food Information Council. Her past research examined the effects of nutritional antioxidants on the immune system’s response to influenza.
Dr. Meyer points to a review published September 2017 in Nutrition Bulletin, which found that teas are especially rich in polyphenols known as flavonols. These plant chemicals have been shown to help lower blood pressure and cholesterol.
As far as your immune system is concerned, antioxidants (like the flavonols in tea) can help protect your body against free radicals generated by pollution, cigarette smoke, and ultraviolet rays, according to Harvard Health. Free radicals can have harmful effects on the body, including a weakened immune system, per a past review.
There are many tea varieties that may support your immune health. Popular options like green, black, white, and oolong all come from the same evergreen plant, Camellia sinensis, according to the Harvard T.H. Chan School of Public Health. “What makes them distinct is how they are prepared,” Meyer says. Differences in processing, geographical location, and plant varieties account for the unique flavors and nutritional compositions of tea, and may mean some teas offer more immune benefits than others.
Herbal teas may also support your immune health. “Most herbal teas are known to have health-supporting qualities,” Lee says.
Herbal teas are not made from the Camellia plant but from dried herbs, spices, roots, seeds, fruit, or leaves of other plants, according to the Harvard T.H. Chan School of Public Health. Depending on the nutritional makeup of a given plant, some herbal teas may be better for your immune health than others.
More Research on Tea and Immune Health Is Needed
While the research on tea and immune health sounds promising, the studies thus far either don’t use humans, or the population sizes are relatively small. Many studies also use tea in capsule or tablet forms, which usually pack a far greater dose of plant compounds than you’d find in a tea bag. Given these limitations, it’s tough to know whether and how a cup of tea will benefit a typical person's immune health. More large studies in humans using brewed tea are needed.
That said, health experts generally agree: Brewed tea sans sweetener is a healthy beverage choice. “I personally believe that teas are a great way to add functional foods and herbs to your diet on a daily basis,” Lee says. So drink up! And if immune health is your top concern, you might want to start with this list of the top teas for a healthy immune system, in order from strongest evidence to weakest.
Green Tea
Mild, bittersweet green tea is a rich source of catechins. “Catechins are polyphenols that have an overall positive benefit to wellness and are notable antioxidants,” Lee says. Epigallocatechin gallate (EGCG) is one of the most abundant and best-known catechins in green tea. It also offers perks for your immune system.
For example, a past study found that treating mice with EGCG increased the number of regulatory T cells in their spleens and lymph nodes. Regulatory T cells modulate immune response, helping your system stay balanced and preventing it from attacking healthy cells.
Research suggests EGCG may also affect immune function in humans. In a study published in April 2021 in Biochemical and Biophysical Research Communications, researchers treated T cells taken from 20 healthy adult males with EGCG they’d isolated from green tea dissolved in water. They discovered that the EGCG prevented the T cells from creating pro-inflammatory proteins known as cytokines, which suggests that the plant compounds in green tea may help regulate the immune system.
While these results offer clues about the link between green tea and immunity, more research in humans, people with weakened immune systems, and larger population sizes are needed to know for sure.
Turmeric Tea
It turns out that turmeric, the yellow orange spice that gives curry its bold color, may also be a boon to your immune system when enjoyed in tea. “Research shows that turmeric can decrease inflammation and that it contains high levels of antioxidants, which both support overall immune function,” Lee says.
The primary active compound in turmeric is curcumin. According to a review published October 2017 in Foods, curcumin effectively scavenges different types of free radicals, controls enzymes that neutralize free radicals, and helps prevent the creation of free radicals. Given the role that free radical damage can play in many diseases, the antioxidants in turmeric may make this spice a handy addition to your immune-health diet.
Researchers have also found that curcumin may play an important role in the immune response. For example, a past study using cultured spleen cells from mice revealed that curcumin could regulate T cells and B cells, two lymphocytes that recognize and respond to foreign substances inside your body. In the aforementioned study, curcumin helped regulate the immune response to prevent immune cells from attacking healthy tissues. Researchers concluded that curcumin may be a promising therapy for keeping the immune system in check.
All the same, research in humans and on turmeric tea specifically is lacking, which means that scientists don’t yet know whether you’ll see these benefits by sipping it in tea form.
Black Tea
This dark, bold tea variety gets its dark color from a group of polyphenols known as theaflavins. “Research supports theaflavins’ antioxidant potential, even compared to ECGC,” Lee says, pointing to a past study that found these two polyphenol types are equally effective antioxidants.
Yet the antioxidants in black tea may have unique effects on the immune system. For example, a past clinical trial found that healthy people (defined in this case as having no major illnesses and normal to mildly elevated systolic blood pressure) who drank three cups of black tea per day for six months showed increased immune activity.
Researchers looked at three markers that indicate your immune system has kicked into gear: neopterin, kynurenine, and tryptophan. While black tea had no significant effect on neopterin or tryptophan levels, it did increase kynurenine, which suggests that the polyphenols in black tea help activate the immune response in healthy people.
The fact that this study had human subjects drink black tea is a plus. But the sample size was small — 45 people drank the tea and 49 were in the control group. To better understand the effect of drinking tea on specific health conditions and the immune system, more studies would be needed with a variety of different patients and, ideally, larger sample sizes.
White Tea
Thanks to minimal processing, white tea is one of the lightest, most delicately flavored varieties on the market. Like its green cousin, white tea offers high levels of catechins, according to a past review. Indeed, previous research suggests that white tea has antioxidant benefits similar to green tea, though the antioxidant potential of green tea is still greater, Lee notes.
Robust human research on white tea and immunity is lacking, which is why this variety is lower on this list. Yet the minimal evidence we have so far suggests it may be worth a closer look in future literature. For example, a past test-tube study found that white tea extract helped protect rat nerve cells against damage when exposed to hydrogen peroxide, a free radical. And another test-tube study found that white tea extract helped tame inflammation in human skin cells caused by free radicals.
As an added perk, white tea may offer antimicrobial benefits. For example, researchers tested the antimicrobial effects of white tea leaf by pitting it against oral Streptococcus mutans and Streptococcus sobrinus bacteria, two microorganisms that contribute to tooth decay. After a 72-hour incubation period, researchers found that the white tea extracts showed significant antibacterial effects against Streptococcus mutans, which suggests that white tea extract may help protect against tooth decay. The findings were published in August 2019 in Materials Today: Proceedings.
While test-tube studies like these can produce interesting results, they don’t offer the whole picture. More studies of humans drinking brewed tea are needed to understand how white tea affects the immune system. “An herb or supplement going through our digestive systems must be absorbed into the bloodstream, go through processing in the liver, and still be effective when diluted in the body,” Lee explains. So, take test-tube studies with a grain of salt.
Ginger Tea
As a close relative of turmeric, ginger may also offer immune-health benefits when sipped in a cup of tea.
Gingerol is the main active compound that’s responsible for ginger’s spicy, peppery flavor and medicinal properties. According to a past review, not only does gingerol offer antioxidant and anti-inflammatory effects, but it may also treat infections.
In addition to gingerol, ginger contains other antiviral compounds that are effective at fighting the common cold, notes a past research paper. The compounds are associated with an ease in pain, fever, and coughing fits linked with the common cold.
That said, few studies have looked at ginger’s effects on the immune system and the effects of ginger tea in particular. More research is needed to conclude whether ginger tea can play a role in immune health.