Oolong Tea: Benefits, Nutrients, & More

Oolong tea is one of many teas from Camellia sinensis, a shrub or evergreen tree native to parts of Asia.

Other teas that come from Camellia sinensis include black tea and green tea. And although these teas have some similarities, they differ in fermentation and processing. Oolong tea, for example, is a semi-fermented tea made from wilted fresh leaves.

Oolong tea is considered a traditional Chinese tea and is commonly consumed due to its purported health benefits. Some studies show that oolong tea may possess antioxidant, anti-inflammatory, anticancer, blood sugar–lowering, heart-protective, and antiseptic properties.

These properties may be due to compounds like polyphenols, polysaccharides, and caffeine found in oolong tea.

However, there is an overall lack of strong research on oolong tea, so many of the health claims surrounding it may be unfounded.

This article will provide an overview of the nutritional benefits of oolong tea and its potential health benefits. Safety, drug interactions, storage information, and tips for using oolong tea will also be discussed.

Getty Images / Yusuke Murata

Oolong tea contains several nutrients and substances, like antioxidants and caffeine, which may add to its health benefits.

Nutrients found in oolong tea include:

Phenolic compounds are phytonutrients (plant-based substances thought to positively affect health) found in oolong tea. Evidence suggests that phenolic compounds in oolong tea act as antioxidants. These antioxidants may reduce oxidative stress and have beneficial effects on cancer, diabetes, and heart disease.

Oolong tea also contains polysaccharides (types of carbohydrates), amino acids, and alkaloids, including caffeine.

Although oolong tea contains some vitamins and minerals, it is not a rich source of these nutrients. It's important to still eat plenty of nutrient-dense, micronutrient-rich foods in addition to drinking oolong tea.

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Many people drink oolong tea for its potential health benefits. These benefits may include:

Although, few health benefits of oolong tea are supported by strong scientific evidence. Many studies on oolong tea have been performed in lab settings or on animal models rather than on humans.

Regardless, there are possible health benefits of drinking oolong tea. Below is a look at the research on some of the more popular uses of oolong tea.

In some studies, tea consumption has been associated with a lower risk of type 2 diabetes. When it comes to oolong tea's effect on type 2 diabetes, research results have been mixed.

According to one review, some human trials have found oolong tea not to affect diabetes prevention. However, other trials mentioned in the review showed that oolong tea may have hypoglycemic (blood sugar–lowering) effects.

Overall, researchers felt that oolong and other types of tea may be useful as an adjuvant (add-on) treatment option for those with type 2 diabetes. However, it is still necessary to consider the safety of individual tea products.

There isn't enough reliable information to know exactly how oolong tea may help manage diabetes. More research should determine oolong tea's potential role in type 2 diabetes.

It's important to remember that no food, drink, or ingredient can single-handedly cause weight loss or maintenance. While oolong tea has been suggested to help with weight management, there isn't convincing evidence to support this claim.

In a small human trial, 12 adult males without obesity were randomized to drink either oolong tea, caffeine, or a placebo two times a day for two weeks.

Through indirect calorimetry testing, oolong tea and caffeine consumption were linked to about a 20% increase in fat oxidation (the breakdown of fats) in the participants. However, these results were only seen with acute intake of oolong tea, which means fat oxidation may not remain increased over time.

At this time, research on this subject is not strong enough, as few human trials have been conducted. Large-scale, well-designed studies are necessary to support any belief that oolong tea may help with weight management.

Many nutrients, supplements, and other substances have been researched for their potential roles in cancer treatment and prevention, including oolong tea.

Researchers from one lab study were able to correlate oolong tea with the prevention of breast cancer. In the study, oolong tea reduced the size and viability of breast cancer cells in a test tube. Oolong tea was also shown to damage DNA in breast cancer cells.

These results have not been duplicated in humans, however.

A 2019 hospital-based study of 646 patient cases found that oolong tea consumption did not prevent esophageal squamous cell carcinoma (ESCC), a type of cancer of the esophagus (tube that carries food from the mouth to the stomach). In fact, drinking hot oolong tea was associated with an increased risk of ESCC in some high-risk patients. This may be due to chronic irritation of the esophagus, which could directly or indirectly stimulate carcinogenesis (cancer formation).

More research is needed on the potential role of oolong tea in cancer.

Oolong tea and other types of tea may offer protective effects against cognitive impairment (a decline in cognition that can range from mild to severe). However, research on this subject is still beginning.

Oolong tea showed neuroprotective effects in one test tube study. In the study, oolong tea extracts prevented cell death, reduced oxidative stress, and increased antioxidants in neurons (types of brain cells).

Yet, in observational studies, oolong tea has not always been associated with neuroprotection.

According to a meta-analysis, some observational studies have yielded positive results of oolong tea use, while others have been inconclusive.

For example, higher oolong tea consumption has been linked to a reduced risk of cognitive impairment in some studies. But in other research, oolong tea use has been found to have no significant impact on cognition.

As with other potential benefits of oolong tea, more research is needed in this area.

There is some evidence that oolong tea may alter the gut microbiome for the better.

In animal studies, oolong tea has been found to act similarly to prebiotics, substances that increase the number of beneficial gut bacteria. Researchers believe that these results may mean oolong tea could enhance the diversity of gut bacteria in humans. But this has yet to be proven.

Other laboratory studies have mirrored these results, attributing the effects of oolong tea on the gut microbiome to the presence of catechins and other polyphenols.

Hopefully, there will be more research, including human trials, on the role of oolong tea in improving gut health.

Oolong tea is considered safe for most people, but there are some things to keep in mind.

Oolong tea contains about 30–50 milligrams (mg) of caffeine per cup. According to the FDA, most healthy adults can safely consume up to 400 mg of caffeine daily. However, some people may find themselves more sensitive to caffeine than others.

Drinking too much caffeine from oolong tea could cause side effects, including:

Additionally, due to its caffeine content, oolong tea may not be right for everyone. For instance, it's recommended that children not consume beverages that contain caffeine. Also, people who are pregnant or breastfeeding should talk with a healthcare provider about safe caffeine consumption.

In some cases, people with certain medical conditions or those who take medications may also need to avoid oolong tea. A healthcare provider or registered dietitian nutritionist can help you determine if oolong tea is safe for you.

If you're thinking of drinking oolong tea, it's important to know how to make it properly. How you make oolong tea will depend on whether you use loose-leaf tea or prepared tea bags.

For loose-leaf tea:

For tea bags:

To make iced tea:

There are different ways to enjoy tea. Some people like to add milk, cream, sugar, or other ingredients to their tea. As you start drinking oolong tea, you'll likely develop your own techniques to make and enjoy it.

It's possible to drink too much oolong tea, and doing so may cause certain side effects and issues.

Remember that oolong tea contains caffeine, a substance you can consume too much of. It's best to keep caffeine intake to 400 mg a day or less, depending on how sensitive you are. Too much caffeine from oolong tea may cause such symptoms as insomnia, jitters, anxiety, rapid heart rate, upset stomach, and headache.

Although research is limited, it is also a concern that caffeine-containing beverages like oolong tea may block the absorption of iron, an important nutrient. Reduced iron absorption could eventually lead to iron deficiency anemia, which can be serious in some cases.

To reduce the risk of poor absorption, it may be best to drink oolong tea one to two hours before or after iron-containing meals.

Certain medications, foods, and supplements may interact negatively with oolong tea.

Although there are no documented interactions for oolong tea, certain compounds found in the tea have known interactions.

Due to its caffeine content, oolong tea may interact with:

The caffeine found in oolong tea may interact with additional medications and supplements, as well as alcohol. It's always a good idea to have a discussion with a healthcare provider before using oolong tea if you take any medications or drink alcohol.

Always carefully read the ingredients list and nutrition facts panel of a supplement (including tea) to know which ingredients are included. Please review nutrition labels with a healthcare provider to discuss any potential interactions with foods, other supplements, and medications.

For optimal freshness, it's important to store oolong tea properly.

It's best to keep oolong tea in an airtight container. This helps protect the tea from oxygen and moisture that could reduce its quality.

Also, be sure to keep oolong tea out of direct sunlight. If possible, store it in an opaque container that won't let any light in. Keep it in a cool, dry place that won't get too hot or cold.

Over time, oolong tea typically doesn't become rancid. However, tea past its prime may not taste as good and may lose some potentially beneficial properties. So, do your best to drink oolong tea before its freshness date expires.

Oolong tea is available in multiple places. It can be purchased online through various websites. Oolong tea can also be found in many grocery stores, retail stores, and specialty stores, like tea shops.

Whenever possible, buy oolong tea from reputable brands that are well-known and have good reviews.

When choosing loose-leaf oolong tea, look for leaves that are uniform in size, shape, and color. A package of fresh oolong tea leaves should have a pleasant fragrance when opened. It may be beneficial to purchase fresh oolong tea from a specialty tea shop that has knowledgeable staff.

Oolong tea is naturally gluten-free and vegan. Many oolong tea products are also certified organic by the U.S. Department of Agriculture (USDA).

Fortunately, tea is regulated by the FDA. This means tea brands must portray nutrition labels accurately and avoid making unfounded health claims.

Recall that oolong tea comes from the Camellia sinensis tree. This tree is accountable for not only oolong tea but also other types of tea that are similar to oolong tea in taste and potential health benefits.

Other teas from Camellia sinensis mostly differ from oolong tea in how they are processed. These teas include:

Research shows these teas may provide antioxidant, anticancer, heart-protective, and antiallergic properties. These properties are thought to be due to the many phytonutrients found in the teas, including flavonoids.

These teas all contain caffeine, so monitor your intake, especially if you're sampling more than one tea at a time.

Oolong tea is a partially fermented tea from the Camellia sinensis tree that may offer health benefits.

Several nutrients are found in oolong tea, including vitamins and minerals. Caffeine is a compound present in oolong tea that may cause various side effects if consumed in excessive amounts.

More research is needed on the potential health benefits of oolong tea. If you're concerned about whether oolong tea is right for you, talk with a healthcare provider or a registered dietitian nutritionist.

The amount of caffeine in one cup of oolong tea can vary greatly from one product to the next. The caffeine content in oolong tea has been reported to be between 10 mg and 60 mg per 8-ounce cup.

Oolong tea brands typically list the caffeine content on their product packaging, so check there for more accurate information.

Oolong tea is said to have a unique taste that varies among individuals.

It is sometimes described as tasting somewhere between black tea and green tea. The taste of oolong tea can vary depending on how it was processed and whether it's loose-leaf or in a prepared tea bag. Most often, oolong tea is said to taste floral, fruity, and earthy.

There are not enough calories in oolong tea to break a fast. This is especially true if oolong tea is unsweetened and milk or creamer isn't added.

This means oolong tea may be safe to drink if you're fasting for religious reasons or if you practice intermittent fasting.

Although oolong tea and black tea come from the same tree (Camellia sinensis), they are not the same.

Oolong tea is semi-fermented and is made with wilted fresh leaves. Black tea is fully fermented and made from crushed tea leaves.

The two teas have different tastes and may offer different health benefits as well.

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By Brittany Lubeck, RDBrittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition.