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Evidence BasedWhat is Oolong Tea and What Benefits Does It Have?

Medically reviewed by Sade Meeks, MS, RD — Written by Jessica DiGiacinto and Alina Petre, MS, RD (NL) — Updated on July 23, 2021

What is oolong?
Nutrition facts
Diabetes protection
Heart health benefits
Weight loss
Improved brain function
Cancer protection
Tooth and bone health
Eczema relief
Safety and side effects
Bottom line

Oolong tea combines the qualities of dark and green teas, giving it several purported health benefits. For example, consuming oolong tea may aid in weight loss and reduce stress.

Oolong tea represents only about 2% of the tea that is produced and consumed around the world, but it’s well worth discovering (1).

This article explains everything you need to know about oolong tea and its health benefits.

What is oolong tea?

Oolong tea is a traditional Chinese tea.

It’s made from the leaves of the Camellia sinensis plant, the same plant used to make green tea and black tea. The difference is in how the tea is processed.

The process of oxidation is what creates green, dark, or oolong teas.

Green tea is produced from fresh tea leaves that have not undergone oxidation, a chemical reaction that begins when the leaves are exposed to the air and which is responsible for the color and taste of different types of tea. Black tea is created when leaves are fully crushed to enhance oxidation, and oolong is created when leaves are wilted in the sun and slightly bruised to create partial oxidation (1, 2, 3).

Summary
Oolong tea is a traditional Chinese tea made from the partially oxidized leaves of the Camellia sinensis plant.

Nutrients in oolong tea

Similar to black and green teas, oolong tea contains several vitamins, minerals, and helpful antioxidants.

A cup of brewed oolong tea contains small amounts of calcium, magnesium, and potassium. It also contains about 38 mg of caffeine. In comparison, a cup of green tea contains about 29mg of caffeine (4, 5).

Some of the main antioxidants in oolong tea, known as tea polyphenols, are theaflavins, thearubigins, and EGCG. These are responsible for many of its health benefits (1).

Oolong tea also contains L-theanine, an amino acid shown to have positive effects on relaxation and cognitive performance (6).

Summary
In addition to caffeine, oolong tea contains vitamins, minerals, amino acids, and beneficial tea polyphenol antioxidants.

Oolong tea may help protect against diabetes

In general, tea has been shown to help protect against diabetes and complications from diabetes, possibly by easing insulin resistance and decreasing inflammation, among other mechanisms (7).

Accordingly, a study from 2021 and a review from 2019 both report links between regular tea consumption, improved blood sugar management, and a lower risk of developing type 2 diabetes (8, 9).

However, the specific effects of oolong tea are generally not as well researched as those of green or black tea.

That being said, one smaller, older study does point to the possible effectiveness of oolong tea in lowering plasma glucose in patients with type 2 diabetes (10).

Nevertheless, not every study agrees on oolong tea’s ability to help ward off or ease type 2 diabetes symptoms, with a 2011 study involving approximately 5,000 Japanese men concluding that consumption of the tea may be a predictor for the onset of the disease (11, 12).

Summary
The polyphenol antioxidants in oolong tea may help maintain normal blood sugar levels and decrease the risk of developing type 2 diabetes. However, the evidence is mixed, and more research is needed.

Oolong tea may improve heart health

Regularly consuming tea antioxidants may also improve heart health (13).

Several studies of regular tea drinkers show reduced blood pressure and cholesterol levels, as well as a reduced risk of heart disease (13, 14, 15).

In a large study from 2003, people who drank more than six cups of tea per day had a “significantly” lower rate of coronary heart disease than non-tea drinkers (16).

Several studies have also investigated oolong tea specifically.

One study of more than 76,000 Japanese adults observed that men who drank 8 ounces (240 mL) or more of oolong tea per day had a 61% lower heart disease risk (17).

What’s more, a study done in China reports that adults who drank 1 to 2 cups per day of either green or oolong tea “significantly” lowered their risk for a stroke (18).

One thing to remember is that oolong tea contains caffeine, which may possibly raise blood pressure, or hypertension, slightly in some people. However, there have been inconsistent results when it comes to studies looking at a link between blood pressure and caffeine, so more research is needed before any definitive conclusions can be made (19, 20).

Furthermore, since the caffeine content in an 8-ounce (240 mL) cup is only about one-fourth of that found in the same amount of coffee, any negative effect regarding hypertension is likely to be quite small (4, 21).

Summary
Oolong tea may help decrease the risk of heart disease, stroke, and high blood pressure in some people, but more research is needed.

Oolong tea may help with weight loss

Tea consumption and weight loss have long been tied together; and indeed, many studies illustrate a connection between the bioactive compounds in tea and weight loss or obesity prevention (22).

While it was long believed that the antioxidant activity from tea was solely responsible for its capabilities to decrease body fat, researchers are beginning to suggest that tea’s ability to enhance enzyme inhibition, and antioxidant interactions with gut microbiota specifically, may actually be what’s driving the weight loss capability (23).

Interestingly enough, it comes to oolong tea itself. A recent animal study showed that extracts from oolong actually did help to increase fat oxidation — meaning they helped decrease body fat directly.

However, when it comes to studies on humans, only one small, older study points to its ability to increase energy expenditure in adults, which is basically the number of calories a body burns while at rest, but not fat oxidation. Clearly, more research has to be done before conclusions can be made (24, 25).

It’s important to note that just because the antioxidant activities, caffeine, and appetite inhibitive qualities of tea have been linked with weight loss in studies doesn’t necessarily mean that drinking a few cups of tea every day is the ticket to losing weight.

Other factors, such as underlying conditions and behaviors, play a big role when it comes to weight loss, and the amount of tea that can be safely consumed varies from person to person (26, 27, 28).

Summary
The combination of caffeine and polyphenols found in oolong tea may help increase specific enzyme inhibition and the number of calories burned each day. This could ultimately aid in weight loss.

Oolong tea may improve brain function

Recent reviews show that tea consumption may help maintain brain function and memory, as well as possibly protect against age-related decline (29, 30).

In fact, several components of tea may benefit brain function.

For starters, caffeine can increase the release of norepinephrine and dopamine. These two brain messengers are thought to benefit mood, attention, and brain function (31).

Further research shows that theanine, an amino acid in tea, may also help boost attention and relieve anxiety. A 2014 review reports that tea containing both caffeine and theanine increased alertness and attention within the first 1 to 2 hours after consumption (32, 33).

Few studies have looked specifically at oolong tea, but a study from 2008 found that a “high level” of tea consumption was associated with a lower risk of cognitive impairment and cognitive decline. This effect was particularly strong for regular black and oolong tea drinkers (34).

Another smaller study from 2010 linked regularly drinking green, black, or oolong tea to improved cognition, memory, executive function, and information processing speed in older Chinese adults (35).

Summary
The caffeine, antioxidant, and theanine content of teas (including oolong tea) may have beneficial effects on brain function and mood.

May help protect against certain cancers

Scientists believe the antioxidants present in black, green, and oolong teas may help prevent cell mutations that can lead to cancer in the body (36, 37).

Tea polyphenols might also decrease the rate of cancer cell division (38).

Over the years, there have been many studies investigating the connection between tea consumption and the lowered risk of certain cancers, including lung, esophageal, pancreatic, liver, and colorectal cancers. While there does seem to be some evidence of a decreased cancer risk, many of the studies caution that the evidence is not always statistically significant (39, 40, 41, 42, 43).

Most research in this field has focused on the effects of green or black teas, with the biggest effects noted for the green variety.

Since oolong tea falls midway between green and black tea, similar benefits may be expected. However, more research is needed on oolong tea specifically.

Summary
Similar to green and black tea, oolong tea may have protective effects against cancer.

Oolong tea helps promote tooth and bone strength

The antioxidants found in oolong tea may help keep your teeth and bones strong.

One study showed that people who drank black, green, or oolong tea daily over a 10-year period had 2% higher overall bone mineral density (44).

Several other reviews report similar positive effects of tea on bone mineral density (45, 46).

A higher bone mineral density could lower the risk of fractures. However, a direct link between oolong tea and fractures has not yet been investigated.

Finally, research has linked tea consumption to better dental health, including decreased plaque and gingivitis, which equals healthier teeth overall (47).

Summary
Oolong tea may help increase bone mineral density. It may also strengthen tooth enamel and reduce the formation of dental plaque.

Oolong tea may help relieve eczema

Both black and green teas have been studied for their ability to help ease the symptoms of atopic dermatitis, otherwise known as eczema, and while results are promising, more research is needed to provide definitive results (48, 49).

Similarly, one small study from 2001 looked at oolong tea’s ability to help manage eczema in 118 individuals with severe cases of eczema. They were asked to drink 33 ounces (1 liter) of oolong tea per day, in addition to maintaining their normal treatment.

After one month, there was “marked to moderate” improvement in their conditions, with signs of improvement noticeable as early as 1 to 2 weeks into the study.

What’s more, the improvement persisted and was still observed in 54% of the individuals 5 months later (50).

The age and scope of this study is important to keep in mind when considering results.

Summary
The polyphenol antioxidants in oolong tea may help relieve symptoms of eczema, and the improvements may last for a long time — but more research needs to be done.

Safety and side effects of oolong tea

Oolong tea has been consumed for centuries and is generally considered to be safe.

That being said, it does contain caffeine.

When consumed in excess, caffeine can lead to anxiety, headaches, insomnia, irregular heartbeat, and in some cases, high blood pressure (51, 52).

Additionally, consuming too many polyphenol antioxidants can make them act as pro-oxidants, which are not good for your health. Excess intake may occur from taking polyphenol supplements, but this is unlikely from simply drinking tea (53).

It’s also possible that the flavonoids in tea may upset iron homeostasis in the body, making iron absorption more difficult, but the amount of flavonoid consumption and exact mechanisms of this issue need more research (54).

Both the United States Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) consider daily intakes of 400 mg of caffeine as safe. This is equivalent to 48–80 ounces of oolong tea (1.4–2.4 liters) per day (55, 56).

Given that the average cup is 8 ounces (240 mL), you could drink a total of 6–10 cups of oolong tea per day without consuming too much caffeine.

However, pregnant women are advised to stick to a maximum of 200 mg of caffeine, which is about 3–5 cups of oolong tea per day (57).

Summary
Drinking up to 10 cups of oolong tea per day is generally considered to be safe for most people.

The bottom line

Oolong tea may not be as well known or as popular as green or black tea, but it has similar purported health benefits. These include benefits for heart, brain, bone, and dental health.

In addition, oolong tea may help decrease your risk for developing type 2 diabetes, aid in protecting you from certain types of cancer, and offer supportive benefits if you’re trying to lose weight.

It also has less caffeine per cup than coffee, making it a good solution for those who are caffeine sensitive.

How we reviewed this article:

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Evidence Based

This article is based on scientific evidence, written by experts and fact checked by experts.

Our team of licensed nutritionists and dietitians strive to be objective, unbiased, honest and to present both sides of the argument.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.

Medically reviewed by Sade Meeks, MS, RD — Written by Jessica DiGiacinto and Alina Petre, MS, RD (NL) — Updated on July 23, 2021

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Nutrition

Nutrition

What is oolong tea?

Nutrients in oolong tea

Oolong tea may help protect against diabetes

Oolong tea may improve heart health

Oolong tea may help with weight loss

Oolong tea may improve brain function

May help protect against certain cancers

Oolong tea helps promote tooth and bone strength

Oolong tea may help relieve eczema

Safety and side effects of oolong tea

The bottom line

How we reviewed this article:

Evidence Based

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