Oolong tea is a traditional Chinese tea. It’s made from the same plant used in black and green teas, but the leaves are processed differently.
This tea-making process is called oxidation. Exposing the tea leaves to air causes them to ferment, and the length of time a tea maker allows the leaves to oxidize impacts the tea’s color, flavor, and to an extent, its nutritional content.
Green tea is unoxidized, which helps it retain some plant-based antioxidants like catechins, which would be lost or converted during oxidation. Black tea is fully oxidized, giving it a deeper, richer flavor. This fermentation process also forms nutrients called theaflavins, powerful antioxidants unique to oxidized teas.
Oolong teas fall somewhere in between green and black tea. Products sold range from low to high levels of oxidation, and the color of the tea gets darker based on how long the leaves were left to ferment. Greener oolong teas tend to have a rich, earthy taste, while darker varieties offer a more roasted flavor.
Many of oolong tea’s health benefits are attributed to its antioxidants like polyphenols, but it also contains other health-boosting vitamins and minerals. Research shows that oolong tea’s fluoride content is comparable to what dentists recommend to prevent cavities. It may also reduce the risk of tooth loss and oral cancer.
Oolong tea is also an excellent source of:
Nutrients per Serving
One cup of brewed oolong tea (about 2 grams of tea leaves in eight ounces of water) contains:
- Calories: 2.4
- Protein: 0 grams
- Fat: 0 grams
- Carbohydrates: 0.36 grams
- Fiber: 0 grams
- Sugar: 0 gram
Because oolong tea contains caffeine, drinking it in high amounts can have adverse side effects like headaches, irritability, increased heart rate, and insomnia. Experts recommend not exceeding 400 milligrams of caffeine a day, and one cup of oolong tea contains about 38 milligrams per serving.
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 29g of caffeine.
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.
How can I benefit from oolong?
As a semi-oxidized tea, oolong tea contains a range of antioxidants, including many found in both green and black teas. Antioxidants are nutrients that protect our cells from damage caused by aging, our lifestyle, and the environment. Over time, this damage contributes to many chronic diseases.
All teas contain high levels of antioxidants that offer a range of health benefits. However, research shows that the nutrients in oolong tea have stronger antioxidant and antimutagenic effects than green or black varieties.
Researchers in China studied the relationship between drinking oolong tea and cholesterol levels, as high cholesterol levels can be associated with an increased risk for heart disease.
They found that people who drank at least 10 ounces of oolong tea per week had lower risks of having high total cholesterol, triglyceride, and LDL or “bad” cholesterol levels. The same was also true of people who drank similar amounts of green and black teas.
People who had been consuming oolong tea for the longest time had lower total cholesterol, triglyceride, and LDL cholesterol levels.
In another study, Japanese men and women were studied for the impact of consuming coffee, green tea, black tea, and oolong tea on their risk of heart disease. Researchers found that men who drank 1 or more cups of oolong tea per day had a lower risk of heart disease.
A study in mice showed that the animals receiving oolong tea extract while being fed a high fat, high sugar diet, gained less abdominal fat than mice on the same diet that did not receive the tea extract.
Green tea and black tea extracts also resulted in less abdominal fat gain. The mice that received the green tea extract also consumed fewer calories.
A study in overweight and obese Chinese adults looked at the effect of oolong tea consumption on body weight. Study participants drank 300 milliliters (mL) of oolong tea four times per day. After 6 weeks, more than half of the participants had lost more than 1 kilogram.
Researchers in Taiwan examined the association between drinking tea and the risk of head and neck or throat cancer.
Each cup of oolong tea consumed per day equated to a 4 percent lower risk, but the result was not significant. Each cup of green tea consumed per day equated to a 6 percent lower risk for head and neck cancer, which was more significant.
Another study in Chinese women found that drinking green, black, or oolong tea was linked to a decreased risk of ovarian cancer.
However, according to the National Cancer Institute there is not currently enough research to say for certain that drinking tea decreases cancer risk.
Some studies have shown that drinking 3 or more cups of tea per day is associated with a lower risk of type 2 diabetes.
However, studies specifically looking at oolong tea have had varied results.
In one study , healthy men drank almost 6 cups per day of oolong tea. At different times, they drank oolong tea that contained supplemental antioxidants, which were in the form of catechins or polyphenols. Each of the teas was consumed for 5 days. Researchers found that drinking oolong tea did not improve blood sugar or insulin levels.
Interestingly, one study found that working men who drank 2 or more cups of oolong tea per day had a higher risk of developing diabetes than men who consumed 1 cup of oolong tea per day or no oolong tea.
Fluoride is an element that is often added to drinking water, toothpaste, and mouthwash to help prevent dental cavities.
Tea leaves naturally contain fluoride, so drinking oolong tea could help prevent cavities. Excess fluoride can be harmful, but drinking less than 1 liter of oolong tea per day is safe for most adults.
Aiding weight loss
Oolong tea is one of the most popular weight-loss teas for a reason. Study showed that oolong tea might help in reducing a “high fat diet-induced gain in weight, hepatic lipids, and white adipose tissue weights. ” Oolong tea may be very helpful in preventing obesity too. In fact, it may even help without any additional effort or intensive exercise. Chinese study on 102 over-weight and obese patients showed that 70% of patients lost 1 kg in only 6 weeks of daily oolong tea consumption. Furthermore, almost one quarter of patients, 22%, lost up to 3 kg. Furthermore, studies have showed that drinking full-strength oolong tea may increase energy expenditure and fat oxidation by 12%.
Improving sleepResearch showed that GABA in combination with L-theanine, might be cause longer sleep and reduce sleep latency. Oolong contains both of them. Regular oolong tea has about 0.25 mg of GABA per 200 ml, while the levels in GABA-enriched tea are around 2 mg per 200 ml
Protecting brainDrinking tea regularly may help in protecting against neurodegenerative diseases such as Parkinson’s disease. Studies showed that drinking 3 cups of tea per day for 10 years might reduce the risk even up to 28%. Scientists say this is because of EGCg and its ability to fight free radicals
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Aids Weight LossLike green tea and black tea, drinking rooibos tea is a good way to enjoy a delicious beverage without packing on the pounds. Each cup of rooibos tea contains only 2 to 4 calories, so you can drink this delightfully smoky beverage without worrying about ruining your diet. Keep in mind that adding sugar, honey or other sweeteners can rack up the calorie count, so keep additions to a minimum if your goal is to lose weight.
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.
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.
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.
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.
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.
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.
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.
Drinking up to 10 cups of oolong tea per day is generally considered to be safe for most people.
How to Prepare Oolong Tea
Oolong tea is widely available where other teas are sold, and you can often find it on café and restaurant menus. It’s available in loose-leaf form or pre-packaged in tea bags.
To make it at home, you want to use water that is just shy of boiling — around 190 degrees Fahrenheit or 90 degrees Celsius. This ensures the best flavor profile but also reduces nutrient loss. Higher water temperatures can destabilize and reduce the tea’s antioxidants like its polyphenols.
Researchers found that oolong tea has the strongest antioxidant activity when soaked at these temperatures for 3 minutes. You can also serve it iced by brewing it with hot water first and then allowing it to cool.
To make the perfect cup:
- Prepare about 2 tablespoons of loose-leaf tea or one tea bag.
- Heat water to just shy of boiling.
- Seep the tea for 3 minutes.
- Test the tea for your preferred taste, but remove it within 10 minutes to preserve the antioxidant activity.
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.