Oolong tea is made from leaves of the same plant that green and black teas come from. The difference lies in how long the leaves ferment. Green tea leaves are unfermented, while leaves for black tea are fully fermented. Oolong comes from leaves that are partially fermented.
Fermentation, or its lack, gives teas their color and aroma. It also alters tea's chemical makeup. The most notable changes happen in a group of chemicals called catechins. These are strong antioxidants that may act directly on human cells. There is good evidence to support tea drinking leads to longevity.
Why do people use oolong tea?
Tea is a caffeinated beverage. A major benefit of drinking oolong tea is heightened awareness and energy along with sharpened thinking skills.
Some drink oolong tea to prevent or treat obesity and diabetes. One study suggests that drinking six cups of oolong tea daily for 30 days might help people with type 2 diabetes reduce blood sugar. Other studies -- in both humans and animals -- suggest that drinking oolong tea can help in weight loss.
Some people drink oolong tea because of a belief that it helps with other conditions, such as:
- Heart disease
- High blood pressure
- Tooth decay
But studies done in these areas have been inconsistent and not conclusive.
Some studies have suggested tea might offer some protection against mental decline. While a recent study in China supported the idea that oolong tea might offer that protection, the results weren't conclusive and further study is needed.
Researchers have been interested in the potential of tea -- especially green tea -- to help treat or prevent some cancers. Studies .have linked high green tea consumption with reduction in cancer risk done on animals have been encouraging. The amount of green tea consumption is relatively high (7 cups a day lowers prostate cancer incidence). There are new studies on endometrial cancer potentially being staved off by green but not black tea. Some evidence suggests that women who drink two cups of tea daily -- green, oolong, or black -- can significantly lower their risk of ovarian cancer.
What are the risks of oolong tea?
The major risks of oolong tea are the risks associated with drinking caffeine chronically or excessively. They include:
- Rapid heartbeat
- Abdominal pain
- Nausea, vomiting, and diarrhea
- Increased urine flow
Caffeine can also cause complications for people with:
- Anxiety disorders
- Bleeding disorders
- Irritable bowel syndrome
- High blood pressure
For people with iron deficiency, drinking tea can interfere with the body's absorption of iron.