Oolong tea is a delightful mix between green and black tea, and has often been called "blue-green tea." This tea is manufactured from the tree, Camellia sinensis, from which other types of tea are also produced. The difference is in the processing. Oolong tea is partially fermented, black tea is fully fermented, and green tea is unfermented. It is harvested when the leaves are partially photosynthesized, anywhere between 10-70%. Thus it generally has a darker, richer flavor than green tea, but a lighter flavor than black tea. It is a familiar taste to anyone who frequents Chinese restaurants, as it is the most frequent tea choice served along with meals.
Tea lovers tend to be fans of numerous varieties of oolong. Most attest that it is not merely the taste but also the fragrance of oolong tea, which lends such appeal to the tea. Taste varies with different varieties. Many attribute a strong initially bitter taste and a sweet, melon-like finish to oolong. Oolong tea is thought to be so fragrant because the leaves are harvested when the essential oils of the tea are most present and strong. Others enjoy oolong tea because the roasting process seems to make the tea rather gentle on the stomach.
In China, oolong tea was often part of traditional medicine for curing digestive problems. It has also been thought to be of help in headaches. The benefits of green and black tea in modern medicine are their presence of antioxidants, which may prove helpful in reducing the effects of aging and in fighting cancer.
Oolong tea is used to sharpen thinking skills and improve mental alertness. It is also used to prevent cancer, tooth decay, osteoporosis, and heart disease. Some people use oolong tea to treat obesity, diabetes, "hardening of the arteries" (atherosclerosis), high cholesterol and skinallergies such as eczema; and to boost the immune system.
Oolong tea contains caffeine. Caffeine works by stimulating the central nervous system (CNS), heart, and muscles. Oolong tea also contains theophylline and theobromine, which are chemicals similar to caffeine.
Oolong tea comes in various grades, and is often considered the most desirable of Chinese teas. Some oolong tea is served after being dried and packaged. Other variants are aged, producing complex flavors and greater expense to the consumer. Most varieties of oolong are roasted after air-drying. They then go through a further drying process before being packaged.
Ooolong tea characteristics lie between green and black tea. The processing of oolong tea is quite complex as compared to other types of teas. Green tea is not at all oxidized, black tea is completely oxidized, while oolong tea is semi-oxidized. It is oxidized in the range of 10 to 70%. Oolong tea is generally harvested in the spring season. Once the leaves are ready for manufacturing, they are plucked and left to dry. After drying, they are collected in baskets for withering. Withering bruises the edges of the leaves which initiates the process of oxidation. Oxidation of leaves is nothing but reaction of fresh leaves with the atmospheric oxygen. To stop the process of oxidation, the leaves are fired. Once the leaves are roasted they are rolled and fired for a few more times and after complete cooling, they are fired once more for the last time. The level of the oxidation decides the quality and features of oolong tea.
Oolong tea prospers best in mountainous regions with relatively harsh climates. Primarily, oolong is grown in China on Wu-Yi mountain. In the south Fujian province, Tie Guan Yin, is also quite popular. On Wu-Yi, Da Hong Pao, is one of the most popular Chinese teas ever.
Since the 1800s Taiwan has also produced numerous excellent oolong teas. These include Dong Ding and Pouchong. Dong Ding is extremely fragrant and will entice any lover of tea. But one enjoys it at a price. 21 ounces (595.33g) of the tea can cost up to 100 US dollars (USD). One can also buy oolong grown in India and in Vietnam. Darjeeling oolong from India is highly prized.
Oolong tea has a number of health benefits. It is considered as one of the effective ways of losing weight and there is scientific evidence for the relation between oolong tea and weight loss. Regular consumption of oolong tea, along with proper diet and exercise has benefited many people in controlling their obesity. There are also other health benefits of oolong tea that include improvement of the immune system. Regarding questions about oolong tea and caffeine, of course caffeine is one of the contents of oolong which plays an important role in weight loss. Caffeine activates the nervous system for a process called thermogenesis. It is a process where fat is used as fuel. This burns the body fat and thereby cuts down weight. Oolong tea also contains polyphenols. These polyphenols increase the rate of metabolism, prevents tooth decay, etc. Oolong tea also helps to destroy free radicals that are responsible for cancer and aging.
The health benefits of oolong tea is almost similar to green tea benefits, as the former is also a rich source of polyphenols. These polyphenols fight the triglycerides and free radicals in the body, which are responsible for many diseases, like cancer. Green tea has proven to lower cholesterol, reduce blood pressure (lowering the risk of heart attacks), aid digestion, fight fatigue, preserve younger-looking skin and promote oral health. Recent animal studies have shown that green tea extracts protect against various cancers.
Contains Antioxidants: Free radicals (obtained from the air, food and sunlight) in the body can cause aging of the skin, wrinkles, dark spots, cancer, Alzheimer's disease, arthritis and certain other diseases. Oolong tea possess antioxidants that help destroy free radicals even before they can harm us. A comparative study done in 2003, by Kenichi Yanagimoto, revealed that oolong tea possessed more potent antioxidants as compared to black tea, but less potent antioxidants as compared to green tea.
Improves Heart Health: A Japanese study conducted in 2001, stated that one month of regular oolong tea consumption could result in reduction of cholesterol levels. In another Japanese study in 2004, it was reported that oolong tea increases plasma adiponectin levels. Low levels of plasma adiponectin result in type 2 diabetes mellitus, obesity, and coronary artery disease (CAD). Triglycerides are the most common form of fat present in the body, and is the cause of many heart health issues. An American study, conducted on rats, in 2007, revealed that oolong tea reduces blood concentrations of triglycerides by 80%. Thus consumption of oolong tea promotes heart health.
Reduces High Blood Pressure: Studies conducted in 2004, stated that drinking oolong tea for a year reduced high blood pressure. Regular tea drinkers having one cup a day were 45% less prone to have high blood pressure and 65% less likely to develop high blood pressure if more than 2 cups were consumed per day.
Heals Skin Ailments: Green tea does have anti-allergic properties. A study was conducted in 2001, by Uehara of the Shiga University, to find out if oolong tea also has similar properties. The study revealed that oolong tea helped treat recalcitrant type (does not respond to conventional treatment) atopic dermatitis (skin disease). The study was carried out on 118 people suffering from atopic dermatitis. These people were asked to drink a liter of oolong tea, made from 10 grams of leaves, every day in addition to their dermatological treatment. After one month, 63% patients showed moderate improvements. It is also believed to improve skin color.
Prevents Tooth Decay: According to a study conducted by Nakahara in 1993, oolong tea is said to inhibit the enzyme activities of the bacteria streptococci. Streptococci bacteria causes dental plaque formed on teeth, thereby resulting in dental caries. Thus by inhibiting this bacteria, oolong tea plays prevents tooth decay. Experts from the Department of Dentistry at Osaka University said that this tea also helps strengthen tooth enamel.
Assists in Weight Loss: Various studies conducted have revealed that oolong tea increases metabolism, burns fat and blocks dietary fat absorption. Oolong tea is known to possess calorie-burning catechin polyphenols, which, in combination with exercise and proper diet, help lose weight.
Taking oolong tea in large or more than required quantity will cause certain side effects. All the oolong tea side effects are basically because of caffeine present in it. Following is a list of some major oolong tea side effects.
Hypokalemia: Hypokalemia is a disorder that is marked by abnormally low concentrations of potassium in serum. It is one of the most common oolong tea side effects because excessive consumption of caffeine interferes with the absorption of potassium and eventually results in hypokalemia.
Upset Stomach: Caffeine and tannin present in oolong tea stimulate the production of gastric acid in stomach. It may be a problem for those who are suffering from heartburn and stomach ulcer. Excess of gastric acid may rise up and spill into the esophagus. It causes mild to severe irritation.
Beriberi: Oolong tea interferes in the absorption of vitamin B1 or thiamine. Thus, over-consumption of oolong tea can lead to deficiency of thiamine in body. Lack of thiamine in body is known as beriberi. This is another example of common oolong tea side effects.
Failure of Medications: Some substances present in oolong tea are believed to interact with certain medications. Thus, excessive consumption of oolong tea can give you side effects in the form of nil or reduced result of some medications.
Pregnancy and Breast-feeding Complications: If you are pregnant or breast-feeding, oolong tea in small amounts is probably not harmful. However, do not drink more than 2 cups a day of oolong tea. That amount of tea contains about 200 mg of caffeine. Too much caffeine during pregnancy might cause premature delivery, low birth weight, and harm to the baby. Too much caffeine during breast-feeding might cause irritability and increase bowel movements in nursing infants.
Kidney Damage: Oolong tea contains some organic acids, better known as oxalates. Oxalates are considered to be one of the causative agents of kidney damage. However, studies have shown that very high levels of oxalates are required to produce such negative effects on human body. Still, you can call kidney failure as one of the other possible oolong tea side effects.
Tea Allergy: Some people are naturally allergic to caffeine and tannin. Their high concentrations obtained from oolong tea may worsen the allergy. Therefore, people hypersensitive to these substances should stay away from oolong tea.
Weak Bones (Osteoporosis): Drinking oolong tea can flush out calcium in the urine. That can affect bone health. If you have osteoporosis, don't drink more than 3 cups of coffee per day. Consider taking calcium supplements to make up for the calcium that is flushed out. If you have a genetic condition that harms the way your body processes vitamin D, get medical advice before consuming a lot of caffeine.
Glaucoma: The caffeine in oolong tea increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes.
Irritable Bowel Syndrome (IBS): Oolong tea contains caffeine. The caffeine in oolong tea, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.
There can be a number of oolong tea effects associated with caffeine present in it. These are restlessness, irritability, heart palpitations, tremor, loss of appetite, sleeping disorders and frequent urination. All of these conditions are also the result of various other types of physiological disorders. Hence, before concluding oolong tea as the exact cause, a medical examination is a must for proper diagnosis.