One of the most widely cultivated plants in the world goes by the botanical name Camellia sinensis. The two most common varieties are the subspecies sinensis, Chinese tea, and the subspecies assamica, Assam tea. The mature leaves of the Chinese tea plant are the source of three distinct beverages: black, green, and oolong teas. These three varieties are differentiated by the degree of oxidation, or fermentation, of the leaves. Black tea leaves are fully oxidized and green tea leaves are not oxidized at all. While green tea is often cited for its healing capabilities, the partially-oxidized oolong tea seems to have its own unique set of healing powers.

Green tea leaves turn black from oxidation, accounting for the green and black versions being named by their colors, but there is not complete agreement about the origin of the name oolong.

a photo of a cup of hot tea

Oolong tea may possess a unique form of polyphenol with unique benefits.

One interesting possibility of the name’s origin is the story of an ancient tea harvester named Wu Liang (pronounced “woo lee-ong”). His name was misunderstood as Wu Long, and then further distorted into Oolong. At any rate the story goes that toward the end of a day of picking tea leaves, he was distracted for a long time by the sight of a deer. By the time he got back to his collection of tea leaves, they had partially oxidized.

It was in the vicinity of 4700 years ago in China that a variety of health benefits were first attributed to drinking tea from the Camellia sinensis plant. Modern research into its possible medicinal value has focused on a particular group of antioxidant nutrients found in plants and known as polyphenols. The oxidation process decreases the level of some of the polyphenols in tea, so that green tea is the richest source overall; however, in oolong tea there is apparently a unique form of polyphenol with its own benefits.


One of the proven effects of oolong and green teas is the protection of teeth from the acid produced by the bacteria Streptococcus mutans. In laboratory cultures, an extract of green tea has succeeded in killing the bacteria. Research has shown that not only the growth of the bacteria, but their adherence to the tooth surfaces, as well as their production of acid, are all inhibited by oolong tea. This translates to a preventive effect against tooth decay.


Eczema is a term that refers to a group of inflammatory skin conditions, the most common type being atopic eczema, or atopic dermatitis. Atopic dermatitis is an inflammation of the skin that occurs in conjunction with allergic sensitivities. In animal studies, black, green, and oolong teas helped to suppress allergic reactions.

In a human study, one in which only the oolong variety was used, 121 patients with atopic dermatitis had failed to respond to treatment with topical steroids, oral antihistamines, and avoidance of factors that were aggravating to inflammation. Their ages ranged from 16 to 58, with an average age of 24. Every day for six months they each drank a liter of oolong tea, dividing it into three servings, one with each meal. The conventional treatment protocol was continued during this period. There was not a placebo control group for comparison, but benefits began to be noticed within the first one or two weeks. At the end of six months, 55% of the patients were rated as either moderately or markedly improved.

Blood Sugar

Yet surely the most impressive demonstration of oolong’s potency as a medicine was the study published in the medical journal Diabetes Care in 2003. This was a trial of twenty patients with Type 2 diabetes, the common condition in which blood glucose (sugar) levels are abnormally elevated. All of the participants were taking prescription medication to try to reduce blood glucose levels. In this study each patient drank 1.5 liters of oolong tea per day for thirty days. Then, in a separate thirty-day period used as a control trial, each drank 1.5 liters of water per day. Blood glucose normally ranges between 70 and 100. At the beginning of the tea-drinking month, the average blood glucose level for the group was 229. By the end of that period, that average had dropped to 162. At the start of the water-drinking interval, average blood glucose was at 209; at the end, it had risen to 232.

The polyphenols are likely responsible for the observed improvement, since their capacity to lower blood glucose is suggested by animal studies. Yet, another possibility is that the favorable change resulted from the lowering of elevated iron levels, iron being a pro-oxidant. Reducing high iron storage levels has been shown to help control diabetes, and both black and green teas are known to inhibit iron absorption. It is likely, then, that the oolong variety does the same. And it may have been a combination of the two, the increased antioxidant effect of polyphenols and the decreased pro-oxidant effect of lowered iron storage levels.

Oolong tea, as we have seen, with its high content of antioxidants, is beneficial to problems of the teeth, the skin, and the metabolism of sugar. This should make us stop and realize that in our desire to live and age healthfully, the higher nutritional potency of the foods and beverages we select may be helping us in widely diverse ways. It is surely a broad range of illnesses that we may never incur by arming our systems with the right chemistry.