Eucommmia bark is the gray, grooved bark of the tree Eucommia ulmoides, commonly called the hardy rubber tree or the gutta-percha tree. The Chinese name for eucommia bark is Du Zhong. This name refers to a Taoist monk who was said to be immortal, suggesting that the herb provides long life, good health, and vitality. The tree is a member of the rubber family and is native to the mountainous regions of China. It normally grows to about 50 ft (15 m) in height. Small patches of bark are harvested from trees over 10 years old in late summer and early autumn. The outer bark is peeled away and the smooth inner bark is dried. This inner bark contains a pure white, elastic latex that is thought to contain the compounds that account for eucommia bark's healing properties. Older, thicker inner bark with more latex is considered more desirable for the herbalist to use than younger, thinner bark.
Although traditionally only the bark of E. ulmoides was used for healing, research in the later half of the 1990s in Japan indicates that the leaves also have healing properties. The green leaves are shiny, narrow, and pointed. The tree's flowers are very small and are not used in healing.
Eucommia bark has been used in traditional Chinese herbalism for over 3,000 years. Since the tree does not grow widely outside China, this herb was not used in other cultures until recently.
Eucommia bark is strongly associated with the kidneys and to a lesser extent with the liver. In Chinese medicine, the kidneys store jing. Jing is an essential life source and associated with whole body growth and development, as well as normal sexual and reproductive functioning. The kidney and liver jing also affects the bones, ligaments, and tendons.
In the Chinese system of health, yin aspects must be kept in balance with yang aspects. Ill health occurs when the energies and elements of the body are out of balance or in disharmony. Health is restored by taking herbs and treatments that restore that balance.
Eucommia bark is the primary herb used to increase yang functions in the body. However, it also supports yin functions. Eucommia bark helps to build strong bones and a flexible skeleton with strong ligaments and tendons. It is a primary herb used to heal tissues that are slow to mend after an injury or that have weakened through stress or age. It is given to treat lower back and leg pain , stiffness, arthritis, and knee problems including continual dislocation. Eucommia bark is also believed to have diuretic properties that aid in reducing swelling. Although it can be used alone, eucommia bark is most often used in conjunction with other herbs that support its functions.
In addition to healing tissues, eucommia bark has two other major functions. In pregnant women it is given to calm the fetus, soothe the uterus, and prevent miscarriage. Eucommia bark also has the ability to reduce blood pressure. This property has been investigated since 1974, and may be related to its mild diuretic action. Eucommia bark is used in almost all Chinese formulas to lower blood pressure.
Other modern uses of eucommia bark include treatment of impotence , premature ejaculation, and as a mild anti-inflammatory. It is included in tonics that boost the immune system and generally improve wellness. However, there is little rigorous scientific research to support these uses.
In the late 1990s Japanese researchers became interested in eucommia bark. In 2000, researchers at Nihon University in Chiba, Japan, published two studies showing that both the leaves and the bark of Eucommia ulmoides contained a compound that encourages the development of collagen in rats. Collagen is an important part of connective tissues such as tendons and ligaments. However, they found that the compound was present in much greater quantities in fresh leaves and fresh bark, and that much of it was destroyed during the drying process.
In modern Japan, eucommia leaves are also believed to help with weight loss by reducing the urge to eat. For this reason, in the late 1990s eucommia leaves became an increasingly popular herb there. However, there are no scientific studies to support this function of the herb.
Eucommia bark is harvested and dried. Before boiling, it is sliced to expose the inside of the bark. The bark is then boiled to make a decoction. Generally this decoction is combined with other herbs and extracts to create yang enhancing tonics to treat kidney and liver deficiencies and impotence.
Eucommia bark has a long history of use with no substantial reported problems.
No side effects have been reported with the use of eucommia bark.
Eucommia bark is often used in conjunction with other herbs with no reported interactions. Since eucommia bark has been used almost exclusively in Chinese medicine, there are no studies of its interactions with Western pharmaceuticals. People who are taking tonics containing eucommia bark should tell their doctors before taking traditional drugs, especially drugs that regulate blood pressure.
Molony, David. Complete Guide to Chinese Herbal Medicine. New York: Berkeley Books, 1998.
Teegaurden, Ron. The Ancient Wisdom of the Chinese Tonic Herbs. New York: Warner Books, 1998.
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