Chinese foxglove root
Chinese foxglove root is a perennial herb found in northern China. It grows 6-8 in (15-20 cm) tall and has long oval leaves that are covered with fine hairs, fluted flowers that are reddish orange tinted with purple, and a round fruit. The root is thick and reddish yellow. Chinese foxglove root is collected in the fall. Its Latin name is Rehmannia glutinosa and it is also called Rehmannia chinensis.
In China, Chinese foxglove root is used as a remedy for many different ailments: blurred vision, chronic fever, constipation, heart palpitations, hearing problems, hot flashes, insomnia, light-headedness, low back pain, menstrual irregularity and uterine bleeding (especially after childbirth), night sweats, restlessness, and stiff joints. It is also used to combat the effects of aging. Its effectiveness in treating these ailments has not been verified.
Chinese foxglove root is washed and dried in the sun. It is sold in large, fleshy brownish-yellow chunks and tastes sweet and moist. The root is used in two stages of preparation: dried and cooked. To make dried Chinese foxglove root, called sheng di huang or dry Rehmannia, the fresh root is removed from the sand, washed well, then dried in the sun during the winter. Cooked Chinese foxglove root, called shu di huang or cooked Rehmannia, is prepared by steaming the fresh root until it is cooked, letting it dry, then steaming and drying it again several times. Cooking Chinese foxglove root is said to enhance the herb's properties as a blood tonic. To combat the effects of aging, the root is prepared with cardamon so that it is easier to digest and used as a tonic. The raw form of the root is a cooler herb and used for symptoms of heat. The cooked root is more of a blood tonic.
Chinese medicine practitioners also make special preparations of Chinese foxglove root for specific ailments. It can be mixed with gelatin for coughing and vomiting blood, nosebleeds, and bleeding from the uterus. It can be mixed with cornus and Chinese yam or freshwater turtle shell as a remedy for symptoms such as forgetfulness, insomnia, and lightheadedness. Rehmannia is the main ingredient in the Chinese six flavor Rehmannia tonic used for ailments and discomfort such as frequent urination, infertility, impotence, and weak and painful knees.
Both cooked Chinese foxglove root and the raw version are available in Chinese pharmacies, Asian markets, and some Western health food stores. There are no formal guidelines for recommended doses of Chinese foxglove root.
People who have digestive problems, especially those who tend to have gas or become bloated, should use Chinese foxglove root with care; the cooked root can swell the belly and cause loose stools. There is no information available on what happens to people who take an overdose of Chinese foxglove root.
The use of Chinese foxglove root can cause diarrhea, nausea, and abdominal pain. Many Chinese herbalists include grains-of-paradise fruit, a kind of cardamon, in their Chinese foxglove root preparations to prevent these side effects.
No interactions due to use of Chinese foxglove root have been reported.
Reid, D. A Handbook of Chinese Healing Herbs. Boston: Shambhala Pubns., Inc., 1995.
Sifton, David W., ed. The PDR Family Guide to Natural Medicines & Healing Therapies. New York: Three Rivers Pr., 1999.
China-Med.net. Traditional Chinese Medicine. "Radix Rehmanniae." Paracel@clarityconnect.com. http://www.chinamed.net/herb_search.html. (May 2000).
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