Mistletoe is a parasitic evergreen plant that lives on trees such as oaks, elms, firs, pines, apples, and elms. The parasitic plant has yellowish flowers; small, yellowish green leaves; and waxy, white berries. There are many species of this plant in the Viscacea and Loranthacea plant families. European mistletoe (Viscum album) and American mistletoe (Phoradendron leucarpum) are used as medical remedies. In addition to Europe and North America, mistletoe is also found in Australia and Korea.
Mistletoe berries are poisonous to cats and other small animals. There is, however, some debate about how toxic the berries are to humans, and there is controversy about whether it is safe to use mistletoe as a remedy. Mistletoe is also known as mystyldene, all-heal, bird lime, golden bough, and devil's fuge.
Mistletoe is known popularly as the plant sprig that people kiss beneath during the Christmas season. That custom dates back to pagan times when, according to legend, the plant was thought to inspire passion and increase fertility.
In the centuries since then, mistletoe has acquired a reputation as a nearly all-purpose herbal remedy. In the seventeenth century, French herbalists prescribed mistletoe for nervous disorders, epilepsy, and the spasms known as the St. Vitus dance.
Mistletoe has also been used in folk medicine as a digestive aid, heart tonic, and sedative. It was used to treat arthritis, hysteria and other mental disturbances, amenorrhea, wounds, asthma, bed wetting, infection, and to stimulate glands.
For centuries, mistletoe also served as a folk medicine treatment for cancer, and the plant is currently used in Europe to treat tumors. Iscador is an extract of the European mistletoe plant that is said to stimulate the immune system and kill cancer cells. It reportedly reduces the size of tumors and improves the quality of life. One team of researchers in France has found evidence that mistletoe extracts increase the efficiency of the body's natural killer cells in destroying cancer cells. A German study published in 2002 indicates that Iscador does indeed inhibit tumor growth. Another recent German case study of an 80-year-old woman with metastasized breast cancer documented that the patient lived for 41 months after first being given Iscador, with good quality of life. Iscador is one brand name of the mistletoe extract in Europe, and other brand names include Helixor and Eurixor.
Other contemporary uses of mistletoe include treatment of rheumatism, anxiety, migraine headaches, dizziness, high blood pressure, relief of spasms, asthma, rapid heartbeat, diarrhea, hysteria, and amenorrhea. Research continues on the use of mistletoe to treat AIDS patients.
There are some differences among the species. American mistletoe is said to cause a rise in blood pressure, while its European counterpart is believed to lower blood pressure.
Although mistletoe appears to be a multipurpose remedy, there is disagreement among medical experts about the safety and effectiveness of this herb. The number of possible interactions with other medications described below indicates that mistletoe should be used with caution.
In alternative medicine, the leaves, twigs, and sometimes the berries of mistletoe are used. In Europe, mistletoe remedies range from tea made from mistletoe leaves to injections of Iscador. While European research indicates that mistletoe is safe and effective, sources in the United States maintain that the berries are poisonous and that the herb can cause liver damage.
Since mistletoe has not been tested by the United States Food and Drug Administration (FDA), many experts urge caution until more research is completed. European research includes work completed by Germany's Commission E, a governmental agency that studies herbal remedies for approval as over-the-counter drugs. An English version of the German Commission E monographs was published in 1997 and was the basis for the 1998 PDR (Physicians'Desk Reference) for Herbal Medicines.
Mistletoe tea may be taken for high blood pressure, asthma, epilepsy, nervousness, diarrhea, hysteria,
Mistletoe wine is prepared by mixing 8 tsp (40 g) of the herb into 34 oz (1 L) of wine. After three days, the wine can be consumed. Three to four glasses of medicinal wine may be consumed each day.
Mistletoe must be stored away from light and kept above a drying agent.
Iscador, the European extract, may be injected before surgery for cancers of the cervix, ovary, breast, stomach, colon, and lung. Cancer treatments can take several months to several years. The treatment is given by subcutaneous injection, preferably near the tumor. Iscador may be injected into the tumor, especially tumors of the liver, cervix, or esophagus.
The dosage of Iscador varies according to the patient's age, sex, physical condition, and type of cancer. The treatment usually is given in the morning three to seven days per week. As treatment continues, the dosage may be increased or adjusted.
European cancer research has been conducted since the 1960s, and most has involved European mistletoe. However, researchers believe there may be some similar active components in other species. In the United States, some cancer patients may qualify for participation in clinical trials of Iscador.
Advocates of Iscador believe it can stimulate the immune system, kill cancer cells, inhibit the formation of tumors, and extend the survival time of cancer patients. They maintain that mistletoe can help prevent cancer and serve as companion therapy for standard cancer treatments. They also think that mistletoe could possibly repair the DNA that is decreased by chemotherapy and radiation.
In general, however, American researchers are skeptical about European claims regarding mistletoe as an effective cancer remedy. The latest information summary on mistletoe extracts, updated in May 2002 and available from the National Cancer Institute web site, states that "There is no evidence from well-designed clinical trials that mistletoe or any of its components are effective treatments for human cancer."
Mistletoe extract has been used to combat AIDS. In 1998 European studies, Iscador injections were used to improve the immune response. Experts reported from early results that when patients were given Iscador, no additional progression of HIV was seen. The combination of Iscador with standard therapy could be potentially beneficial, but more research is needed.
In 1996, the first United States patent was issued for T4GEN, a pharmaceutical version of the mistletoe extract. ABT Global Pharmaceutical of Irvine, California (the patent owner) has developed the synthetic version to be tested and potentially approved as a drug by the FDA. As of summer 2000, there have been no further announcements about T4GEN research.
Opinions are sharply divided on how safe and effective the herb is as a home remedy and in the treatment of conditions like cancer and AIDS. There is controversy about which parts of the plants are poisonous. Although the berries are classified as poisonous in the United States, some sources say that eating berries is only dangerous for babies, and only if handfuls are consumed. Pregnant or breast-feeding women, however, should not use the plant.
According to a report from the Hepatitis Foundation International, mistletoe is toxic to the liver. However, the PDR for Herbal Medicines advises that there are no health hazards when mistletoe is taken properly and in designated therapeutic dosages. Other sources state that mistletoe's toxicity could cause cardiac arrest.
People considering mistletoe should consult with their doctor or practitioner. Until there is definitive proof otherwise, there is a risk that the herbal remedies will conflict with conventional treatment.
Herbal experts including Varro Tyler advise against using mistletoe as a beverage or home remedy until more definitive research is completed. Tyler, a respected pharmacognosist, is the coauthor of the 1999 Tyler's Honest Herbal.
Mistletoe may be potentially toxic to the liver. For people diagnosed with hepatitis, use of an herb like mistletoe may cause additional liver damage. However, advocates of mistletoe point out that the herb has been tested in Europe. That research indicated less severe side effects. Mistletoe extracts can produce chills, fever, headache, chest pain, and orthostatic circulatory disorders.
Commercial mistletoe extracts may produce fewer side effects. The body temperature may rise and there may be flu-like symptoms. The patient may experience nausea, abdominal pain, and (if given the extract injection) inflammation around the injection sight. In a slight number of cases, allergy symptoms have resulted.
Mistletoe shouldn't be used by people who take monoamine oxidase (MAO) inhibitor antidepressants like Nardil. Potential reactions include a dangerous rise in blood pressure and a lowering of blood potassium levels (hypokalemia). In addition, mistletoe appears to interfere with the action of antidiabetic medications; to increase the activity of diuretics; and to increase the risk of a toxic reaction to aspirin or NSAIDs. Cancer patients considering mistletoe treatment should first consult with their doctor or practitioner.
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Rebecca J. Frey, PhD