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Photo copyright Martin Wall

Mistletoe

Common name: European mistletoe

Botanical name: Viscum album

Parts used and where grown: Mistletoe grows as a partial parasite on a variety of trees—particularly pine, apple, plum, poplar, and spruce—across northern Europe and Asia. The young leafy twigs with flowers are used. Mistletoe’s white berries are potentially toxic and should be avoided. American mistletoe, various species of Phoradendron, are similar but have not been widely studied. They should not be substituted for European mistletoe until more information is available.



Mistletoe has been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
1Star Breast cancer
Diabetes
High blood pressure
HIV support
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Historical or traditional use (may or may not be supported by scientific studies): The ancient Druids of northern Europe and other pagan groups revered mistletoe, particularly when it infected oak trees (a rare occurrence). Over time, this reverence of mistletoe was translated into the Christian ritual of hanging mistletoe over doorways at Christmas. The custom of kissing under the mistletoe may be a remnant of pagan orgies held before mistletoe altars.1

The name mistletoe is said to derive from the Celtic word for “all-heal.” This correlates with its historical use for everything from nervous complaints to bleeding to tumors.2 It is difficult to categorize all of the uses of mistletoe, particularly when one looks at the vast number of uses for this herb in traditional Chinese and Korean medicine. In the early 20th century, Rudolf Steiner created what is known as anthroposophical medicine. This mystical system used a variety of unusual remedies, including special extracts of mistletoe for injection. Steiner helped bring mistletoe into the modern era of scientific research, particularly as a potential treatment for cancer.3

Active constituents: Several constituents have been shown to contribute to the medicinal action of mistletoe. Most notable are mistletoe lectins (also called viscotoxins), choline derivatives, alkaloids, polypeptides, and polysaccharides. Human pharmacological studies have found that mistletoe extract given by injection stimulates immune system function.4 5 6 Some test tube and animal studies suggest that certain mistletoe constituents, including the alkaloids, can also kill cancer cells.7 8 Numerous clinical trials have found that subcutaneous injections of mistletoe extracts can help people with cancer of various organs, though some have also failed to show any benefit.9 10 There is no evidence that people with cancer would benefit from receiving mistletoe orally.

Mistletoe’s other uses have been less rigorously studied. Preliminary trials carried out using oral mistletoe have found it can reduce the symptoms of high blood pressure, particularly headaches and dizziness.11 12 However, mistletoe has a small (if any) effect on actually lowering blood pressure.13

Test tube and animal studies suggest that mistletoe extracts can stimulate insulin secretion from pancreas cells and may improve blood sugar levels in people with diabetes.14 15 Given both mistletoe’s tradition around the world for helping people with diabetes and these promising preclinical results, human clinical trials are needed to establish mistletoe’s potential for this condition.

How much is usually taken? Traditionally a cold water extract (cold infusion) is made by soaking 2–4 teaspoons (10–20 grams) of chopped mistletoe in two cups (500 ml) of water overnight.16 This is taken first thing in the morning and can be sweetened with honey. Another batch is left to steep during the day and drunk at bedtime. Alternately a hot tea can be made by infusing 1 teaspoon (5 grams) of leaves in a cup (250 ml) of just-boiled water for 5–10 minutes. Two cups (500 ml) are consumed per day.17 A tincture, approximately 1/8 teaspoon (1/2 ml) three times per day, can also be used.

At least three standardized, injectable extracts have been studied in Europe: Iscador, Helixor, and Eurixor. These products are not designed for self-treatment and are not commercially available in the United States. Iscador is the only fermented extract of the three, and each is standardized in a different way, making comparisons between the extracts difficult. In addition, there are different forms of each extract taken from mistletoe growing on different host trees. Typically, one weekly injection providing 1 mg of mistletoe lectin I per kilogram of body weight is given. People interested in subcutaneous or other injectable forms of mistletoe should consult with a physician.

Are there any side effects or interactions? In the oral amounts mentioned above, mistletoe is rarely associated with side effects.18 Two reports, however, have confirmed the danger of ingesting mistletoe leaves and berries in large quantities, particularly when children accidentally eat the berries at Christmas.19 20 Many of these exposures involved American mistletoe and not European mistletoe. European mistletoe is less toxic than the American species. If six to twenty berries or four to five leaves are eaten, then activated charcoal or ipecac can be used at home to induce vomiting. Emergency room care is only indicated if more than 20 berries or five leaves are ingested or if symptoms develop at lower levels of exposure. Possible symptoms of overdose are nausea, vomiting, low blood pressure, or dizziness. Injectable forms of mistletoe may cause local redness and pain but otherwise have not been associated with serious side effects. It is not recommended to use mistletoe during pregnancy or breast-feeding. Mistletoe is not recommended for use in children.

At the time of writing, there were no well-known drug interactions with mistletoe.

References:

1. Walker BG. The Woman’s Encyclopedia of Myths and Secrets. San Francisco: Harper & Row, 1983, 661–3.

2. Duke JA. CRC Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press, 1985, 512–3.

3. Urech K. Mistletoe constituents and cancer therapy. J Anthroposophical Med 1993;10:54–63.

4. Hajto T. Immunomodulatory effects of Iscador: A Viscum album preparation. Oncology 1986;43(suppl 1):51–65.

5. Bocci B. Mistletoe (Viscum album) lectins as cytokine inducers and immunoadjuvant in tumor therapy. A review. J Biol Reg Homeostatic Agents 1993;7:1–6.

6. Bloksma N, Schmiermann P, de Reuver M, et al. Stimulation of humoral and cellular immunity by Viscum preparations. Planta Med 1982;46:221–7.

7. Jurin M, Zarkovic’ N, Hrzenjak M, Ilic’ Z. Antitumorous and immunomodulatory effects of the Viscum album L preparation Isorel. Oncology 1993;50:393–8.

8. Khwaja TA, Dias CB, Pentecost S. Recent studies on the anticancer activities of mistletoe (Viscum album) and its alkaloids. Oncology 1986;43(suppl 1):42–50.

9. Yarnell E. Is Viscum album a potential treatment for pancreatic cancer? HealthNotes Review 1999;6:88–90 [review].

10. Kleijnen J, Knipschild P. Mistletoe treatment for cancer. Review of controlled trials in humans. Phytomedicine 1994;1:255–60.

11. Bowman IA. The everlasting mistletoe and the cardiovascular system. Texas Heart Inst J 1990;17:310–4 [review].

12. O’Hare JP, Hoyt LH. Mistletoe in the treatment of hypertension. New Eng J Med 1928;199:1207–13.

13. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1985, 158–60.

14. Gray AM, Flatt PR. Insulin-secreting activity of the traditional antidiabetic plant Viscum album (mistletoe). J Endocrinol 1999;160:409–14.

15. Swanson-Flatt SK, Day C, Bailey CJ, Flatt PR. Evaluation of traditional plant treatments for diabetes: Studies in streptozotocin-diabetic mice. Acta Diabetologica Latina 1989;26:51–5.

16. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1985, 158–60.

17. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1985, 158–60.

18. Weiss RF. Herbal Medicine. Gothenburg, Sweden: Ab Arcanum and Beaconsfield, UK: Beaconsfield Publishers Ltd, 1985, 158–60.

19. Krenzelok EP, Jacobsen TD, Aronis J. American mistletoe exposures. Am J Emerg Med 1997;15:516–20.

20. Spiller HA, Willias DB, Gorman SE, Sanftleban J. Retrospective study of mistletoe ingestion. Clin Toxicol 1996;34:405–8.