Mistletoe (Viscum album)
Also known as Iscidor, Helixor, Isorel in European countries, mistletoe is a plant that grows on trees such as apple, pine, oak, and elm. Scientifically, it is known as viscum album and is a semiparasitic plant due to its ability to absorb nutrients from its host plant. Though there are many regional variants, the most recognizable is the Western European version, which is characterized by its rounded emerald leaves as well as white berry clusters that can have anywhere from 2 – 6 berries. The Eastern European version can have as many as 10 berries and shorter broader leaves.
Historically speaking, mistletoe was considered an antidote for poisons as well as a remedy for barrenness and constipation. It has cultural significance, as some Cornish traditions made replicas of the Cross out of mistletoe. There is also, of course, the common act of kissing someone if you are both "under the mistletoe".
As an alternative form of medicine in European countries, mistletoe is regarded as an effective medication in treating cancer. Mistletoe extract has been shown to kill cancer cells in laboratory animals and to boost the immune system by increasing the number of white blood cells. It has also been shown to reduce the side effects of chemotherapy and radiation therapy and improve quality of life. There have been numerous studies addressing these uses, though weaknesses in these research studies have prevented mistletoe from being available commercially in the U.S. Researchers believe it fights cancer by preventing the creation of blood vessels that help cancerous tumors grow. For this reason, mistletoe has been classified as a biological response modifier and anti angiogenic.
Researchers believe viscotoxins, polysaccharide and lectins are the active ingredients in mistletoe extract.
Parts Used and Preparations Available
Mistletoe extracts can vary greatly depending on the species of plant used, how it is prepared and even what time of year it is harvested, making study results difficult to generalize. Mistletoe extracts are available in many parts of Europe and are usually given by injection under the skin. Less often they are given into a vein, pleural cavity or directly into a tumor. The U.S. Food and Drug Administration (FDA) has not approved the use of mistletoe for any medical purpose in the US outside of research. For this reason, it is still under development as a conclusive adjunct therapy for cancer treatment.
Side Effects and Safety Concerns of Herbal & Nutritional Supplements
Depending upon which species of mistletoe is used, side effects can vary. Due to the poisonous properties, raw mistletoe leaves, branches and berries should not be consumed. Mistletoe can cause stomach pain, diarrhea, low heart rate, seizures and even death.
Purified mistletoe, which is formulated for injection, is considered safer and side effects include inflammation at the injection site, headache, fever, and chills, though these are not very common. Side effects of purified mistletoe have been considered minor and not prevalent enough to warrant concern, unless of course one is allergic and it results in anaphylactic shock.
Mistletoe extracts. National Cancer Institute. 2019.
Mistletoe from the National Center for Complementary and Alternative Medicine (NCCAM). 2016.
Grossarth-Maticek, R., Kiene, H., Baumgartner, S. M., & Ziegler, R. (2001). Use of Iscador, an extract of European mistletoe (Viscum album), in cancer treatment: prospective nonrandomized and randomized matched-pair studies nested within a cohort study. Alternative therapies in health and medicine, 7(3), 57.
Kienle, G. S., & Kiene, H. (2010). Review article: Influence of Viscum album L (European mistletoe) extracts on quality of life in cancer patients: a systematic review of controlled clinical studies. Integrative Cancer Therapies, 9(2), 142-157.
Kleijnen, J., & Knipschild, P. (1994). Mistletoe treatment for cancer review of controlled trials in humans. Phytomedicine, 1(3), 255-260.
Ostermann, T., Raak, C., & Büssing, A. (2009). Survival of cancer patients treated with mistletoe extract (Iscador): a systematic literature review. BMC cancer, 9(1), 451.