Zia Zaidi RN/ BSN Candidate
University of Pennsylvania School of Nursing
Last Modified: May 3, 2013
Also known as Iscidor, Helixor, Isorel in European countries, Mistletoe is a plant that grows on trees such as 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. Leaves and branches are used in herbal remedies, though the berries are not used.
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 lescins and viscotoxins are the active ingredients in mistletoe extract.
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 or, less often, into a vein, pleural cavity or 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.
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 pulse, seizures and even death.
Purified mistletoe, which is formulated for injection, is considered safer and side effects include inflammation at injection sites, 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.