What does mistletoe do to humans?

Mistletoe is a parasitic plant that grows on trees and has been associated with various mythical properties over the centuries. In modern times, mistletoe has become a popular Christmas decoration, with the tradition that if two people meet under mistletoe, they must kiss. But what effects does mistletoe actually have on humans?

Quick Answers

In brief, some key points about mistletoe effects on humans include:

  • Eating mistletoe can cause gastrointestinal upset and is generally not recommended.
  • Mistletoe extracts have been used as alternative treatments for cancer, but clinical evidence is mixed.
  • Ingesting mistletoe can rarely induce allergic reactions or lower blood pressure.
  • Mistletoe contains compounds with potential antibacterial and anti-inflammatory properties.
  • Standing under mistletoe and kissing someone is not known to have any direct physiological effects.

Does Eating Mistletoe Have Any Effects?

Mistletoe is considered poisonous if eaten, though the toxic effects depend on the amount consumed. The main poisonous compounds in mistletoe are lectins and viscotoxins. Lectins can irritate the gastrointestinal tract, while viscotoxins act as neurotoxins and cardiotoxins.

Ingesting a few mistletoe leaves or berries may cause:

  • Stomach pain
  • Vomiting
  • Diarrhea
  • Dizziness
  • Blurred vision
  • Headaches

Consuming larger quantities of mistletoe could potentially lead to more dangerous effects like seizures, cardiac effects like slowed heart rate, and even death in rare cases. However, fatalities are generally seen only in cases of massive overdoses.

Due to these risks, purposefully ingesting mistletoe is not recommended. Mistletoe teas or extracts should be avoided without medical supervision. Accidental ingestion of a few berries or leaves may cause temporary digestive complaints but is unlikely to be life-threatening.

Table 1: Effects of Ingesting Mistletoe

Amount Ingested Possible Effects
A few leaves or berries Gastrointestinal upset, dizziness, headache
Larger quantities Seizures, slowed heart rate, potentially fatal in rare cases

Medical Uses of Mistletoe

While ingesting mistletoe is not recommended, mistletoe extracts have been used for centuries as an alternative therapy. In Europe, mistletoe extract injections are a common complementary treatment for cancer patients.

Mistletoe contains various compounds thought to have anti-cancer effects, including:

  • Lectins – May stimulate immune system to attack cancer cells
  • Viscotoxins – Cytotoxic effects that could kill cancer cells
  • Polysaccharides – Anti-inflammatory and immunostimulatory actions

However, clinical evidence on mistletoe efficacy against cancer is mixed:

  • Some studies show improved quality of life and possible anti-tumor effects
  • Other studies find no benefits for cancer treatment
  • More rigorous research is needed to confirm effects

Mistletoe extracts may also rarely trigger allergic reactions or lower blood pressure. Mistletoe injections should only be administered under medical supervision.

Table 2: Evidence for Mistletoe in Cancer Treatment

Potential Benefits Limitations
– Improved quality of life
– Possibly slowed tumor growth
– Lack of definitive evidence
– Potential side effects

Antimicrobial Effects

In addition to potential anti-cancer activities, some early research suggests mistletoe extracts may have other therapeutic effects stemming from their antimicrobial and anti-inflammatory properties:

  • Antibacterial – Lab studies indicate mistletoe lectins and viscotoxins may fight certain bacteria like Staphylococcus aureus and Escherichia coli.
  • Antiviral – Some components may combat viruses like HIV and herpes in test tube studies.
  • Anti-inflammatory – Mistletoe extracts reduced inflammation markers in animal models of arthritis.
  • Immunomodulatory – Mistletoe polysaccharides may enhance immune system function.

However, these antimicrobial and anti-inflammatory effects still require verification in human clinical trials before mistletoe can be recommended specifically for these uses.

Table 3: Potential Antimicrobial Effects

Proposed Effect Relevant Compounds
Antibacterial activity Lectins, viscotoxins
Antiviral activity NA-4 and other lectins
Anti-inflammatory Polysaccharides

Symbolic and Mythological Associations

Beyond any tangible medicinal uses, mistletoe has long been associated with mystical and legendary properties:

  • In Norse mythology, mistletoe was sacred to the god Baldur, said to have power over death.
  • The Celts believed mistletoe possessed magical healing powers, using it as an antidote to poisons.
  • Ancient Greeks called mistletoe “all-heal” and used it to remedy illnesses.
  • Mistletoe played a role in Druid rituals, believed to bestow fertility and protect against witchcraft.
  • In European folklore, branches hung over doorways were said to ward off evil spirits.

Of course, these mythical associations are not supported by scientific evidence. But the historical mystique around mistletoe may have contributed to its continued intrigue and use into modern times.

Table 4: Mythological Associations of Mistletoe

Ancient Culture Associated Beliefs
Norse Power over death and protection
Celtic Magical healing abilities
Greek Ability to cure illnesses
Druid Fertility, protection from witches

Romantic Associations and Kissing

In modern times, mistletoe has become firmly linked to Christmas traditions. The tradition of kissing under mistletoe seems to stem from European folk beliefs that mistletoe was an aphrodisiac or represented the generosity of the spirit of Christmas.

Some details on mistletoe’s romantic associations include:

  • 18th century England popularized kissing under mistletoe as a Christmas custom.
  • Tradition holds that a couple departing without a kiss will have bad luck.
  • Each kiss removes a berry, and no more kisses should occur when berries run out.
  • Mistletoe kissing played a role in marriage traditions, with unmarried men and women allowed kisses.

Standing under mistletoe and kissing passionately is unlikely to have any inherent physiological stimulation. However, the symbolism of mistletoe and romantic mindset certainly may contribute to feelings of affection!

Table 5: Traditions of Kissing Under Mistletoe

Traditional Belief Origin
Kiss for good luck England, 18th century
Remove berry per kiss Victorian era
Allowed unmarried to kiss 18th century marriage customs

Decorative and Culinary Uses

Today, mistletoe is most commonly incorporated into Christmas traditions through decorations and some limited culinary uses:

  • Mistletoe sprigs are hung in doorways and ceilings.
  • Mistletoe wreaths are placed on walls and used as table centerpieces.
  • The white berries are sometimes used in Christmas floral arrangements.
  • Teas made from younger mistletoe leaves are an occasional novelty drink.

While the leaves and berries are considered toxic, mistletoe teas are generally harmless in small quantities. The CDFW Poison Control Center notes that most commercial mistletoe preparations have the toxins removed. Larger ingestion of leaves or teas could potentially cause adverse effects like GI problems.

Table 6: Modern Uses as a Holiday Decoration

Use Details
Hanging sprigs Doorways, ceiling, over beds
Wreaths On walls, table centers
Floral arrangements Berries used decoratively
Teas Novelty drink from young leaves


Mistletoe is steeped in tradition and mythological associations dating back centuries. While ingesting the plant can cause toxicity, mistletoe extracts have been incorporated into alternative cancer therapies. Evidence is still preliminary and conflicting on any direct health benefits.

In modern times, mistletoe remains most prominent around Christmas, where it plays a decorative role and perpetuates the tradition of kissing beneath its branches. While no physiological effects stem from standing under mistletoe and kissing, the romantic symbolism persists.

So while mistletoe itself may not physically transform or heal humans, its enduring symbolism and incorporation into customs continue to intrigue people during the holiday season.

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