Mistletoe...usually it invokes thoughts of stolen smooches, or if you're a pet owner you may think of it as a no-no because it's toxic to most pets. But there are some who think of it as a therapeutic.
Last year around this time I researched the literature on mistletoe as an herb and found that a European variant is being sold by herbalists as a companion to cancer treatment. Now, that doesn't mean that the holiday mistletoe is not toxic, quite the opposite actually. The American variant of the plant, Phoradendron spp., is what we hang from the rafters in December, the herb being sold as an herbal supplement is the European variant, Viscum album. These are two completely different genus of plant, they just happen to be members of the same order (Santalales).
Ingestion of Phoradendron is known to cause death within 10 hours, and it should never be ingested, even as a light tea. The offending chemical components are beta-phenylethylamine, tyramine, and phoratoxin.
Viscum album, on the other hand, isn't toxic, but high doses can severely increase blood pressure (though the herb providers claim it decreases blood pressure). Studies on the anti-tumoral effects of the plant have been inconclusive, but advocates claim it activates the immune system and can used to treat AIDS.
Anecdotal evidence, the only kind of evidence for any physiological action of the plant, from chemotherapy patients is that it eases the pain of therapy. No wonder...it's been known since the 1600s that it's a narcotic. And it's also often mixed with valerian root, a sedative and mo0d-altering substance.
So is it the narcotic effect or a real phsyiological effect? It's probably similar to its American cousin's kiss - the anticipation is usually better than the real effect.