amygdalin
Meaning of amygdalin: A bitter kernel compound sold as a cancer cure under the name laetrile, whose breakdown in the gut releases cyanide.
Definition of amygdalin
Amygdalin is a plant compound found in the kernels of bitter almonds, apricots, peaches and cherries, and in apple seeds. Chemically it is a sugar joined to a fragment carrying a cyanide group. Enzymes within the plant, and bacteria in the human gut, split the molecule apart and release hydrogen cyanide. It has been promoted for decades as a cancer treatment under the name laetrile.
Is it the same thing as laetrile?
Not exactly, although the names are used interchangeably. Laetrile is a semisynthetic compound patented as a modified version of the natural product, and the material sold under either name has varied widely in what it actually contains. It has also been marketed as vitamin B17, which it is not. No vitamin status has ever been established for it: there is no deficiency state, no requirement for it in the diet, and no role for it in normal body chemistry. The name was chosen for marketing.
Was the anticancer claim tested?
It was, and the theory behind it collapsed first. Advocates argued that cancer cells hold more of the enzyme that liberates cyanide and less of the enzyme that neutralizes it, so the poison would be released selectively inside the tumor. Measurements did not bear that out; the pattern of enzymes in tumor and normal tissue is not arranged that way. Formal clinical testing in people with advanced cancer followed and found no shrinkage of tumors, no improvement in symptoms and no gain in survival, while several participants showed blood cyanide levels approaching the toxic range. The compound is not approved in the United States, and its interstate shipment is prohibited.
Why is it dangerous?
| Route | What happens |
|---|---|
| By mouth | Gut bacteria split the molecule and free cyanide |
| Into a vein | Far less cyanide released, so far less toxic |
| Raw kernels eaten | Plant enzymes release cyanide during chewing |
Cyanide blocks the step by which cells use oxygen, so tissues suffocate while the blood remains fully oxygenated. Headache, dizziness, nausea, confusion and drooping of the eyelids give way to seizures and coma as the dose rises. Poisoning cases continue to appear, usually after tablets bought online or handfuls of raw apricot kernels eaten as a health food.
Also known as
Used in a sentence
The patient disclosed taking amygdalin obtained outside the country.
Good to know
Amygdalin releases hydrogen cyanide when split by gut bacteria, so swallowing it is far more toxic than injecting it, and high-dose vitamin C taken alongside has been reported to increase that toxicity.
Word origin
Where “amygdalin” comes from
From Greek amygdale, almond, the source in which the compound was first identified.