Amygdalin is a naturally occurring cyanogenic glycoside derived from nuts, plants, and the pits of certain fruits, primarily apricots. It was first used as a cancer treatment in Russia in 1845 and later, in the 1920s, in the United States. It became popular once again in the 1970s, faded away after negative study results, and saw a resurgence in the early 2000. Although patients use amygdalin in oral, injectable and IV forms, there is no evidence documenting effectiveness. Amygdalin is metabolized by the enzyme beta-glucosidase into benzaldehyde, glucose and cyanide(1).
Claims of its anticancer activity rely on the theory, now proven false, that cancer cells contain elevated amounts of the beta-glucosidase compared to normal cells (1). The cyanide resulting from the hydrolysis of amygdalin is believed to be cytotoxic (2). It was further postulated that normal cells convert the cyanide to benign thiocyanate. However, there is no convincing evidence for this selective effect on neoplastic cells. It has also been claimed by some promoters that amygdalin is in fact a vitamin (B17) and that cancer develops due to deficiencies in B17, but no data substantiate this idea.
Laboratory studies suggest that amygdalin has anticancer properties (3) (13), but a 1982 clinical trial conducted by the National Cancer Institute failed to find any effectiveness. Moreover, several study patients had symptoms of mild cyanide toxicity or significant levels of cyanide (4). Systematic reviews of several studies concluded that amygdalin is ineffective as a cancer treatment (5) (6).
Amygdalin is banned in the United States, but is available in Mexico and via the Internet. Evaluation of the parenteral formulation showed contamination with both pyrogens and microbes, and both oral and parenteral formulations did not contain the labeled amounts of amygdalin. Oral administration of Amygdalin has resulted in cyanide toxicity and death. Patients should not use this supplement.