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Against allopathy
Alternative medicine
Clinically unproven

Laetrile, or laevomandelonitrile, is a trade name used for a synthetic form of amygdalin, a cyanogen compound found in the seeds of stone fruits of the Prunus genus (particularly apricots) that has been sold as a cancer cure for many years by quacks. In the last few years, it's often misrepresented as vitamin B17 (even though it's not a vitamin).

Laetrile can refer to two different substances: amygdalin, which occurs naturally in apricot and peach pits and in minuscule amounts in some foods (bitter almonds, brewer's yeast, buckwheat, sorghum, apple seeds, etc.), and synthetic Laetrile, a distinct but chemically related substance. The "laetrile" obtained in Mexico is usually in fact amygdalin. Laetrile treatment is generally associated with the expat altie community in Mexico, and is not approved for use in the United States[note 1] due to a lack of evidence that it produces any effect other than cyanide[note 2] poisoning in the patient. In the State of Indiana, a physician may prescribe "amygdalin (laetrile)" for use as a "dietary supplement".[1]

Proposed mechanism and the sad truth[edit]

The cancer-killing effect of amygdalin is attributed to the hydrogen cyanide ions, or cyanides, formed as a result of its decomposition. In addition to this, amigdalin decomposes into compounds that are not important, including benzoaldehyde and glucose. Cyanide ions block the action of cytochrome oxidase in the respiratory chain, or simply cause cell death by asphyxiation.[2] So, in order for the ions to work, the cell must use cytochromes for its respiration and hence must use the respiratory chain. In most healthy cells, this is the case, as cellular respiration consists of three steps: glycolysis, the Krebs cycle,[note 3] and the respiratory chain. However, cancer cells are far more dependent on glycolysis than the latter two.[3][4][5] This means that the effect of cyanide on most cancer cells is very limited.

Proponents of the use of leatril to treat cancer believe that cancer cells contain an enzyme (β-D-glucosidaseWikipedia) that breaks down amigdalin to cyanide ions, which are thought to damage the cell, while healthy cells contain another enzyme (rhodaneseWikipedia) that converts cyanide ions to rhodanides (thiocyanates) excreted in the urine with much less toxicity. However, cancer cells have been found to contain rhodanese in amounts comparable to that of liver and kidney. Some cancer cells have also been found to contain only trace amounts of β-D-glucosidase.[6][7]

Laetrile fans often cite anecdotal evidence of individual cases where laetrile appeared to work, but in every case where a sufficiently large sample size was studied, laetrile has not been shown to be effective (i.e., no statistically significant results).[8][9][10][11] In spite of all this, laetrile is still presented as a "suppressed" treatment by many conspiratorially-minded quacks.

Then there is the fact that eating tons of fruit seeds is a common suicide practice because it allows for a quick death due to overdose of cyanide. Numerous cases of cyanide poisoning after taking amygdalin have been reported.[12][13][14] There really is nothing holding you back from dying via those seeds: fruit is not a controlled substance.Wikipedia

See also[edit]


  • Braico KT. Humbert JR. Terplan KL, et al.: Laetrile intoxication: report of a fatal case. New Engl. J. Med. 238 240,1979
  • Milazzo, S. et al. (2006): Laetrile for cancer: a systematic review of the clinical evidence. Supportive Care in Cancer. 15(6), p. 583–595.
  • Herbert, V. (1979): Laetrile: the cult of cyanide. Promoting poison for profit. Am. J. Clin. Nutr. Bd. 32, S. 1121-58. PMID 219680 PDF
  • 'Unproven Methods of Cancer Management. Laetrile. In: 1991, CA Cancer J. Clin. Bd. 41, p. 187-192. PMID 1902140 PDF
  • Moertel, C.G., et al. (1982): A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. N. Engl. J. Med. Bd. 306, p. 201-206. PMID 7033783
  • Brant J, Graceffa J: Rutherford, Priviteria, and Chad Green: Laetrile's setbacks in the courts. Am. J. Law Med. 1980 Summer;6(2):151-71
  • Irving J. Lerner: Laetrile: A Lesson in Cancer Quackery. CA Cancer J. Clin. 1981; 31:91-95. doi: 10.3322

External links[edit]


  1. FDA regulations ban its use in the United States in "interstate commerce", but 24 states passed laws specifically legalizing laetrile within those states between 1976 and 1981; from 1977 to 1987, an affidavit system was set up by federal court order where terminally-ill patients could legally obtain laetrile if a physician signed an affidavit authorizing it, but this was ended in 1987. It may still be legal in as many as 20 states as long as the laetrile never crosses state lines, a rather difficult proposition. Most usually to obtain it legally, people have to travel to Mexico.
  2. Not always mild.
  3. One of the most known proponents of using amygdalin to cure cancer was a notorious American conman Ernst Krebs.Wikipedia He is not to be confused with the German-born British biochemist and Noble laureate Hans Krebs,Wikipedia who discovered the Krebs cycle.


  1. Indiana Code, Section 16-42-23-4.
  2. Heather B. Leavesley, Li Li, et al., "Interaction of Cyanide and Nitric Oxide with Cytochrome c Oxidase: Implications for Acute Cyanide Toxicity", Toxicological Sciences, Volume 101, Issue 1, January 2008, Pages 101–111, doi:10.1093/toxsci/kfm254.
  3. Pelicano H, Xu RH, Du M, et al. "Mitochondrial respiration defects in cancer cells cause activation of Akt survival pathway through a redox-mediated mechanism". J Cell Biol. 2006 Dec 18;175(6):913-23. doi: 10.1083/jcb.200512100. Epub 2006 Dec 11. PMID: 17158952; PMCID: PMC2064701.
  4. Sajnani, Karishma et al. "Genetic alterations in Krebs cycle and its impact on cancer pathogenesis." Biochimie vol. 135 (2017): 164-172. doi:10.1016/j.biochi.2017.02.008.
  5. Reznik, Ed et al. "Mitochondrial respiratory gene expression is suppressed in many cancers." eLife vol. 6 e21592. 18 Jan. 2017, doi:10.7554/eLife.21592
  6. Greenberg, D M. "The case against laetrile: the fraudulent cancer remedy." Cancer vol. 45,4 (1980): 799-807. doi:10.1002/1097-0142(19800215)45:4<799::aid-cncr2820450432>;2-6
  7. Duke JA (2003). CRC Handbook of Medicinal Spices. CRC Press. pp. 261–262. ISBN 978-0-8493-1279-3.
  8. "The claims that laetrile or amygdalin have beneficial effects for cancer patients are not currently supported by sound clinical data." from Milazzo, Stefania et al. "Laetrile treatment for cancer." The Cochrane database of systematic reviews ,11 CD005476. 9 Nov. 2011, doi:10.1002/14651858.CD005476.pub3
  9. "Substantial in-vitro and in-vivo testing in animal tumor systems has shown that amygdalin is entirely devoid of significant anticancer activity." from Dorr, R T, and J Paxinos. "The current status of laetrile." Annals of internal medicine vol. 89,3 (1978): 389-97. doi:10.7326/0003-4819-89-3-389
  10. "Amygdalin (Laetrile) is a toxic drug that is not effective as a cancer treatment." from Moertel, C G et al. “A clinical trial of amygdalin (Laetrile) in the treatment of human cancer.” The New England journal of medicine vol. 306,4 (1982): 201-6. doi:10.1056/NEJM198201283060403
  11. "Therefore, the claim that laetrile has beneficial effects for cancer patients is not supported by sound clinical data." from Milazzo, Stefania et al. "Laetrile for cancer: a systematic review of the clinical evidence." Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer vol. 15,6 (2007): 583-595. doi:10.1007/s00520-006-0168-9
  12. Melbourne Man Has Cyanide Poisoning After Self-Medicating With Apricot Kernels: But he still won't give up the daily ritual. by Lara Pearce (12/09/2017 9:17 AM AEST | Updated 12/09/2017 9:27 AM AEST) Huffington Post Australia.
  13. Jeffrey R Suchard, Kevin L Wallace, Richard D Gerkin, "Acute Cyanide Toxicity Caused by Apricot Kernel Ingestion", Annals of Emergency Medicine, Volume 32, Issue 6, 1998, pp. 742-744, ISSN 0196-0644, doi:10.1016/S0196-0644(98)70077-0.
  14. Sauer, H., Wollny, C., Oster, I. et al. "Severe cyanide poisoning from an alternative medicine treatment with amygdalin and apricot kernels in a 4-year-old child". Wien Med Wochenschr 165, 185–188 (2015). doi:10.1007/s10354-014-0340-7