Health Care Professional Information

Scientific Name
D-mandelonitrile-b-D-glucosido-6-b-D-glucoside
Common Name

Apricot pits, vitamin B17, mandelonitrile-beta-glucuronide (semi-synthetic), mandelonitrile beta-D-gentiobioside (natural product), laevorotatory and mandelonitrile, prunasin

Brand Name

Laetrile®, Amigdalina, NovoDalin B17

Clinical Summary

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.

Purported Uses
  • Cancer prevention
  • Cancer treatment
Constituents
  • D-mandelonitrile-b-D-glucosido-6-b-D-glucoside
Mechanism of Action

The mechanism of action is unknown. Claims for amygdalin's activity rely on the theory, now proven false, that cancer cells contain elevated amounts of beta-glucosidase and reduced levels of rhodanese compared to normal cells (1) (2). Based on this incorrect assumption, cancer cells were claimed to metabolize amygdalin into cyanide and die, while healthy cells would convert cyanide to benign thiocyanate via rhodanese. Limited in vitro data support the idea that cyanide, benzaldehyde, and prunasin are cytotoxic. It has also been postulated that cancer develops due to deficiencies in vitamin B17, but no data substantiate this idea (7).

Pharmacokinetics

Hydrocyanic acid, or cyanide, and benzaldehyde are formed from mandelonitrile when amygdalin is metabolized by beta-glucosidase enzymes in the cell. Administration of amygdalin 4.5 grams/m2 intravenously to cancer patients displays two-compartment open model kinetics. Elimination half-life is approximately 2 hours with a mean clearance of 99 ml/min. No changes in whole blood levels of cyanide or thiocyanate were noted with parenteral administration (8). Repeated oral administration of amygdalin 500 mg tablets in cancer patients resulted in increased whole blood cyanide levels of averaging approximately 1 mcg/ml (range 0-3 mcg/ml) (2).

Warnings

Amygdalin is not approved for use in the United States.
Pharmaceutical evaluation of the injectable formulation showed pyrogen and microbial contamination, and both injectable and oral dosage forms did not contain labeled amount of amygdalin.
(12)

Adverse Reactions

Reported (oral): Dermatitis and cyanide toxicity consisting of nausea, vomiting, headache, dizziness, mental obtundation, cyanosis, hypotension, ptosis, neuropathies, coma, and death.
(4) (8) (10) (11)
Reported (oral): Severe cyanide poisoning following ingestion of 3 grams of amygdalin with concurrent use of high doses of vitamin C.
(12)

Literature Summary and Critique

Milazzo S, Ernst E, Lejeune S, Boehm K, Horneber M. Laetrile treatment for cancer. Cochrane Database Syst Rev. 2011 Nov 9;11:CD005476.
This review was conducted to assess the anti-cancer and possible adverse effects of laetrile and amygdalin. The databases CENTRAL (2011, Issue 1); MEDLINE (1951-2011); EMBASE (1980-2011); AMED; Scirus; CancerLit; CINAHL (all from 1982-2011); CAMbase (from 1998-2011); the MetaRegister; and the National Research Register were searched for the review. A total of 69 studies were evaluated, but none met the inclusion criteria. Researchers concluded that the claims of beneficial effects made for laetrile or amygdalin are currently not supported by any clinical data. Further, there is a great risk of serious side effects from cyanide poisoning, espeically following oral consumption of laetrile or amygdalin.

Dosage (Inside MSKCC Only)
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References
  1. Newmark J, Brady RO, Grimley PM, et al. Amygdalin (Laetrile) and prunasin beta-glucosidases: distribution in germ-free rat and in human tumor tissue. Proceedings of the National Academy of Sciences of the United States of America. Oct 1981;78(10):6513-6516.
  2. Ames MM, Moyer TP, Kovach JS, et al. Pharmacology of amygdalin (laetrile) in cancer patients. Cancer chemotherapy and pharmacology. 1981;6(1):51-57.
  3. Fukuda T, Ito H, Mukainaka T, et al. Anti-tumor promoting effect of glycosides from Prunus persica seeds. Biological & pharmaceutical bulletin. Feb 2003;26(2):271-273.
  4. Moertel CG, Fleming TR, Rubin J, et al. A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. The New England journal of medicine. Jan 28 1982;306(4):201-206.
  5. Milazzo S, Lejeune S, Ernst E. 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. Jun 2007;15(6):583-595.
  6. Milazzo S, Ernst E, Lejeune S, et al. Laetrile treatment for cancer. Cochrane Database Syst Rev. 2011;11:CD005476.
  7. Greenberg DM. The case against laetrile: the fraudulent cancer remedy. Cancer. Feb 15 1980;45(4):799-807.
  8. Moertel CG, Ames MM, Kovach JS, et al. A pharmacologic and toxicological study of amygdalin. JAMA : the journal of the American Medical Association. Feb 13 1981;245(6):591-594.
  9. Davignon JP, Trissel LA, Kleinman LM. Pharmaceutical assessment of amygdalin (Laetrile) products. Cancer treatment reports. Jan 1978;62(1):99-104.
  10. Sadoff L, Fuchs K, Hollander J. Rapid death associated with laetrile ingestion. JAMA : the journal of the American Medical Association. Apr 14 1978;239(15):1532.
  11. Kalyanaraman UP, Kalyanaraman K, Cullinan SA, et al. Neuromyopathy of cyanide intoxication due to "laetrile" (amygdalin). A clinicopathologic study. Cancer. Jun 1 1983;51(11):2126-2133.
  12. Bromley J, Hughes BG, Leong DC, et al. Life-threatening interaction between complementary medicines: cyanide toxicity following ingestion of amygdalin and vitamin C. The Annals of pharmacotherapy. Sep 2005;39(9):1566-1569.
  13. Chen Y, Ma J, Wang F, et al. Amygdalin induces apoptosis in human cervical cancer cell line HeLa cells. Immunopharmacol Immunotoxicol. 2013 Feb;35(1):43-51.

Consumer Information

How It Works

Bottom Line: Amygdalin (Laetrile) has toxic side effects and has caused decreased survival in cancer patients.

Amygdalin (also called Laetrile®) is an extract from apricot pits that can be metabolized to cyanide, a known poison. It was first used in the 1920s and was promoted widely in the 1950s as a cancer therapy. Promoters claimed that the cyanide released from amygdalin selectively killed cancer cells, leaving normal tissue cells alone. This theory has been proven false by laboratory experiments that showed that amygdalin, when fed to laboratory animals that had cancer cells implanted in them, was not able to reduce the size or slow the growth of their tumors. This was true for many different types of cancer cells. Cyanide does kill cells in laboratory experiments, but affects all cells (both cancerous and healthy) in the same way, which explains the handful of cyanide poisonings that have been reported in cancer patients using amygdalin/Laetrile®.

Purported Uses
  • To prevent and treat cancer
    Laboratory and clinical evidence does not support this use.
    Amygdalin (Laetrile®) has been linked to several cases of cyanide poisoning in cancer patients.
Research Evidence

Cancer treatment:
A review was conducted to determine the anti-cancer and possible adverse effects of laetrile and amygdalin. The databases CENTRAL (2011, Issue 1); MEDLINE (1951-2011); EMBASE (1980-2011); AMED; Scirus; CancerLit; CINAHL (all from 1982-2011); CAMbase (from 1998-2011); the MetaRegister; and the National Research Register were searched for the review. A total of 69 studies were evaluated, but none met the inclusion criteria of the review. Researchers concluded that the claims of beneficial effects made for laetrile or amygdalin are currently not supported by any clinical data. Further, there is a great risk of serious side effects from cyanide poisoning, espeically following oral consumption of laetrile or amygdalin.

 

Patient Warnings
  • Amygdalin is not an approved drug in the United States.
  • Laboratory analysis showed that some samples of amygdalin have been contaminated with microbes and pyrogens (substances that induce fever). This analysis also showed that both the injectable and oral dosage forms contained less active product than was claimed on the label.
Side Effects
  • Dermatitis (inflammation and redness of the skin)
  • Cyanide toxicity from high doses or prolonged use of amygdalin can cause nausea, vomiting, headaches, dizziness, mental confusion, cyanosis (bluish discoloration of the skin), low blood pressure, ptosis (drooping of the eyelids), nerve dysfunction, coma, and death.
Special Point

The Food and Drug Administration has banned the sale and use of amygdalin (Laetrile®) due to the risk of cyanide poisoning. For this reason, Laetrile® is only offered at alternative medicine clinics in Tijuana, Mexico as a component of multi-modality metabolic therapies. Such therapies generally have not been found effective and are discussed at greater length in a separate monograph about metabolic therapies.

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