Written by Helen Cooke, Helen Seers and the CAM-Cancer Consortium.
Updated April 29, 2014

Laetrile

Is it safe ?

Adverse events

Cyanide is believed to be the active cancer-killing ingredient in Laetrile, which has caused concern over toxicity. Adverse events linked with Laetrile treatment are like the symptoms of cyanide poisoning. These symptoms include: nausea and vomiting, headache, dizziness, bluish discolouration of the skin due to lack of oxygen in the blood, liver damage, abnormally low blood pressure, difficulty walking, droopy eyelids, fever and mental confusion, coma and death. Several deaths have been attributed to Laetrile17,18. If taking Laetrile orally, the potential risk of cyanide poisoning symptoms are increased if any from the list of foods containing Laetrile are eaten (see above) or high doses of vitamin C are taken19. A recent adverse drug reaction case of severe life-threatening accidental cyanide poisoning has been reported in Australia. The report suggests a patient increased her risk of cyanide toxicity by co-ingesting amygdalin with a megadose of Vitamin C (4800mg)20. More severe adverse events (i.e. cyanide poisoning) are seen when Laetrile is administered orally than when it is given by injection, as intestinal bacteria contain enzymes that promote the release of cyanide in the digestive system21.

A review concluded that the risk of people developing cyanide poisoning who ingest Laetrile is high6.

Contraindications

In addition to the above serious concerns, for those with liver problems/damage Laetrile may compromise liver function18. Furthermore, this treatment should be avoided by pregnant or breast-feeding women.

Interactions

Ascorbic acid (vitamin C) may increase the toxicity of Laetrile/Amygdalin/B1719.

Citation

Helen Cooke, Helen Seers, CAM-Cancer Consortium. Laetrile [online document]. http://www.cam-cancer.org/CAM-Summaries/Dietary-approaches/Laetrile. April 29, 2014.

Document history

Updated in April 2014 by Barbara Wider.
Assessed as up to date in December 2012 by Helen Cooke.
Most recent update and revision in December 2011 by Helen Cooke.
Fully revised and updated in July 2009 by Helen Cooke.
Summary first published in September 2005, authored by Helen Seers.

References

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  2. Chandler, RF, Phillipson, JD & Anderson, LA. Controversial Laetrile. Journal of Pharmacology. 1984; 232: 330-332
  3. Ellison, NM, Byar, DP, & Newell, GR. Special report on Laetrile: the NCI Laetrile Review. Results of the National Cancer Institute's retrospective Laetrile analysis.New England Journal of Medicine. 1978; 7;299 (10):549-52.
  4. McCarrison, SR. “Nutrition and National Health.” Journal of the Royal Society of Arts. 1936. lxxxiv, 1047, 1067, 1087.
  5. Milazzo S, Ernst E, Lejeune S, Boehm K, Horneber M. Laetrile treatment for cancer. Cochrane Database of Systematic Reviews 2011, Issue 11. Art. No.: CD005476. DOI: 10.1002/14651858.CD005476.pub3
  6. Milazzo S, Lejeune S, Ernst E. Laetrile for cancer: a systematic review of the clinical evidence. Support Care Cancer. 2007 Jun;15(6):583-95.
  7. Moertel, CG, Ames, MM, Kovach, JS, et al. A pharmacologic and toxicological study of amygdalin. Journal of the American Medical Association. 1981. 245 (6): 591-4.
  8. Moertel, CG, Fleming, TR, Rubin, J, et al. A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. New England Journal of Medicine. 1982; 306 (4): 201-6.
  9. Kochi, M, Takeuchi, S, Mizutani, T, et al. Antitumor activity of benzaldehyde. Cancer Treatment Reports. 1980; 64 (1): 21-3.
  10. Kochi, M, Isono, N, Niwayama, M, et al. Antitumor activity of a benzaldehyde derivative. Cancer Treatment Reports. 1985; 69 (5): 533-7.
  11. Wodinsky, I, & Swiniarski, JK. Antitumour activity of amygdalin MF (NSC-15780) as a single agent and with beta-glucosidase (NSC-128056) on a spectrum of transplantable rodent tumours. Cancer Chemotherapy Reports. 1975; 59, (5): 939-50.
  12. Overjera, AA., Houchens, DP., Barker, AD. et al. Inactivity of DL- amygdalin against human breast and colon tumor xenografts in athymic (nude mice). Cancer Treatment Reports. 1978; 62 (4): 576-78.
  13. Manner HW, DiSanti SJ, Maggio MI, et al. Amygdalin, vitamin A and enzyme induced regression of murine mammary adenocarcinomas. Journal of Manipulative Physiolgical Therapy. 1978; 1 (4): 246-8.
  14. Bhatti RA, Ablin RJ, & Guinan PD. Tumour-associated directed immunity in prostatic cancer: effect of amygdalin. IRCS Medical Science research Biochemistry. 1981; 9 (1): 19.
  15. Biaglow JE, & Durand RE. The enhanced radiation response of an in vitro tumour model by cyanide released from hydrolysed amygdalin. International Journal of Radiation Biology. 1978; 33 (4): 397-401.
  16. Syrigos KN, Rowlinson-Busza G, & Epenetos AA. In vitro cytotoxicity following specific activation of amygdalin by beta-glucosidase conjugated to a bladder cancer-associated monoclonal antibody. International Journal of Cancer. 1998; 78 (6): 712-9.
  17. Braico, KT, Humbert, JR, Terplan, KL, & Lehotay, JM. Laetrile intoxication: report of a fatal case, New England Journal of Medicine. 1979; 1; 300 (5): 238-40.
  18. Sadoff, L, Fuchs, K, & Hollander, J, Rapid death associated with Laetrile ingestion, Journal of the American Medical Association. 1978; 14; 239 (15): 1532.
  19. Lee, M, Berger, HW, Givre, HL, et al. Near fatal Laetrile intoxication: Complete recovery with supportive treatment, Mount Sinai Journal of Medicine. 1982; 49 (4): 305-307.
  20. Bromley J, Hughes BG, Leong DC, Buckley NA. Life-threatening interaction between complementary medicines: cyanide toxicity following ingestion of amygdalin and vitamin C. Ann Pharmacother. 2005 Sep;39(9):1566-9.
  21. Newmark J, Brady, RO, Grimley, PM, Gal, AE, Waller, SG, & Thistlethwaite, JR. Amygdalin (Laetrile) and pruasin 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. 1981; 78 (10): 6513-6.
  22. Chen Y, Ma J, Wang F, Hu J, Cui A, Wei C, Yang Q, Li F. Amygdalin induces apoptosis in human cervical cancer cell line HeLa cells. Immunopharmacol Immunotoxicol 2013; 35(1): 43-51.