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. Laetrile can refer to two different substances: amygdalin, which occurs naturally in apricot and peach pits and in miniscule amounts in some foods (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 due to a lack of evidence that it produces any effect other than mild cyanide poisoning in the patient. It is occasionally misrepresented as a vitamin ("B-17"), better described as a pseudovitamin. In the State of Indiana, a physician may prescribe “amygdalin (laetrile)” for use as a “dietary supplement”.
 Hypothesised mechanism
The intent of using laetrile against cancer is that the cyanide would be liberated as the amygdalin was metabolized by the body, and that the cyanide would kill cancer cells. According to this claim, laetrile would break down into cyanide and two other substances only in the presence of an enzyme released by cancer cells which the cyanide would then attack; the laetrile would allegedly remain intact in the presence of healthy, non-cancerous cells.
 Sad reality
In practice, this has not been shown to happen; in fact, where laetrile breaks down into three substances (including cyanide) is in the small intestine, and several scientific studies have shown it useless as a cancer treatment. Laetrile fans often cite anecdotal evidence of individual cases where laetrile appeared to work, but in every case where a statistically significant sample size was studied laetrile has not been shown to be effective. Laetrile is still presented as a "suppressed" treatment by many conspiratorially-minded quacks.
- 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. In: 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. In: 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
- See the Wikipedia article on amygdalin.
- History of laetrile at Quackwatch
- National Cancer Institute FAQ
- Sloan-Kettering fact sheet on Laetrile
- ↑ 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 affadavit system was set up by federal court order where terminally ill patients could legally obtain laetrile if a physician signed an affadavit 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.
- ↑ Hopefully.
- ↑ Indiana Code, Section 16-42-23-4.