laetrile
American Heritage Dictionary:
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la·e·trile
(lā'ĭ-trĭl', -trəl) 
n.
A drug derived from amygdalin and purported to have antineoplastic properties.
n.
A drug derived from amygdalin and purported to have antineoplastic properties.
[lae(vorotatory) (variant of LEVOROTATORY) + (NI)TRILE.]
Oxford Food & Nutrition Dictionary:
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laetrile
Name given to an extract of apricot kernels, amygdalin. Claimed as a cancer cure, although there is no supporting evidence, and sometimes called vitamin B17, although there is no evidence that it is a dietary essential or has any metabolic function.
Oxford Food & Fitness Dictionary:
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laetrile
A water-soluble compound first extracted from apricot kernels in the 1950s. Its full scientific name is laevo-mandelonitrile-beta-glucuronoside but it is also known as amygdalin. It is often present in foods with vitamin B complex. This has led to laetrile being marketed by some producers as vitamin B17, but it is not a vitamin and has no known function in the body.
Laetrile is a source of organic cyanide. Cancer cells are believed to convert this into inorganic cyanide that destroys the cells. Consequently, laetrile has been used in cancer therapy. However, its use is very controversial. Excess laetrile is toxic to normal cells and causes cold sweats, headaches, nausea, lethargy, breathlessness, and low blood pressure. Consequently, the sale of laetrile has been restricted in some countries due to its potential toxicity. In the UK it is available only on prescription. Its use in the USA is illegal because of its toxicity, and because there is not enough convincing evidence that it is beneficial.
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vitamin B17
A water-soluble compound often found with members of the vitamin B complex. It is sometimes marketed as a vitamin, but it is not a true vitamin.
Columbia Encyclopedia:
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laetrile
laetrile (lā'ətrĭl'), name given to the chemical amygdalin, a substance derived from an extract of the kernels of many fruits, notably apricots, bitter almonds, and peaches. The idea that laetrile might selectively destroy cancer cells was developed by Dr. Ernst T. Krebs, Sr., a German immigrant to the United States, in the 1920s and was later refined by his son Ernst T. Krebs, Jr., who used the name "vitamin B17" for amygdalin and the derivatives of amygdalin that he developed. The Krebses had hypothesized that an enzyme that was more abundant in tumor cells than normal cells acted on laetrile to produce cytotoxic cyanide. (Cyanide is naturally produced in the intestines when laetrile is acted upon by intestinal bacteria.) This hypothesis and several refinements of it were proved to be untrue, as was the younger Krebs's later classification of the substance as a vitamin.
The subject of controversy for many years, laetrile was subjected to much scientific scrutiny in the 1970s. Investigations showed that anecdotal reports of improvement with laetrile were insufficient proof of effectiveness. Clinical trials showed no effectiveness in shrinking tumors, prolonging survival, or improving the quality of the patient's life. Toxicity from cyanide poisoning in some patients, coupled with the drug's ineffectiveness, led the Food and Drug Administration to label laetrile a fraud. Interstate shipment and shipment from other countries are illegal, but it is still legal in some states and in Mexico.
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American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
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Oxford Food & Nutrition Dictionary
A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved.
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Oxford Food & Fitness Dictionary
Food and Fitness: A Dictionary of Diet and Exercise. Copyright © 1997, 2003 by Oxford University Press. All rights reserved.
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Oxford Dictionary of Sports Science & Medicine
The Oxford Dictionary of Sports Science & Medicine. Copyright © Michael Kent 1998, 2006, 2007. All rights reserved.
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