Laetrile
What is it?
Laetrile, which is also known as amygdalin, was isolated in 1952 by biochemist Ernest Krebs who named it vitamin B17 and promoted it as a cancer preventative and cure. Laetrile is found in apricot kernels and contains a cyanide molecule which means it may be toxic in large doses. These concerns have led to laetrile being made illegal as a treatment for cancer in the USA.
What it does in the body
Laetrile in cancer treatment
In a clinical trial in cancer patients reported in 1982, laetrile did not appear to cause shrinkage of tumors or alleviate cancer symptoms. Survival time was not increased and there were no improvements in feelings of wellbeing.1 There have also been several reports of laetrile causing serious, life-threatening toxicity when taken in large doses.2 Krebs claimed that laetrile preferentially killed cancer cells but laboratory evidence suggests that this is not the case.3
Absorption and metabolism
Laetrile is not digested in the stomach but passes into the small intestine where it is acted on by enzymes that split it into various compounds, which are then absorbed.
Sources
Laetrile is found in apricot kernels and in the kernels of other fruits such as plums, peaches, cherries, peaches and apples. Mung bean sprouts and almonds also contain laetrile.
Toxic effects of excess intake
Laetrile in large doses may be toxic due to its 6 per cent cyanide content. Treatment amounts are usually limited to 1 g to reduce side effects.