evidence: Although the names laetrile, Laetrile, vitamin B-17, and amygdalin are often used interchangeably, they are not the same product. The chemical composition of U.S.-patented Laetrile (mandelonitrile-beta-glucuronide), a semisynthetic derivative of amygdalin, is different from the laetrile/amygdalin produced in Mexico (mandelonitrile beta-D-gentiobioside), which is made from crushed apricot pits.[15,16] Mandelonitrile, which contains a cyanide group, is a structural component of both products.[15] It has been proposed that released (hydrogen) cyanide is the active cancer-killing ingredient in laetrile, but two other breakdown products of amygdalin—prunasin (which is similar in structure to Laetrile) and benzaldehyde—may also be cancer cell inhibitors.[17-20] The studies discussed in this summary used either Mexican laetrile/amygdalin or the patented form. In most instances, the generic term laetrile will be used in this summary; however, a distinction will be made between the products when necessary.