Cyanide intoxication by apricot kernel ingestion as complimentary cancer therapy.

N O V E M B E R 2 0 1 3 , V O l . 7 1 , N O 9 © Van Zuiden Communications B.V. All rights reserved. Dear editor, Complementary and alternative medicine (CAM) is frequently used in patients with cancer, up to 90% within one year for at least part of their therapy. Both beneficial and adverse effects of such therapy remain controversial, and CAM has even been associated with shorter overall survival. The use of amygdalin, usually in the form of laetrile, has been one of the most popular alternative ‘cancer cures’ in the past 40 years. Importantly, laetrile and amygdalin are pharmacologically distinct compounds and their names are often used interchangeably. Amygdalin is a cyanogenetic glycoside compound found in the pits of many fruits and can be applied, e.g. via ingestion of apricot kernels. Laetrile is an acronym from laevorotatory and mandelonitrile, used to describe a purified form of amygdalin. Briefly, the working mechanism of amygdalin has been proposed to rely on the specific vulnerability of malignant cells to cyanogenic glycosides because of 1) a higher level of beta-glucosidases and beta-glucuronidase as compared with normal cells, leading to a more rapid intracellular release of cyanide from amygdalin and 2) a deficiency in rhodanese, an enzyme that converts cyanide into the harmless compound thiocyanate. There is circumstantial evidence that amygdalin is a potential anti-cancer drug, mostly based on in vitro experimental studies, although no clinical evidence supporting these findings has emerged over the past decades. Moreover, it was even associated with toxic blood cyanide levels and reduced overall survival when used in the form of laetrile as described. Despite this, use of amygdalin is recently increasingly advocated as an anticancer therapy. It can be applied by intravenous administration, tablet or apricot kernel ingestion. In the present case report we describe the occurrence of elevated liver chemistry tests in correlation with chronic cyanide intoxication after apricot kernel ingestion as CAM in a patient suffering from metastatic colon carcinoma. l e t t e r t o t H e e d i t or