If laetrile is consumed it can be potentially lethal for enzymes (primarily glycosidase) located in the intestine and in various types of seeds.
Several glycosidase enzymes act on amygdalin leading to its destruction in various ways. Maltase leading to partial degradation giving D-glucose and mandelonitrile glycoside. On the other hand emulzin decomposes it to benzaldehyde, cyanide and two molecules of glucose. This eznim is present in bitter almonds and therefore almond contain free cyanide and benzaldehyde. Amygdalin β-glycosidase and prunasine β-glycosidase catalyse the loss of two glucoses by giving mandelonitrile which is further broken down to free cyanide and benzaldehyde.
The action of this enzyme leads to the release of cyanide, which acts as a poison in the body.