amygdalin

Amygdalin is a naturally occurring cyanogenic glycoside found in the seeds of several Prunus species, including bitter almonds, apricots, peaches, and plums. It is a glucose-bound form of mandelonitrile and benzaldehyde, and is commonly described as a potential source of hydrogen cyanide when enzymatically broken down.

Chemically, amygdalin consists of a glucose moiety linked to mandelonitrile, which can be cleaved by the enzyme beta-glucosidase to yield glucose, benzaldehyde, and hydrogen cyanide. In humans, hydrolysis can occur in the gut through plant and microbial enzymes, releasing cyanide that can be toxic in sufficient amounts. The benzaldehyde gives an almond-like odor.

Historically, amygdalin has been promoted as laetrile or vitamin B17 as a cancer therapy. There is no robust evidence that it improves survival or cures cancer, and major medical authorities consider it ineffective and potentially dangerous. Cyanide poisoning is the principal safety concern, with adverse effects ranging from headache and dizziness to seizures and death with sufficient exposure.

Regulatory agencies in many countries restrict or warn against using amygdalin-containing preparations for medical purposes. Because of the lack of proven benefit and the risk of cyanide toxicity, amygdalin is not approved as a cancer therapy and is not recommended as a dietary supplement.