The current status of laetrile.

Area of Science:

• Biochemistry
• Pharmacology
• Toxicology

Background:

• Amygdalin, a cyanogenic glycoside, is the primary component in laetrile.
• Its chemical properties were documented in 1837.
• Enzymatic breakdown yields hydrogen cyanide (HCN), benzaldehyde, and glucose.

Observation:

• Oral ingestion of cyanogenic glycosides has led to worldwide toxicities.
• Amygdalin is metabolized by gut bacteria, not human intracellular enzymes.
• Acute cyanide toxicity signs, symptoms, and treatments are reviewed.

Findings:

• In vitro and in vivo studies demonstrate amygdalin's lack of significant anticancer activity in animal models.
• Control animals in studies often survived longer than amygdalin-treated animals.
• Human clinical studies are absent, but animal data and observed toxicities suggest contraindication.

Implications:

• Amygdalin's toxicity and ineffectiveness as an anticancer agent necessitate caution.
• Further human trials appear unwarranted given existing evidence.
• Legal and judicial aspects of laetrile cancer therapy are discussed.