Amygdalin

botanical

provenance:botanical

first introduced:1830

regulatory status:banned

context:Isolated by French chemists in 1830 from the kernels of bitter almonds and related stone-fruit pits (apricot, peach, plum); used experimentally as a cancer treatment in Russia as early as 1845, per the NCI PDQ summary. Ernst T. Krebs Jr. named a semisynthetic derivative 'Laetrile' and proposed it as an anticancer drug in 1952; he and his father promoted amygdalin-derived compounds. Laetrile was also marketed as 'Vitamin B17.'

MECHANISM CLAIMED

Proponents offered four theories: Krebs's trophoblastic theory was paired with a proposed beta-glucuronidase/rhodanese imbalance that would make cancer cells more susceptible to cyanide; a separate theory proposed an excess of beta-glucosidase and a deficiency of rhodanese in cancer cells; the 'Vitamin B17' theory treated cancer as a vitamin-deficiency disorder; and another theory proposed that cyanide acidified tumors and disrupted lysosomes. NCI states that laetrile has not been shown to be a vitamin or to have anticancer activity in human clinical trials.

INTERVENTIONS USING IT

Laetrile (Amygdalin, marketed as "Vitamin B17")

NOTES

Amygdalin is a cyanogenic glycoside naturally present in the kernels of apricots, bitter almonds, and related fruit pits; in the body it breaks down to release hydrogen cyanide. Promoters proposed several mechanisms for its supposed anticancer effect, including that released cyanide would selectively kill cancer cells while sparing healthy tissue. The U.S.-patented semisynthetic form marketed as “Laetrile” (mandelonitrile-beta-glucuronide) differs chemically from the amygdalin/laetrile manufactured in Mexico from crushed apricot pits (mandelonitrile beta-D-gentiobioside), though both are marketed interchangeably as “vitamin B17.” The FDA has never approved amygdalin or laetrile for any medical use in the United States; a May 2024 FDA warning found commercially sold bitter-apricot-seed products still carried acutely toxic amygdalin levels.