Amygdalin — Laetrile (Cyanogenic Glycoside · HCN Toxicity · Informational Reference)

Compound	Amygdalin (D-Mandelonitrile gentiobioside)
Chemical class	Cyanogenic Glycoside (Aromatic nitrile glycoside)
CAS	29883-15-6
Primary source	Prunus amygdalus var. amara (bitter almond seeds), Prunus persica (peach kernels), Prunus armeniaca (apricot kernels)
Key applications	Informational reference — HCN poisoning risk; historical Laetrile controversy; anti-cough (low-dose traditional)
Claim strength	Emerging (traditional) / Informational only (supplement context)
Typical form	Not commercially available as a supplement — regulatory prohibition in most markets
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Name origin: From Amygdalus (old genus name for almonds, from Greek amygdale). Amygdalin is a cyanogenic glycoside — a compound that releases hydrogen cyanide (HCN) upon enzymatic hydrolysis. The glycoside consists of mandelonitrile (benzaldehyde cyanohydrin) linked to two glucose units (gentiobiose). Hydrolysis by β-glucosidase (from gut microbiota or plant sources) releases HCN, benzaldehyde, and glucose. Traditional use: Bitter almond preparations have been used in very small amounts across traditional Chinese medicine (Ku Xing Ren, bitter apricot kernel) for cough suppression and constipation — at doses far below the toxic threshold. The TCM use of Ku Xing Ren for respiratory applications (anti-tussive) is based on very low-dose amygdalin preparations where HCN exposure is considered sub-toxic. Laetrile controversy: Amygdalin was marketed in the 1970s–1980s as “Laetrile” or “Vitamin B17” as an alternative cancer treatment, with claims that HCN release selectively kills cancer cells. Multiple controlled clinical evaluations by the NCI found no evidence of anticancer efficacy for amygdalin/Laetrile, and documented significant HCN toxicity cases. Laetrile is banned in the US, EU, UK, and most other regulated markets as a supplement or drug claim. Safety status: Amygdalin is not available as a commercial supplement ingredient in major markets due to HCN toxicity risk.

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Amygdalin — Safety and Regulatory Context

Cyanide toxicity: Amygdalin hydrolysis by intestinal β-glucosidases releases HCN at a rate dependent on enzyme activity. Ingestion of 50 bitter almond kernels can release lethal HCN doses in adults (approximately 50–60 mg HCN for a 70 kg adult). Children are particularly susceptible — documented HCN fatalities from small numbers of bitter almond or apricot kernel ingestion. The FDA proposed ban on Laetrile in 1977 and has taken enforcement action against amygdalin products marketed for cancer treatment. EU food safety authorities have issued warnings on apricot kernel consumption — maximum safe intake is estimated at 3 small bitter apricot kernels per day for adults. This is an informational reference only.

Traditional low-dose anti-tussive (TCM context): In traditional Chinese medicine, bitter apricot kernel (Ku Xing Ren) is used in prescribed compound formulations at doses of 3–9 g dried kernel/day — delivering controlled sub-toxic amygdalin doses. The anti-tussive effect is attributed to HCN at trace concentrations acting centrally to suppress the cough reflex. This is a pharmacologically real but dose-critical application — requiring trained TCM practitioner supervision. Claim strength: Moderate (TCM clinical use; sub-toxic dose dependency is critical).

Laetrile/“Vitamin B17” — cancer claims: No credible evidence of anticancer efficacy. Multiple NCI-sponsored studies and systematic reviews find no anti-tumour activity for amygdalin/Laetrile at non-toxic doses. The “Vitamin B17” designation is incorrect — amygdalin is not a vitamin and has no defined nutritional function. Cancer patients who have used Laetrile have experienced cyanide toxicity alongside untreated cancer progression. Claim strength: Not applicable (claims are not evidenced and regulatory prohibitions apply).

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Frequently Asked Questions — Amygdalin

Is amygdalin the same as Laetrile?
Laetrile is a patented semi-synthetic derivative of amygdalin (D-amygdalin) used in the “Vitamin B17” alternative cancer treatment, sometimes incorrectly used interchangeably with amygdalin. Laetrile is specifically banned in the US (FDA), EU, and UK for sale as a cancer treatment or supplement. Amygdalin in natural plant sources (bitter almonds, apricot kernels) is not “banned” as a food per se, but marketing amygdalin supplements with therapeutic claims violates food/drug laws in most markets.

How many apricot kernels are safe to eat?
The European Food Safety Authority (EFSA) estimated that even three small bitter apricot kernels can exceed the acute tolerable intake of HCN for a 60 kg adult. Sweet apricot kernels (from commercial apricot varieties) have much lower amygdalin content and are safer. Wild or bitter apricot kernels used in certain traditional preparations are significantly higher in amygdalin. EFSA advises against commercial products made from bitter apricot kernels.

Are there any legitimate supplement applications for amygdalin?
In regulated Western markets (US, EU, UK, Australia): no — amygdalin cannot be sold as a dietary supplement with health claims due to HCN toxicity risk and regulatory prohibition. In traditional medicine contexts (TCM, Unani) where trained practitioners prescribe compound formulations at controlled low doses — there is a legitimate traditional use for Ku Xing Ren (bitter apricot kernel) in respiratory compound prescriptions. These are practitioner-supervised, low-dose formulations that are not analogous to retail supplement products.

Why did so many people believe Laetrile cured cancer?
The Laetrile cancer movement reflected the combination of desperation among cancer patients, anecdotal reports, institutional mistrust, and the appealing but incorrect narrative that “natural” HCN selectively targets cancer cells. Systematic review of the evidence (NCI evaluations, independent meta-analyses) found no controlled evidence of anticancer efficacy. The Laetrile movement is a case study in why anecdotal evidence and alternative medicine narratives require rigorous clinical evaluation before therapeutic claims are made.

Related compounds: Linamarin, Sinigrin, Glucoraphanin, Colchicine

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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