“Vitamin B17” is not actually a vitamin. It’s a marketing name given to amygdalin, a naturally occurring compound found in apricot pits, apple seeds, and other fruit kernels. The name was coined by E.T. Krebs Jr. to promote the substance as a cancer treatment, but it has never been recognized as a vitamin by any nutritional or medical authority. Amygdalin breaks down into hydrogen cyanide in the body, and both the FDA and the European Commission have banned its sale as a medicine.
What Amygdalin Actually Is
Amygdalin is a naturally occurring chemical classified as a cyanogenic glycoside, meaning it’s a sugar-containing compound that releases cyanide when broken down. It’s found in the seeds and pits of many fruits, particularly bitter apricot kernels, peach pits, plum pits, and apple seeds. Around 2,000 plant species across 110 families contain cyanogenic glycosides like amygdalin.
The term “laetrile” is often used interchangeably with amygdalin, but they aren’t identical. Laetrile refers to a semi-synthetic, purified version originally patented in the United States. The product sold in Mexican clinics under the same name is typically just crushed apricot pit extract. Both versions share a core structural component that contains a cyanide group, which is the source of the toxicity risk.
How It Produces Cyanide in the Body
When you eat crushed fruit pits or take amygdalin tablets, an enzyme called beta-glucosidase breaks the compound down into glucose, benzaldehyde, and hydrogen cyanide. This enzyme is present in the foods themselves and also produced by bacteria living in your gut. The oral route is particularly dangerous because gut bacteria are highly active in triggering this breakdown, releasing cyanide steadily as the substance moves through your digestive system.
A 500-milligram dose of amygdalin can release roughly 30 milligrams of cyanide. The minimum lethal dose of cyanide for humans is approximately 50 milligrams, or about 0.5 milligrams per kilogram of body weight. That means just two or three standard amygdalin tablets could deliver a fatal amount of cyanide.
Where It’s Found Naturally
Bitter apricot kernels are the most well-known source, containing around 26 milligrams of amygdalin per gram of kernel. In terms of cyanide potential, apricot kernels can release about 785 milligrams of hydrogen cyanide per kilogram of kernel material. Peach pits are similar at 710 mg/kg, and plum pits at 696 mg/kg. Apple seeds come in at around 690 mg/kg. Bitter almonds are also extremely high, containing up to 50,000 milligrams of amygdalin per kilogram.
The European Food Safety Authority has estimated that eating just three small apricot kernels could push an adult past the safe one-time exposure limit. For a toddler, half of one small kernel is enough to exceed that threshold. These aren’t large quantities, which is why raw bitter apricot kernels carry real risk even in seemingly small amounts.
The Cancer Treatment Claims
The idea that amygdalin could treat cancer emerged in the 1950s and gained popularity through the 1970s. Proponents claimed that cyanide released from amygdalin selectively targeted cancer cells while leaving healthy tissue unharmed. This theory has no scientific support.
The most significant clinical test came from a trial published in the New England Journal of Medicine. Researchers treated 178 cancer patients with amygdalin combined with a broader “metabolic therapy” program that included dietary changes, enzymes, and vitamins. The results were definitive: no substantive benefit was observed in terms of tumor response, symptom improvement, or survival. The study’s conclusion was blunt, calling amygdalin “a toxic drug that is not effective as a cancer treatment.”
A Cochrane systematic review, the gold standard for evaluating medical evidence, reached the same conclusion. It found no reliable evidence from any clinical trials supporting the use of laetrile or amygdalin for cancer. The review went further, stating there is neither scientific nor ethical justification for conducting additional clinical trials. The risk-benefit balance was described as “unambiguously negative.”
Cyanide Poisoning Risk
Cyanide poisoning from amygdalin is not a theoretical concern. Published case reports document patients who developed severe toxicity after taking amygdalin tablets at recommended doses sold by alternative medicine providers. In one case, a patient took 1,500 milligrams of amygdalin as directed. That dose contained roughly 90 milligrams of cyanide, about 1.8 times the minimum lethal dose.
Symptoms of cyanide poisoning include headache, dizziness, nausea, vomiting, rapid heart rate, and drops in blood pressure. In severe cases it progresses to seizures, loss of consciousness, and cardiac arrest. Oral ingestion is more dangerous than intravenous administration because gut bacteria continue converting amygdalin to cyanide over an extended period, making the exposure prolonged and harder to manage.
Regulatory Status
The FDA banned laetrile from interstate sale in the United States in the early 1980s after concluding the substance was both toxic and ineffective. The European Commission followed with its own ban. Neither jurisdiction authorizes laetrile or amygdalin for sale as a medicinal product.
Despite these bans, amygdalin tablets and raw bitter apricot kernels remain available online and through alternative health channels, often marketed as “vitamin B17” or as a nutritional supplement rather than a drug. This labeling sidesteps some regulatory enforcement, but it does not change the chemistry. The compound still breaks down into cyanide regardless of what the label calls it.