“Vitamin B17” is not actually a vitamin, and it has no proven health benefits in humans. The name is a marketing term for amygdalin, a compound found naturally in apricot kernels, bitter almonds, and other stone fruit seeds. It gained popularity in the 1970s as an alternative cancer treatment sold under the brand name Laetrile, but clinical trials showed it does not work against cancer, and it carries serious risks of cyanide poisoning.
What B17 Actually Is
Amygdalin is a plant compound made up of two sugar molecules bonded to a structure that contains cyanide. It occurs naturally in the seeds and pits of fruits in the Prunus family: apricots, peaches, plums, bitter almonds, and to a lesser degree, apple seeds. When you eat it, your body breaks it down in stages. Enzymes in the gut split off the sugars first, then further processing releases hydrogen cyanide and benzaldehyde.
The “vitamin B17” label was coined by advocates who promoted it as an essential nutrient. It is not recognized as a vitamin by any scientific or regulatory body. Your body does not need it for any biological function, and no deficiency state exists.
The Cancer Treatment Claim
The central claim behind B17 is that it selectively kills cancer cells. Proponents argued that cancer cells contain an enzyme that releases the cyanide from amygdalin directly at tumor sites while healthy cells remain unharmed. This theory was tested and failed.
The National Cancer Institute conducted a phase II clinical trial in 1982, enrolling 175 evaluable cancer patients. Only one patient showed any response: a person with stomach cancer whose tumors partially shrank for 10 weeks before growing again. By the end of the treatment course, 54% of patients already had measurable disease progression. Seven months after completing therapy, every single patient’s cancer had progressed. The NCI’s conclusion was blunt: laetrile showed little anticancer activity in animal studies and no anticancer activity in human clinical trials.
No subsequent trial has overturned those findings. There is no credible evidence that amygdalin treats, slows, or prevents any type of cancer.
Other Claimed Benefits
Some alternative health sources claim B17 can lower blood pressure, reduce pain, or boost immune function. None of these claims are supported by clinical evidence in humans. While amygdalin has shown antioxidant properties in laboratory settings, test-tube results do not translate into health benefits you can count on. No human trials have demonstrated meaningful effects for any condition other than the failed cancer studies.
Why B17 Is Dangerous
The core problem with amygdalin is straightforward: your body converts it into cyanide. The severity depends on how much you consume and whether you take it orally (which releases more cyanide through gut enzymes) or intravenously.
Mild to moderate poisoning causes difficulty breathing, bluish discoloration of the skin, weakness, and lightheadedness. Severe poisoning can cause seizures, coma, cardiovascular collapse, and death. The FDA has issued specific warnings about apricot kernel products containing high levels of amygdalin, noting that consumption “could lead to fatal cyanide toxicity.”
Long-term exposure at lower doses carries its own risks. Chronic consumption of foods high in amygdalin can damage the nervous system, causing impaired vision from optic nerve damage, hearing loss, loss of balance, and dysfunction of sensory or motor nerves.
The Vitamin C Interaction
One particularly dangerous combination involves taking high-dose vitamin C alongside amygdalin, something some alternative therapy protocols actually recommend. Vitamin C in large amounts depletes cysteine, an amino acid your body uses to detoxify cyanide by converting it into a less harmful substance called thiocyanate. With that safety mechanism weakened, cyanide accumulates faster. In one documented case, a 68-year-old cancer patient developed seizures, reduced consciousness, and severe metabolic acidosis after taking 3 grams of amygdalin with 4,800 milligrams of vitamin C per day.
How Much Amygdalin Is in Common Foods
Not all seeds carry the same risk. Bitter apricot kernels are by far the most concentrated source, containing between 5,530 and 24,000 micrograms of amygdalin per gram. That corresponds to hydrogen cyanide levels approaching 1,200 parts per million. Sweet apricot kernels contain dramatically less, ranging from 31 to 296 micrograms per gram. Regular almonds from the grocery store contain almost none, at roughly 2.5 micrograms per gram or below detectable levels.
Eating a handful of bitter apricot kernels is genuinely dangerous. Sweet varieties and standard almonds pose minimal risk at normal serving sizes. Apple seeds contain amygdalin too, but you would need to chew and swallow an unusually large number to reach harmful levels.
Legal Status
Laetrile is not approved by the FDA for the treatment of any condition. It cannot be legally sold as a drug in the United States. The FDA has issued safety alerts about specific apricot kernel products sold online, warning that they contain amygdalin at levels that could be lethal. Despite this, amygdalin supplements and raw bitter apricot kernels remain available through online retailers and in some health food stores, often marketed with carefully worded claims that skirt regulatory boundaries.
Some countries outside the United States have similarly restricted or banned laetrile. A handful of alternative medicine clinics in Mexico and elsewhere still offer it as part of cancer treatment programs, but these operate outside mainstream medical oversight.