Apricot seeds do not cure cancer. No clinical trial has ever shown that eating apricot kernels or taking their extract (sold as laetrile or “vitamin B17”) has any benefit for cancer patients. A systematic review that evaluated over 200 references on the topic found zero studies meeting basic standards of evidence, and concluded that the risk-benefit balance is “unambiguously negative” because of the real danger of cyanide poisoning.
Despite this, the claim persists online and in alternative health circles. Understanding where the idea came from, what actually happens in your body when you eat these seeds, and why they’re genuinely dangerous can help you evaluate the claims for yourself.
Where the Claim Comes From
Bitter apricot kernels contain a compound called amygdalin. In the 1920s, cyanide (one of amygdalin’s breakdown products) was proposed to have anti-cancer properties, and by the 1950s a semi-synthetic version called laetrile was being promoted as an alternative cancer therapy in the United States. The idea was simple: when amygdalin breaks down in the body, it releases hydrogen cyanide, and proponents believed this cyanide would selectively kill cancer cells while leaving healthy cells alone.
When the FDA began demanding evidence that laetrile actually worked, its main promoter, Ernst T. Krebs, rebranded the compound as “vitamin B17.” He claimed, without evidence, that cancer was simply a deficiency of this supposed vitamin. The strategy was clever: the public was becoming familiar with the benefits of vitamins, and calling something a vitamin made it sound essential and harmless. But amygdalin is not a vitamin by any scientific definition. Vitamins are substances your body cannot make and must get from food to prevent deficiency diseases. No such deficiency exists for amygdalin. The B17 label is a marketing invention, not a scientific classification.
What Happens When You Eat Apricot Seeds
When you swallow a bitter apricot kernel, your body breaks down the amygdalin through a multi-step process. Enzymes first split it into simpler sugars and an intermediate compound, which is then further broken down into benzaldehyde and hydrogen cyanide. That last product is the problem.
Hydrogen cyanide interferes with your cells’ ability to use oxygen. It binds to a key enzyme in cellular respiration, essentially suffocating cells from the inside. This triggers a state called lactic acidosis, where your body shifts to an emergency energy mode that produces dangerous levels of acid in the blood. The cyanide does not distinguish between cancerous and healthy tissue. Research has confirmed that hydrogen cyanide is produced in normal cells too, meaning it damages everything indiscriminately.
Interestingly, some recent lab research suggests that amygdalin may have some anti-tumor effects through a mechanism that doesn’t involve cyanide at all. But this is preliminary cell-study work, not evidence that eating apricot seeds treats cancer in a living person. The gap between “something interesting happened in a petri dish” and “this cures cancer in humans” is enormous.
What Clinical Evidence Actually Shows
The Cochrane Collaboration, widely considered the gold standard for medical evidence reviews, has examined the laetrile question multiple times. Their systematic review screened over 200 references and evaluated dozens in detail. Not a single study met the basic criteria for reliable clinical evidence. Their conclusion: “There is no reliable evidence for the alleged effects of laetrile or amygdalin for curative effects in cancer patients.”
The most notable clinical trial was conducted by the National Cancer Institute on patients with advanced cancer. The editorial published afterward stated plainly: “The evidence, beyond reasonable doubt, is that it doesn’t benefit patients with advanced cancer, and there is no reason to believe that it would be any more effective in the earlier stages of the disease.” Following multiple reports of toxicity and death, the FDA banned laetrile as a cancer treatment. That ban remains in effect today.
The Real Risk of Cyanide Poisoning
The danger from apricot kernels is not theoretical. A single bitter apricot kernel contains roughly 0.5 milligrams of cyanide, and cyanide concentrations can range up to 3.8 milligrams per gram of kernel. The lowest published lethal dose of hydrogen cyanide in humans is 0.56 mg per kilogram of body weight. For a 70-kilogram (154-pound) adult, that puts the lethal threshold at around 39 milligrams, a quantity you could reach by eating a relatively small handful of bitter kernels.
Documented cases of apricot kernel poisoning show a range of serious outcomes: severe metabolic acidosis, dangerously low blood pressure, seizures, coma, and cases severe enough to require mechanical ventilation. In one case series of poisoned patients, nine out of the group developed lactic acidosis, nine developed abnormally high blood sugar, and several required intensive care. The European Food Safety Authority recommends no more than one to three kernels per day for adults and half a small kernel for young children to stay within safe limits.
A Potential Conflict With Chemotherapy
For people already undergoing cancer treatment, apricot seeds may pose an additional risk. One laboratory study examined how amygdalin interacts with cisplatin, a widely used chemotherapy drug. The results were mixed: while the combination showed some synergy against cancer cells in a dish, it also showed antagonism in normal cells, meaning amygdalin appeared to interfere with the chemotherapy’s effects on healthy tissue. This is early lab data, not a definitive finding, but it raises a genuine concern that taking apricot seeds alongside conventional treatment could complicate your care in unpredictable ways.
Why the Myth Persists
The apricot seed cure appeals to a deep and understandable desire: the hope that a natural, simple remedy could defeat a disease that conventional medicine often struggles with. The “vitamin B17” framing makes it sound like something your body needs. Testimonials circulate online from people who believe the seeds helped them, though none of these accounts have been verified under controlled conditions.
Cancer sometimes goes into spontaneous remission. People often take alternative remedies alongside conventional treatments and credit the wrong one. And the emotional weight of a cancer diagnosis makes people especially vulnerable to claims that sound hopeful. None of this means the seeds work. It means the conditions are perfect for a persistent myth.
What the evidence consistently shows is a compound that doesn’t selectively target cancer, has never demonstrated clinical benefit in any rigorous trial, carries a real risk of cyanide poisoning, and is banned by the FDA for the specific purpose it’s being promoted for. The risk is concrete. The benefit remains entirely unproven.