Laetrile, the apricot-pit compound sold as 'vitamin B17', cures cancer and was suppressed by the FDA and drug industry

Why so many people believed, and still do

It would be a mistake to treat the laetrile movement as simple gullibility. It grew in the hardest soil there is, and the distrust it drew on was not irrational. A cancer diagnosis is one of the most frightening things a person can face, and the conventional treatments of the 1970s (disfiguring surgery, brutal early chemotherapy) were grueling and often failed. Set against that, a natural extract of apricot pits that promised to work gently, without poison, had an obvious and human appeal.

The suspicion of institutions had earned some of its force, too. The drug industry has, provably, put profit ahead of patients at times, and some treatments cost more than families can bear. To a person watching a loved one suffer, the story that a cheap plant remedy was being kept from them by a rich industry and its regulators was a clean, morally satisfying explanation with clear villains, far easier to hold than the fragmented reality of cancer medicine.

Laetrile was never only a medical claim. It became a political cause, fought in the language of freedom and choice.

And laetrile became a genuine political movement, not just a fringe remedy. Campaigners cast it as a matter of “health freedom”: your body, your choice, your right to try what you wished. That framing was potent enough that more than twenty state legislatures passed laws to legalize it, and the cause reached the Supreme Court. When the fight is over liberty, the government's refusal to approve a drug stops looking like a scientific judgment and starts looking like an act of control. That is the real, understandable engine of the belief, and it deserves to be taken seriously before it is answered.

The moment it was actually tested

For years the strongest argument for laetrile was that it had never been given a fair, rigorous trial: that the establishment condemned it without testing it. In 1982 that argument ran out. Under real political pressure, the National Cancer Institute sponsored a clinical study led by Charles Moertel of the Mayo Clinic and carried out across four cancer centers. Crucially, the researchers did not use their own protocol; they administered laetrile together with the “metabolic therapy” of diet and vitamins exactly as the treatment's own promoters recommended, so the test could not be waved away as unfair.

The result, published in the New England Journal of Medicine, was unambiguous. Among the 178 patients, not one was cured or even stabilized by laetrile. There was no improvement in symptoms, no extension of survival, and the cancer advanced in the overwhelming majority within months. Worse, the study documented a real hazard: several patients showed blood-cyanide levels approaching the toxic range, confirming that the treatment was not the harmless natural substance it was sold as.

Nothing since has overturned that finding. A 2015 Cochrane systematic review, the most rigorous kind of evidence summary there is, examined the published record and concluded there was no reliable evidence that laetrile or amygdalin has any beneficial effect against cancer, while the risk of cyanide poisoning is real. The National Cancer Institute, the American health and cancer authorities, Cancer Research UK, and Memorial Sloan Kettering all say the same thing in plain language: it has not been shown to work, it is not a vitamin, and it can poison you.

The suppression story also struggles against a simple fact of the record. Laetrile was notkept out of patients' hands. More than twenty states legalized it; tens of thousands of Americans used it; clinics abroad dispensed it freely. It had every opportunity to reveal the cures its promoters promised, in front of doctors who would have been thrilled to document them. The cures never materialized. The FDA declined to approve it for the same reason it declines to approve any drug: no one ever produced substantial evidence that it was safe and effective. That is not a cover-up; it is the evidence standard working as designed.

The cautionary case of Steve McQueen

No single story shaped the public image of laetrile more than the death of Steve McQueen. In late 1979 the actor, one of the biggest film stars of his era, was diagnosed with pleural mesothelioma, an aggressive cancer of the lung lining that was, and largely still is, very hard to treat. Told that conventional medicine could offer little, he turned in 1980 to a clinic in Mexico and an unconventional regimen that included laetrile alongside a punishing schedule of diets, enzymes, and injections overseen by a practitioner whose only license, in orthodontics, had been revoked.

McQueen died in Juarez on November 7, 1980, hours after surgery to remove a large tumor. Supporters sometimes invoke his name as if his willingness to try laetrile were an endorsement of it. The record does not support that reading. He sought the treatment when his disease was already advanced, it did not save him, and physicians at the time described the episode as a warning about desperate patients being drawn to unproven cures. His fame gave laetrile enormous publicity; it did not give it a single documented cure.