Laetrile cures cancer
| Laetrile cures cancer | |
|---|---|
| FALSE | |
| "Laetrile, a compound derived from apricot kernels and marketed as "vitamin B17," cures or prevents cancer, and the medical establishment suppresses it." | |
| Domain | Health & Medicine |
| Tactic | Pseudoscience / Junk Science Fraud or Scam Conspiracy Theory |
| Era | Historical |
| First seen | 1952 |
| Origin | Promoted by Ernst T. Krebs Jr. and Ernst T. Krebs Sr. in California in the 1950s |
| Last reviewed | 2026-10-26 |
| Further reading: books on Health & Medicine | |
Laetrile is a substance derived from amygdalin, a compound found in apricot kernels, bitter almonds and other fruit pits. In the 1970s it became the most popular unproven cancer treatment in the United States, used by tens of thousands of patients and championed by a political movement that framed access to it as a matter of personal freedom. A large clinical trial sponsored by the US National Cancer Institute found in 1982 that laetrile had no benefit against cancer, and that some patients showed signs of cyanide poisoning. Laetrile is still sold online and at clinics outside the United States.
The claim
Promoters claimed that cancer was caused by a vitamin deficiency and that laetrile, which they named "vitamin B17," corrected it. They argued that laetrile released cyanide selectively inside cancer cells, killing them while sparing healthy tissue. As the movement grew, its central claim expanded: laetrile worked, but doctors, drug companies and regulators were suppressing it to protect the profits of conventional cancer treatment.
Origin
Amygdalin had been investigated as a cancer treatment in the nineteenth century and abandoned as ineffective and toxic. In the early 1950s, Ernst T. Krebs Sr., a San Francisco physician, and his son Ernst T. Krebs Jr. revived the idea. The younger Krebs patented a semi-synthetic version, which he called laetrile, and later popularized the label "vitamin B17." Laetrile is not a vitamin; the body does not need it, and no deficiency disease is associated with its absence.
How it spread
Laetrile grew from a fringe remedy into a national movement in the 1970s. Several factors drove it:
- Fear and desperation. Cancer was frightening, conventional treatments were harsh, and many patients were told there was little hope.
- A freedom-of-choice campaign. The Committee for Freedom of Choice in Cancer Therapy, founded in 1972 and linked to the John Birch Society, recast laetrile as a civil-liberties issue. More than 20 US states passed laws legalizing laetrile within their borders by the late 1970s, even though the federal government did not approve it.
- Clinics in Mexico. Patients traveled across the border to clinics in Tijuana that offered laetrile. In 1980, the actor Steve McQueen sought treatment for mesothelioma at a Mexican clinic that used laetrile and other unproven therapies; he died later that year.
- Books and testimonials. Popular books and patient stories reported dramatic recoveries, usually without verified diagnoses or long-term follow-up.
By the late 1970s, an estimated 70,000 or more Americans had used laetrile.
How it was tested
Under public pressure, the National Cancer Institute sponsored a clinical trial led by the Mayo Clinic and other centers. Its results, published in the New England Journal of Medicine in 1982, covered 178 patients with cancers for which no standard treatment was known to be effective. Patients received laetrile along with the diet, vitamins and enzymes recommended by its promoters.
The results were clear. No patient was cured, and none showed lasting improvement or stabilization. Tumors grew in most patients within a few months. Several patients had blood cyanide levels approaching the toxic range. The researchers concluded that laetrile was a toxic drug that was not effective as a cancer treatment.
Animal studies conducted earlier, including at Memorial Sloan Kettering Cancer Center, had also failed to find reliable anti-tumor effects. A 2015 Cochrane review found no reliable evidence that laetrile or amygdalin has beneficial effects for cancer patients.
What the evidence shows
Laetrile does not cure, control or prevent cancer. It can cause cyanide poisoning, particularly when taken by mouth, and especially alongside vitamin C or foods that increase cyanide release, such as raw almonds. Cases of serious cyanide toxicity and deaths have been reported. Its promotion as "vitamin B17" is a marketing term without scientific basis.
Why it persisted
Laetrile persisted because it offered hope, a sense of control and an enemy to blame. The suppression narrative made negative evidence self-defeating: when trials found no benefit, supporters said the trials were rigged. The "freedom of choice" framing also shifted the debate from whether laetrile worked to who had the right to decide, a powerful argument that left the scientific question unanswered for many followers.
The case has a direct modern parallel: the online marketing of apricot kernels and "B17" supplements, and the broader suppressed-cure narratives that circulate on social media.
Lessons for readers
- Calling a substance a "vitamin" does not make it one.
- "They are hiding the cure" is a claim that makes any negative evidence look like proof.
- Testimonials of recovery are not reliable evidence, particularly when diagnoses and outcomes are not verified.
- The freedom to choose a treatment is a separate question from whether it works.
See also
- Snake oil cures pain and disease
- The MMR vaccine causes autism
- Trick or Treatment (Singh and Ernst)
- Bad Science (Goldacre)
Sources
- Charles G. Moertel et al., "A Clinical Trial of Amygdalin (Laetrile) in the Treatment of Human Cancer," New England Journal of Medicine 306 (1982).
- Stefanie Milazzo and Markus Horneber, "Laetrile treatment for cancer," Cochrane Database of Systematic Reviews (2015).
- National Cancer Institute, "Laetrile/Amygdalin (PDQ)," health professional and patient versions.
- Benjamin Wilson, "The Rise and Fall of Laetrile," Quackwatch.