Laetrile (Amygdalin, marketed as "Vitamin B17")

Expelled from medical school, then awarded an honorary doctorate

In 1973, California convicted Ernst Theodore Krebs Jr. of practicing medicine without a license and falsely representing laetrile as a cancer cure. Krebs had been expelled from Hahnemann Medical College in Philadelphia after three years, having failed his coursework. He tried again at the University of Illinois, earning a Bachelor of Arts only after failing science courses at several other colleges along the way. He never completed an earned doctorate; his one doctoral degree was an honorary award from the American Christian College, a small, unaccredited Bible college in Tulsa, Oklahoma. None of that stopped him from working alongside his father, Ernst T. Krebs Sr., a physician with his own history of promoting treatments outside conventional medicine. Working with his father, Krebs Jr. promoted a semisynthetic derivative of amygdalin, a cyanide-releasing compound doctors in Russia had experimented with against cancer as early as 1845 and that American physicians had tried and abandoned as too poisonous in the early 1920s. He named the derivative “Laetrile” and proposed it as an anticancer drug in 1952 through the John Beard Memorial Foundation, which he directed. He also marketed laetrile as “Vitamin B17.”

A compound marketed as a vitamin

Two of the rationales offered for laetrile were the trophoblastic theory and the vitamin-deficiency claim. One, laid out in a 1950 paper Krebs co-authored with his father in the journal Medical Record, revived a discarded 1902 theory from embryologist John Beard: that cancer is not a random mutation but a resurgence of primitive “trophoblast” cells, the same tissue type that drives the placenta’s aggressive early growth, and that the body’s pancreatic enzymes normally keep this tissue in check. Another rationale gave the compound its consumer-facing name: Krebs designated laetrile “Vitamin B17,” while proponents described it as a missing vitamin and argued that cancer resulted from a dietary deficiency of it. Those claims did not hold up. The National Cancer Institute states plainly that there is no evidence laetrile is needed for normal metabolism or functions as a vitamin in humans or animals at all. The trophoblastic theory fared no better in the National Cancer Institute’s own assessment.

Ten thousand patients a day

Krebs directed the John Beard Memorial Foundation, which defended laetrile’s theoretical basis. TIME’s 1976 report called Andrew R. L. McNaughton, a Canadian it described as a former gunrunner turned self-styled philanthropist, the key figure in the federal charges and reported that he had financial links to one of Tijuana’s two plants that manufactured the Mexican form of laetrile. By TIME’s account, the operation supplied roughly 10,000 cancer patients a day; manufacturing cost was under a dollar a vial, while American patients paid up to fifty dollars for three daily injections. The indictment said some defendants had accumulated bank accounts totaling millions of dollars. In May 1976 a San Diego federal grand jury indicted sixteen people, including McNaughton, Contreras, Robert William Bradford, and physician John A. Richardson, along with three Mexican manufacturing firms, over an alleged cross-border smuggling operation. An NCI-commissioned laboratory analysis published in 1978, examining amygdalin products manufactured by Cyto Pharma of Mexico, found the vials and tablets fell below U.S. pharmaceutical manufacturing standards: chemically subpotent, mislabeled, and, in more than twenty ampule samples, contaminated with microorganisms, a combination the analysis concluded made both dosage forms unfit for use in patients. The McNaughton Foundation of California later filed a friend-of-the-court brief supporting laetrile access when the case reached the Supreme Court.

A 1973 conviction, a Supreme Court loss, and apricot seeds still for sale

The disconfirmation arrived from courts, regulators, and clinical science alike. A federal prosecution fined Krebs and his foundation in March 1962 and placed him on probation under injunction-like conditions. California convicted him specifically over laetrile in 1973, for practicing medicine without a license and falsely representing it as a cancer cure while dispensing it; after he violated probation from that 1973 case, he served six months in jail in 1980, the same year California’s governor signed a state law permitting laetrile prescriptions for the terminally ill. On the science, the National Cancer Institute’s 1978 retrospective review solicited the strongest case evidence laetrile’s own advocates could supply, mailing requests to 385,000 physicians; of an estimated 70,000 Americans who had used the drug, only 93 cases were submitted, and a blinded panel of oncologists judged just six of 68 laetrile courses to show any response at all. A National Cancer Institute-sponsored clinical trial, published in the New England Journal of Medicine in 1982, found no substantive benefit in cure, tumor response, survival, or symptom relief among 175 evaluable patients, and recorded several cases of cyanide toxicity, with some patients’ blood cyanide levels approaching the lethal range. In 1979 the U.S. Supreme Court held that the Federal Food, Drug, and Cosmetic Act’s safety and effectiveness requirements applied to drugs used by terminally ill patients, reversing an injunction that had permitted laetrile use; the Court did not decide the separate constitutional privacy claim. A 2011 Cochrane systematic review concluded that benefit claims were not supported by sound clinical data and described the risk-benefit balance as unambiguously negative given the danger of cyanide poisoning. Krebs died in San Francisco in 1996 at 85. Laetrile is still manufactured and administered as a cancer therapy today, primarily in Mexico and at some clinics in the United States. The FDA was still warning consumers as recently as May 2024, when it flagged three bitter-apricot-seed products sold by the retailer Apricot Power for containing toxic levels of amygdalin capable of causing cyanide poisoning; Memorial Sloan Kettering’s current monograph on the compound states plainly that it “has not been shown to treat or prevent cancer.”