The Rise and Fall of Laetrile

Benjamin Wilson, M.D.

Laetrile is the trade name for laevo-mandelonitrile-beta-glucuronoside, a substance allegedly synthesized by Ernst T. Krebs, Jr., and registered with the U.S. Patent Office for the treatment of "disorders of intestinal fermentation." This compound is chemically related to amygdalin, a substance found naturally in the pits of apricots and various other fruits. Most proponents of Laetrile for the treatment of cancer use the terms "Laetrile" and amygdalin interchangeably.

Amygdalin was originally isolated in 1830 by two French chemists. In the presence of certain enzymes, amygdalin breaks down into glucose, benzaldehyde, and hydrogen cyanide (which is poisonous). It was tried as an anticancer agent in Germany in 1892, but was discarded as ineffective and too toxic for that purpose. During the early 1950s, Ernst T. Krebs, Sr., M.D., and his son Ernst, Jr., began using a "purified" form of amygdalin to treat cancer patients. Since that time scientists have tested substances called "Laetrile" in more than 20 animal tumor models as well as in humans and found no benefit either alone or together with other substances. Along the way its proponents have varied their claims about Laetrile's origin, chemical structure, mechanism of action, and therapeutic effects [1,2]. Its place in history is assured, however, as a focus of political activities intended to abolish the laws protecting Americans from quackery.

Krebs, Sr.—Laetrile's "grandfather"—worked as a pharmacist before attending the San Francisco College of Physicians and Surgeons, from which he received his medical degree in 1903. During the influenza pandemic of 1918, he apparently became convinced that an old Indian remedy made from parsley was effective against the flu. He set up the Balsamea Company in San Francisco to market the remedy as Syrup Leptinol, which he claimed was effective against asthma, whooping cough, tuberculosis and pneumonia as well. During the early 1920s, supplies of Syrup Leptinol were seized by the FDA on charges that these claims were false and fraudulent. During the 1940s, Krebs, Sr., promoted Mutagen, an enzyme mixture containing chymotrypsin, which he claimed was effective against cancer. He and his son also patented and promoted "pangamic acid" (later called "vitamin B15"), which they claimed was effective against heart disease, cancer, and several other serious ailments. Krebs, Sr., died in 1970 at the age of 94.

Ernst T. Krebs, Jr.—Laetrile's "father"—has often been referred to as "Dr. Krebs" although he has no accredited doctoral degree. He attended Hahnemann Medical College in Philadelphia from 1938 to 1941, but was expelled after repeating his freshman year and failing his sophomore year [3]. After taking courses in five different colleges and achieving low or failing grades in his science courses, he finally received a bachelor of arts degree from the University of Illinois in 1942 [3]. In 1973, after giving a 1-hour lecture on Laetrile, he obtained a "Doctor of Science" degree from American Christian College, a small, now-defunct Bible college in Tulsa, Oklahoma. The school, founded by evangelist Billy James Hargis, had no science department and lacked authority from Oklahoma to grant any doctoral degrees.

Laetrile's Origin

Several versions of Laetrile's development have been published. In a 1962 book, Krebs, Sr., said that he had theorized that "cancer proteins" could be broken down by an enzyme he had prepared when he was a pharmacy student. When the substance proved too toxic in animal experiments, he boiled it and obtained better results. However, according to Michael Culbert, another prominent Laetrile promoter, Krebs ran a lucrative business analyzing smuggled whiskey for wood alcohol and developed Laetrile while working on a bourbon flavoring extract. During experiments with a mold growing on the barrels in which the whiskey was aged, he isolated an enzyme that he thought might have anti-tumor activity. When his supply of barrel mold was exhausted, he switched to apricot pits and used extracts (which he called Sarcarcinase) for various tests on animals and humans during the next two decades. In 1949, Krebs, Jr., modified his father's extraction process and named the result Laetrile.

Historian James Harvey Young has noted that Krebs, Sr., presented yet another version to FDA officials during an interview in 1962. Then he dated Laetrile's birth to 1951 and said he had tested it on patients but kept no records [1]. Noting that this version was made public much earlier than the others, Dr. Young suspects that Laetrile's origin was backdated to try to evade new drug provisions of 1938 and 1962 FDA laws. In 1977, after thorough investigation, FDA Commissioner Donald Kennedy concluded:

While it appears that Dr. Krebs, Sr., was utilizing some substance, which apparently had the trademark Sarcarcinase, before 1938, there is no evidence that the substance is identical . . . to the present-day Laetrile [4].

Proponents' Rationales

In 1902, a Scottish embryologist named John Beard theorized that cancer cells and cells produced during pregnancy called trophoblasts are one and the same. According to Beard, trophoblasts invade the uterine wall to form the placenta and umbilical cord. The pancreas then produces chymotrypsin, which destroys the trophoblasts. Beard postulated that if the pancreas fails to produce enough chymotrypsin, trophoblasts circulate through the body of both mother and infant, making them vulnerable throughout life to cancer.

In 1945, Krebs, Jr., founded the John Beard Memorial Foundation to "develop and apply" Beard's theories. In 1950, the Krebs published a version of Beard's thesis and stated that amygdalin kills trophoblast cells where trypsin has failed. They claimed that cancer tissues are rich in an enzyme that causes amygdalin to release cyanide which destroys the cancer cells. According to this theory, noncancerous tissues are protected from this fate by another enzyme which renders the cyanide harmless. After enforcement agencies began trying to ban Laetrile as a drug, the Krebs claimed that amygdalin is a vitamin ("B17") and that cancer is caused by a deficiency of this vitamin. None of these theories is valid.

Claims for Laetrile effectiveness have also shifted. At first it was claimed to cure cancer. Later it was claimed to "control" cancer. When the "vitamin" theory was developed, it was touted as a cancer preventive. It has also been claimed to be effective in relieving pain associated with cancer and in facilitating treatment with chemotherapy.

Scientific Review

One of the first practitioners to use Laetrile was Arthur T. Harris, M.D., who had trained in Scotland and reportedly studied embryology under John Beard. Harris, who had been doing family practice in Southern California, renamed his office the Harris Cancer Clinic. Within a year he submitted a report to Coronet Magazine which claimed that he was "working on something out here that is going to be the answer to cancer if there will ever be one," but the magazine did not report what he was doing.

By that time, the California Medical Association was receiving inquiries about Laetrile. When members of its Cancer Commission approached Krebs, Sr., he claimed that "limited" trials of toxicity in animals had been performed with satisfactory results, but that the records had been destroyed. No human trials involving Laetrile had been undertaken, but the Commission was offered case reports of patients in which spectacular results had supposedly been observed. However, the details claimed by the Krebs team could not be confirmed by other sources. The Commission was able to obtain a small supply of Laetrile for animal tests at three medical centers—all of which produced negative results.

At one point, the Krebs' agreed to supply Laetrile for a controlled clinical investigation at Los Angeles County Hospital. But later they said they would do so only if a Laetrile advocate were put in charge—which was not acceptable to hospital authorities. The Commission then evaluated the records of 44 patients treated according to the Krebs' recommendations. Two years had elapsed since the first of these patients had been treated with Laetrile. Nineteen had already died and there was no evidence that Laetrile had helped any of the others.

Marketing Increased

In 1956 Ernst T. Krebs, Jr., was introduced to Andrew R.L. McNaughton, who has been dubbed Laetrile's "godfather" by its supporters. McNaughton is the son of the late General A.G.L. McNaughton, commander of the Canadian Armed Forces during World War II. General McNaughton also served as president of the United Nations Security Council and the National Research Council of Canada.

Andrew McNaughton was educated at a Jesuit College and subsequently received training in electrical engineering, geology, mining, and business administration. During the war he was the chief test pilot for the Royal Canadian Air Force. Subsequently, he made a fortune by converting cheaply obtained war surplus items into useful products for other nations. He provided arms for the emerging nation of Israel and was also a double agent for Fidel Castro, ostensibly working for the Batista government in Cuba but often arranging for purchases to be hijacked by Castro supporters. For his efforts, Castro made him an "honorary citizen of Cuba."

McNaughton met Krebs shortly after he had incorporated the McNaughton Foundation, which was seeking projects "on the outer limits of scientific knowledge." Intrigued by Krebs' account of the "Laetrile Wars," McNaughton began promoting and distributing Laetrile. In 1961, to facilitate distribution in Canada, he founded International Biozymes Ltd. (later renamed Bioenzymes International Ltd), located in the same building as the McNaughton Foundation. Eventually, he built factories in seven countries.

It has been alleged that a major Biozymes stockholder (under someone else's name) was a New Jersey mobster who was convicted of conspiring to bribe public officials in connection with gambling. In 1977, McNaughton told American Medical News that he had treated the man's sister with Laetrile and that the man was a "wonderful guy" who had given $130,000 to the McNaughton Foundation.

During the 1970s, McNaughton experienced considerable difficulty in his financial dealings. In 1972, he was permanently enjoined from selling Biozymes stock in the United States as a result of a suit brought by the Securities and Exchange Commission. In 1973, he was charged by Italian police with having taken part in a $17 million swindle involving purchasers of Biozymes stock who were under the impression that they were investing in an Italian Laetrile factory. In 1974, in a Canadian courtroom, McNaughton was found guilty of stock fraud involving a company named Pan American Mines. It appears that $5 million had mysteriously disappeared. McNaughton was fined $10,000 and sentenced to serve one day in jail. A warrant for his arrest was issued after he refused to pay the fine and left Canada without serving his sentence.

Publicity Mounts

Besides overseeing production, McNaughton also sought publicity for Laetrile. He was able to convince a Jersey City surgeon, John A. Morrone, to attend a presentation that Krebs, Jr., gave in Montreal. After having lunch with Krebs, Jr., Morrone reportedly went back to New Jersey a "convinced laetrilist," and began using Laetrile on his patients.

At McNaughton's request, Morrone wrote a report on ten patients he had treated with Laetrile, which was published in 1962 in Experimental Medicine and Surgery, a journal no longer being published. McNaughton also arranged for a freelance writer named Glenn Kittler to write two magazine articles and a book on Laetrile. Kittler, who had studied to become a priest before becoming a journalist, had been an associate editor of Coronet magazine in 1952. The articles were published in March 1963 in American Weekly, a Sunday supplement to the Hearst newspapers. Immediately afterward, Kittler's book, Laetrile: Control for Cancer, was rushed into print with an initial press run of 500,000 copies. The book carried a foreword by McNaughton—with his Foundation's Montreal address. According to Kittler, the book's publisher was so confident that publicity from the articles would boost sales that he didn't send prepublication advertising to book distributors. When sales lagged, Kittler claimed that pressures from the AMA and FDA were partially responsible.

Support Groups

The efforts of McNaughton and Kittler were not fruitless, however. Cecile Hoffman was a San Diego schoolteacher who had undergone a radical mastectomy in 1959. After reading Kittler's book, she visited the McNaughton Foundation in Montreal and received Laetrile. Although she was unable to find an American physician who would administer her intravenous Laetrile injections, she did find Ernesto Contreras, M.D., just across the Mexican border in Tijuana. This was perhaps the most fortunate thing that ever happened to Dr. Contreras.

Contreras was a former Mexican Army pathologist who was in private practice in Tijuana. After he administered the Laetrile, Mrs. Hoffman became convinced that it controlled her cancer and saved her life. She remained a fervent Laetrile supporter until she died of metastatic breast cancer in 1969. Hoffman's convictions led her to form the International Association of Cancer Victims and Friends (IACVF) in 1963. (The word Victims was later changed to Victors.) IACVF's purpose was "to educate the general public to the options available to cancer patients, especially terminal cancer patients." Joining forces with health food industry promoters, the association began holding annual conventions in Los Angeles that drew thousands of people. These meetings provided a forum for virtually anyone who either promised or sold a cancer remedy that was not recognized as effective by the scientific community. The Krebs spoke often at these conferences. IACVF also founded the Cancer Book House, which sold literature promoting unorthodox cancer treatments. In addition, it arranged for room, board and transportation to Contreras' clinic from a California motel near the border.

Contreras, meanwhile, expanded his clinic and added translators to his staff to accommodate the influx of American patients. Business was so brisk that in 1970 he constructed a new clinic-the Del Mar Medical Center and Hospital—which he promoted as "an oasis of hope." (His facility is now called Oasis Hospital.)

In 1973, several leaders left IACVF to found the Cancer Control Society, whose activities are similar to those of IACVF. Another group promoting dubious cancer therapies is the National Health Federation (NHF), which supports a broad spectrum of questionable health methods. This group was founded in 1955 by Fred J. Hart, president of the Electronic Medical Foundation, a company that marketed quack devices. NHF sponsors meetings, generates massive letter-writing campaigns, and helps defend questionable methods in court cases. Four people who have served on its board of governors and the husband of its current president have been convicted of laetrile-related crimes.

Legal Problems

The first seizure of Laetrile in the United States occurred in 1960 at the former Hoxsey Cancer Clinic, which was then being operated by osteopathic physician Harry Taylor, a former Hoxsey employee. Two months before the seizure, a federal court judge had ordered Taylor to stop distributing the various Hoxsey concoctions. The seizure was not contested by Taylor.

In 1961, Krebs, Jr., and the John Beard Memorial Foundation were indicted for interstate shipment of an unapproved drug-not Laetrile but pangamic acid. After pleading guilty, Krebs was fined $3,750 and sentenced to prison. However, the sentence was suspended when Krebs and the Foundation agreed to terms of a 3-year probation in which neither would manufacture or distribute Laetrile unless the FDA approved its use for testing as a new drug.

In 1959, the California legislature had passed a law similar to the Federal Food, Drug, and Cosmetic Act, banning commerce of hazardous foods, drugs and cosmetics within California. The California Department of Public Health then formed a Cancer Advisory Council which studied Laetrile and other dubious cancer treatments. The ten physicians and five research scientists carried out their investigation from 1960 to 1962 and issued their report in May 1963.

During 1962 and 1963, the Cancer Advisory Council examined more than 100 case histories submitted by various proponents and concluded that none provided any evidence that Laetrile was effective against cancer. The Council also reviewed the California Medical Association's 1953 report on Laetrile, as well as a "new synthetic" Laetrile purportedly developed by Krebs, Jr. In addition, medical records of 144 patients treated with Laetrile were reviewed from physicians in both the United States and Canada.

After the Council determined that the drug was "of no value in the diagnosis, treatment, alleviation or cure of cancer," it recommended that regulations be issued to ban the use of Laetrile and "substantially similar" agents for the treatment of cancer. Despite considerable opposition from Laetrile promoters, the regulation was issued under provisions of California's Cancer Law and became effective November 1, 1963.

The Krebs family returned to court several more times. In 1965, Krebs, Sr., was charged with disobeying a regulatory order forbidding interstate shipment of Laetrile and pleaded "no contest." The following year he pleaded guilty to a contempt charge for shipping Laetrile in violation of injunctions and failing to register as a drug manufacturer. He received a suspended 1-year sentence. In 1974 Ernst, Jr., and his brother Byron pleaded guilty to violating the California state health and safety laws. Each was fined $500, given a suspended sentence of six months, and placed on probation. Byron had his osteopathic license revoked the same year for "mental incompetence", and died shortly thereafter. In 1977, Ernst, Jr., was found guilty of violating his probation by continuing to advocate Laetrile and was sentenced to 6 months in the county jail. He was jailed during 1983 after the appeals process ended.

Meanwhile, Howard H. Beard (not a relative of John Beard), who had worked with Krebs and Dr. Harris, suffered an unfavorable ruling from the California Cancer Advisory Council. For many years he had promoted various urine tests purported to measure the level of human chorionic gonadotropin (HCG). Both Krebs and Beard had claimed that all cases of cancer could be diagnosed on the basis of an elevated HCG test. In 1963 Krebs, Jr., stated that the "scientific implementation" of Laetrile relied upon Beard's test.

Beard had further claimed that an elevated HCG level was sufficient indication for treatment with Laetrile, even in the absence of clinical findings or a positive biopsy for cancer. A true believer in his test, he reportedly began taking Laetrile himself after noting that his urine test was not quite normal. Beard maintained a laboratory offering mail-order service, including measurement of the urinary HCG levels.

Beard developed at least three alleged cancer tests, the most notable of which was his Anthrone Color Test. He claimed nearly 100% accuracy if patients who were pregnant, had liver disease or diabetes, or were taking sex hormones were excluded. He also claimed that the test was so sensitive that it was able to detect the development of cancer within 2-3 weeks after malignant transformation took place.

During the early 1960s, the California Cancer Advisory Council had provided Beard with 24-hour urine specimens from 198 patients, as well as two "urine" specimens which consisted of lactose dissolved in water. Simultaneous tests were performed at the California State Public Health Laboratories. Beard was unable to identify which urine came from patients with cancer and which came from patients with other conditions. The investigation also demonstrated that Beard's test results had nothing to do with cancer but depended mainly on the amount of lactose in the urine. Consequently, the test was banned in California as of August 1965. In 1967, Beard was indicted by a federal grand jury in Texas on nine counts of mail fraud related to the marketing of his test. After pleading no contest, he was given a 6-month suspended jail sentence and 1-year probation.

Further Efforts toward Respectability

The McNaughton Foundation persisted in trying to make Laetrile respectable. They commissioned the SCIND Laboratories in San Francisco to conduct animal studies involving a transplanted tumor system in rats. Although the Foundation had reported that weekly doses of 1 or 2 grams of Laetrile had produced "a brilliant response" in cancer patients and the rats received human equivalents of 30-40 grams, the results were negative.

Undaunted by the negative report, the McNaughton Foundation filed an Investigational New Drug application with the FDA. The FDA responded with a routine form letter giving permission—subject to further review—for investigational clinical trials involving Laetrile. However, eight days later, when the review was completed, the agency requested additional information from the McNaughton Foundation to correct "serious deficiencies" in the application. When this was not produced, the authorization for clinical trials was withdrawn.

While the McNaughton Foundation was attempting to have Laetrile recognized as a drug, Krebs, Jr., began claiming that it was a vitamin, which he called B17. (It only took him about 20 years to come to this conclusion.) Krebs apparently hoped that as a "vitamin" Laetrile would not be subject to the "safety and efficacy" requirements for new drugs. He may have also hoped to capitalize on the popularity of vitamins.

By 1974, Dr. Contreras stated that he was seeing 100-120 new patients per month, with many more patients returning to obtain additional Laetrile. Patients typically were charged $150 for a month's supply. Contreras acknowledged that few of his cancer patients were "controlled" with Laetrile. While admitting that 40% of the patients displayed no response, he claimed that 30% showed "most definite responses" to the drug. However, these statistics may not be reliable. In 1979, he claimed to have treated 26,000 cancer cases in 16 years. Yet when asked by the FDA to provide his most dramatic examples of success, Contreras submitted only 12 case histories. Six of the patients had died of cancer, one had used conventional cancer therapy, one had died of another disease after the cancer had been removed surgically, one still had cancer, and the other three could not be located [5].

The First "Metabolic" Doctor

John Richardson was a general practitioner who began practice in the San Francisco Bay area in 1954. In 1971, after discussions with Krebs, Jr., he decided to become a cancer specialist. He had not encountered overwhelming success as a general practitioner. His 1972 income tax return revealed that he had grossed $88,000 in his medical practice, leaving a net of only $10,400 taxable income.

Richardson's practice boomed as a result of his newly found status as a cancer "expert." He states that "Our office soon was filled with faces we had never seen before—hopeful faces of men and women who had been abandoned by orthodox medicine as hopeless or "terminal" cases." In 1974, he reported that his medical practice had grossed $783,000, with a net income of $172,981. By charging patients $2,000 for a course of Laetrile, Richardson managed to increase his net income 17-fold in just two years. According to his income tax returns, Richardson grossed $2.8 million dollars from his Laetrile practice between January 1973 and March 1976. The actual amount of money he received may have even been higher. In Laetrile Case Histories, he claimed to have treated 4,000 patients, with an average charge of $2,500 per patient. Culbert states that by 1976 Richardson had treated 6,000 patients. If these figures are correct, Richardson would have grossed between $10 and $15 million dollars during this time.

Richardson's practice changed significantly after he began treating cancer patients with Laetrile. He also began treating what he termed "pre-clinical syndrome" patients with Laetrile. These were patients with no identifiable tumor or lesion who complained of feelings of "impending doom, malaise, unexplained or vague pains, headaches, bowel changes, loss of appetite, loss of energy, and depression." According to Richardson, cancer patients reported a reduction in pain, an improved appetite, return of strength, and an improved mental outlook. In addition, high blood pressure returned to normal.

In spite of these "dramatic improvements," Richardson admitted that most of his cancer patients died. In an attempt to overcome this, he increased the Laetrile dosage to nine grams, six days a week, and placed patients on a vegetarian diet and "massive" doses of regular vitamins. Richardson coined the phrase "metabolic therapy" to refer to this combination of diet manipulation, vitamins and Laetrile.

In June 1972, Richardson's office was raided and he was arrested for violating California's Cancer Law. He was convicted of this charge, but the conviction was overturned on a technicality and a new trial ordered. Two more trials followed which resulted in hung juries. Hearings before the California Board of Medical Quality Assurance in 1976 resulted in the revocation of his California medical license. He then worked at a Mexican cancer clinic. During the 1980s, he practiced under a homeopathic license in Nevada until he had open heart surgery and entered an irreversible coma.

The Political Explosion

Dr. Richardson's arrest triggered the formation of the Committee for Freedom of Choice in Cancer Therapy (now called the Committee for Freedom of Choice in Medicine). The group's founder and President was Robert Bradford, a former laboratory technician at Stanford University. Michael Culbert, who at the time of Richardson's arrest was an editor at the Berkeley Daily Gazette, became a major spokesman for the Committee, editing their newsletter, The Choice, and writing two books promoting Laetrile: Vitamin B-17: Forbidden Weapon Against Cancer (1974) and Freedom From Cancer (1976).

Culbert was assisted in editing The Choice by Maureen Salaman, wife of Committee vice-chairman Frank Salaman. The Committee's legislative advisor was Georgia Congressman Larry McDonald, a urologist who used Laetrile. CFCCT's activities were closely allied with the John Birch Society, to which Richardson, Bradford, Culbert, the Salamans and McDonald all belonged. Soon after its formation, CFCCT established local chapters throughout the United States and used bookshops associated with the John Birch Society to hold meetings and distribute literature.

In May 1976 Richardson was indicted, along with his office manager, Ralph Bowman, and fellow CFCCT members Robert Bradford and Frank Salaman, for conspiring to smuggle Laetrile. A year later all were convicted of the charges. Bradford was fined $40,000, Richardson $20,000, and Salaman and Bowman $10,000 each. During the trial it was disclosed that Bradford had paid $1.2 million dollars for 700 shipments of Laetrile and that Richardson had banked more than $2.5 million during a 27-month period.

The NCI Scientist

Although facing problems on some fronts, the Laetrile movement gained adherents. Dr. Dean Burk was a biochemist with a Ph.D. from Cornell Medical College who had joined the National Cancer Institute (NCI) in 1939 as a research fellow. After ten years he was appointed as Head of NCI's Cytochemistry Section, which had a staff of four persons at the time of his retirement 25 years later.

At McNaughton's request, Burk did an experiment in which Laetrile was used to kill a tissue culture of cancer cells. He reported to McNaughton that he could "see the cancer cells dying off like flies." Eventually Burk concluded that Laetrile was the most effective treatment available for cancer, that it relieved the pain of terminal cancer victims, and that it might be useful in preventing cancer. He also claimed in Congressional testimony that Laetrile was less toxic than sugar. Burk became fast friends with Krebs, Jr., and was given a permanent room in Krebs' San Francisco mansion. He was soon on the "Laetrile circuit" and was given the Cancer Control Society's "Humanitarian Award" in 1973.

Burk also became active in opposing fluoridation and spoke against it in many cities throughout the United States and Europe. An inveterate tobacco user, he claimed in Congressional testimony that he had developed a safer cigarette.

The Professor

In 1977, Harold W. Manner, Ph.D., chairman of the biology department at Loyola University in Chicago, achieved considerable notoriety by claiming to have cured mammary cancers in mice with injections of Laetrile and proteolytic enzymes and massive oral doses of vitamin A. What he actually did was digest the tumors by injecting digestive enzymes in amounts equivalent to injecting a woman with a pint of salt water containing about 1 1/2 ounces of meat tenderizer every other day for six weeks. Not surprisingly, the mice developed abscesses where the enzymes were injected, the tumors were liquefied, and the injected tissue fell off. Since no microscopic examinations were conducted and the animals were observed for only a few weeks following treatment, no legitimate assessment of this type of therapy could have been made. But Manner announced at a press conference sponsored by the National Health Federation that a combination of Laetrile, vitamins and enzymes was effective against cancer. He reported his experiments in a chiropractic journal and wrote a book called The Death of Cancer.

Manner also founded the Metabolic Research Foundation whose stated purpose was research into "metabolic diseases," which—according to him—included arthritis, multiple sclerosis and cancer. Sponsored by the Nutri-Dyn company he held seminars throughout the country for chiropractors and unorthodox physicians [6]. Nutri-Dyn manufactured processed animal glands ("glandulars"), which Manner said would help the corresponding body parts of cancer patients. In 1982, a reporter from WBBM-TV Chicago became Metabolic Physician #219 by attending a seminar in Los Angeles and donating $200 to the Metabolic Research Foundation. To indicate his "professional" background the reporter used the initials "D.N.," which, he later explained, stood for "Doctor of Nothing." Manner promised to refer ten patients a year to him.

According to Manner, Loyola University officials became upset with his activities and asked him to either give them up or resign from his position at the school. During the early 1980s, he left his teaching position, became affiliated with a clinic in Tijuana that offered "metabolic therapy." He died in 1988, but the clinic is still operating.

The Rutherford Case

Glen Rutherford was a 55-year-old Kansas seed salesman who was found to have a grape-sized polyp of the colon in 1971. When a biopsy revealed that it was cancerous, he was advised to have it removed. Fearful of surgery, he consulted Dr. Contreras, who treated him with Laetrile, vitamins and enzymes, and cauterized (burned off) the polyp. Although cauterization usually cures this type of cancer when it is localized in a polyp, Rutherford emerged from this experience claiming that Laetrile had cured him and was necessary to keep him alive. People Magazine reported that he also began taking 111 pills (mostly vitamins) costing $14 per day. In 1975, he became lead plaintiff in a class action suit to force the FDA to allow "terminal" cancer patients to obtain Laetrile for their own use.

The case was heard before Judge Luther Bohanon in the Western Oklahoma United States District Court. Bohanon was extremely sympathetic to Rutherford's wishes. In 1977, Bohanon issued a court order permitting individuals to import Laetrile for personal use if they obtained a doctor's affidavit stating they were "terminally ill." Two years later, the U.S. Supreme Court rejected the argument that drugs offered to "terminal" patients should be exempted from FDA regulation [7]. However, further efforts by Rutherford and his supporters plus defiant rulings by Bohanon enabled the affidavit system to remain in effect until 1987, when it was finally dissolved.

Legislative Action

During the mid-1970s, Laetrile promoters portrayed themselves as "little guys" struggling against "big government" and began trying to legalize the sale of Laetrile. Eventually, 27 states passed laws permitting the sale and use of Laetrile within their borders. Federal law still forbade interstate shipment of Laetrile, and since it was impractical to manufacture it for use in just one state, these state laws had little or no practical effect. Proponents hoped, however, that if enough states legalized its use within the states, Congress would change the federal law as well. Although bills were introduced to exempt Laetrile from FDA jurisdiction, they were unsuccessful and petered out with the death of Congressman McDonald in 1983.

In 1977, a U.S. Senate subcommittee chaired by Senator Edward Kennedy (D-MA) held hearings on Laetrile that developed interesting testimony. Dr. Richardson claimed that the FDA, AMA, NCI, American Cancer Society, Rockefeller family and major oil and drug companies had all conspired against Laetrile. Robert Bradford said that he would welcome a test of Laetrile but that "orthodox medicine was not qualified" to do one. However, he Krebs, Jr., and Richardson were unable to agree on the formula for Laetrile. Senator Kennedy concluded that the Laetrile leaders were "slick salesmen who would offer a false sense of hope" to cancer patients. The New York Times commented that the Laetrile promoters were regarded by the Senators "with a blend of amusement and contempt."

Victims in the News

As Laetrile became newsworthy, several cancer victims treated with it drew widespread media scrutiny. One was Chad Green, who developed acute lymphocytic leukemia at age 2. Although he was rapidly brought into remission with chemotherapy, his parents started him on "metabolic therapy" administered by a Manner Metabolic Physician. When Chad developed signs of cyanide toxicity, Massachusetts authorities had him declared a ward of the court for treatment purposes only. His parents then brought suit to reinstitute "metabolic therapy." When the court ruled against them, they fled with Chad to Mexico, where he was treated by Dr. Contreras. Several months later Chad died in a manner suggestive of cyanide poisoning. Dr. Contreras stated that the boy had died of leukemia, but was a good example of the effectiveness of Laetrile because he had died a pleasant death! Chad's parents stated that he had become very depressed because he missed his grandparents, his friends and his dog.

Joseph Hofbauer was a 9-year-old with Hodgkin's disease. Unlike Chad Green's parents, Joseph's parents never allowed him to receive appropriate treatment but insisted that he receive Laetrile and "metabolic therapy." When New York State authorities attempted to place him in protective custody, his parents filed suit and convinced family court judge Loren Brown to let the parents make the treatment decision. Brown stated that "This court also finds that metabolic therapy has a place in our society, and hopefully, its proponents are on the first rung of a ladder that will rid us of all forms of cancer." The parwents rejected standard treatment, and Joseph died of his disease two years later. Acute lymphocytic leukemia and Hodgkin's disease both have a 95% 5-year survival rate with appropriate chemotherapy.

During 1980, movie star Steve McQueen attracted considerable attention when he was treated with Laetrile at another Mexican clinic under the supervision of William D. Kelley, a dentist who had been delicensed by the State of Texas after several brushes with state and federal law enforcement authorities. Although McQueen gave a glowing report when he began his treatment, he died shortly afterward.

NCI Studies

In response to political pressure, the National Cancer Institute did two studies involving Laetrile. The first was a retrospective analysis of patients treated with Laetrile. Letters were written to 385,000 physicians in the United States as well as 70,000 other health professionals requesting case reports of cancer patients who were thought to have benefited from using Laetrile. In addition, the various pro-Laetrile groups were asked to provide information concerning any such patients.

Although it had been estimated that at least 70,000 Americans had used Laetrile—only 93 cases were submitted for evaluation. Twenty-six of these reports lacked adequate documentation to permit evaluation. The remaining 68 cases were "blinded" and submitted to an expert panel for review, along with data from 68 similar patients who had received chemotherapy. That way the panel did not know what treatment patients had received. The panel felt that two of the Laetrile-treated cases demonstrated complete remission of disease, four displayed partial remission, and the remaining 62 cases had exhibited no measurable response. No attempt was made to verify that any of the patients who might have benefited from Laetrile actually existed. The reviewers concluded that "the results allow no definite conclusions supporting the anti-cancer activity of Laetrile."

Although the NCI mailing had not been designed to uncover negative case reports, 220 physicians submitted data on more than 1,000 patients who had received Laetrile without any beneficial response.

In July 1980, the NCI undertook clinical trials of 178 cancer patients who received Laetrile, vitamins and enzymes at the Mayo Clinic and three other prominent cancer centers. The study included patients for whom no other treatment had been effective or for whom no proven treatment was known. All patients had tumor masses that could easily be measured, but most of the patients were in good physical condition. Since Laetrile proponents were unable to agree on the formula or testing protocol for Laetrile, NCI decided to use a preparation that corresponded to the substance distributed by the major Mexican supplier, American Biologics. The preparation was supplied by the NCI Pharmaceutical Resources Branch and verified by a variety of tests. The dosage of Laetrile was based on the published recommendations of Krebs, Jr., and the Bradford Foundation.

The results of the trial were clear-cut. Not one patient was cured or even stabilized. The median survival rate was 4.8 months from the start of therapy, and in those still alive after seven months, tumor size had increased. This was the expected result for patients receiving no treatment at all. In addition, several patients experienced symptoms of cyanide toxicity or had blood levels of cyanide approaching the lethal range [8]. An accompanying editorial concluded:

Laetrile has had its day in court. 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 . . . The time has come to close the books [9].

Bradford and American Biologics responded to the study with three different lawsuits against the National Cancer Institute, alleging that as a result of the study, they had sustained serious financial damage from a drastic drop in demand for Laetrile. All three suits were thrown out of court. Today few sources of laetrile are available within the United States, but it still is utilized at Mexican clinics and marketed as amygdalin or "vitamin B17" through the Internet.

Some Final Thoughts

As long as there remain crippling and fatal diseases, there will undoubtedly be individuals eager to offer "alternatives" to scientific treatment and large numbers of desperate individuals willing to purchase them. The Laetrile phenomenon started with a pharmacist-physician who developed one concoction after another for the treatment of serious diseases, especially cancer. It continued with his son, a self-imagined scientist, who spent many years in college but failed to earn any graduate degree. A man who earned his fortune from gun-running and a catholic newspaper columnist promoted it as a persecuted drug that cured cancer. A cadre of John Birch Society members saw the repression of Laetrile as a sinister plot against their basic freedoms. After it was dubbed "vitamin B-17," an army of health food devotees promoted Laetrile, along with vitamins and diet, as nature's answer to cancer.

After peaking in the late 1970s, the "Laetrile Movement" ran out of steam in the wake of the Supreme Court decision, the NCI study, the death of Steve McQueen, and other unfavorable publicity. But as the Laetrile fantasy faded, its prime movers added many other "miracle cures" to their arsenal and added AIDS, arthritis, cardiovascular disease, and multiple sclerosis to the list of diseases they claim to treat. Although they appear to speak with sincerity, they still fail to sponsor the type of research which could persuade the scientific world that anything they offer is effective.

A systematic review that included all reports available through 2005 concluded that the claim that laetrile has beneficial effects for cancer patients is not supported by sound clinical data [10].

Recent Enforcement Actions

  • On April 20, 2000, the U.S. Justice Department obtained a preliminary injunction barring Christian Bros. Contracting Corp., of Whitestone, New York, and its president, Jason Vale from making or distributing amygdalin, Laetrile, "Vitamin B-17," or apricot seeds [11]. Although Vale signed a consent decree, he continued his sales activity through a network of Internet sites, toll-free telephone numbers, and shell companies. In 2003, a federal jury in Brooklyn found him guilty of criminal contempt [12] for which he was sentenced to prison.
  • In July 2000, Kenneth N. Michaelis and his company, Holistic Alternatives, both of Louisville, Ohio, were indicted for conspiring to distribute Laetrile and hydrazine sulfate in interstate commerce. The indictment also alleged that with intent to mislead the FDA, the defendants failed to register their drug manufacturing facility [13]. The company, which defied the FDA for many years, described itself as "the oldest supplier of laetrile and hydrazine sulfate in the US." In 2001, Michaelis pleaded guilty and was fined $10,000 and sentenced to six months in prison followed by a year of supervised release. He also agreed to a permanent injunction. After reviewing the relevant documents, the Ohio State Medical Board suspended Michaelis's massage therapy license for at least 180 days and issued terms under which he could apply for instatement [14].
  • On September 1, 2000, a United States District Court Judge issued a preliminary injunction against World Without Cancer, Inc., The Health World International, Inc. of Bay Harbor Island, Health Genesis Corporation, an Arizona concern that does business in Bay Harbor Island, Florida, and David E. Arizona, an officer of the three corporations. The ruling enjoins the defendants from introducing or causing the introduction into interstate commerce of laetrile products, apricot seeds, or any other unapproved drug product as well as manufacturing, processing, packing, labeling, promoting, or distributing these or any other new drug. The order also requires the defendants to modify their Internet web sites to cease using the web sites to promote the sale of or offer for sale their laetrile products [15].
  • In January 2004, Jack Edwin Slingluff, D.O., of Canton, Ohio, pled guilty to one count of introducing an unapproved new drug into interstate commerce [16]. The one-count criminal information stated that he "caused thirty (30) vials of the unapproved new drug Amigdalina B-17 (AKA Laetrile) to be shipped from West Palm Beach, Florida, to Salem, Ohio; in violation of Title 21, Sections 331(d), 355(a) and 333(a)(1), United States Code." The State Medical Board of Ohio suspended his medical license for a year and permanently revoked it in 2008 [17]. He died in 2011.

For Additional Information


  1. Young JH. Laetrile in historical perspective. In Merkle GE, Petersen JC, editors. Politics, Science, and Cancer: The Laetrile Phenomenon. Boulder, CO: Westview Press, 1980.
  2. American Cancer Society. Laetrile background information. New York: Amerian Cancer Society, 1977.
  3. Bruzelius, NJ. The merchants of Laetrile. Boston Sunday Globe, June 17, 1979.
  4. Kennedy D. Laetrile: The Commissioner's Decision. H.E.W. Publication No. 77-3056.
  5. Laetrile: The political success of a scientific failure. Consumer Reports 42:444-447, 1977.
  6. South J. The Manner clinic. Nutrition Forum 5:61-67, 1988.
  7. United States vs. Rutherford, 442 U.S. 544 (1979).
  8. Moertel C and others. A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. New England Journal of Medicine 306:201-206, 1982.
  9. Relman A. Closing the books on Laetrile. New England Journal of Medicine 306:236, 1982.
  10. Milazzo S and others. Laetrile for cancer: A systematic review of the clinical evidence. Support Care Cancer 15:583-595, 2007.
  11. Barrett S. Laetrile spammers facing $631,585 penalty. Quackwatch, Sept 9, 2000.
  12. Lewis C. Online laetrile vendor ordered to shut down. Quackwatch, Nov 28, 2003.
  13. Licking County man and his company man and his company indicted for distributing laetrile and hydrazine sulfate. U.S. Justice Department news release, July 18, 2000.
  14. Corrected entry of order. In the matter of Kenneth N. Micaelis, L.M.T. Before the State Medical Board of Ohio, Dec 11, 2002.
  15. FDA takes action against firms marketing unapproved drugs. FDA Talk paper, T00-39, Sept 6, 2000.
  16. Plea agreement. United States of America v Jack Edwin Slingluff. U.S. District Court for the Northern District of Ohio, Eastern Division Case No. 4:04 CR 74, filed March 16, 2004.
  17. Entry of order. In the matter of Jack Slingluff, D.O. Before the State Medical Board of Ohio, Dec 10, 2008.

This article was revised on January 7, 2014.

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