Discussion of the cancer-fighting properties of a chemical (variously referred to as amygdalin, laetrile, or "vitamin B17") has been a fixture of the so-called alternative medicine movement for decades. Despite an exhaustive body of research demonstrating that its use is both ineffective and potentially dangerous, these claims still make their way onto the internet’s most popular “natural health” blogs and continue to fuel anti-government conspiracies.
The story of “B17 deficiency” has the two key qualities of a classic snake oil campaign: a simple, easy cure for all cancer provided by Mother Nature herself, and a purported widespread conspiracy to prevent the public from knowing about it.
This string of loosely connected words from a viral September 2016 post is representative of the way this issue is frequently framed:
You would recall that in the past, quite a large number of seamen lost their life to a named disease (scurvy); a disease that took the life of numerous people as well. And a number of people got an enormous income from it. Afterwards, it was discovered that scurvy was just a deficiency of vitamin C. That means it wasn’t a disease (illness).
Cancer is also just like that! The colonizing world and the enemies of humanity established the cancer industry and made it into a business from which they earn billions in income.
The prevention and cure of cancer will be obtained simply through the following strategies:
Those who have cancer should first try to know what cancer is. Do not panic! You should investigate the condition. Nowadays does anyone die of an illness called scurvy? No. Because it gets cured.
Since cancer is only a deficiency of vitamin B17, eating 15 to 20 pieces of apricot stone/nucleus (fruit stone) everyday is enough. This matter is present in the fruit stone of apple and is the extracted form of vitamin B17 (Amygdalin).
Before digging into this reassuring bit of nonsense, we have to be clear on one key point: The notion of “vitamin B17” was essentially made up by a man named Ernst Krebs, Jr., inventor of a partially synthetic chemical called laetrile that was at one point rebranded as a vitamin in an effort to get around FDA new drug regulations. No official pharmacopoeia lists it as a vitamin, and it does not possess any of the required characteristics of a vitamin.
In a hearing about an 1976 injunction demanding that a company cease selling supplements with this compound, a federal court described the vitamin defense as "a patently absurd and transparent attempt to avoid the drug labeling provisions of the Federal Food, Drug, and Cosmetic Act."
Amygdalin is a naturally occurring compound that can be found in a variety of foods, most notably bitter almonds and the pits of apricots and other fruits. Claims that it is a potential cancer therapy can be credited to the father and son team of Ernst Krebs Sr. (a doctor and pharmacist with a long history of promoting fringe folk remedies) and Ernst Krebs Jr. (who was not a doctor nor even the recipient of any degree in science, save an honorary doctorate from a now-defunct university). Their work is described in a 1981 review on the topic:
In the 1920s, working in a home laboratory to find a method for improving the taste of bootleg whiskey, an obscure San Francisco general practitioner, Dr. Ernst Krebs, Sr., suggested that an extract of apricot seeds reduced rodent tumors. Dr. Krebs warned that the material, which in 1936 appeared to be predominantly the common chemical amygdalin, was too unpredictable and too dangerous for general human use.
Its promotion did not really begin until over 20 years later when his son, Ernst Krebs, Jr.. claimed to have synthesized a safe congener of amygdalin, for which he coined the term “laetrile”. In spite the younger Mr. Krebs' claims, most of what has since been sold as laetrile has consisted of a variety of components and the active portion has usually been amygdalin itself.
One of the tell-tale warning signs of a pseudoscientific remedy is that the explanation for how it works (or even what it does, and in this case even what it is) changes every time someone points out that a previous explanation was demonstrably unworkable, without acknowledgement of the previous lack of veracity.
There have been at least four explanations for why laetrile might work. As summarized by a National Institutes of Health Physician Data Query report, most invoke the fact that laetrile is toxic to cancer cells (which is almost certainly related to the fact that it metabolizes into cyanide) but not other cells:
The [first] rationale for laetrile use is the suggestion that malignant cells have higher than normal levels of an enzyme called beta-glucuronidase [...] and that they are deficient in another enzyme called rhodanese [...]. it has been proposed that cancer cells are more susceptible to the toxic effects of laetrile than normal cells because of an imbalance in these two enzymes.
The second theory states that cancer cells contain more beta-glucosidase [which is different than beta-glucuronidase mentioned above] activity than normal cells and, as in the first theory, that they are deficient in rhodanese.
The third theory states that cancer is the result of a metabolic disorder caused by a vitamin deficiency. It states further that laetrile, or amygdalin/vitamin B-17, is the missing vitamin needed by the body to restore health. [...] there is no evidence that laetrile is needed for normal metabolism or that it can function as a vitamin in animals or humans.
The fourth theory suggests that the cyanide released by laetrile has a toxic effect beyond its interference with oxygen utilization by cells. According to this theory, cyanide increases the acid content of tumors and leads to the destruction of lysosomes (compartments inside cells that contain enzymes capable of breaking down other cellular molecules). The injured lysosomes release their contents, thereby killing the cancer cells and arresting tumor growth.
In fact, the rationale for laetrile’s efficacy is not the only thing that has shifted over the course of its promotion; what conditions or health problems it is meant to ameliorate have also jumped around, as discussed in a 1977 FDA report:
Over the years, proponents have claimed that Laetrile is a cure for cancer, that it is palliative, that it prevents cancer, that it is a painkiller, or that it facilitates other cancer treatments. There have even been claim that Laetrile raises the red count in blood, is of value in treating in treating sickle cell anemia, can be used to treat parasitic diseases, helps regulate intestinal flora,, causes a lowering of blood pressure in cancer victims and provides relief from arthritis.
The definition of what chemically constitutes both laetrile and “vitamin B17” has been equally fluid. Though classically defined by Krebs Jr. as a specific compound named "laevo-mandelonitrile-beta-glucuronoside," numerous tests have shown that this product is not what is found in most laetrile or B17 products.
In many studies, amygdalin and laevo-mandelonitrile-beta-glucuronoside are taken to be the same thing, despite the fact that they are not (recall that the reason a “synthetic version” of amygdalin was needed was rooted in Kreb Sr.’s conclusion that the natural version was too toxic for human use). Other claims suggest an even broader definition, which includes an entire class of structurally related compounds variously named nitrilosides or laetrile.
Overshadowing this unceasing onslaught quacktastic red flags are two hard truths: 1) there is effectively no evidence that laetrile, amygdalin, B17, etc., have any efficacy as a cancer treatment for humans and 2) there is plenty of evidence to suggest that amygdalin and related compounds are extremely toxic to humans, a problem compounded by the fact that several studies have shown that amygdalin supplements vary wildly in the accuracy of their concentrations and are completely unregulated.
In response to pressure from pro-laetrile groups during its heyday in the 1970s, the National Cancer Institute conducted a retrospective review, published in 1976 of people who had been treated with laetrile for cancer. They did this by soliciting information by mail from 385,000 physicians and 70,000 other health professionals known to treat patients with laetrile, as well as by soliciting information directly from members of pro-Laetrile groups.
Of the 70,000 cases estimated to have been treated with the chemical at the time, only 93 were submitted for review. A further 26 were eliminated due to insufficient data, revealing, ultimately, only six that could be described as “producing a response”:
A panel of 12 oncologists, who had no knowledge of the actual treatments given, was then asked to evaluate the results of 160 courses of treatment (68 Laetrile, 68 chemotherapy, 24 "no treatment") in the abstracted records from 93 patients. The panel judged six Laetrile courses to have produced a response (two complete and four partial). These results allow no definite conclusions supporting the anti-cancer activity of Laetrile. The National Cancer Institute will use the data in deciding if further study is needed.
In a followup to this report, a 1982 human trial that treated 78 cancer patients with amygdalin, published the New England Journal of Medicine, concluded:
No substantive benefit was observed in terms of cure, improvement or stabilization of cancer, improvement of symptoms related to cancer, or extension of lifespan.
A 2015 review of over 200 citations related to amygdalin, laetrile, and cancer concluded:
The claims that laetrile or amygdalin have beneficial effects for cancer patients are not currently supported by sound clinical data.
These results are not to say that amygdalin and related compounds do not do anything. In that same 1982 human trial, researchers documented both the aforementioned lack of efficacy, as well its potentially fatal toxicity:
The hazards of amygdalin therapy were evidenced in several patients by symptoms of cyanide toxicity or by blood cyanide levels approaching the lethal range. Patients exposed to this agent should be instructed about the danger of cyanide poisoning, and their blood cyanide levels should be carefully monitored. Amygdalin (Laetrile) is a toxic drug that is not effective as a cancer treatment.
This, too, was echoed in the previously cited 2015 evidence review, which stated:
There is a considerable risk of serious adverse effects from cyanide poisoning after laetrile or amygdalin, especially after oral ingestion. The risk-benefit balance of laetrile or amygdalin as a treatment for cancer is therefore unambiguously negative.
The weight of this evidence has not deterred natural health evangelists like Joseph Mercola (who was recently ordered by the FTC to pay back over five million dollars in money generated from selling his own brand of indoor tanning beds that, in his words, “slash your risk of cancer”) from suggesting that the weight of scientific evidence is on their side.
Mercola, in a 2014 post that appears on many other websites, lists five studies which he says demonstrates the effectiveness of laetrile. None of these studies were based on human trials or data generated by the compound’s actual clinical use (unlike the large scale clinical trials and retrospective reviews and meta-reviews mentioned above); they were either cell line studies or studies based on laboratory animals.
That promotion of “vitamin B17” is still a viable business model online is thanks, in large part, to the efforts of individuals with political or financial motives, but whose medical background might best be described as non-existent.
That movement got a huge lift in 1973 when a public relations officer at Sloan Kettering Hospital, which was given the task by the NIH of performing a series of laetrile trials, alleged a cover up of, and leaked, data that claimed potential for laetrile as an anti-cancer agent. Despite the fact that no scientist could reproduce those results in a series of followups, the view of a government cover-up created a media sensation, and has left a mark on its research that still resonates today.
That former public relations writer, Dr. Ralph W. Moss (who has a Ph.D in classics, not science) is now one of the leading advocates for laetrile. For the low price of $297.00, he will provide you with a personalized “Moss Report” about your cancer diagnosis. He even provides one hour phone consultations to discuss treatment options. The legally required disclaimer on his website reads “nothing Ralph W. Moss, PhD, says in your telephone consultation constitutes medical advice.”
Perhaps the most prominent force keeping the laetrile myth alive is the book “World Without Cancer: The Story of Vitamin B17” (which was very positively reviewed by “Dr.” Ernst Krebs Jr himself!) by G. Edward Griffith, a libertarian activist with no medical training. Despite his book being basis for many pro-laetrile arguments, Griffith himself seems to be less enthused by that notion these days, as evidenced by this fairly convoluted introduction on his web site VitaminB17.org:
As webmaster of VitaminB17.org, certainly I believe in B17. I wouldn't have spent my time and personal resources on this site all these years if I didn't believe in it. The thing about life is, you can only go by the best information you have at the time. You don't know what you don't know. While I still believe in B17, new information has come to light that I believe is not only also valid information, but more central to cancer than B17. That said, I still would pursue B17 as a treatment for cancer.
The scientific view, however, has not shifted much at all. This 1981 assessment is still the opinion held by the scientific community today:
All prior forms of cancer quackery [...] pale in comparison with the laetrile crusade, unquestionably the slickest, most sophisticated, and certainly the most remunerative cancer quack promotion in medical history.