Q) Have you any statis-tics or views on the use of vitamin B17 in the treatment of can-cers? I have read a considerable amount regarding Laetrile, amygdalin, apricot kernels and the like in the successful treatment of mice, but have not seen any proper study undertaken to prove or disprove its use in humans. There are many anecdotal reports, but no real proof. Can you dispel a myth or is it,in fact, true?-C. T., via e-mail
A) Amygdalin and vitamin B17 are among the various names given to the nitriloside found in some 1200 plants, including the kernels of plums, apricots, peaches and bitter almonds. Laetrile is the patented name of a product (from 'laevo-mandelonitrile', yet another name for amygdalin) pioneered by a group of California doctors. It's been referred to as a B vitamin because some people maintain that cancer patients lack what they consider is a vital substance in the body.
Amygdalin has always been thought to be lethal to cancer because beta-glucosidase, one of the many enzymes of the body, breaks the substance down into benzaldehyde, glucose and hydrogen cyanide, thereby releasing the poisonous cyanide gas within the body. Since cancer cells contains thousands of times more beta-glucosidase than do normal cells, they trigger an even greater release of cyanide gas, which is toxic to the cancer, but rendered harmless to healthy cells by other enzymes in the body. Theoretically at least, vitamin B17 provides the perfect means for cancer to self-destruct without harming the rest of the body.
Manufactured in Mexico, Laetrile is not approved by the US Food and Drug Administration (FDA), although certain states, including Montana and Indiana, allow doctors to prescribeit as a 'dietary supplement'.
The evidence for amygdalin is decidedly mixed, and largely coloured by the politics surrounding cancer. It first came into favour on the heels of a series of meticulous studies carried out by Dr Kanematsu Sugiura, one of the most well-known researchers in cancer research, based at the Sloan-Kettering Institute for Cancer Research in New York City from1972 to 1977.
Lethal to cells
According to Sugiura, the studies (carried out on mice with tumours) showed that Laetrile prevented the metastasis (spread) of cancer in these animals while improving their health, inhibiting the growth of small tum-ours and preventing the development of further cancer. Other researchers at Sloan-Kettering replicated the studies-and obtained even better results. Nevertheless, according to noted cancer researcher Ralph Moss, then a science writer at Sloan-Kettering, the institute-which was more interested in a drug-based cure-covered up these positive findings.
In spite of this, similar research on mice at other research centres have also shown either improved survival times and even regression of tumours (Pelton R, Overholder L. Alternatives in Cancer Therapy. New York: Simon & Schuster, 1994). However, findings in animals may not necessarily apply to humans.
The rest of the lore about vitamin B17 concerns the fact that a number of native or traditional cultures that have been found to be virtually free from cancer-such as the Hunzas, Esquimos, Abkhazians (in the repub-lic of Georgia), Hopi and Navajo Native Americans, and the Karakor-um (in the republic of Mongolia)-all are said to have diets rich in B17.
But what about human studies? One study of patients with breast and bone cancers claimed that it could increase survival times, but only at dosages higher than those normally used (70 g/day). But even at these higher doses, leukaemia patients failed to respond (Choice, 1977; 3: 8-9).
Many studies show that amygdalin is lethal to cancer cells when isolatedin a test tube. A laboratory study of the effect of amygdalin on prostate-cancer cells demonstrated that it increased the expression of a protein that is involved in cell death (Biol Pharm Bull, 2006; 29: 1597-602). In another study, amygdalin inhibited genes related to the cell cycle of human colon-cancer cells (World J Gastroenterol, 2005; 11: 5156-61).
Nevertheless, when amygdalin was given to patients, the effect has been variable. In one trial, Laetrile failed to shrink tumours, increase survival time, alleviate cancer symptoms or enhance wellbeing (CA Cancer J Clin, 1991; 41: 87-92).
In another, earlier, clinical trial, breast-cancer patients (one-third of whom had not undergone any chemo-therapy) given Laetrile together with a metabolic-therapy programme of diet, enzymes and vitamins did not receive any "substantive benefit" in terms of cure, improvement or stabilization of cancer, improvement of cancer symptoms or extension of life (N Engl J Med, 1982; 306: 201-6).
However, these studies were not the randomized, double-blind, con-trolled trials that are considered the 'gold standard' today, but only compared patients receiving the treatment with those taking a placebo.
According to a University of Exeter review of the medical literature, amydalin has undergone only 11 case series and 25 case reports-and nota single properly controlled clinical trial (Cochrane Database Syst Rev, 2006; 19: CD005476).
And given the agent's chequered reputation, it may be difficult, if not impossible, to obtain adequate funding for better research.
Sullying its reputation even further are a number of worrying reports of severe or fatal toxicity in children (Pediatrics, 1986; 78: 269-72) as well as adults. A number of those reports concerned patients who ingested high doses that should have been injected, or who were self-medicating and unsure of the correct dosagesto take. Among the breast-cancer patients mentioned above, several patients presented with symptoms of cyanide toxicity or had their blood cyanide levels approaching the lethal range (N Engl J Med, 1982; 306: 201-6).
Such incidents were also seen in patients who were concurrently tak-ing high doses of vitamin C, as the vitamin increases the conversion of amygdalin to cyanide, and reduces the ability of normal cells to detoxify the gas. In one case-report, a 68-year-old cancer patient was rushed to the emergency department of a hospital suffering from life-threatening seiz-ures and coma after taking her first3-g dose of amygdalin. It was soon revealed that she'd also taken 4800 mg of vitamin C (Ann Pharmacother, 2005; 39: 1566-9).
Intravenous amygdalin appears to be less toxic. In one study, when benzaldehyde was given intravenously (daily doses of 720-1800 mg/m2) to 65 patients with advanced-stage inoperable cancers, 55 per cent res-ponded to the agent: seven patients had a complete response; 29 patients, a partial response; 24 patients remained stable; and in only five did the disease progress.
Many of the patients had their survival prolonged, and no toxic reactions were observed, not even with long-term injection of the substance (Cancer Treat Rep, 1985; 69: 533- 7). This may be because, as observed in one study of the pharmacology of amygdalin, after intravenous administration, it is quickly cleared from the body, leaving only a scant percentage of the dose systemically available (Arch Toxicol, 1982; 49: 311-9).
The benzaldehyde connection
One of the problems with this therapy may be taking amygdalin in its raw form, with the cyanide intact, rather than as a chemical derivative of another of its active ingredients. Patients assume that it's the cyanide that is fighting the cancer, but it may have more to do with the benz-aldehyde, a chemical relation of benzene. Indeed, in the above-mentioned study of intravenous amygdalin, Dr M. Kochi and his colleagues were using a gluconated form of benzal-dehyde, which may explain the com-plete lack of observ-ed toxic reactions in all of the study patients (Cancer Treat Rep, 1985; 69: 533-7).
Another study achieved similar results, with an overall response rate of 58.3 per cent (Br J Cancer, 1990; 62: 436-9)-and, as with Kochi's study,no toxic side-effects.
Yet another study from Norway found that benzaldehyde changed malignant cells back to normal (Anticancer Res, 1991; 11: 1077-81).
The benzaldehyde connection has also shown a positive effect in animal studies as well. Japanese research in the 1970s showed that a distillateof figs, which is also rich in benz-aldehyde, was able to successfully treat cancer in mice.
Ironically, the forms of amygdalin derivatives that have been somehow chemically enhanced have proved to have the more powerful effects. One study found that, although three different benzaldehyde derivatives exerted anticancer actions-albeit weak ones-without side-effects, when the chemical structure of benzaldehyde was altered (with the application of 'heavy hydrogen' or 'deuterium'), it produced a form that proved to be the best at inhibiting cancer-cell growth.
When the chemical was synthes-ized with ascorbic acid [called 'zilascorb' (2H)], it was found to be the most effective at inhibiting protein synthesis in human cells, compared with three other benz-aldehyde compounds. As soon as the agent was stopped, protein synthesis returned to normal within an hour (Anticancer Res, 1991; 11: 1077-81).
In yet another study, when a newly developed acid-boiling method was used to prepare an extract from peach kernels, the amygdalin remained in an active state and proved highly lethal to leukaemia cells (Arch Pharm Res, 2003; 26: 157-61).
In a laboratory study, when beta-glucosidase was piggybacked ontoa tumour-associated monoclonal antibody (a highly specific antibody that recognizes only one antigen-in this case, one related to tumour cells), it proved lethal to bladder cancer cells, and was 36 times more effective than beta-glucosidase on its own (Int J Cancer, 1998; 78: 712-9).
The bottom line
To all intents and purposes, isolating an active ingredient from a com-pound such as amygdalin in effect makes a drug. So why aren't the pharmaceutical companies leaping up and down to create what could become a top-selling anticancer drug?
The answer, according to Ralph Moss, is largely because there's no money in it. Benzaldehyde is remark-ably cheap-only 30 cents an ounce. Since the typical cancer patient only requires 1 gram a day, the annual cost per cancer patient taking this drug would be only $2-or less than a penny a day.
All told, the evidence suggests that raw amygdalin has variable effects, hasn't been fully proven and may be toxic, at least when taken orally. If you're going to try taking amygdalin, it might be better to take it intra-venously and only under the careful supervision and monitoring of a physician.
Benzaldehyde appears to have a promising (but short) history, and may be the best option of all, although you may have to travel outside of the US or UK to get your hands on any. Once again, given the history of this chemical compound, it's important that you don't attempt to self-medicate and that you avoid taking it together with high dosesof vitamin C.
And if you do ever suffer from cyanide poisoning, there are cyanide-antidote kits and a hydroxocobalamin treatment that may help you achieve a rapid recovery.