Unconventional Cancer Therapies
Laetrile / Amygdalin
/ Vitamin B17 / Sarcarcinase / Nitriloside
http://www.bccancer.bc.ca/PPI/UnconventionalTherapies/LaetrileAmygdalinVitaminB17SarcarcinaseNitriloside.htm
The role of your cancer health professional is to create an
environment of openness and trust, and to help in making informed decisions
about alternative/complementary therapies. Collaboration will improve the safe
integration of all therapies during your experience with cancer. The
"Summary" and "Professional Evaluation / Critique" sections
of this Unconventional manual are cited directly from the medical literature,
and are intended to help in the objective evaluation of alternative/complementary
therapies.
Summary
In 1980, the National Cancer Institute began a clinical study of
laetrile in terminal cancer patients. "Conducted in collaboration with
four major
"Moreover, laetrile has been banned by the FDA because of the
risk of poisoning from its cyanide content." (Fetrow)
Description / Source / Components
Although
not chemically identical, amygdalin and Laetrile are
terms frequently used interchangeably. Both belong to a family of compounds
called cyanogenic glycosides.
"It is also sometimes referred to as vitamin B17,
although it is definitely not a vitamin." (
"It is obtained from the kernels of apricots, peaches, plums,
cherries, nectarines, apples, and almonds." (Fetrow)
"Amygdalin occurs naturally in a
number of plant materials; however, the usual commercial source is the kernel
of various varieties of Prunus armeniaca L. (family Rosacea),
commonly referred to as apricot pits. These vary appreciably in there amygdalin or laetrile content, which may reach 8 percent,
but the kernels of some wild varieties contain twenty times as much as those of
cultivated varieties of apricots." (
"Laetrile is a poisonous chemical found in the kernels of
some fruits and nuts." (
"Laetrile (amygdalin) is a cyanogenic glycoside that was proposed for cancer treatment
on the basis that it would be broken down by an enzyme in cancerous tissue to
liberate cyanide which would 'kill the cancer'." (Jukes)
"Amygdalin is a naturally occurring
cyanogenic glycoside, which can be cleaved by sweet
almond beta-glucosidase to yield free cyanide."
(Syrigos)
Amygdalin, when extracted from oil of bitter
almonds, yields 2 units of glucose, 1 unit of benzaldehyde,
and 1 unit of hydrogen cyanide. (White)
"Laetrile is most commonly given intravenously for two to three
weeks. This treatment is followed by oral doses for maintenance therapy."
(
History
Amygdalin, perhaps first documented by Dioscorides
of Anazarbos 2,000 years ago, is usually administered
in the form of bitter almonds. (Moertel)
It was "rediscovered" in 1920 by a
"Laetrile was developed by Ernst T. Krebs, Sr., MD, and his
son Ernst T. Krebs, Jr., and was first used to treat cancer patients in
"The Committee for Freedom of Choice in Medicine is the
political arm of several interlocking corporations promoting and/or marketing
questionable remedies for cancer and other serious disease. Operating during
the 1970s as the Committee for Freedom of Choice in Cancer Therapy, the
organization fought for legalization of Laetrile and claimed to have many
members. Today the committee appears to be a small group whose principal
activities are speeches and press conference by its
leaders, protests to government agencies, and publication of a small
circulation newsletter." (CA 1993)
"Lacking any proof of safety and efficacy, the Food and Drug
Administration banned laetrile from interstate commerce in 1971. However,
several state legislatures, reacting to political pressures, legalized
intrastate sale and use of the product. In 1980, similar pressures forced the
National Cancer Institute to begin a clinical study of laetrile in terminal
cancer patients." (
"...its 1970 popularity waned even before the 1982
publication of a Mayo Clinic investigation showing its ineffectiveness." (Cassileth)
Proponent / Advocate Claims
"The
noted biochemist Ernest Krebs, Jr., PhD., first
specifically identified amygdalin as an anticancer
agent. His discovery was based on a theory that cancer grows from misplaced trophoblast cells; these are cells found in a pregnant
human uterus that multiply rapidly during the first few weeks after conception.
Under normal, healthy conditions, trophoblast cells
are destroyed by the pancreatic enzyme, chymotrypsin.
If they escape destruction, they can lodge in the embryo and remain there,
dormant, for decades, waiting to develop into a tumor when the pancreas becomes
dysfunctional." (Diamond)
Laetrile advocates advance two theories:
1. Cyanide Release Theory
"Advocates of laetrile therapy for cancer believe that an
enzyme, beta-glucosidase, capable of breaking down
the laetrile to release toxic cyanide, exists in large amounts in tumorous tissue but only in small quantities in the rest of
the body. They further hypothesize that another enzyme, rhodanese
(sic), which has the ability to detoxify cyanide, is present in normal tissues
but deficient in cancer cells. These two factors supposedly combine to effect a
selective poisoning of cancer cells by the cyanide released from the laetrile,
while normal cells and tissues remain undamaged." (
Beta-glucosidase, an enzyme occurring in
malignant neoplasms, was believed to release
sufficient amounts of hydrogen cyanide from Laetrile to stop tumour respiration and thus destroy cancerous tissue.
(Levi)
2. Vitamin Deficiency Theory
Cancer is a vitamin deficiency disease, and Laetrile is the
missing "vitamin B17". (Martin 1983)
Professional Evaluation / Critique
"The
National Cancer Institute (NCI) sponsored an independent study of Laetrile with
cancer patients. Fifty-four percent of the 178 patients had measurable cancer progression
after 21 days of intravenous treatment with Laetrile. After 3 months, 91
percent had disease progression, and after 7 months, all patients' tumors had
grown larger. Very few patients reported any change in their symptoms. Half of
all patients in the study died within 5 months after starting treatment; within
8 months, 85 percent were dead." (National Cancer Institute)
"NCI tested Laetrile in laboratory animals several times but
found no convincing evidence that it is effective against animal cancers."
(National Cancer Institute)
"Consumption of peach kernels is potentially fatal, and there
are no valid clinical studies documenting the effectiveness of hydrocyanic acid
in the prevention or treatment of cancer. The potential risks associated with the
consumption of peach kernels outweigh any potential benefits, and their used
should be discouraged." (Fetrow)
No evidence is available to support either of the proposed
theories. All data published in reputable scientific journals reveal that
Laetrile has no selective antitumor activity against
either animal or human cancers. (Martin 1983)
1. Cyanide Release Theory
Dr. Charles G. Moertel described a
clinical trial involving 178 patients. Patients were selected who had histologically proven cancer for which no standard
treatment was known to be curative or to extend life expectancy. All patients had had no surgery, radiation
therapy or chemotherapy for one month. The amygdalin
used for treatment was prepared from apricot pits and supplied by the Pharmaceutical
Resources Branch of the National Cancer Institute.
Patients selected were in good general condition, were ambulatory
and able to maintain good nutrition. Patients who were disabled and bedridden
were ineligible for the study.
The routes, dosage and schedule of administration were chosen to
be representative of current Laetrile practice. Patients were also placed on a
diet identical to the one recommended by most Laetrile practitioners.
"Each patient had either a tumor area which could be measured
in two dimensions or malignant hepatomegaly with a
clearly defined liver edge extending at least 5 cm below the costal margin.
Lesions demonstrable by radioisotope liver scan or by computerized tomographic scan were accepted if they measured 5 cm in
diameter." (Moertel)
Of 171 fully documented patients, only one patient met the
criteria for partial response. However, all patients had tumor progression by 7
months.
"The fact that amygdalin therapy
did not slow the advance of malignant disease or induce
"stabilization" is evidenced by the fact that more than half these
patients had measurable tumor progression when they terminated the intravenous
induction therapy and that over 90 percent had progression by 3 months." (Moertel)
2. Vitamin Deficiency Theory
A vitamin is defined on the basis of several properties not
applying to Laetrile:
- A vitamin is required in small amounts for the complete health
and well-being of vertebrate organisms.
- Vitamins are not used primarily to supply energy or as a source
of structural tissue components of the body.
- A vitamin promotes physiological processes vital to the
continued existence of the organism.
- A vitamin (except vitamin A) cannot be synthesized by the cells
of the organism.
- In man, deficiency of a specific vitamin is the cause of certain
well-defined diseases. These diseases are cured or prevented by the addition of
the appropriate vitamin. (Greenberg)
The following facts have been established about Laetrile
(incorrectly called vitamin B17):
1. Laetriles are not essential
nutritional components.
2. Laetriles have never been shown to
promote any vital physiological processes.
3. No specific disease has been associated with a lack of
Laetrile. (Greenberg)
Laetrile may be a carcinogen (itself cause cancer); mutagenic
effects have been observed as determined by the Ames Salmonella lyphimurium test. (Fenselan)
Two researchers in
An inquiry reported in the New York Times in 1977 revealed a
profit of $150,000 to $200,000 a month to one Laetrile promoter. (Martin 1977)
Toxicity / Risks
"A
clinical trial conducted at the Mayo Clinic and three other prominent cancer
centers found no anticancer effect but found significant blood levels of
cyanide in some of the patients." (Hafner)
While taking Laetrile, patients may suffer nausea, vomiting, headache,
and dizziness. (
"Symptoms following cyanide poisoning include sudden, severe
vomiting and epigastric pain followed by syncope [a
faint], lethargy, coma, and seizures. Chronic consumption of plants high in cyanogenic glycosides has resulted in optic atrophy [a
wasting away of the optic disc], nerve deafness, spastic paraparesis
[a partial paralysis of the lower extremities], ataxia [failure of muscular
coordination], clonus [alternate muscular contraction
and relaxation in rapid succession], and peripheral neuropathy." (Fetrow)
"Serious cases of poisoning have been reported as a result of
eating quantities of these seeds." (
Several patients participating in the clinical trial conducted by Moertel had symptomatic toxicity (nausea and vomiting,
headache, dizziness, mental obtundation, dermatitis).
These symptoms subsided promptly when oral amygdalin
was discontinued. They were sometimes (but not always) associated with
relatively high levels of blood cyanide. The cyanide approached levels known to
be lethal to animals. (Moertel)
"In addition, the Laetrile was generally available from
Mexican suppliers and was found to be contaminated with infectious agents and endotoxin. Deaths attributable to laetrile have been
reported." (Spencer)
Taken by injection, amygdalin is non-toxic, however, when a source of beta-glucosidase
is injected with amygdalin, the toxicity is greatly
increased. Orally administered, amygdalin is
definitely toxic, presumably due to the presence of beta-glucosidase
in the small intestine. (Greenberg)
Ingested with plant material containing beta-glucosidase,
amygdalin can be lethal. (Schmidt)
Two reports of deaths from swallowing amygdalin
preparations intended for the treatment of cancer have been published, one of a
child (Humbert); the other of a seventeen year old
girl. (Sadoff)
A three year old boy suffering from leukemia died in
A woman suffering from breast cancer died of cyanide poisoning
after taking massive doses of Laetrile. (
Prolonged ingestion of cyanogenic
glycoside-containing plant food stuffs is suspected of being a cause of
tropical amblyopia (dimness of vision) and other
obscure neurological disorders. (
Costs
"Laetrile
is usually given as part of a larger treatment program which can cost between
$2,000 to $5,000
The Richardson Centre in
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Revised February 2000