http://www.cancerhelp.org.uk/help/default.asp?page=21859
This page tells you about laetrile (also known as amygdalin or
vitamin B17) in people with cancer. There is information on
What is laetrile?
Laetrile is a partly man made (synthetic) form of the natural
substance amygdalin. Amygdalin is a plant substance found naturally
in raw nuts and the pips of many fruits, particularly apricot pips.
Some people call laetrile vitamin B17, although it isn’t a vitamin.
It also has the scientific names
- Mandelonitrile beta-D-gentiobioside and
- Mandelonitrile-beta-glucuronide
Manufacturers of laetrile promote it as an
alternative cancer treatment. This means it is used instead of
conventional cancer treatment. The first use of laetrile as a
treatment for cancer was in Russia in 1845, but it wasn’t used in
the USA until the 1920s. In the 1950s people began promoting
laetrile as a ‘highly active compound’ that can cure cancer.
Unfortunately, this is simply not true – laetrile cannot cure
cancer. The supposed active ‘cancer killing’ ingredient in laetrile
is cyanide. Cyanide, as you probably know, is highly poisonous.
Laetrile can cause serious
side effects. We
don’t recommend that you replace your conventional cancer treatment
with any type of alternative cancer therapy, such as laetrile. Or
that you use laetrile alongside your cancer treatment.
Why do people with cancer use laetrile?
People with cancer use alternative cancer therapies such as
laetrile, for various reasons. They may use it because
There is no
scientific evidence to support
any of these reasons for using laetrile.
If your cancer can’t be cured
Your doctor may tell you that there are no further conventional
cancer treatments available that could cure your cancer. But
treatments to control your symptoms are still possible. The news
that your cancer can’t be cured is very difficult to accept. And in
this situation, many people consider alternative therapies,
including laetrile.
Controlling or curing
your cancer
Some people promote alternative therapies such as laetrile to cure
or treat cancer. But there is no scientific evidence to prove that
laetrile can do this.
Evidence on laetrile for treating cancer
There isn’t enough proof that laetrile is an effective treatment for
cancer or any other disease. Most of the websites promoting
laetrile base their claims on unsupported opinions and
anecdotal evidence.
The USA’s
National Cancer Institute reviews the results of clinical
research into the use of laetrile for cancer on its website. One
animal study claimed that amygdalin slowed the growth of cancer in
animals and helped stop tumours spreading to the lungs. But
repeated studies couldn’t show similar results, so the treatment
remains unproven.
Amygdalin (the active ingredient in laetrile) has shown anti-cancer
activity in two studies when given with enzymes. This is most
probably because the enzymes cause the amygdalin to release cyanide,
which killed the cancer cells grown in the lab. One website
promoting laetrile includes the quote "When we add laetrile to a
cancer culture under the microscope, providing the enzyme
glucosidase is also present, we can see the cancer cells dying off
like flies." This isn’t surprising, as the glucosidase makes the
laetrile release cyanide, which is a poison. The difficulty is
getting the amygdalin close enough to cancer cells, along with the
glucosidase, to cause it to kill them without poisoning surrounding
normal tissues or the whole body.
This mirrors the main difficulty in a great deal of cancer research
– as many
cancer therapies are poisons. As cancer develops initially from
normal body cells, the only way to kill cancer cells would be to use
treatments that are poisonous to human cells. The mainstay of
research today is how to get such treatments to the cancer cells
without killing or damaging too many normal cells. Or to develop
treatments that are directed at the subtle differences between
normal cells and cancer cells – in other words targeted treatments.
Another study claimed that amygdalin might make cancer cells more
sensitive to radiation. Doctors have known for a long time that
cancer cells at the centre of tumours have less oxygen than cells
nearer the outside of tumours. This absence of oxygen makes the
central cells more resistant to
radiotherapy. Apparently, during this study, amygdalin stopped
cells in a laboratory dish from absorbing oxygen. The researchers
then wondered whether preventing the cells on the outside of a
tumour from absorbing oxygen with amygdalin, would mean more oxygen
getting to the cells in the centre. But the problem remains of how
to get the oxygen into the cells at the centre of the tumour. A
great deal of cancer research has been carried out for many years
simply to try to find a way of doing this. Since this research was
first reported in 1978, it has not been confirmed by any other
research.
There have only been two published human studies testing the
efficacy of laetrile as a treatment for cancer. They were both
sponsored by the American
National
Cancer Institute in the late 1970s and early 1980s. The first
study was a
phase I clinical trial looking at safe levels of laetrile, and
involved only 6 patients. It tested the dosage and different
ways of giving laetrile. Although the
researchers reported very few side effects, 2 patients developed
symptoms of cyanide poisoning because they ate raw almonds while
taking amygdalin.
The second study looked at whether laetrile had any effect on
shrinking cancer tumours in 175 patients. Of these patients, only
one person had any apparent response to laetrile and this only
lasted for 10 weeks. Seven months after the study, all the
patients’ cancers had continued to grow. There haven’t been any
randomised controlled clinical trials using laetrile.
A
systematic review was published by the Cochrane Library in
January 2006 which looked at laetrile treatment for cancer. It
concluded that the claimed benefits of laetrile are not supported by
controlled clinical trials. You can read a
plain
language summary of this review on the Cochrane website.
What taking laetrile involves
If you take laetrile, you have it
- As an injection (intravenously)
- As tablets
Taking laetrile as tablets has more
toxic side
effects than having it as an injection. Our digestive bacteria,
and the enzymes in the food we eat, break down the laetrile and
release cyanide.
Laetrile’s promoters typically recommend you have daily
intravenous injections for 2 and 3 weeks, followed by laetrile
tablets for some time. Laetrile is also used in enemas and lotions
that you can apply to your skin.
People who promote laetrile usually also suggest that you also
- Take high doses of vitamins
- Follow a special diet
So it can be quite a rigid and complex regime to stick to.
Side effects of laetrile
Laetrile contains cyanide, which is a type of poison. So the side
effects of laetrile are the same as those of cyanide. These include
- Sickness
- Headache
- Dizziness
- Liver damage
- A lack of oxygen to the body tissues
- A drop in blood pressure
- Drooping eyelids
- Fever
- Nerve damage, causing loss of balance and difficulty
walking
- Confusion, coma and eventually death
If you do take laetrile as tablets, it is very important that you
avoid eating
- Raw almonds
- Crushed fruit stones or pips
- Celery
- Apricots
- Peaches
- Beansprouts
- Carrots
- High doses of vitamin C
- Beans - mung, lima, butter and other pulses
- Flax seed
- Nuts
All these can increase the risk of cyanide poisoning if you take
them with laetrile because they contain low levels of amygdalin.
(These foods are safe when you eat them without laetrile because the
levels of amygdalin in them are low.)
The
cost of laetrile
Because of the
lack of evidence that
laetrile works, and the serious
side effects it
has, it is not authorised for sale in the European Union. The Food
and Drugs Agency in the US (FDA) have also banned it.
But some hospitals and
clinics in Mexico offer laetrile. And there are many websites
that promote its use. These websites often encourage people with
cancer to travel to the Mexican clinics for treatment. As well as
the considerable cost of the treatment, you also have to come up
with money for your airfares and accommodation when you are there.
Our advice is to be careful if you read any websites that promote
the use of laetrile and recommend treatment in overseas clinics.
You may find it useful to read the following information in our
about complementary and alternative therapy section on
A word of caution
At the end of the day, only you can decide whether or not to use
alternative cancer therapies such as laetrile. But we don't
recommend using any alternative therapies, including laetrile, in
place of conventional treatment. There is often little (if any)
scientific or medical evidence to back up the claims made by their
promoters. If you have cancer, using unproven methods instead of
conventional medical treatment can seriously affect your health.
Many internet sites advertise and promote laetrile as a treatment to
cure cancer. But no reputable scientific cancer organisations
support any of these claims. Our advice is to be very cautious
about believing this type of information or paying for any
alternative cancer therapy over the internet.
Whenever we put up information on alternative treatments that have
not been properly tested, we receive angry emails that say we are
trying to prevent people with cancer from getting effective
treatment. This is not what we want to do. We are concerned that
products are marketed as potential cures, and often sold for a great
deal of money, when they lack
scientific
evidence to prove they help. It is not in the interests of drug
companies or research organisations such as ours to ignore potential
new treatments. Thousands and thousands of compounds are screened
every year to try to find those that might be the basis of effective
treatments. If laetrile or amygdalin had any therapeutic benefit,
drug companies would have developed it into a potential treatment
long ago.
It is understandable that you and your loved ones will want to try
anything if you think it might help treat or cure your cancer. So
our message is
- Be careful
- Make sure you look into all the information that is
available, and check who provides it
-
Talk to your cancer doctor before you spend money for any
therapy, whether it’s conventional, complementary or alternative
Where to find more information
Our section
about complementary and alternative therapies is a useful place
to start for general information about complementary and alternative
therapies in cancer care. The
complementary therapy organisations and
complementary therapy websites may be able to offer more
information about laetrile. There is detailed information on the
CAM-cancer
website.