This page tells you about laetrile (also known as amygdalin or vitamin B17) in people with cancer. There is information about
What laetrile is
Why people with cancer use laetrile
Evidence on laetrile as a cancer treatment
What taking laetrile involves
Side effects of laetrile
The cost of laetrile
A word of caution
Where to find more information
What laetrile is
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, or kernels. 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, and it was used in the USA from the 1920s. In the 1950s, some people began promoting laetrile as a ‘highly active compound’ that can cure cancer. Unfortunately, this is simply not true – laetrile cannot cure cancer. The active ingredient in laetrile is cyanide, which 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 people with cancer use laetrile
Some people with cancer use laetrile because
They think it can improve their health, energy levels and well being
They want to detoxify and cleanse the body
They hope it will help them to live longer
Some people want to use it if they are told that their cancer can't be cured with conventional cancer treatments because they hope that laetrile will be able to control or cure their cancer.
There is no scientific evidence to support any of these reasons for using laetrile.
Evidence on laetrile as a cancer treatment
Most of the websites or magazines promoting laetrile base their claims on unsupported opinions and anecdotal evidence. There isn’t any evidence that laetrile is an effective treatment for cancer or any other illness.
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 laboratory studies when given with particular enzymes called glucosidase. This is probably because the enzymes made the amygdalin release cyanide which killed the cancer cells grown in the lab. But in the body the cyanide would also damage healthy cells. This problem is the main difficulty in a great deal of cancer research – as many cancer therapies are poisons. Researchers have developed some treatments that are directed at the subtle differences between normal cells and cancer cells – in other words targeted treatments. But there is no evidence that this is possible with laetrile.
Another study claimed that amygdalin might make cancer cells more sensitive to radiation. Cancer cells at the centre of tumours have less oxygen than cells nearer the outside of tumours. Lack of oxygen makes the central cells more resistant to radiotherapy. Apparently, during one study, amygdalin made cells in a laboratory dish absorb more oxygen. 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 whether laetrile works 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 could shrink 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 summary of the Cochrane review about laetrile on the Cochrane website.
What taking laetrile involves
If you take laetrile, you may have it
As an injection (intravenously)
As tablets
Taking laetrile as tablets has more 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 that you have daily intravenous injections for 2 and 3 weeks, followed by laetrile tablets for some time. Laetrile is also used in lotions that you can apply to your skin and enemas.
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
It is estimated that eating approximately 50 to 60 apricot kernels, or 50g of laetrile can cause 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 foods 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.) It is also important for anyone with liver problems to know that laetrile may cause further damage to their liver.
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. The treatment itself may cost thousands of pounds and you also have to pay for your airfares and for your accommodation when you are there.
Our advice is to be careful if you read any websites that promote the use of laetrile or recommend treatment in overseas clinics. You may find it useful to read the following information in our about complementary and alternative therapy section on
The cost of therapies
Searching for information on the internet
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, instead 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 harm 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 the people close to you 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.
What laetrile is
Why people with cancer use laetrile
Evidence on laetrile as a cancer treatment
What taking laetrile involves
Side effects of laetrile
The cost of laetrile
A word of caution
Where to find more information
What laetrile is
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, or kernels. 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, and it was used in the USA from the 1920s. In the 1950s, some people began promoting laetrile as a ‘highly active compound’ that can cure cancer. Unfortunately, this is simply not true – laetrile cannot cure cancer. The active ingredient in laetrile is cyanide, which 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 people with cancer use laetrile
Some people with cancer use laetrile because
They think it can improve their health, energy levels and well being
They want to detoxify and cleanse the body
They hope it will help them to live longer
Some people want to use it if they are told that their cancer can't be cured with conventional cancer treatments because they hope that laetrile will be able to control or cure their cancer.
There is no scientific evidence to support any of these reasons for using laetrile.
Evidence on laetrile as a cancer treatment
Most of the websites or magazines promoting laetrile base their claims on unsupported opinions and anecdotal evidence. There isn’t any evidence that laetrile is an effective treatment for cancer or any other illness.
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 laboratory studies when given with particular enzymes called glucosidase. This is probably because the enzymes made the amygdalin release cyanide which killed the cancer cells grown in the lab. But in the body the cyanide would also damage healthy cells. This problem is the main difficulty in a great deal of cancer research – as many cancer therapies are poisons. Researchers have developed some treatments that are directed at the subtle differences between normal cells and cancer cells – in other words targeted treatments. But there is no evidence that this is possible with laetrile.
Another study claimed that amygdalin might make cancer cells more sensitive to radiation. Cancer cells at the centre of tumours have less oxygen than cells nearer the outside of tumours. Lack of oxygen makes the central cells more resistant to radiotherapy. Apparently, during one study, amygdalin made cells in a laboratory dish absorb more oxygen. 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 whether laetrile works 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 could shrink 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 summary of the Cochrane review about laetrile on the Cochrane website.
What taking laetrile involves
If you take laetrile, you may have it
As an injection (intravenously)
As tablets
Taking laetrile as tablets has more 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 that you have daily intravenous injections for 2 and 3 weeks, followed by laetrile tablets for some time. Laetrile is also used in lotions that you can apply to your skin and enemas.
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
It is estimated that eating approximately 50 to 60 apricot kernels, or 50g of laetrile can cause 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 foods 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.) It is also important for anyone with liver problems to know that laetrile may cause further damage to their liver.
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. The treatment itself may cost thousands of pounds and you also have to pay for your airfares and for your accommodation when you are there.
Our advice is to be careful if you read any websites that promote the use of laetrile or recommend treatment in overseas clinics. You may find it useful to read the following information in our about complementary and alternative therapy section on
The cost of therapies
Searching for information on the internet
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, instead 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 harm 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 the people close to you 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.
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