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Laetrile (amygdalin)

What Should I Know About It?


Updated June 27, 2014

What is Laetrile?

Other names: amygdalin, vitamin B17, sarcarcinase, nitriloside

Laetrile is a substance found naturally in the some fruits and vegetables, particularly apricot pits and bitter almonds. The active ingredient in laetrile is believed to by cyanide, which is also a potentially lethal substance.

What is the History of Laetrile?

Russian doctors tried using amygdalin as a cancer treatment in the mid-1800s but it proved to be too toxic. In 1924, laetrile was synthesized from amygdalin and promoted as a cancer treatment. Laetrile continued to gain popularity. By 1978, over 70,000 people in the United States had used laetrile.

In 1980, the National Cancer Institute began a study to evaluate the use of laetrile in cancer patients. Although some patients reported that they felt better while taking laetrile, the cancer continued to progress in all patients. The National Cancer Institute concluded that further research into laetrile was not warranted. Some proponents of laetrile expressed concerns over the study methodology.

Why Do People Use Laetrile?

Some doctors believe that laetrile can help to relieve the pain of cancer. One theory is that cancer cells contain large quantities of the enzyme beta-glucosidase. This enzyme breaks the amygdalin down and releases cyanide, a toxic chemical that then kills cancer cells.

According to the National Cancer Institute, laetrile has shown little anticancer effect in laboratory studies, animal studies, or human studies. Laetrile is not approved by the Food and Drug Administration (FDA). It is used as a cancer treatment in Mexico.

How is Laetrile Used?

Laetrile is given as an orally or taken as an injection or intravenously.

Side Effects

The side effects depend on how the laetrile is administered. The risk of cyanide poisoning is thought to be higher when laetrile is taken in pill form, although there are thought to be risks with any form. Cyanide poisoning can be life-threatening and may result in death.

Side effects include nausea, vomiting, headache, dizziness, and liver damage.

There was a case report of severe cyanide poisoning after ingestion of laetrile. The 68 year old woman was admitted to emergency with seizures after having taken a dose of amygdalin (3 grams) while taking 4.8 grams of vitamin C. Vitamin C is believed to increase the conversion of amygdalin to cyanide in the body. It is also believed to reduce the amount of cysteine, which is used to detoxify cyanide.

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