Written by Ryan Raman, MS, RD — Updated on December 23, 2017

Laetrile is often wrongly called amygdalin or vitamin B17.

Rather, it is a drug that contains purified amygdalin — a compound found in the seeds or kernels of many fruits, raw nuts, beans and other plant foods.

Laetrile is best known as a controversial treatment for cancer. However, there is little scientific evidence to support this hefty claim.

This article explains everything you need to know about laetrile, backed by science.

 

What Is Laetrile?

Laetrile is the name of a drug created in 1952 by Dr. Ernst T. Krebs, Jr.

It contains purified amygdalin, which is a compound found naturally in the following:

  • Raw nuts: Such as bitter almonds, raw almonds and macadamia nuts.
  • Vegetables: Carrots, celery, bean sprouts, mung beans, lima beans and butter beans.
  • Seeds: Millet, flaxseeds and buckwheat.
  • Pits of: Apples, plums, apricots, cherries and pears.

You can take laetrile as a pill or receive it as an injection into the veins or muscles.

It is a controversial cancer treatment that was popular in the 1970s. However, it was banned in many US states after research deemed it ineffective and potentially poisonous.

When laetrile passes through the body, it is converted into hydrogen cyanide — a compound that can prevent cells from using oxygen and eventually kill them.

Some theories suggest that hydrogen cyanide may have anticancer effects. Yet, these theories don’t have much evidence to support their claims.

Interestingly, there is some evidence that laetrile may provide health benefits. Studies have found that it may help reduce blood pressure, relieve pain and boost immunity.

 

How Does It Work?

The body breaks down laetrile into three compounds: hydrogen cyanide, benzaldehyde and prunasin.

Hydrogen cyanide appears to be the main compound responsible for its health benefits. It is also thought to be the primary anticancer ingredient in laetrile.

Certain enzymes in the body convert hydrogen cyanide into a less toxic molecule called thiocyanate. This molecule was previously used to treat blood pressure, as it may dilate blood vessels. It was later discontinued because of its toxic effects.

There are four possible theories on how laetrile may fight cancer, though these theories are not supported by scientific evidence.

Two theories state that cancer cells are rich in enzymes that convert laetrile into cyanide. Since cyanide kills cells, this means that cancer cells may break down laetrile and kill the cancer.

However, there is no evidence that cancer cells contain the enzymes that help convert laetrile into cyanide.

The third theory suggests that cancer is caused by a deficiency in vitamin B17.

No evidence proves that amygdalin is actually a vitamin. It is also not naturally found in the body, and your body cannot be deficient in amygdalin.

The last theory proposes that hydrogen cyanide, which is made by breaking down laetrile, will make cancer cells more acidic and cause them to die.

But hydrogen cyanide does not differentiate and may also kill healthy cells as well as cancer cells.