Laetrile or Amygdalin: Uses, Properties and Risks

In popular culture, laetrile or amygdalin is known as vitamin B17. However, it isn't actually a B-complex vitamin. So what's it used for?

Reviewed and approved by the pharmacist Franciele Rohor de Souza.

Written by Daniela Echeverri Castro

Last update: 30 May, 2022

Laetrile is also known as amygdalin or vitamin B17. However, some experts disagree with the latter term, since this is actually a drug that contains purified amygdalin, extracted from the seeds of several plants belonging to the subfamily Amygdaloideae.

As detailed in an article in the National Library of Medicine, it’s found mainly in raw nuts, seeds, vegetables, and fruit pits, such as plums, apricots, and apples. Although it’s said to have medicinal properties, its use is controversial due to the lack of solid evidence. So what do you need to know about it?

Laetrile or amygdalin: what you need to know

Laetrile or amygdalin is the name of a drug that Dr. Ernst T. Krebs Jr. created in the 1950s. A review in the medical journal CA: A Cancer Journal for Clinicians comments that Krebs believed that this substance could “kill cancer cells”.

And although it became popular during the 1970s, it was banned in many U.S. states, as studies questioned its safety and efficacy. It was even reported to cause a high risk of cyanide poisoning, which can be very serious.

In nature, purified amygdalin is present in the following foods:

• Seeds: millet, flaxseed, and buckwheat.
• Raw nuts: bitter almonds, raw almonds, and macadamia nuts.
• Vegetables: carrots, celery, bean sprouts, beans, among others.
• Pits: of apricots, cherries, pears, and plums.

Now, although not approved by the Food and Drug Administration (FDA), it’s available in pill form or for intravenous or intramuscular injection. Many sites on the web have success stories about this treatment, but the truth is that science doesn’t back them up. In all cases, the risk of side effects is high.

Main uses of laetrile or amygdalin

The best-known use of laetrile has to do with its supposed anticarcinogenic potential. According to its proponents, it contributes to a mechanism known as apoptosis, which inhibits the growth of cancer cells.

The body breaks amygdalin down into three substances: hydrogen cyanide, benzaldehyde, and prunasin. According to a publication in the Cochrane Database of Systematic Reviews, hydrogen cyanide is the main anti-tumor compound of laetrile.

In particular, scientists have suggested three possible mechanisms of action against this disease:

• First, scientists thought that cancer cells contained enzymes that could transform amygdalin into cyanide. This would stop the cancer from growing. However, evidence overturned this hypothesis.
• Some also suggested that a deficiency of vitamin B17 (amygdalin) could affect the occurrence of cancer. Studies also disproved this, since amygdalin isn’t a vitamin and isn’t naturally present in the body.
• The last hypothesis suggested that hydrogen cyanide could cause cancer cells to become more acidic, which would result in their death. Regarding this, studies found that the substance destroys both healthy and malignant cells.

To date, research remains limited, and has only been performed in the lab and with animals. Moreover, the results are mixed and controversial. For now, scientists don’t consider it as a valid treatment option to fight cancer.

Other possible benefits

Much of the research on laetrile discusses its possible anti-tumor effects. Still, other research has determined that it may have different health benefits. However, it’s important to know that the evidence to support all of this is quite weak.

Lowering blood pressure

A study in the Journal of Al-Ma’moon College reported that amygdalin was helpful in lowering systolic blood pressure by up to 28.5%. Similarly, it reduced diastolic blood pressure by up to 25%. So, laetrile should have a positive effect on heart health.

Pain relief

Biological and Pharmaceutical Bulletin reports that amygdalin has an anti-inflammatory and analgesic effect. This means it’s been able to reduce the pain of conditions such as arthritis. Studies have been carried out in animals and human trials are needed.

Immunomodulator

Some scientists believed laetrile has the ability to stimulate immune system functions. In research reported in The Journal of Microbiology, Biotechnology, and Food Sciences , this substance enhanced the ability of immune cells to attach to prostate cancer cells.

Recent studies on laetrile

Several studies from recent years have focused on the anticarcinogenic effects of laetrile. One of them, reported in the International Journal of Nanomedicine in 2020, found that a combination of amygdalin with an enzyme called beta-glucosidase (ß-glu) helped eliminate prostate cancer cells.

The same year, a study in Current Molecular Pharmacology reported that amygdalin can kill certain breast cancer cell lines and, in turn, prevent their spread throughout the body.

The most recent study, published in March 2021 in the Journal of Biomolecular Structure & Dynamics, found that amygdalin induces apoptosis and has potential in cancer therapeutics. Still, the results weren’t conclusive.

Possible side effects

There’s also evidence related to the potential side effects that laetrile may cause, the most serious being hydrogen cyanide poisoning. Regarding this, clinical symptoms include the following:

• Nausea and vomiting
• Headaches
• Dizziness
• Bluish skin due to lack of oxygen
• Liver damage
• Abnormally low blood pressure
• Drooping upper eyelid (ptosis)

These symptoms tend to worsen if amygdalin is taken orally or together with vitamin C. Eating fruits, vegetables, or other food products that naturally contain the substance can also have an effect.