Why Vitamin B17 Is Dangerous and Not Effective for Cancer

Vitamin B17, or amygdalin, is not recommended as a treatment for cancer.
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Vitamin B17 is not actually a vitamin and can't be classified as one because your body doesn't produce it or need it. The name vitamin B17 was given to a specific component found in plants and identified as amygdalin, per the National Library of Medicine.


A concentrated synthetic form of amygdalin, called laetrile, was patented in the 1950s, and the two terms are often interchangeable. Laetrile is best known as a controversial treatment for cancer and carries the risk of some dangerous side effects.

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What Is B17?

Vitamin B17, or laetrile, is a partly man-made derivative of amygdalin, a natural cyanogenic glycoside plant compound.

Amygdalin is made from kernels of apricots and other plant species from the genus Prunus. It hasn't been approved as a vitamin by the American Institute of Nutrition Vitamins, according to the National Cancer Institute.

Laetrile has also been banned by the FDA since the 1980s and can't be sold as a medicinal product in the U.S., per an April 2015 systematic review in the Cochrane Library.


Adverse Effects of B17

Foods that contain amygdalin may be part of your daily diet. These foods contain a natural plant toxin called cyanogenic glycosides. They have the potential to generate toxic hydrogen cyanide, which serves as a defense for the plants against herbivores.

Although generally not a problem with the food you eat, laetrile supplements or medications containing high doses of amygdalin can cause cyanide toxicity. This can lead to symptoms and health problems such as the following, per the Centers for Disease Control and Prevention:


  • Headache
  • Nausea
  • Vomiting
  • Abdominal pain
  • Dizziness
  • Weakness
  • Mental confusion
  • Convulsions
  • Cardiac arrest
  • Circulatory and respiratory failure

Foods Containing Amygdalin

The most common B17 foods that contain amygdalin are the following, per the Cancer Research UK:

  • Raw almonds
  • Carrots
  • Celery
  • Apricots
  • Peaches
  • Bean sprouts
  • Beans
  • Nuts
  • Flaxseed
  • Crushed fruit stones



Normally, eating small amounts of cyanogenic foods doesn't pose a health risk. But, cases of poisoning have been reported from amygdalin in bitter apricot kernels (the stone inside the apricot).

When the kernel is ground or chewed, it releases hydrocyanic acid, and breaking down 1 gram of amygdalin releases 59 milligrams of hydrocyanic acid, per a March 2016 report in the ‌EFSA Journal‌.


The European Food Safety Authority set a safe level for cyanide at 20 micrograms per kilogram of body weight. This rating is 25 times below the lowest lethal dose reported.

Based on these limits and the amygdalin content of raw apricot kernels, it's estimated that the lethal amount for adults is three small apricot kernels — for children, the amount would be about half of one small kernel.


B17 in Apple Seeds

Even though apples are very nutritious, you should not eat apple seeds because they have cyanide-containing compounds. But the amount of apple seeds that would need to be eaten to result in these symptoms is very high, and swallowing a few seeds by accident shouldn't pose a health risk.

Why B17 Isn't an Effective Treatment for Cancer

There's no scientific evidence proving that laetrile or amygdalin can treat cancer. Despite this, vitamin B17 still gets promoted as an alternative and complementary medicine to treat cancer and is used in Mexico and some U.S. clinics, per the National Cancer Institute (NCI).

The theory is that because cyanide kills cells, it can eradicate tumors and stop cancer cells from reproducing.


Laetrile is often administered in combination with special diets, high-dose vitamins and pancreatic enzymes. It's available in several forms: as a tablet, by intravenous or intramuscular injection, as a skin lotion or as a liquid put on the rectum, per the NCI.

Taking laetrile orally incurs a much greater toxicity level than other methods of administering it. This is due to your digestive system breaking down the laetrile and releasing cyanide.


Even though they can come from questionable sources or be contaminated, there's no government control of vitamin B17 preparations — and there's a high risk of developing serious adverse effects due to cyanide poisoning. This risk could increase with the intake of vitamin C or in vegetarians with vitamin B12 deficiency, per an April 2015 systematic review in the Cochrane Library.

The ‌Cochrane Library‌ review assessed the alleged anti‐cancer effect and possible side effects of amygdalin and laetrile — the authors' conclusion was that, in regard to the use of laetrile or preparations containing amygdalin, no claims could be supported by clinical data for the use of either as having any beneficial effect for people with cancer.

There are conflicting reports due to some positive feedback from in-vitro and animal studies. But human clinical trials have not found that laetrile has similar effective outcomes and considers laetrile or amygdalin as a treatment for cancer to be dangerous due to side effects and lack of survival rate, per a July 2018 report in Biochemistry and Biophysics Reports.

The takeaway is that laetrile or amygdalin as a treatment for cancer is discouraged. And researchers suggest that there is neither scientific nor ethical justification for further clinical trials with amygdalin or laetrile for the treatment of cancer.


The reason why you won't find vitamin B17 for sale is that this so-called nutrient doesn't exist in the first place. Some manufacturers, though, sell laetrile or amygdalin tablets illegally on social networks and other online platforms. These products have been banned by the FDA.




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