Apricot kernels, laetrile

Also called: amygdalin, vitamin B17, Laetrile.

Last reviewed 2026-09-16. How this works.

When to call your team — this entry is incomplete

Whatever you are taking or thinking of taking, the people treating you can only weigh it if they know about it. That is true when nothing has been written down here, and it is most true then.

A source for this part is missing. Harm has been recorded in people for this entry and the register cannot yet say what it looks like, because no source it holds describes that. What is written below is the gap itself, not a summary of the signs.

Amygdalin releases cyanide, and the trial on this page recorded symptoms of cyanide toxicity. The register holds no source describing what those symptoms look like to the person experiencing them, so no signs are written here. Writing them from general knowledge of cyanide would be a guess. Until a source describing what that looks like is found, this part of the entry is unfinished rather than empty.12

This block is about what to watch for, and it is not all this page holds: an interaction recorded against a treatment class and what has been recorded about harm are below. Nothing in this block is an all-clear for a question it does not mention.

Treating cancer Grade X

Documented harm, with no benefit to weigh against it.

Harm has been recorded in people for this claim. The grade measures how strong the evidence for benefit is; it says nothing about the harm, and the two are read from different parts of this page.

This was tested properly in 178 people, it did not work, and it can poison you with cyanide.

Tested in 178 people, no benefit, and it releases cyanide.

The harm

Amygdalin releases cyanide when it is broken down in the body. That is not a side effect of the preparation; it is what the molecule does.1

The Cochrane review records that the risk of cyanide poisoning could increase alongside vitamin C, and in vegetarians with vitamin B12 deficiency. Both of those describe a large share of the people most likely to try this, which is the worst possible overlap.2

This entry is graded X rather than D because the harm is real and the benefit question is not open. It was asked and answered.12

The claim

The claim is that amygdalin, sold as laetrile or as vitamin B17, is a natural cancer treatment suppressed by the medical establishment. It is among the oldest claims in this book and it has never gone away.

What it does

The proposed mechanism is that an enzyme more abundant in tumours releases cyanide preferentially inside cancer cells. The selectivity that idea depends on has not been demonstrated in a person, and the cyanide is released regardless.

The evidence

It was tested. A clinical trial gave amygdalin to 178 patients alongside a metabolic therapy programme of diet, enzymes and vitamins. No benefit was found.1

A Cochrane review searched for randomised or quasi-randomised controlled trials and found none had ever been conducted. So the strongest evidence is a single-arm trial from 1982, and it was negative.2

The claim of suppression is worth addressing directly, because it is the reason people persist. A suppressed treatment does not get a trial in the New England Journal of Medicine. This one did.1

The studies this rests on

  • Clinical trial of amygdalin in the treatment of human cancer1

    A trial with no comparison group, open label, phase 2, measured a clinical outcome, 178 participants.

    no benefit found; symptoms of cyanide toxicity recorded.

What is absent

No randomised or quasi-randomised controlled trial of laetrile has ever been conducted, and a Cochrane review searched for one.

Scope: any tumour type, any endpoint.

Established by published review, Cochrane Database of Systematic Reviews 2015;4:CD005476, checked 2026-09-16. Result: no randomised or quasi-randomised controlled trials were found.2

What to ask

If someone were taking apricot kernels alongside vitamin C, what would you want to know about it?

The dish-to-person gap

The register holds no human pharmacokinetic measurement for amygdalin against any laboratory concentration.

Interactions

The Cochrane review records that the risk of cyanide poisoning could increase with concomitant intake of vitamin C, and in vegetarians with vitamin B12 deficiency. Vitamin C is among the most commonly taken supplements in this readership, which is why this is on the page.2

Apricot kernels or laetrile, with vitamin C

Recorded as documented, between two compounds rather than against a cancer treatment.

Can you look at what I have read about laetrile and vitamin C together raising the risk of cyanide poisoning?

The whole interaction list, and how to turn it into a pharmacy review request.

Find a trial instead

No trial of laetrile is recruiting. The Cochrane review found no randomised trial had ever been conducted.

References

  1. Moertel CG, Fleming TR, Rubin J, Kvols LK, Sarna G, Koch R, Currie VE, Young CW, Jones SE, Davignon JP. A clinical trial of amygdalin (Laetrile) in the treatment of human cancer. New England Journal of Medicine 1982;306(4):201-206.

    doi:10.1056/NEJM198201283060403

    How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 10 note 6.

  2. Milazzo S, Horneber M. Laetrile treatment for cancer. Cochrane Database of Systematic Reviews 2015;4:CD005476.

    doi:10.1002/14651858.CD005476.pub4

    How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 10 note 7.