1. What Is Amygdalin, and Which Part of a Peach Holds It?
A peach has soft flesh, a woody stone, and inside the stone a seed (often called the kernel). Amygdalin is found in the seeds of many fruits in the rose family, such as peaches and apricots, and in bitter almonds [2]. The U.S. National Cancer Institute describes it as a bitter substance found in fruit pits, raw nuts, lima beans, and some other plants [1].
Amygdalin is a cyanogenic glycoside: a sugar joined to a cyanide-containing piece. Joined up like that, it is fairly stable. The trouble starts when the sugar is cut away.
2. How Does a Crushed Seed Release Cyanide?
Plants that make these compounds usually also carry enzymes (protein tools that speed up chemical reactions) that cut them apart. One enzyme, β-glucosidase, removes the sugars; another, hydroxynitrile lyase, then splits what is left into benzaldehyde and hydrogen cyanide. When the plant tissue is damaged, for example when an animal chews it, the amygdalin and the enzymes meet and hydrogen cyanide is released [2]. Heating may reduce the activity of these enzymes in some cases, but I did not confirm the conditions, so do not count on cooking to make a seed safe.
A simple way to picture it is a two-part glue that stays liquid until you mix the tubes. Real seeds are more complicated than that, so treat it only as a picture.
The important catch: the enzymes do not live only in the plant. The same review says β-glucosidase is also present in the human small intestine, and gut microbes can supply it too, so amygdalin that is swallowed can still be broken down inside the body [2]. The NCI makes the same point about laetrile, a purified form of amygdalin once sold as a cancer treatment: cyanide poisoning was much more common when it was taken by mouth, because gut bacteria and some foods contain enzymes that release cyanide [1]. So "crushing makes it worse" is true, but "swallowing it whole is safe" is not something these sources support.
3. Why Would a Peach Tree Put This Chemical in Its Seeds?
The review explains that the natural role of cyanogenic glycosides is to protect the plant against insects and larger plant-eating animals [2]. I did not read how this works in peach seeds specifically. This is a description of what the chemical does for the plant, not a claim that the tree "planned" anything. Natural selection simply kept plants that were less eaten.
4. Is the Peach Flesh We Eat Dangerous Too?
The sources I could read do not give a safe or unsafe amount for peach flesh, so I will not invent one. What they do say is that the chemical is concentrated in seeds, and that cases of cyanide poisoning from fruit-pit products involve people eating or taking the seeds, kernels, or purified amygdalin [1][2]. The review also lists how much cyanide different plant parts could release, and the figures for peach and apricot kernels are similar in size [2]. Amounts vary from plant to plant, so the cautious rule is simple: do not eat the seed, and check official food-safety information if you have worries about the fruit.
5. If Peach Seeds Can Release Cyanide, Why Do Traditional Medicines Use Them?
In Traditional Chinese Medicine the dried peach seed is called Taoren (Persicae Semen), and it is used as an ingredient in herbal formulas [3]. Japanese herbal medicine, called Kampo, uses the same ingredient under the name touin, though I did not confirm that from an English source. I could only confirm the Taoren use directly from the abstract of a 2025 research paper, and none of the sources I read explains how the amygdalin is handled during preparation, so I cannot say how the two facts fit together.
What the abstract does say is that Taoren is used in Traditional Chinese Medicine formulas [3]. That is not the same as crushing a seed from a kitchen bin. As a caution from the other side, the NCI reports that laetrile showed little anticancer activity in animal studies and none in human clinical trials, and says it is not approved in the United States [1].
6. What Can You Safely Look at Yourself?
Rinse and dry a peach stone and look at it without cracking it open: the grooves and ridges are a good drawing subject. If you have apricot or plum stones, line them up and compare shapes. Do not remove or taste the seed inside.
For a question to follow up: the review tabulates how much cyanide different seeds could release, and the numbers vary by plant. Why might a seed make more of it than another kind? The review in the sources below is open to read and is a good place to start.