Apple Seeds Release Cyanide When Crushed
Apple seeds contain amygdalin, a plant compound known as a cyanogenic glycoside. It’s part of the seeds’ chemical defenses, but when apple seeds are chewed or crushed and metabolized, the amygdalin turns into hydrogen cyanide.
Hydrogen cyanide, in turn, is a poisonous substance that prevents your cells from using oxygen properly, leading to death within minutes at high-enough exposure levels.
It’s perhaps most known for its use as a chemical warfare agent by the Germans during World War II, but it was also reportedly used during the Iran-Iraq War in the 1980s, also as a chemical weapon.
Apple seeds aren’t the only food to contain cyanide precursors. Amygdalin is also found in apricot, peach and cherry pits, for instance, and much more (over 2,500 plant species in all).
But consuming a few apple seeds is not the same thing as being exposed to straight hydrogen cyanide, and here’s why: apple seeds have a protective coating that’s resistant to digestion.
If you’ve ever eaten whole apple seeds, you may have noticed that they pass through your body basically unharmed. The cyanide is only produced if the seeds are damaged (i.e., crushed or chewed), so swallowing a few seeds whole is likely to be of little consequence.
It’s one of mother nature’s ingenious protections, as the seeds’ ability to produce cyanide when crushed discourages animals from chewing them, thus allowing for the whole undamaged seeds to return to the Earth and grow new apples.
You’d Have to Eat a Lot of Crushed Apple Seeds for Them to Be Dangerous
While consuming the number of apple seeds in one apple (the average apple contains 5 seeds, according to the Washington State Apple Commission3) is not cause for alarm, it is possible to be harmed by apple seeds — if you crush them and consume a large enough quantity.
Children and pets, due to their smaller size, may be at increased, though still infinitesimal, risk.
To put things in perspective, the Illinois Poison Center (IPC) blog noted that cyanide toxicity resulting from unintentional ingestion of amygdalin-containing pits, such as cherry pits, is extremely rare in the U.S., explaining:4
"Realistically, the pits and seeds are more of a choking hazard than a poisoning risk. At least a couple of times a year here at IPC, we get called about a child who has ingested 10-20 cherry pits whole. These kids have done just fine and developed no symptoms at all.
… Intentional large ingestions however, have resulted in toxicity, including a few cases of ingestion of 20 [to] 40 chewed apricot pits by adults, which resulted in cyanide toxicity but no fatalities."
To look at it in more mathematical terms, 1 gram of apple seeds contains anywhere from 1 to 4 milligrams (mg) of amygdalin. If chewed, the same amount of apple seeds may turn into 0.06 to 0.24 mg of cyanide, with a lethal dose of cyanide from apricot kernels reported as being 0.5 to 3.5 mg/kg body weight.