Apple seeds contain amygdalin, which is converted into cyanide when the seeds are chewed or crushed. Cyanide is highly poisonous and can be deadly in high doses.
Apples are one of the world's most popular fruits.
They contain small, black seeds that are usually avoided because of their bitter taste, but people may occasionally eat them by accident or not bother to spit them out.
Apple seeds contain a plant compound known as amygdalin.
It is found in relatively high amounts in the seeds of fruits in the rose family, which includes apples, almonds, apricots, peaches and cherries.
Amygdalin is a part of the seeds' chemical defenses. It is harmless when intact, but when the seeds are damaged, chewed or digested, amygdalin degrades into hydrogen cyanide. This is very poisonous and even lethal in high doses.
Cyanide has been used as a poison throughout history. It works by interfering with cells' oxygen supplies, and may lead to death within minutes at a sufficiently high dose.