Apple seeds contain a substance called amygdalin, which is a cyanogenic glycoside composed of cyanide and sugar. When metabolized in the digestive system, this chemical degrades into highly poisonous hydrogen cyanide (HCN). However, it takes quite a few apple seeds to cause harm, and only if they have been crushed or chewed. A whole unbroken seed will pass right through the digestive system without releasing any amygdalin. The human body can process small doses of HCN, so a couple of chewed seeds are usually completely harmless. The average adult would need to eat anywhere from 150 to several thousand crushed seeds (depending on the apple variety) to be at risk of cyanide poisoning. The amount of cyanide derived from the seeds is much lower than the lethal dose of hydrogen cyanide, which may be around 50–300 mg. Apple seeds have the potential to release 0.6 mg of hydrogen cyanide per gram, which means that a person would have to eat 83–500 apple seeds to develop acute cyanide poisoning. Therefore, it is highly unlikely that eating a few apple seeds by accident or occasionally would cause any harm. However, it is recommended to avoid eating apple seeds, as well as the pits of fruits such as peaches, apricots, and cherries, which also contain amygdalin and can cause cyanide poisoning.