"An apple a day keeps the doctor away." True enough. However, apple seeds contain a substance that can convert into poisonous hydrogen cyanide in the intestine. But there is no need to panic. The chance of consuming enough apple seeds to produce a toxic effect is slight, and proper handling can reduce the risks further.
Fruit Seed Poisons
Apples are only one of a number of fruits that contain amygdalin in their seeds. The biggest offenders are apricot and peach pits, followed plums, apple seeds, almond and quince, in descending order of amygdalin content. The amount of amygdaline contained in apple seeds is tiny, and the seed must be chewed up to release the substance.
Amygdalin is a glycoside toxin that combines with a gastrointestinal enzyme to produce hydrogen cyanide, the same poison that was called Cylon B and used for mass executions in concentration camps during World War II. Very often, the fruit or seed with amygdalin, and other precursors to cyanide called cyanogens, can be processed to remove the toxic substance. Cassava root has a very high cyanogen content and is used for tapioca and other food stuffs. Proper processing of cassava and thorough cooking renders the cyanogen harmless. The toxins in almonds also are processed in such a way to either remove the toxin or convert it into a harmless substance.
How Cyanide Acts
Hydrogen cyanide, the form of toxin produced by amygdalin conversion in the intestine, acts by robbing the blood cells of the ability to carry oxygen. While the body can process and eliminate small amounts of hydrogen cyanide, larger amounts can be deadly. There is no antidote.
Symptoms of Poisoning
Persons who experience apple seed poisoning may have trembling, spasms, dizziness, nausea, vomiting, restlessness, rapid heart rate, weakness and headache. Large amounts of cyanide can cause difficulty breathing, coma, respiratory failure, low blood pressure, convulsions, lung damage or death. Survivors of serious poisoning can show evidence of heart and brain damage.
The Good News
Swallowing a few apple seeds whole will not cause poisoning. The hard seed hulls keep the poison contained within the seed and it can pass through the digestive system whole. The problem comes from chewing up the seed. Although a large quantity of seed would would have to be ground or chewed up and consumed, amygdalin poisoning is still possible. Remove the seeds before eating and do not give the pips to children, who may have a lower tolerance to amygdalin. Do not grind the seeds when processing the fruit for juice, applesauce, or preserves. Following these simple precautions will ensure your safety when eating apples.