Bitter almonds contain glycoside amygdalin. When eaten, glycoside amygdalin will turn into prussic acid, a.k.a. hydrogen cyanide, which incidentally was the key ingredient to Zyklon B, the pesticide used in the Nazi gas chambers.
So if you’re walking out in the woods and spot and almond tree, don’t just naturally assume it’s safe to eat the almonds. It doesn’t take much hydrogen cyanide to kill you. Specifically, it only takes about 100-200 mg of cyanide, when eaten, to kill you within minutes (about .68 mg per pound of body weight). For reference, each raw bitter almond will produce about 4-9 mg of hydrogen cyanide. So a few handfuls of raw bitter almonds are enough to kill you quite swiftly and lesser amounts may cause you other serious health issues such as kidney failure.
Interestingly, people who can smell cyanide (about 40% of humans can detect an odor when smelling cyanide, for others it’s odorless) say that it smells a bit like almonds.
Processed bitter almonds though can safely be eaten as all the hydrogen cyanide is leached out during the heating process. Due to their toxicity before being processed, in the United States it is illegal to sell bitter almonds that are unrefined.
Apple seeds are just as poisonous as bitter almonds. Go here to find out more about this and why cyanide is poisonous, in terms of what’s going on in your body after you ingest it: Apple Seeds Contain Cyanide
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