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Hello Laidback Gardener,
You’re pretty good at investigating myths having something to do with plants and here’s one that I’m pretty sure isn’t true.
I saw on a Facebook page that apple seeds are poisonous. I don’t know how that could be possible. All my life, I’ve had the habit of sucking on an apple seed or two after eating an apple, much like some people chew on gum, then I swallow them. I’m 38 years old and in fine health.
So, what’s the truth behind that?
Answer: That actually isn’t a myth! Apple seeds are poisonous. It’s just that sucking on the seeds or swallowing them isn’t releasing the poison.
Apple seeds (and seeds of many fruit trees in the Rose family: cherries, peaches, plums, etc.) contain a compound called amygdalin. It isn’t harmful in itself, but breaks down into cyanide when crushed or chewed on. And cyanide can be deadly.
The poisonous content of the apple seed (or pip) is designed by nature to protect it from predators. It’s part of the apple tree’s distribution system. The tree “wants” animals to eat its fruit, which why it is so sweet and tasty, but not to destroy its seeds. Either the animal doesn’t eat the core (humans) or doesn’t chew the seeds (frugivorous animals) and the pips are either thrown away or passed intact through the digestive system. The idea is that encourages the distribution of seeds far from the mother tree (the animal might pick up the fruit and eat or defecate it elsewhere) and that allows apple trees to spread in the wild.
Besides releasing poison, chewing on apple seeds releases a very bitter taste: a warning not to go any further. We may not notice it too much, but birds and small animals will.
Frugivorous animals that don’t learn not to chew on the seeds would be made ill and weakened or killed, thus eliminated, and only those that leave the pips intact would survive. Such is natural selection. And that’s how apples get around.
Any Danger to Humans?
Sucking or swallowing apple pits is harmless, since the pits remains intact. They go right through your digestive system and come out the other end in one piece. It’s probably best, though, not to teach toddlers to put apple seeds in their mouths, as they might chew them.
Even if you occasionally chew on an apple pit, the amount of poison in one seed won’t hurt you. You’d need to chew on hundreds to make yourself sick and thousands to ingest a lethal number.
What About Pets?
Cats usually have little interest in apple cores, but dogs often love them and like to chew on them. They probably do manage to break the skin of a few pips as they chew, but don’t do this often enough to poison themselves. One estimate suggests that a medium-size dog would have to thoroughly chew the pips of some 200 apples to be seriously poisoned. That’s just not going to happen.
Do be aware that smaller animals like guinea pigs and rabbits and chewing birds like parrots can be fed apples, but it’s best to remove the core first. Their smaller bodies mean a lethal dose is more easily reached. Poisoning under such circumstances is still exceedingly rare (a small rabbit would have to chew 50 or so apple pits at one sitting!), but it could still theoretically happen and so is best avoided.
But what about the cumulative effect of cyanide? Doesn’t it build up in the system over time?
That’s a common belief … but a false one. The body (human or pet) breaks down cyanide quite rapidly, in mere hours. Cyanide does not build up over time and is quickly removed by the liver and kidney.
So, yes, apple seeds are indeed poisonous, but no, they’re not likely to poison anyone. But don’t make a habit of munching on them!