Yet despite all the mythology surrounding apples, Islamiyat Bolarinwa, a senior lecturer of food science at the Ladoke Akintola University of Technology in Nigeria, tells Inverse there are still grains of truth wrapped up in these tall tales — especially when it comes to the toxicity of apple seeds.
While these seeds won’t grow an apple tree in your stomach (as your chiding older sibling may have told you) they aren’t exactly harmless either. And if you’re not careful, an overzealous apple habit may just put you in the hospital, Bolarinwa warns.
What are apple seeds made of?
Like many natural materials, apple seeds are primarily made of fiber and hold inside them the recipe for sprouting new apple trees, Bolarinway explains.
However, they also hold a poisonous secret.
“Apple seeds are not safe for consumption because they contain a component called cyanogenic glycosides,” she says. “Apple seeds contain a specific cyanogenic glycoside called amygdalin.”
Hidden deep inside the cells of the apple seed, this compound can be broken down by the body's enzymes and transformed into a form of poison called cyanide. In its other forms, cyanide can be used as a chemical weapon (e.g. hydrogen cyanide) or can be inhaled near fires or metal polishing.
“While cyanogenic glycosides are harmful to human beings, it acts like a soldier — a natural protector — for plants from external forces,” Bolarinwa adds.
Are apple seeds poisonous?
Although these seeds contain cyanide (only about 0.5 - 3.5 milligrams of toxin per 1 kilogram of body weight), that doesn’t necessarily mean they’ll poison you, Bolarinwa explains.
First of all, apple seeds have to be crushed up pretty thoroughly to actually release amygdalin into the gut. If you’re just casually chomping through an apple core, there’s a possibility you might swallow the seeds whole (which would be harmless) instead of crunching them up.
But even if you do end up mashing up some apple seeds with your molars, Bolarinwa says that the risk of cyanide poisoning is proportional to the eater’s weight. For example, an adult weighing 60 kilograms (or about 132 pounds) would need to eat 25 apples — seeds and all — to experience any poisonous effects.
A child on the other hand who might weigh only 25 kilograms (or about 55 pounds) would be more susceptible to cyanide poisoning and could become ill after only 10 whole apples. Smaller animals, like dogs or goats, are also extra susceptible to cyanide poisoning if they were to eat apples fallen from a tree or get into the groceries.
But before you ban apples from your grocery list, Bolarinwa says that the risk of ever reaching this level of toxicity is pretty remote. After all, when’s the last time you sat down to eat 25 apples at once?
Meanwhile, in a 2015 paper published in Food Chemistry, Bolarinwa found that processed forms of apples (e.g. apple juice) are safe to consume — even if a few seeds do slip in.
“These seeds are not totally removed [during processing,]” Bolarinwa says. “Some of the seeds get disintegrated and then they come out with the juice... However, the dosage is very very low.”
Can eating apple seeds kill you?
That said, what would happen if you did one day consume that many apples? Bolarinwa says there are some key signs to look out for with cyanide poisoning that would likely occur within hours of consuming your 25th apple (stomachache aside.)
These symptoms include:
- And even coma
If detected early, Bolarinwa says cyanide poisoning can be treated in a hospital with something like activated charcoal (which, when used medically, can draw out toxins) or a cyanide “antidote” which involves both inhaling and having an IV of a chemical cocktail.
In some extreme or untreated cases, though, Bolarinwa says cyanide poisoning from apple seeds could lead to death.
Risks beyond apples
Part of what keeps the risk of apple seed poisoning low is that apples are not usually a staple food in the human diet, Bolarinwa says. We don’t eat apples like we consume rice or potatoes. Similarly, apricots or peaches (which also carry this poisonous compound in their pits) are often eaten more sparingly.
This is the opposite story when it comes to cyanide poisoning from cassava in Nigeria, says Bolarinwa. This starchy, root vegetable can be ground into flour, stir-fried, put in soups, or eaten as a mash. It also contains a compound similar to amygdalin that can create cyanide in the body. This staple vegetable is poisonous only when eaten raw but it can take as little as two cassavas to be poisonous. Cassava is also a popular food in parts of Asia as well, including India and China.
The big takeaway: Consumers shouldn’t stop eating these fruits in vegetables, but they should be mindful of how much they are eating. Meanwhile, Bolarinwa says, increased care processing this food (and even alternative methods, like fermentation) can help decrease its poisonous risk.