If your mother ever warned you not to eat apple cores, it was with good reason. Yeah OK, so apples don't really have cores, but they do have those rough middle sections full of seeds, and those seeds can harbor concentrations of molecules called cyanogenic glycosides. One of those is amygdalin, and when it gets down into your gut bacteria, it can turn into cyanide, which can do a pretty good job of killing you.

So, it seems like a good idea to steer clear of that crunchy center, right? But here's where that logic is off: A single apple's worth of seeds can't produce nearly enough cyanide in your belly to make you even a little bit sick. So if you're throwing out the rest of your apple, you're not actually saving yourself from anything. You're just wasting half an apple.

Apples aren't the only fruits with cyanogenic glycosides, either. Peaches, apricots, cherry pits, almonds, even lima beans—they've all got 'em. But you don't usually eat fruit pits whole anyways, which is where the amygdalin is, and almonds and beans don't have enough to harm you. You'd have to chew or grind a cherry pit into a fine powder for the glycosides to do their work. A small number of children have gotten sick from eating too many amygdalin-loaded seeds, but "it's extremely rare, and would require significant ingestion beyond any normal amount," says Kate Sweeney, a registered dietician who manages the Nutrition and Wellness Center at Brigham and Women's Hospital.

And assuming you're really good at grinding up peach pits with your teeth (ouch), or you really like chewing on apple seeds, the cyanide that would form in your gut if you ate a bunch of amygdalin is quite different than the cyanide formed in the lab. Chemists have been extracting glycosides from fruit pits since Carl Wilhelm Scheele dissolved them in water back in 1782, creating a highly toxic chemical that was really useful for making pen ink or hardening certain metals. Today, commercial cyanide comes in the form of highly concentrated gases, liquids, and crystals, which are used to make everything from paper to plastic.

Inhaling or ingesting these ultra-strong man-made chemicals can cut off oxygen supplies to your cells, causing immediate damage to your heart and brain. When you swallow, or even chew, a few apple seeds, it might produce trace amounts of hydrogen cyanide, but the amount and concentration is so minute that your body just flushes it out during digestion. So while cyanide poisoning is nothing to scoff at, it's not going to happen if you eat more than, say, seven almonds in one sitting. Thanks, Obama.