The Science Behind Apples Seeds And Cyanide Poisoning : Short Wave Many folks eat an apple and then throw out the core. It turns out, the core is perfectly ok to eat - despite apple seeds' association with the poison cyanide. In today's episode, host Maddie Sofia talks to producer Thomas Lu about how apple seeds could potentially be toxic to humans but why, ultimately, most people don't have to worry about eating the whole apple. And they go through some listener mail.

Micro Wave: How 'Bout Dem Apple...Seeds

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MADDIE SOFIA, HOST:

Maddie Sofia here with NPR SHORT WAVE producer Thomas Lu. Hi, Thomas.

THOMAS LU, BYLINE: I'm back, Maddie. Howdy, howdy.

SOFIA: (Laughter) Welcome back, Thomas. You are here with a Micro Wave for us - a short, bite-sized, fact-filled episode ending with some lovely listener mail. So what do you got, Thomas?

LU: OK. Well, you know how they say an apple a day keeps the doctor away?

SOFIA: I'm familiar with the phrase, yes.

LU: I can't say that I had an apple every single day growing up, but I did start doing something as a kid to maybe compensate a little for all my missed apple days.

SOFIA: OK, go on (laughter).

LU: You see, many people eat their apples by biting around the core or cutting it up into little tiny pieces and slices and then tossing out the core.

SOFIA: You have - yes. You have described how people eat apples now, Thomas (laughter).

LU: But that sounds like a lot of work just to keep the doctor away. So I started eating the entire apple.

SOFIA: Like, what do you mean the entire apple? Like, the core? Like, the seeds?

LU: Core and all.

SOFIA: Oh, my God (laughter).

LU: And I have plenty of company.

SOFIA: Do you?

LU: Oh, yeah, yeah, yeah, totally. Many folks I know also do this. At its core...

SOFIA: OK.

LU: ...We've been conditioned to throw out the fleshy center of the apple because we're afraid of swallowing the seeds. But the idea of a core, it's totally fake. It's a myth, a fabric of society's collective imagination.

SOFIA: Wow, wow, wow, Thomas. Tell us how you really feel.

LU: I mean, Maddie, come on. You're losing out by not eating all that apple goodness.

SOFIA: First of all, Thomas, gross. Second of all, isn't there, like, cyanide in seeds or something? I feel like I learned this at one point.

LU: OK, OK, fair question. I've actually heard that from lots of folks, too. And full disclosure - apple seeds do have a bit of toxic nature to them. But after an in-depth apple investigation, I am happy to report, Maddie, that I'm safe to continue eating the whole apple. And I can explain what the whole cyanide thing is all about.

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SOFIA: So today on the show, a case for eating the entire apple. And we explore the toxic nature of apple seeds. I'm Maddie Sofia.

LU: I'm Thomas Lu.

SOFIA: And you're listening to SHORT WAVE from NPR.

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SOFIA: OK, Thomas, we are talking about apples today. Why don't you tell our listeners how you even got started down this weird little apple path?

LU: So a few weeks ago, I saw a video of a dude eating an apple from the bottom up.

SOFIA: (Laughter).

LU: And, you know, I brought it up to the pitch meeting.

SOFIA: Right.

LU: And at the time, all I wanted to find out from the team was whom amongst us was with me in eating the entire apple. It was just like, you know, a way to start - get the conversation going.

SOFIA: Yeah, I remember. And I was horrified to find out so many members of our team eat the whole apple. Like, we were pretty divided down the middle.

LU: Yeah, that's right. And the discussion led to the possible dangers of eating the apple seeds. Some of us had heard they might be toxic; some of us hadn't. So here we are chatting away about them apples.

SOFIA: (Laughter) And the science behind whether or not you can eat the core - why we are here today - is pretty cool.

LU: Yeah, totally. And I found a food scientist to help explain it all.

ISLAMIYAT FOLASHADE BOLARINWA: Good afternoon. My name is Islamiyat Folashade Bolarinwa. I am a senior lecturer in the department of food science at the Ladoke Akintola University of Technology.

LU: Islamiyat is a food scientist based in Nigeria. And she told me, on the one hand, apples are these magical fruits that are really nutritious and good for you.

BOLARINWA: Apples are poplar fruits that are rich in nutrients such as antioxidants, minerals, vitamins, dietary fibers and other nutrients.

LU: But their seeds are different than their flesh.

SOFIA: Yeah, exactly. What I'd always heard is that apple seeds have, like, some amount of cyanide in them, you know, like, generally not something that is good for humans.

LU: I mean, yes and no. I asked Islamiyat to explain it, and it's a little more complicated.

BOLARINWA: Seeds that is in the center of apple are capable of causing poisoning because the seed contains a compound that is called amygdalin.

LU: Amygdalin is a compound that's found in lots of natural plants and things that humans eat, such as apples, but also peaches, apricots and almonds. There is a similar compound in cassava, a staple in Nigeria. And on its own, Maddie, in seeds, amygdalin is usually harmless to people - no concerns there. But what is potentially concerning is when digestive enzymes in our bodies come in contact with the amygdalin. And when they combine, the enzyme breaks away the sugars in the amygdalin and leaves cyanide, which could potentially lead to cyanide poisoning.

SOFIA: What do you mean potentially, Thomas? Say more (laughter).

LU: Well, the conditions have to be just right, Maddie, for this to be more of a concern. For starters, the amygdalin in apple seeds is encased by a pretty tough outer layer. In order to expose the amygdalin to our digestive enzymes, we would have to chew those seeds really, really well.

SOFIA: Yeah. OK, I get it. And even whole-apple-eating monsters like you, Thomas, aren't generally crushing those seeds down to a fine paste with your teeth, right?

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LU: Exactly, Maddie. As much as I love that title, more importantly, though, there's not enough apple seeds in one or two apples to really show an effect on our bodies. The amount of cyanide that does get formed, if at all, our livers are pretty good at filtering out those toxins.

SOFIA: OK. All right, Thomas. But you did say that there was a situation in which this could be dangerous. So, like, how many apple cores would you have to slam before you are in the cyanide danger zone? Like, give me a number.

LU: So the potentially lethal amount of cyanide depends on the amount of amygdalin present, the type of apple and its overall health, not to mention the body weight of the person consuming those apples.

SOFIA: OK, I love caveats. You know that about me, Thomas. But stop avoiding my question.

LU: OK, OK, OK. So according to Islamiyat, for an adult weighing about 60 kilograms, or 132 pounds...

BOLARINWA: You must have consumed, as an adult, at least 25 apples at once, which is not usually possible.

SOFIA: Twenty-five - even you, Thomas, couldn't do 25 apples at one.

LU: Well, Islamiyat's research does point to at least 25 in one sitting, but other scientists have suggested a range of about 18 to 40 apples. Of course, this is assuming that those seeds were pretty well chewed and the amygdalin was sufficiently exposed to meet your digestive enzymes. That said, however, Maddie, I want to emphasize here that cyanide is dangerous. So please, please, please don't try this at home.

SOFIA: Yes. Listeners, please consume apples responsibly. OK, Thomas, final question - what about apple juice and ciders, where a processor might throw in, like, the entire fruit or something all at once?

LU: Right. I'm glad you brought this up, Maddie. In her research, she found that the processing techniques used to make apple juice can actually reduce the amount of amygdalin concentrated in these beverages and, therefore, the potential for cyanide production.

BOLARINWA: And I also reported in my research that for those juice to cause poison, the person has to drink about 20 liters...

SOFIA: (Laughter) Wow.

BOLARINWA: ...Because when you are extracting using a commercial extractor, just small amount of the core disintegrated with the extraction. So the concentration is minimal.

LU: So, Maddie...

SOFIA: (Laughter).

LU: ...Now that it's pretty clear you can't be poisoned by the occasional eating of the whole fruit - core, seeds and all - I have one question for you. How do you like them apples?

SOFIA: (Laughter) Oh, my God. Thomas, did you write this entire episode to be able to say that for this one moment?

LU: You know what? Matt Damon did a pretty good character in "Good Will Hunting."

SOFIA: (Laughter) All right, Thomas, I will tell you what - Matt Damon aside, I am not eating those seeds. But I do like knowing that I can. That's my choice.

LU: OK, fine. Moving on. It's time for listener mail.

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LU: Here's one from Lory Brennan (ph). She says, hello, my kids and I are big fans of the show, and we really enjoyed the episode about rainbows.

SOFIA: Yes.

LU: We do have a follow-up question - can animals see rainbows? If so, which ones?

SOFIA: Wow, wow, wow. Just when you thought we were going to have one episode without a critter in it, you know.

LU: Sorry, not sorry, Maddie.

SOFIA: (Laughter).

LU: But, yes, Lory and kids, animals can see rainbows. Depending on the animal, though, it might look a little different.

SOFIA: Right. Like, my dog Elisa probably has less-cool rainbow view than I do because she can see fewer colors of the rainbow.

LU: Sorry, Ellie.

SOFIA: (Laughter).

LU: But some animals, like birds and butterflies, can see more colors than we humans can.

SOFIA: Right.

LU: So when they see a rainbow, they probably see extra colors, like even ultraviolet light.

SOFIA: So wild. So wild. To be a butterfly looking at a rainbow, Thomas, you know? You know what I mean?

LU: Or a bird, Maddie. Or a bird.

SOFIA: All right. Big thanks to Lory and her kids for listening and writing in. And thank you, T. Lu, for bringing us this fruit fact of an episode.

LU: Thank you, Maddie. It was apple-solutely (ph) my pleasure.

SOFIA: OK. All right, everybody, we will see you next week.

LU: (Laughter).

SOFIA: This episode was produced by Brit Hanson, edited by Gisele Grayson and fact-checked by Ariela Zebede. I'm Maddie Sofia.

LU: And I'm Thomas Lu.

SOFIA: You're listening to SHORT WAVE from NPR.

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