Short Wave - The red flags that may be hiding in your poop

Episode Date: August 7, 2026

When’s the last time you looked at your poop? Dr. Trisha Pasricha says you should look every time because it could save your life. A change in bowel habits is the number one indicator someone might have colon cancer, a disease on the rise in people under 50 in the United States. Host Regina Barber gets into what’s driving this trend with Trisha; plus, some shapes and colors you should keep an eye out for (did you know silver poop is a thing sometimes?). If you liked this episode, check out our first episode with Dr. Trisha: Are you pooping all wrong?Interested in more science health news? Email us your question at [e-mail] public media with NPR+ and enjoy perks for over 25 podcasts like this one. This show’s perks include sponsor-free listening. Learn more at plus.npr.org.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

Are you following Shortwave yet? It's the best way to get new episodes as soon as they drop. Look for the follow button at the top of our show page in your podcast app of choice. Or in Apple, it's a plus sign. Give it a little tap and you're good to go. All right, here's the show. You're listening to Shortwave from NPR. It's time to talk about something we all have in common, our poop.

Starting with the interesting shades it might come in. A silver poop is so rare, but it is possible that it was written up in the New England Journal of Medicine a few years ago. And what had happened was there was a person who was simultaneously experiencing two emergencies. And who better to talk about it with than Dr. Trisha Pusrecha, a gastroenterologist and medical journalist. Talking with her was a good reminder to me that paying attention to your stool could save your life, especially in the case of silver poop. They had an ulcer in their stomach and it was bleeding and it caused their poop to turn that tarry, sticky, shiny black. But at the same time, there was something blocking their Billy Rubin. So then they had this white stool mixed with the shiny black and it came out this like silver bullet, beautiful diamondy silver poop.

As fun and interesting as it may look, it's also a sign to take immediate action. Yeah, take a pick, but definitely go right to the emergency. Trisha says there's another reason to keep an eye on your number two's. Since the 1990s, the rates of colon cancer have increased among people under 50 years old. In 2018, the American Cancer Society lowered the recommended age for people screening from 50 to 45 years old, which can mean a colonoscopy. Colonoscopies save lives because they prevent cancers, not because they detect cancers. We catch these polyps, which are these groats that are not yet cancer, but, you know, 5 to 10% of them will go on to become cancer if we don't remove them.

For folks who haven't gotten their colonoscopy, Trisha says one of the biggest indicators that you need to see a doctor is a change in the color, shape, or frequency of your bowel movements. I really do think that this deep stigma we have about talking about pooping and talking about our bowels is tied to these cases in some ways because about one in three people will avoid talking to their doctor about their bowel habits because they're so embarrassed by them. And when it comes to early onset colorectal cancer, one of the biggest problems is that we're catching these cases late.

So today on the show, why paying attention to your poop could prevent colon cancer. Plus, life hacks to keep you healthy and stinky free. I'm Regina Barber and you're listening to Shorewave, the science podcast from NPR. All right, Dr. Trisha, we're talking a lot about the fact that our poops can change. And those changes are worth noting to your doctor. So let's give people some foundation on how their poops can look. Like there's the scale called the Bristol scale. And it's like basically ranking your poop, right? Yeah. So this is a nice, easy way to look at what your stool looks like. Look at that shape and that consistency. And so the scale is from one to seven with four being right in the middle. It's that like perfect, smooth, snake-like stool that people dream of. And then above that,

you have types one, two, and three. And one on the extreme end of that spectrum is like these hard little rabbit pebbles. And if you're seeing that, it probably means that poop has been in your colon for the longest. And as you make your way down that scale from two to three, it starts to become a little bit more formed, more bunched together. When you hit four, it's this like smooth sausage. And then five and six, it starts to get fluffier and fluffier. And by the time you hit the end of the scale, which is a type seven, it's just water. Most people actually do live in a in America, live in a type three or four stage, which is like smooth sausage or maybe like a little, a couple little cracks in that sausage. So what are, what are the things that people would

see in, like, what are the changes that they should be, you know, cautious of? Yeah. Certainly anything that looks like blood, that is a literal red flag. Unless you've had beats. If you've had a beet salad, you'll get a pass for one maroon-colored stool. But like, and even if you're like, no, I had it two days ago, it might be two, three days late. But then black, like tarry, sticky, black shiny stool. That too could happen if the blood mixes with the acid from your stomach, it can turn black. So those things are emergencies. Those are like, talk to your doctor. Like red and black, bad. Yes. Pain and abdominal pain. It doesn't have to be 10 out of 10. I think my appendix has burst kind of pain. It can just be this like kind of low grade,

dull pain that's there and it wasn't there before. That should bring you in. And then anything that's like weight loss that you didn't intend, iron deficiency anemia. And then the most important one, which I tell people about, is a change in your bowel habits. This means something has changed to your pattern. Maybe it's new diarrhea. Your stools are more loose than they used to be. Maybe they're suddenly more narrow and thin than they used to be. Any change for you, and this requires you, looking every day, you have to know what's normal for you, probably there will be some ideology that is perfectly reassuring, but you should at least just get someone to lay eyes on the situation. And there's other reasons why your poop could suddenly turn a different color, right?

It's actually funny. I get this a lot from college students who like start drinking for the first time in large quantities, but they'll often poop like purple when they come to college, but they'll have drunk like half a bottle of red wine the night before. And I'm like, you know what? First of all, we have to have a conversation about this, but also it's probably the anthocyanans that were in your red wine that gave you this like nice, purplish blue poops the next day. I should have said this earlier for our listeners. You wrote a book all about this called You've Been Pooping All Wrong. And you say in the book, yellow and green are also okay. It depends. So if you were to say, I have this like new yellowish poop and I have diarrhea and I feel

ill, I would say you need to go to the maybe even the urgent care or the emergency room because maybe you have an infectious diarrhea. If you were to say my poop is a little yellow and I've been doing this keto diet for the last two, three weeks, that I might say, you know what, maybe that's okay. All that fat. Yeah, exactly. There's another color that is an emergency, which is white. White poop or grayish pale clay-colored poop, that is actually the natural color of our poop without Billy Rubin. Billy Rubin is this digestive enzyme that we produce on our own. That's what gives it the brown color, the bile salts in this juice called Billy Rubin. But if you have a gallstone potentially, if you have a cancer potentially, or something else

obstructing that Billy Rubin, your poop can turn white. So that is an emergency no matter what. In your book, you said like poop is stinky and farts are stinky, but there are a way to make them not stinky. Yeah. This is like one of the biggest life hacks, I feel like for people, especially relevant on dates, like relevant when you're meeting the in-laws for the first time, whatever the situation might be that you've deemed high risk, you can take peptobismol beforehand. So it's the sulfur gas that gives farts their smell. And bismet subsiliculate, which is the compound that is in peptobismal, that actually really, really effectively binds those sulfur producing gases. And so you'll be able to kind of neutralize that sulfur. Now, you probably shouldn't take it for days and

days and days on end, especially if you're taking something like aspirin at the same time. But for just like a couple day trip, like, or even just one night, totally safe to do. But your, but your poop will be black. Yeah, be foreworn that there will be a change. But hopefully not one that others will notice just looking at you. Okay, totally. So going back to the more serious situation, like the high amount of cancer in young people, why are more young people getting this kind of cancer nowadays?

Yeah, that's the question. One of the most common ideologies that a lot of the data is pointing towards is our diets, and it is specifically ultra-processed foods. And it's probably a lot of different factors beyond that as well. But ultra-processed foods do two things. One, they introduce these chemicals and additives and high sugar and high salt that our microbiome doesn't love at all

and can cause microscopic inflammation. And then the second thing is that ultra-processed foods, notoriously are low in fiber. Fiber is protective against colorectal cancer. And then I think what's really disturbing about that is that in these early onset cancer cases, particularly, a lot of the studies point towards our diets when we're young, like in our adolescents and our teenage years, when we're eating ultra-processed foods as young kids, when we're drinking these sugar, sweetened beverages. That's been shown to be linked. And so sometimes it's not necessarily like what you did in your 30s and then you get diagnosed at 37, a lot of the time it's stuff that has been brewing for a long time. And in some cases, well before you really even had conscious control over and kind of even the knowledge over what you were doing because it happens so early in life.

Let's end on something that people can do for themselves to make themselves healthier, happier. What advice do you have for me, for our listeners, to poop better? I mean, you know, the first thing I ask myself in a day, or at least the last thing I ask myself towards the end of the day, is like, what have I done to feed my microbiome today? And I think if you think about that question, it'll change what you do over the course of the day. Because I've studied the gut brain connection now for more than a decade. And the enteric nervous system that is this network of nerves that lives in your guts has really made me view the gut as this brain. It's not just this set of plumbing and pipes. And I want people to think and treat their guts like this really delicate brain, which it is, and to think about their microbiome, which is kind of running the

show behind so much of your health as something that you, it is your responsibility to feed and nourish. And so for me, practically speaking, what that means is I try every day to meet my fiber goals. And I'm doing that because I'm thinking specifically about what are my microbes going to eat. If you don't give them fiber, they don't have anything to eat. And then two, I think about, if I can, I try to eat something fermented every day, like a probiotic food. Maybe that's Greek yogurt. Maybe that's sauerkraut or kimchi or in Indian cuisine, we have dosas, which are fermented, which are lovely, but something fermented also helps fuel the microbiome, and there have been very big studies on fermented foods will change those microbes in a really good way.

So if I could do one thing, meet your fiber goals. Like that's one, two, and three, and then four, toss in a little fermented food. I hope that our, you know, discussion helps other people talk about their poop. And I want to thank you so much. I really appreciate you having me on. Thank you. SureWavers, if you found this episode to be helpful and fun, share it with a friend, especially if that friend, like me, is due for their first colonoscopy. Sharing is caring. This episode was produced by Brother McCoy and edited by a showrunner Rebecca Ramirez. It was fact-checked by Tyler Jones and the audio engineer was On Le Quang.

I'm Regina Barber. Thank you for listening to Shortwave from NPR. My inbox, my medical inbox, I don't accept personal photos, okay, but my medical inbox is filled with pictures of people's poof.