Have you ever really looked at your own poop?

Justine Zwiebel / BuzzFeed

When my poop is bright red, the culprit is usually beets I ate a day or two before. As beets have become a larger part of my diet, the number of seconds I stare at bright red poop while thinking I’m about to die have steadily decreased. But recently, faced with another clean white bowl of shocking red poop, I ran through everything I’d eaten in the past week and came up beet-free. Panic naturally followed.

The longer I spent googling poop colors, the more intrigued I got. What about other colors besides red? What about texture, or size, or smell? Could I hack my own poop? Eventually I called up Dr. Anish Sheth, gastroenterologist at the Princeton Medical Group and co-author of What’s Your Poo Telling You? (Chronicle Books, 2007), to find out more.



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BROWN Poop isn’t brown because all the gloriously colored foods you’ve eaten have mixed together to create a single shade; it’s brown because of bile. Bile is a liquid, produced by our livers and stored in our gallbladders, that mostly serves to break down fats and remove them from digested foods so that our small intestines can snag the fats and process them. “Bile is green,” says Sheth, “but as it goes through the GI [gastrointestinal] tract it’s actually metabolized by bacteria in the small intestine.” That interaction of bile with the intestine’s bacteria also results in a byproduct we don’t need, called stercobilin, which is disposed of with the poop. And stercobilin, surprise surprise, is brown.

Ultimately, if your poop is brown, you know that all kinds of gross mushy guts are working properly — your liver, intestine, gallbladder, everything has worked together to come up with that lovely brown color.

CHALKY GRAY OR WHITE Poop that comes out kind of chalky gray or white-colored is a classic sign that something has gone wrong way back in your system. Pale poop could mean you have a gallstone that’s blocking the gallbladder from injecting its bile, but it could also be caused by pancreatic cancer. Pale poop: very bad.

YELLOW Similarly, beware of notably gross yellow poops. You’ll know that something’s wrong here; they’ll smell terrible, for one thing, and feel greasy and disgusting. They’re the result of fat finding its way into your poop — remember, your bile was supposed to take care of fat. The problem could be a parasite like giardia, it could be a result of taking an over-the-counter weight loss drug like Alli, it could be evidence of celiac disease. Who knows? See a doctor.

BLACK Black poop is also very bad. It’s called melena, and it means you’ve got something bleeding in your upper gastrointestinal tract. “This could be caused by something like an ulcer in the stomach,” says Sheth. “The blood is red in the stomach, but by the time it goes down through the system, it gets digested and turns thick and tarry and black.”

GREEN Green poop can be caused by totally innocuous things, which we’ll get to later. But it can also be caused by what’s called “rapid transit,” meaning the bile doesn’t spend enough time (it usually needs a few hours) in the intestine, getting broken down and churning out brown stercobilin. Green poop caused by rapid transit is usually pretty loose or straight-up diarrhea, and can be the result of some kind of intestinal bug.

RED Red poops can be bad, sometimes; blood in the lower gastrointestinal tract that hasn’t had time to turn black could turn your poops red. That’s bad! But red poops are easily caused by dyes, so don’t panic. Speaking of dyes…

How to hack your poo if you actually want it to turn other colors: After my recent panic in the bathroom, Google helped me come up with the answer: the fancy purple carrots I’d eaten the day before.

See, your digestive tract doesn’t bother removing certain kinds of dyes, both natural and artificial, from foods. They’re of no particular use or harm, so the body just lets them ride all the way from your mouth to your butt. “Fruits and vegetables that have certain natural colors, that color will be transmitted to your stool and will change the way things look,” says Sheth. He specifically named beets (red), blueberries (bluish), and carrots (orange) as common color bandits.

TURN IT RED! Artificial dyes like Red #40 can have the same effect. A landmark study in 1972, which was, swear to god, subtitled “The Franken Berry Stool,” discovered that the red dye in then-new Franken Berry cereal, when consumed in enough quantity, would turn poop red. Red #40 is the most commonly used red food dye in the U.S., though it’s been banned in lots of other countries and is on its way to being banned in others. You can find it in Kool-Aid, red candy (Starburst, Jolly Ranchers, cinnamon-flavored gum), cereal like Froot Loops and Trix, Jell-O, Doritos, strawberry ice cream… pretty much everything that’s red and comes in a package has Red #40 in it. Want to color your poop red? Drink a bunch of cherry Kool-Aid.

TURN IT GREEN! Let’s go back to our old friend, the green poop. Green poop can show up if you eat an excess of chlorophyll, found especially in dark leafy greens like kale and spinach. The body doesn’t break down the colors in chlorophyll, so they head right out the butt. You can achieve this same effect by taking chlorophyll supplements, if you don’t want to eat your greens. But, the primary reason leafy greens turn your poop green is because of their high insoluble fiber content. If you want a truly hacked green poop, you’re better off going artificial — something with Green #3 dye.

Green #3 isn’t as common as Red #40, but you can still find it in canned vegetables and green desserts like popsicles. It’s probably worth noting that Green #3 is banned outright in the European Union and has been found to cause tumors. We do not recommend eating enough popsicles to turn your poop lime green, but it will, if you do.

Here’s something weird: You can also turn your poop bright green by eating foods with Blue #1, an artificial dye (also, again, banned by several countries for possible deleterious health effects) found commonly in blue- and purple-colored foods. Anything grape- or blue-raspberry-flavored could have Blue #1 in it, and many informal tests have indicated that, instead of turning your poop blue, Blue #1 will turn your poop bright green. That’s a fun game! Drink tons of grape Gatorade or eat blue raspberry slushies and watch your poop turn, against all odds, green.

TURN IT ORANGE! It’s also easy, and healthier, to go for orange poops. Foods rich in the vibrant natural pigment beta carotene, like orange carrots, sweet potatoes, and pumpkins, have the potential to turn your poops orange.



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Texture, like so many of the variables that change our poops, is all about fiber. There are two kinds of fiber: soluble and insoluble. You need both of them, but they have in some ways opposite effects. Soluble fiber dissolves in water, helping your poops to be firm by attracting water to them while keeping their structure intact. Soluble fiber also slows down your digestive system (and makes you feel full), and is found in stuff like oatmeal, lentils, nuts, beans, carrots, and apples. Insoluble fiber isn’t dissolved in your system, so it finds its way into your poop and speeds up the process of digestion, as well as making your poop a bit looser. It’s found in dark vegetables and the skins of potatoes.

IF YOUR POOPS ARE LOOSE… If you’re having green, liquid poops due to rapid transit, you might be able to turn the poops firm and brown again by eating a whole mess of soluble fiber, like in, say, oatmeal, which is what Sheth recommends (instead of Grape-Nuts or fiber supplements) to increase your fiber intake.

IF YOU’RE HAVING SMALL, FIRM POOP PELLETS… Small, pellet-like poops have a couple potential causes. The scary one would be diverticulosis, a condition in which sort of pocket-like protuberances form on the intestine, which affects how you expel the poop. But you can have that disease for years without knowing it, and the more likely issue with poop pellets is that you’re simply not getting enough insoluble fiber to keep your poop nice and pliable and in large pieces. Eat some leafy greens!

IF YOUR POOP FEELS JUST WAY TOO BIG… Have you ever had a poop that feels like it’s too big to even make its way out of you? Assuming you eventually can pass it, that would be called a low-level form of constipation, which can be caused by all sorts of things: not enough physical activity and a lack of insoluble fiber would be the main culprits. Remember how insoluble fiber speeds up digestion? Well, if you don’t get enough insoluble fiber, the poop can stay in your intestine for longer than it’s supposed to, and your body will naturally keep leaching out all the liquid until the poop is dry and hard. That’s very bad news; to make its way out through the gauntlet of muscles between the intestine and the toilet, a poop needs to be a little bit malleable. If it’s dry and hard, it can get stuck in there, which is called a “fecal impaction.” This can be very painful, and the solutions are all pretty extreme; you may even have to get a doctor to lube themselves up and scoop the poop out.

IF YOUR POOP FEELS SHARP… Sharp poop is another concern; it can be caused by a lack of insoluble fiber (thus making parts of the poop dry and hard, but not actually stopping it from exiting as in a full fecal impaction) or by eating things that are actually sharp, like sunflower seed shells. But there’s also a risk that the poop only feels sharp as a result of some kind of weakness in your inner tissue, like swollen hemorrhoids, a cyst, or the horrific-sounding “anal fissure,” which is basically a small tear in your anus. Repeated or particularly severe sharp-feeling poop would definitely be grounds for a trip to the gastroenterologist.

IF YOU HAVE THE RUNS… What about the other end of the spectrum? Diarrhea, excessively soft or liquid poops, has more causes than most poop-related troubles; it can be caused by bacteria, a lack of bacteria, a virus, a bad meal, stress, various prescribed medications, a food intolerance you didn’t know you had (like, say, a minor lactose intolerance), and all kinds of scarier diseases like diabetes and hyperthyroidism. There’s not even all that much you can learn based on when you get diarrhea; some causes (like eating dairy despite a lactose intolerance) can produce diarrhea within an hour, and some (like the contraction of various bacteria) take several days to saddle you with liquid poops.

As far as treatments for diarrhea, well, those are pretty basic and familiar. Drink more liquid than you’re losing, get some rest, and see a doctor if it doesn’t go away within a day or two or if you’re experiencing particularly awful pain.



Justine Zwiebel / BuzzFeed

“People always think it’s methane, but the foul smell of stool actually comes from a group of compounds called mercaptans,” including hydrogen sulfide, says Sheth. Certain foods are especially high in mercaptans, like red wine, coffee, red meat, and cheese; these are sure to cause both smelly gas and smelly poops. But classic smelly vegetables, like broccoli and brussels sprouts, aren’t naturally that high in mercaptans. “Vegetarians actually produce more gas than people who eat meat,” says Sheth, “but the gas tends to not smell as bad.”

Have you ever made bread by putting some yeast in warm water and waiting for it to emit a bunch of air and turn foamy? That’s pretty much what’s going on in our gut. Fruits and vegetables that are high in fiber are broken down in the small intestine by various bacteria. As a byproduct, the bacteria produce gas, which, well, has to go somewhere. A healthy diet, high in fiber, will produce a lot of gas. Weird but true. But it won’t really affect the smell of poops, and Sheth says there probably isn’t a way to reliably change the smell of your poops.


The fact that my purple carrot salad turned my poop such a lovely shade of magenta was alarming, but perfectly healthy. And the experience turned me on to so many fun variables in poop — color, texture, frequency, and smell are all like canaries in the coal mine, emerging from my body to alert me to what’s going on within. “Hey, Dan!” shouts the red poop. “You ate a whole package of strawberry Jell-O yesterday!” Thanks, poop. I’ll never ignore you again.

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