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MLA Full: "Why Is My Poop Green?" YouTube, uploaded by SciShow, 10 September 2014,
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One of the most commonly googled questions in the world is why feces can be green. Well, Quick Questions has the answer!

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You can ask the Internet anything you want -- like, how big is the universe? Or what’s the average lifespan of an Olive ridley sea turtle? Or why are sloths so lazy?   But many of you turn to the wisdom of the Internet to explain what you find in the toilet bowl.

  According to our friends at Google, one of the most commonly googled questions in the world -- at least in English -- is: why is my poop green?   And hey, fair enough. We’re all about fostering curiosity here, and what’s more fascinating than the human body?   So in order to answer this question, we should really start with why poop is normally brown.

  The brown color of most mammalian feces comes from a substance called bilirubin, which is produced by your liver when it processes dead, used-up red blood cells and prepares them to be excreted.   The bilirubin is actually made from hemoglobin, the protein that your blood cells use to ferry oxygen around your body.    But even though your red blood cells are red, the bilirubin itself is yellow. And it’s absorbed by your liver and excreted as bile, which is yellowish green because of all the bilirubin in it.

  The liver secretes bile into your small intestine, where its main job is to digest fats, breaking down lipid molecules into fatty acids. But, since the bile is on its way down your body anyway, it’s also chock full of waste material, including that bilirubin.   So. The fact is, because of all of the bile in it, your feces actually start out a yellowish green color.

  Typically, as your feces travel through your digestive system, the bilirubin is broken down by your gut bacteria -- those wonderful microbial minions that live inside your intestines and help you absorb nutrients while decomposing waste.   These bacteria eat the bilirubin and metabolize it into a byproduct that’s colorless. But when that byproduct reacts with oxygen, it turns brown, forming a pigment called stercobilin. Stercobilin is what makes your poop brown.

  So, if your poop is green, it means it went through your digestive system too fast, and the bacteria didn’t have time to digest your bilirubin into its byproducts.    So if you notice that stuff’s a little greener after you take a laxative, or have a touch of food poisoning, or maybe super hungover, something else might be goin’ on that’s hurrying your poop along too quickly.

  So the occasional green turd is probably nothing to worry about, but if it’s always that color, it could mean that your feces aren’t spending enough time inside of you for your intestines to absorb all the nutrients you need.

  Mystery solved!   Thanks for asking, and thanks to our Subbable subscribers who keep these answers coming!   If you have a quick question you’d like to ask us, let us know on Facebook or on Twitter or down in the comments below, and don’t forget to go to and subscribe!