Why kids “poop” changes colors? (Pedcast)

Hello, I am Dr. Paul Smolen, also known as Doc Smo.  I started the docsmo.com blog as an educational resource for parents and families who need information on their time framework, fast and on the go. After 32 years of pediatric practice, I know a thing or two about what parents want to know. A common question I get from parents is why poop has different colors?  Parents ask this all the time so I thought we would go deep into the caca today and talk “poop talk”. I have discovered that if you want to break the ice with a 6 year old as a pediatrician, just start talking poop talk. They almost always think that word is hilarious. Based on the number of articles I saw in preparation of this pedcast, I concluded that adults like to talk “poop talk” as much as children do. And for good reason… they spend so much time cleaning it up after they have children. So here goes with my contribution to the poop color literature. I hope after listening or reading this article you will have a good understanding of what makes poop different colors and what medical conditions poop color might indicate. When to worry and when not to worry.


We are going to start with a walk down Science Lane, that street I love to visit. In order to understand poop color, we need to first start with an understanding of the digestive process. So here goes; If your child’s poop was simply what was left over after some nutrients had been absorbed from their food, stool would probably always be the color of the food that a child had eaten recently, right? If this were true, babies would have only white poop since they eat mostly white food (milk), children who ate mostly vegetables would have only green poop, and children who eat lots of fruits and berries would have red, purple or yellow poop.   Well we all know this doesn’t happen very often. Why not?  A trip through a child’s intestines is a fairly slow affair and a lot happens to our food once consumed before it exits as poop. In the stomach, food is broken up both mechanically by grinding in the stomach and chemically with strong acids. Next, bile is added as a detergent and this is key to understanding poop color, bile is bright lime jello green when it is dripped into our intestines by our gallbladders. If that bright green bile passes through your child’s intestines quickly, like when they are newborn or when they have diarrhea, it comes out green.  Bright green.  But if things pass through a little slower, intestinal bacteria convert the bile to different color pigments, first a yellow colored pigment and finally a brown pigmented bile. You can see the final and big determining factor of poop color is how long the intestinal bacteria have to work on your child’s bile. Green means fast transit, yellow- medium speed transit, and brown- slow transit time.  Should your child’s poop be white or very light in color over an extended period of time, this could mean that there is no bile being added and your child’s doctor needs to test their liver to make sure everything is OK.


Certainly other substances in stool can cause it to change colors, the big one parents need to be on the lookout for is blood.  Blood has a bright red color so if blood is introduced into poop at the end of the intestines it comes out bright red in color. On the other hand, blood introduced up stream, especially if it goes through the very acidic stomach, is the iron is oxidized by this acid changed  into a rusted state that is black in color. If bleeding occurs at the stomach or above, poop comes out black, sticky, and very smelly. The black because of the rusting of the iron, sticky because of all the protein from the blood, and smelly because intestinal bacteria have loads of new food to ferment into smelly gasses.


Now let’s get out of the theoretical and get into the real world of kids and poop color. Here are a few things that pediatricians see fairly commonly that drastically affect the color of stool and can mimic disease states;

Pepto bismol- black stools- bismuth

Iron contatining vitamins- black stool-rusted iron

Red stools- usually purple or red dyes in foods

White stools- antacids, barium containing contrast media


Remember, unless there is a large amount of a colored substance added to stool, it’s color is determined by the amount of bile and how long the bacteria in the gut have to “digest” that bile before it exits.  Green means a fast trip through the gut (bile in the raw so to speak), yellow means a slower transit, and brown means a slow trip from mouth to rear with plenty of time for the bacteria to digest your child’s leftovers.  While other colors can indicated disease, usuually a child doesn’t have an illness unless the stool is black, sticky and smelly or bright red and your child is ill. Remember as well, if your child has severe stomach pain, or is very pale or sick, no matter what color their stool is, visit that wonderful person you call your child’s pediatrician, won’t you?

Well thanks for joining me today.  I hope you found that informative and entertaining.  Your comments are welcome at my website, www.docsmo.com and I love reviews on iTunes. Please take the time to join us on a regular basis. Your free pediatric education is available, tuition free, right here.  This is Dr. Paul Smolen, hoping you now have the scoop, on the color of your child’s poop. Until next time.