I was talking to my sister and four-year-old nephew the other day and my sister prompted him to tell me what he wanted to study when he grew up. He looks right at me and answers “poop”. Totally funny coming from the boy who really is obsessed with his own poop, but as a scientist, I responded that I could tell him lots about poop and asked, “what about poop are you interesting in studying?” His response, “All of it.” Well, I agree. Poop is far more interesting than we give it credit for. In the next two posts, I will share with you all the interesting stuff I know about poop. This post will be facts about poop and the second post will be about using poop as a cure for diseases. Let’s get down and dirty...
I’m not one of those people fascinated by poop. I have never read any of the most popular books on the topic “Everyone Poops” or “What’s Your Poo Telling You“. In fact, I won’t even admit that I poop myself (as my husband will attest I insist that it’s all butterflies and rainbows down there). But (butt!) being in a lab makes you think about things you never expected. A common laboratory activity is something called a journal club. Held weekly, undergrads, graduate students and post-docs take turns discussing a scientific topic or journal article. I like talking about the newest technology and controversial topics, so when it was my turn, I decided to look into the ancient, but recently rediscovered, therapeutic uses of poop to help cure diseases. As a started my research on the topic, I realized that I knew very little about poop in general. Being the scientist that I am, I went to learn more. And lucky you, I’m going to share!
First and foremost, what is poop made of? The majority (75%) is water! The remaining 25% is a mix. About a third of this 25% (doing the math, that’s 7.5% of your poop) is dead bacteria (back to that later) and a third fiber and undigested food (like those corn kernels you didn’t chew before swallowing). The final third contains living bacteria, protein, cell linings, fats, salts, and substances released from the intestines and liver. In fact, the brown color of poop comes from some of these secreted substances such as bile and also bilirubin, which comes from dead red blood cells.
There are seven different types of poop that have been categorized in the Bristol Stool Form Scale (or BSF for short) developed by Dr. Ken Heaton from University of Bristol. I was going to spend the next 5 minutes wondering exactly what sort of methodology brought him to discover this seven type system, but then I just looked at the original article. “Sixty-six volunteers had their whole-gut transit time (WGTT) measured with radiopaque marker pellets and their stools weighed, and they kept a diary of their stool form on a 7-point scale and of their defecatory frequency.” I’m glad I was not a volunteer in that study – keeping a daily diary of my stool form and have the length of time from mouth to poop tracked – ick! However, Dr. Heaton was able to conclude that the form the stool takes depends on the time it spends in the colon, with 3 and 4 being ideal stools. Now one more thing for siblings, partners, and spouses to argue about – who’s poo is better?
But(t) let’s get serious. Besides being an indication of intestinal health, poop is also filled with bacteria. These bacteria are representative of the bacteria that can be found in your gut and are part of your “microbiome“. Your microbiome (all of the bacteria and other bugs in and around your body) outnumber your human cells 10 to 1, and scientists think that 300-1000 bacterial species inhabit the GI tract alone! We’re not entirely sure exactly how many species because most of these bacteria don’t grow outside the gut (in the presence of oxygen), and when we look for gut bacteria by sequencing the DNA of poop samples, we’re not sure if the bacteria in poop represents all the bacteria that are found in the gut.
Either way, what do all those bacteria do? They help with digesting food and producing vitamins. They regulate fat storage and do some crazy things like influence the immune system and the brain (more on that in a future post). These bacteria are also protective against pathogens, like bad infectious bacteria or viruses. How the gut microbiome protects against pathogens is still being studied, but we know that some gut microbiome bacteria create antimicrobials that kill bad bacteria. In other cases, its all about the balance of the good bacteria versus the bad. When this balance changes, it can be a cause or consequence of the disease. And one of the cures to these diseases, might just be poop itself, which is what I’ll discuss in my next post.
Want to learn more about poop? Check out some of these resources:
- The Scoop on Poop from WebMD
- Everybody Poop. But here are 9 surprising facts about feces you may not know from Vox
- Feces on Wikipedia