Sci Snippet – How long from eating to pooping?

Based on my two posts about poop (Facts about Poop and Fecal Transplant), I received a great question about how long it actually takes for food to pass through the gut? Although I posted my answer in the comments and on Facebook, here is the answer with a few more details in case you didn’t see it.


Thanks to North Shore Colonics for the image

The actual time from mouth to pooping depends on a number of factors (for example, what you eat and drink), and can be a critical measure of how the bowel is functioning – because we all know that things just aren’t right if we’re constipated or have diarrhea. There are a number of ways to measure “colon transit time” or “whole gut transit time”, but the most common is having subjects swallow 20-25 radioactive markers in a pill (link to what they look like here). The poop is collected and the number of radioactive rings in the stool are counted. And just in case you’re imagining researchers poking through poop – they didn’t have to do that! Because the rings are radioactive, they can count them using an x-Ray. After 5 days, researchers found that on average 80% of these rings were expelled, and 20% were still making their way out (the journal article is here). In one study, the median whole gut transit time is 27.7 hours though in other studies they find the mean to be slightly longer at 30-40 hours. Also, in general women had longer transit times than men – maybe because women’s intestines are, on average, about 10 cm longer than men’s. As an aside, you may wonder to yourself “why are women’s intestines about 10 cm longer than men’s?”  It’s not entirely known but two prevailing theories are 1) to get around the larger female internal organs like the ovaries or 2) to absorb more nutrients during pregnancy. This transit time is also affected by race – transit time is much shorter in Chinese men and women.

As you can imagine, this is a bit of an imprecise way to measure transit times and researchers are creating new tools (like electronic wireless motility capsulesthat can more accurately track how things transit through the gut. Or you can be like my friend Sarahjane who says that she informally tracks this using one of the lowest-tech options of them all – corn!

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No s**t?!?! Sharing poop to cure disease – it happens, it works, and here’s why!

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 this series of posts, I will share with you all the interesting stuff I know about poop. The first post was facts about poop and post is about using poop as a cure for diseases.  Let’s get down and dirty…


Changes in the percentage of different bacterial species in found in patients with various diseases compared to healthy control. From a review in Nature Reviews Microbiology

Your gut is filled with bacteria – estimates of over 100 trillion bacteria – weighing nearly 3 pounds! These bacteria are essential to help digest food and produce vitamins.  These bacteria are also protective against pathogens, like other bad infectious bacteria or viruses.  By studying the proportions of different gut bacterial species, scientists have found that the percentages of these bacterial species is different in patients with various diseases .  Although it isn’t clear if the changes in the gut mircobiome are a cause or consequence of the disease, scientists and clinicians are exploring whether changing the balance of bacteria back to normal can cure (or reduce the symptoms) of these diseases.


C. Diff bacteria

In one particular case, it’s clear that a change in the gut microbiome is the cause of the disease and that’s Clostridium Difficile (also known as C. Diff) infection. This infectious bacteria releases toxins that cause mild but annoying symptoms like watery diarrhea 2-3 times per day with abdominal pain or tenderness, but can lead to more severe life-threatening issues like watery diarrhea over 15 times per day or creating a hole in the intestines.  C. Diff is responsible for  ~1% of all hospitalizations per year (>330,000 patients per year) and > 20,000 deaths per year and costs over $3.2 billion dollars for care. The elderly, hospitalized patients or patients taking antibiotics are most at risk for transmission, which is caused by fecal-oral transmission or through hospital workers (since the C. Diff spores aren’t killed by alcohol).

Although an annoying, deadly and expensive disease, C. Diff infection has recently gotten worse.  C. Diff infection is becoming more common and relapse after treatment is more frequent. The bacteria has become more virulent with an increased capacity to produce the symptom-inducing toxins while at the same time becoming resistant to the most common antibiotics used to treat this infection: metronidazole and vancomycin.

So what does this have to do with the microbiome? Well, the normal bacteria in your gut can protect against C. Diff infection.  C. Diff is found in 2-5% of all people who aren’t sick, because the gut microbiome can inhibit C.Diff growth or toxicity directly by making antimicrobial peptides or indirectly by creating an inhospitable environment for C. Diff to grow. Because of this, scientists thought – what if we just fixed the microbiome in C. Diff infected patients so that it’s normal again? And how would they do that? Fecal (POOP) transplant!

poopeatersAlthough you may not be aware, there is a long and storied history of using poop as a treatment – primarily though the eating of poop.  Yes, this is gross, but maybe if we use the official name for eating poop it will sound less gross?  Coprophagy is the consumption of feces, with the distinctions of heterospecific coprophagy being eating feces of other species, allocoprophagy being eating feces of other individuals, and autocoprophagy being eating your own feces. If you have a dog, you know that they love eating poop (their own, cats poop, random poop, all poop really) and so do lots of other animals.   At this point (if I haven’t lost you), you may be wondering why in the world would any animal or person eat poop?? It can help in the  development of the GI tract by helping colonize the gut with bacteria, in developing resistance to pathogens, or in obtaining nutrients. In humans the practice goes back to 300AD in China where fresh, fermented, dried or infant-derived feces, charmingly named “yellow soup”, was used to treat multiple food poisoning or severe diarrhea.  In 1696, Christian Paullini wrote a book on the medical uses of human and animal feces and in 1958 the first modern description of a fecal transplant was described to treat pseudomembranous colitis.

How does fecal transplant work today? The goal is to recolonize the patient’s gut with “normal” gut bacteria.  To get this “normal” gut bacteria, you need a donor. Donors are often family or friends of the patient who are healthy and don’t have any recent antibiotic use.  There is some testing (costing $500-$2000) required to make sure that the poop doesn’t contain particular bacteria or viruses.  Then the poop is prepared for transplant. 50-60 grams of stool is added to a liquid like saline or milk and mixed together in a blender to create a liquid slurry (often patients are requested to provide their own blender). The slurry is then filtered through a coffee filter or metal strainer to remove particulates.

nasolThe feces mix then needs to get into the patient’s gut – and this can be done in a few different ways.

  • Naso-duodenal – from the nose into the stomach using a tube. Although fast and 76% effective, it’s not palatable and often has disgusting side effects like vomiting
  • Transcolonoscopic, which invloves drizzling the fecal mixture out of a colonoscpy tube in the large and small intestines. 89% effective, this method puts the poop directly where it needs to be.
  • Enemas are also highly effective (95%) and are both cheap and safe.  It can be performed at home, but it isn’t recommended.

New methods continue to be developed for fecal transplant to decrease the “gross” factor.  The feces has been dried out and turned into pills.  This is less smelly, but requires ingestion of 24-35 capsules and is more expensive.  Scientists are also trying to culture the correct bacteria mixture in the lab so that a poop donor and poop sample preparation aren’t needed. The best part about this method is that scientists have dubbed it “rePOOPulating” the gut!  Until then, a new business of stool biobanks like OpenBiome are cropping up to meet the need of poop for fecal transplants. For $500, your doctor can request a poop sample for fecal transplant.

For everyone who is completely grossed out right now, it’s important to point out that in patients with C. Diff, this treatment has been over 90% effective in recurrent infections whereas all other treatments were less than 40% effective. Patients are completely on board for this treatment. The biggest issue has been doctors who are grossed out and getting them to use poop to treat these horrible diseases.brownforyou

So next time you look at your poop as you flush it down your toilet, remember how useful poop can be and knowing “what brown can do for you.”

No s**t?!?! Interesting facts about poop

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...

fecalmatterI’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!

watering_poopFirst 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.

seven types of poopThere 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: