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  • Alex Cloherty

Why do we transplant poop?

This post is inspired by one of my friends who went through the full cycle of acceptance regarding the idea of fecal transplants. Stage 1: Disgust. Stage 2: Interest. Stage 3: Can I get one?

Those who've never heard of a fecal transplant may be re-reading that sentence and trying to imagine exactly what it might look like. Or maybe you're actively trying not to imagine it. Anyways, the process involves taking feces from a healthy donor and transplanting it into a sick patient. Usually, the transplant is either done via an enema (basically pumping it into your butt), a colonoscope (inserting a tube from your anus to your gut), or nasogastric tube (inserting a tube from your nose to your guts). If you're like me and wondering if that smells like an outhouse, I did ask in class if it was smelly to get feces pumped through your nose... And indeed that is one of the possible negative effects of treatment.

Regardless of smell, why would anybody have somebody else's poop pumped into them? As you've probably guessed, it all comes down to microbes! When we think about bacteria, many of us think about getting sick. There is a whole other side to things, though: little bacterial buddies in our intestines help us out every day with digestion and with fighting off "bad" bacteria that can make us ill. We have a healthy relationship with these"good" bacteria. Biologists call this type of relationship a mutualistic symbiosis: mutual as in we both get something good out of it. This mutualism is at the root of the benefits of a fecal transplant.

Currently, fecal transplants are mostly used to treat diseases that involve bowel inflammation - things like infections with Clostridium difficile (a type of "bad" bacteria), Crohn's disease, and ulcerative colitis. These diseases all have something in common: the bacteria in the gut are out of balance. This is a theme you'll see often on Microbial Mondays. There is nothing intrinsically "bad" or "good" about bacteria; rather it is their number, balance, and location that results in health or disease. Therefore, the goal of a fecal transplant is to restore a healthy balance of the different types of bacteria in your gut. The idea is that if you take bacteria from a healthy gut and place them in an unhealthy gut, you can make that sick gut healthy again.

Fecal transplants and gut microbiology (the study of the microbes in your intestines) are recent sciences in the scheme of things, and that means that there many different research projects are looking into these areas in more detail. One new-ish area of research that I find pretty neat is the exploration into new potential uses for fecal transplants. For instance, there have been a few case studies that found that patients who received a fecal transplant had large changes in their weight afterwards. This makes sense, since the bacteria in our gut help us with digestion. It is now thought that your weight largely depends on the type of bacteria in your gut. It may be much harder for obese people to lose weight as compared to thin people, because their gut bacteria are just too good at extracting nutrients from food. In other words, people of a healthy weight poop out more nutrients, while overweight people absorb them. In a historical human population where there was rarely enough food, this mega-absorption would be a good thing... But you can see for yourself where it goes wrong these days. That leads us back to fecal transplants: scientists are now starting to investigate whether poop transplants can be used for weight control.

This might be where you ask, "So where do I get mine?" For now, fecal transplants are usually only given in cases of severe intestinal diseases like Crohn's. However, if you think this is super interesting and want to contribute to science, there are a lot of ongoing research studies that you could try to participate in, either as a poop donor or recipient. You should keep in mind, though, that you cannot expect to get the result you might hope for in early studies such as these. Science works in tiny increments, not leaps and bounds, so it's perfectly possible that fecal transplants only change weight in 1% of the population. One more short disclaimer: I am not telling you that you should participate in poop transplant studies. I'm just informing you they exist and that many universities are currently holding them, since I received some questions on this subject.

I should also mention that there is new research coming out that indicates that "good" viruses could be helping us out after fecal transplants, too. If you're interested in that line of research, check out the article at this link.

Until next week, stay healthy and poop well!


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