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Episode 75: One Species' Trash Is Another's Treasure

Episode 75: One Species' Trash Is Another's Treasure

Typically, we don’t think about picking up the waste byproducts of another species and using them to our advantage. But when it comes to short chain fatty acids - the metabolites of byproducts of our microbes - there’s actually a lot we humans benefit from. 

Some examples include promoting barrier stability in our intestines and brain (goodbye leaky gut and head!) and feeding the other bacteria taking up residence in our body.

On this episode, Andrea Wien speaks with neuroscientist and Traverse Science founder Stephen Fleming about the basics of short chain fatty acids and why they’re important for optimal health.

You’ll learn what short chain fatty acids are and what they do, the implications of them in the body and where they’re found, and how exogenous and endogenous SCFA from fermentation are two different things. 

Connect with Stephen on LinkedIn or through his website, Traverse Science

Questions? Ideas? Email us at or reach out on Instagram @DreEats or @BIOHMHealth

On This Episode, You’ll Learn: 

  • What a short-chain fatty acid is [2:31]
  • How SCFAs are microbe poops [4:31]
  • How SCFAs function in the stomach and body [5:23]
  • SCFAs as fuel [10:33]
  • The current state of research about SCFAs [13:02]
  • SCFAs outside of the body [28:45]

Mentioned On This Show:

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BIOHM gut quiz


Andrea Wien: Hey, everyone. Just a quick housekeeping item before we get started today, the show is going to be moving to once monthly episodes again, for the next few months. We have some exciting projects in the work that are going to take some resources to get off the ground. So we are moving the show to once a month from the time being. Shows will still be on Thursdays, so you will have a new Microbiome Report every Thursday of each month. (music).

Welcome to the Microbiome Report powered by BIOHM Health. I'm your host, Andrea Wien, and I am talking to Stephen Fleming today for this mini episode on short chain fatty acids. If you're not familiar with that term, you may have heard about acetate or butyrate, which are two of the most widely discussed short chain fatty acids. Now, I met Stephen at a microbiome conference where he was the only one brave enough to sit in my hot seat and let me ask him questions about his business in front of the other attendees.

Stephen is the founder of Traverse Science. While he found his roots, first in psychology and later as a neuroscientist at the University of Illinois, he now combines a passion for data science, tech transfer, and entrepreneurship to help accelerate research in the microbiome space.

Short chain fatty acids, these are also called metabolites or postbiotics, and they are a very emerging area of science in the microbiome world. We touched on them before, but they are really so important that we think that they warrant more talking about, and we will continue to talk about them. So this is just the beginning. On this show, we give a little background. We talk about what a short chain fatty acid is, what they do, the implications of them in the body and where they're found. Hint, it is not just in the gut. We also talk about how exogenous and endogenous short chain fatty acids from fermentation are two very different things. Okay. Let's get to it. Stephen, welcome welcome.

Stephen Fleming: Hello. I'm very happy to be here.

Andrea Wien: Well, we're very happy to have you. So I think to set the stage, we have talked about short chain fatty acids, also called metabolites, also called postbiotics, they have many names, on the show in a number of different ways before, but we have never really taken a look at what these things are, where they're produced, what they do in the body. Can you give us just the lay of the land here? What is a short chain fatty acid?

Stephen Fleming: Yeah, I am also, or was also, very confused by all those terms. People call them a lot of different things. Short chain fatty acids, I guess I'll try not to give the chemical definition, but some people call them organic acids. Other people call them volatile fatty acids. They are, as the name implies…Actually, the name almost has exactly what it is. It's a fatty acid with a short chain, so they have fewer than six carbons.

They're predominately found in the gut of humans and animals, after fermenting things like fiber. They're in the highest concentrations in the gut, but you can also find them in different parts of the body. I first heard of them as being just called short chain fatty acids. They're in papers called SCFAs right now. When I first heard the term post biotic, I was like, "What is that?" And I was like, "Oh, you're just talking about short chains. Okay, cool." I think postbiotics might be a broader umbrella category that short chains could include.

There's a lot more than six, but most people only talk about six, and even less than that, really just three. So the ones that most people throw around are, are acetate, propionate, and butyrate, or they talk about them in their acid forms like ascetic acid, butyric acid. Then we have three others that pop up in a lot of literature, too. Those are isovalerate, valerate and isobutyrate. I just call the acetate, propionate, and butyrate the big three, I don't think that's really caught on anywhere, maybe no one does that but me, and the others the small three, because they're also just in smaller concentrations in the colon.

Andrea Wien: My understanding of what these are, we've kind of talked about them with some other guests on the show, too, is almost being the waste byproducts of our microbes. It's the output of the microbes that are in our gut and in other places in the body. Is that an accurate way to think about it?

Stephen Fleming: Yeah, I feel like that's fair. They're the bacteria's poop, which makes it sound bad. You know, a by-product, right? If we consume fiber, it's not going to be digested by our mammalian enzymes, but bacteria are going to gobble it up. They're going to digest it, absorb it, metabolize it. They'll excrete a lot of different things, and short chains are one of them.

Actually, beyond being a waste product, though, too, there's cross feeding between bacteria. So some bacteria will consume a short chain and use it as an energy source. So it's both. I guess it's both. It can be both an input and an output.

Andrea Wien: Just like dogs.

Stephen Fleming: Oh man. Oh, so a quick tangent. Yeah. I worked in pigs in my PhD, and I learned what coprophagia means, which maybe you guys have talked about. It's when you're eating your own poop. I'm sure every dog owner knows that. So, I guess bacteria practice that, too.

Andrea Wien: Okay, so specifically this is bacteria that's doing this? These aren't coming from protozoa or fungi or any of the other viruses that might be hanging out somewhere in the body?

Stephen Fleming: That's a great question. I don't know the answer to that. I think people only…The papers I read only really talk about them in how they relate to bacterial fermentation, whether fungi do that, or protozoa or others. I don't think viruses would be capable of fermentation. For lay purposes, it's from bacteria.

Andrea Wien: Okay, that's good to know. Then you mentioned that they're mostly in the gut, but they can be in other parts of the body. Now we're really starting to learn that each organ of the body, all the different systems, has its own ecology and microbiome. Is that why we're finding these in other places, just not in as high of quantities?

Stephen Fleming: I don't think it relates to like other organs having a microbiome or fermentation in sites other than the gut. What I researched a lot was on gut/brain relationships. My research questions were, for some reason when we feed fiber or prebiotics, there's a benefit to cognition and mood. I got on this thread of, is it short chain fatty acids?

Going into that, there's fermentation in the gut, all along the gut, but usually highest after the end of the small intestine, the ileum, right into the colon. But there's absorption. I was kind of turned off immediately because they were like, "No, there's not going to be a lot of absorption. The cells in the colon are going to gobble them up, and they're just going to end there." But they do get absorbed. They travel through the portal vein into the liver. The liver will metabolize them further. They are in circulation in small amounts. They can even be in brain tissue, as well. It's like the further you go, the lesser the concentration.

So I think it's not as much about other organs or other sites of the body having affirmative capacity. It's more so that they're originating from the colon. That said, there's not a ton of studies on tracing, "We fed something a fiber that was fermented. Those specific metabolites that are originated from fermentation were absorbed and got to all these other places." But you could take samples of liver, bone, kidney, brain, blood, I think lung even, and you can find some concentration of some of these short chains. I think they do originate from the colon, but I'm not entirely sure.

Andrea Wien: Is there also a question, potentially, of a leaky gut intestinal permeability standpoint, where maybe they're actually not supposed to be in these other places and we find them there because there's some barrier integrity loss?

Stephen Fleming: Maybe is the short answer. Short chains, though, in a variety of barriers, like the epithelial barrier, as well as the blood-brain barrier, they actually promote barrier integrity, right? So you do want some things to pass, but not everything.

There have been studies where they look at what are called tight junctions in a barrier, like the intestinal barrier or the blood-brain barrier, and those kind of help…You hear that called permeability or integrity. We typically want high integrity. High permeability means things are ducking through, getting in between cells. At least if you look at in vitro evidence, short chains should promote that.

I guess to your point, though, maybe something already has a leaky gut and there should be absorption of these but there isn't, or they're exhibiting paracellular diffusion. I would think that enterocytes. They would especially be gobbling up butyrate. Maybe if there was an element of a leaky gut, they're not. At this point, if you can't tell, I'm speculating. So I don't know. That's the short answer.

Andrea Wien: No, that's fine. I mean, that's what we're here for, right? I think it's very important for everyone. This is such a new area of research, the microbiome in general, relatively, to science, is such a new area. So everything we talk about on the show is always up for debate down the line, always up for more theorizing and speculation.

Stephen Fleming: A hundred percent.

Andrea Wien: That's a very important piece that we always like to remind people. Everything we talk about here is not written in stone. In fact, this is how it is.

Stephen Fleming: Right, yeah.

Andrea Wien: We did mention that we know that they can be good for barrier integrity. What else do they do in the body? What else are we starting to learn about these short chain fatty acids?

Stephen Fleming: Okay, yeah. They do so many things. This is where it gets a little bit murky and tricky, because what we know about them I think mostly comes from in vitro evidence, meaning someone is studying cells, isolated in that culture, or from preclinical evidence, from animal work. I did animal work, myself, but I still try to be careful in terms of how much I interpret from that.

On a really simple level, it's an acid, so it will lower the pH of the contents of the colon. They do act as a substrate for energy, for colonocytes. Those are really obvious and simple functions, I guess.

There's others that I think are really interesting. One is, if you think about DNA and gene expression, our DNA is tightly wrapped in this coil called chromatin, and in order to transcribe that, our enzymes need to get in there. I kind of describe it like your DNA is like a scroll and it needs to be open to be read. There are these proteins called histones that can help open or close that scroll. Essentially, some of these short chains will help that DNA stay in an open position, like an open scroll, so that it can be read and transcribed. So, they can affect gene expression, and that can have this just downstream cascading effect on a lot of other things.

We've talked about them promoting barrier stability or integrity and feeding other bacteria. Acetate, acetic acid, if you ever had anything pickled, you're consuming acetate. If you have a bottle white vinegar in your home, I don't know what it is, like 5% acetic acid. Anyways, I didn't know before that drinking vinegars where this popular fad. I wonder if it's coming back now, actually.

Andrea Wien: Yeah, they are. I mean, drinking vinegars shrubs, for sure. That's all kind of back in vogue. I went to a new restaurant opening a couple of weeks ago, and they had a shrub on the menu. It's like, "Huh, okay. They're really making a comeback."

Stephen Fleming: Okay, I've never heard of a shrub. What is that?

Andrea Wien: A shrub is like a fermented vinegar, flavored, and then you add soda water to it. So it almost turns into like a healthy soda. I mean, a lot of them have a ton of sugar, which negates the benefit of that, but you can make them at home with no sugar, or minimal sugar, just for fermentation.

Stephen Fleming: So, yeah. I don't know how many whiskey old fashions I have with vinegar bitters and still get these helpful effects, but okay. On that point then, they can stimulate fatty acid oxidation, inhibit lipolysis. I wrote a blog, and I'm literally just reading off of it right now.

Andrea Wien: We're going to link to it because that was what drew me to talking to you about this. We'll link to that in our show notes, definitely, at

Stephen Fleming: It's really tricky, though, because we have looked into this. It's such an annoying fallback to say, "Oh, we don't know. We have to do more research." But there's all these dose effects. We do have, I think, some good theoretical evidence that some short chain fatty acids act on what are called G protein-coupled receptors, which can have a variety of effects in different tissues, to have an overall effect that I guess people would say is good, would promote something like weight loss.

To me it seems remain to be seen. How much of that activity do they actually have? How much vinegar would you actually have to consume to do that? It's really interesting to me on a cellular and molecular side, but does that just get washed out by so many other things happening? How strong is that effect? That's where I guess I kind of step back and be a little bit more skeptical, when someone's talking about, "Hey, we have this prebiotic or probiotic or post biotic, and it does all these things." It's like, I feel confused and I'm in this space. So I'm just wondering how we even know some of these claims are true.

Andrea Wien: If you've ever thought about getting your gut tested and stopped yourself because it's either too expensive, too inconvenient, or you're not sure about its accuracy, listen up. Biome has recently launched This is a website where you can go and get gut results in under two minutes for free. Let me just repeat that. You can get a good sense of where your gut health is, for free, in two minutes.

Now, how is this possible? As you might know, Biome has a gut test where you can go send in your stool sample and get the contents of your microbiome back. They also a series of questions when you send in your stool sample. What the brilliant minds on the data side have figured out is that they can fairly accurately predict if someone is going to have gut imbalance or gut dysbiosis or be in balance, based on how they answer these questions. So they've made these questions available to you, to be able to analyze your gut for free in under two minutes. Go to No strings attached. Get your gut analyzed under two minutes for free. You're welcome.

There's a couple different things. When you were just talking about the drinking vinegars, is there a tie to…Oftentimes I'll have a client drink apple cider vinegar or some type of bitters to boost digestion, to boost the actual hydrochloric acid. Is there a tie then with the acidity of the stomach and the food that's moving through the digestive tract, that actually ends up triggering not only the enzymes to be released from the pancreas, but also some type of chemical reaction with the microbes, that have them spit out more short chain fatty acids? Again, complete speculation, right?

Is there something there, or is that acetate in the vinegar feeding more of the bacteria that are then having that reaction? There's so many schools of thought to kind of go down. I think one of the biggest ones when I started learning about these, one of my biggest questions was, "Okay, it's the end product of a bacterial waste product, basically."

Stephen Fleming: What are those gross pathways of fermentation?

Andrea Wien: Why can't we just supplement with that, then, right? Why can't we just skip that step and just supplement with those? Do we have a good answer for that yet?

Stephen Fleming: Okay. I have a half-answer to that. Well, I think you could just supplement with them, but you might get a different effect.

Okay, so I did my research at University of Illinois Urbana-Champaign, and I did it in the animal science program. First off, I'm just a suburban kid. I don't know anything about farming, but I did my research on a research farm in pigs. Through that, I just learned a lot about animal science and agriculture and livestock. On that side, first off, people who study dairy and beef, ruminants, they know so much about this. The human researchers are just starting to learn about it, and they're like, "This is old news. We're bored."

This is where some people call them more like organic acids. I initially thought, "Isn't the stomach pretty good at regulating its own pH?" But you can feed organic acids to pigs, and it helps keep the pH lower. In that sense, it is more efficient, in the sense of the stomach doesn't have to put as much work into regulating that pH because the food stuff, or the feed stuff going in, already has a low pH. So livestock producers were looking into, "Okay, what type of acids could we add to feed, typically at very low levels, so that, one, they would have a bacteria static or bactericidal…" Think of salmonella, in terms of reducing salmonella outbreaks. So you could add these, I guess what a lot of us call postbiotics, into the feed for animals, and that would actually help reduce the incidents of pathogenic bacteria. It would help improve their feed efficiency, like how much weight do they gain for amount of food going in.

But a lot of the reason is things that happened way before the colon or the gut or fermentation. It's promoting gastric digestion. I think maybe an argument could be made for lessening the amount of bacteria in the small intestine. We know they're there. I mean, we may not want a ton of them in there. This is the super long-winded way of answering your question.

Andrea Wien: We like those answers here.

Stephen Fleming: So I guess, yes, I could supplement with them. I think you're going to get a really different action. To make this even more long-winded, more long-windeder, the research I was doing, we were feeding pigs prebiotics and looking at brain development. This was in context of there's a lot of what are called oligosaccharides in human milk, that are seemingly special in really high concentrations, but they're not in infant formula. If we add them to formula, is that a good thing? Should we be doing that?

So I would feed pigs these milk replacers that did or did not have those prebiotics. Okay, so they go through the small intestine pretty much undigested. They get to the large intestine, all the bacteria can feed on them. Yay. They should be producing short chain fatty acids. What I ended up looking at is, I would then correlate, "Okay, well, how much short chain fatty acid do they have in their gut, and how well do these animals perform on behavioral tasks?"

This is in my dissertation, which if you just search Stephen Fleming UIUC dissertation, you can download it there. What I found is that the location of the short chains was important. Humans don't have a cecum, but pigs do and a lot of animals do. Food, we eat it, it goes to our stomach, that goes into our small intestine, duodenum to jejunum and ileum. Then it goes from the small intestine to the large intestine, through the ileocecal junction. If you're a non-ruminant, like a pig, it's going to go into the cecum, and there's tons of fermentation there. Then that food progresses through the ascending colon, they have a thing called the spiral colon, descending colon, rectum, and out. When you start closer to the small intestine, you have lots of fermentation. I'm still talking about in the large intestine. As you get closer to the rectum, you have less and less fermentation because, usually, the substrate has been fermented already.

With that to set the stage there, I looked at a couple of different regions, like the cecum, the ascending colon, and the descending colon. In the cecum and the descending colon, so you could almost capture that as the start and the end of the colon, I found that these hardly related to behavior at all, the concentration of these short chains. But it was relevant in the ascending colon, which is kind of more of a middle portion. I thought that was really interesting and weird, that maybe there's this local relationship where it's important in a specific part of the colon. I looked into, "Have other people found this?" I didn't find a ton. There's probably more now, since I did that work. There had been some people showing that you can alter behavior of mice and horses by injecting them with propionate. In the context of those papers, that was viewed as a bad thing.

Andrea Wien: But injection, that's bypassing digestion altogether. So that becomes a whole nother-

Stephen Fleming: Okay, yes. This is the whole other part, too. I've heard of fermentation being related to autism a lot, too. There's some animal work where what they do is, they make a cranial window, which is basically…This sounds so barbaric.

Andrea Wien: You cut a hole in the brain?

Stephen Fleming: Yeah. You cut a hole in the skull. Then you can do a bath application of a drug or whatever it is. People have done that with these, and they're like, "Look, the behavior is bad." It's like, "Okay, well, you just put this stuff directly on the brain. I don't know if that's relevant."

Andrea Wien: Yeah. Oh, humans.

Stephen Fleming: But yeah, I think there is absolutely a local action that short chains are doing. With respect to the brain, to argue that these things are being absorbed and they get through the portal vein, they get through the liver, they get all the way to the brain, past the blood brain barrier…By the way, the blood-brain barrier, you now have astrocytes which interface between neurons and the blood. There's so many steps to make a claim that they have a direct effect on a distant organ. Whereas, the brain also has the vagus nerve, that innervates so many different organs, but it also innervates the gut, it innervates the colon.

I'm super curious, now I'm in unfounded territory, I'm super curious to see if the vagus nerve is sensing metabolites, like short chain fatty acids. The vagus nerve itself, it doesn't just have nerve endings freely in the colon, hanging out. There's a couple pieces of tissue between those. I really feel strongly that there is a connection with the vagus nerve. We know from other people's research that if you feed a pre or a probiotic, but that vagus nerve is severed, you don't get as beneficial of an effect. Of course, all these things are happening at the same time. There's probably some absorption and direct effect on organs, at the same time as the vagus nerve might be sensing these, and in some way relaying that information to the brain, which could then have some sort of behavioral effect.

Andrea Wien: I'm thinking, too, what if there's a critical mass of short chain fatty acid, like when you hit X number, that then it's triggering some production of hormone and neurotransmitter, that that's getting picked up by the vagus nerve.

Stephen Fleming: Yeah, that's very interesting. Yeah, like something maybe concentration dependent, or both concentration and duration dependent. I have low hopes that that will be figured out, because it's extremely difficult and tricky to record from neurons and then do it in a controlled fashion. There's definitely labs that can do it. They're just the minority of labs.

Andrea Wien: Well, and I do think too, and this is no knock on science because obviously this whole show is about that and we love the scientific process, but things are often overlooked. I think specifically of Dr. Ghannoum's work. For years, I mean, for 30 years, 25, 30 years, no one wanted to look at fungi as a contributor in the microbiome. He was kind of beating that drum for a long time, before he was ever able to get funding. So you wonder who's out there, that's maybe doing some ancillary research on this, that's just not getting funding or not getting visibility, and what are we missing right now that will have very large impacts in the future?

Stephen Fleming: Yeah, I agree. I agree completely. Of course with that, I don't know anything about the microbiome and fungi, but presumably they're in a lower amount in the gut, right? Just with everything, we always just have this tendency to be like, "Well, there's less of them. Who cares? We want more."

I was talking to you before about flux. In a lot of studies, especially human, you're just limited by what you can do. You know, you can get a fecal sample. You could probably, with willing participants, use a probe to get something further up in the colon, but way fewer participants are going to want to do that, so you have a recruiting issue. With animals, we're a lot of the times collecting organ tissue and we can look at what happens throughout that, but still, it's just this static snapshot in time.

So if you are trying to make the argument that we want more short chains, okay, well, why is there more there? There could be more because nothing else is absorbing it, and that's a problem. It could be more because there's this abnormal production. How much fermentation is going on? How much absorption is going on? What about cross feeding?

I don't know how to appropriately answer these things without super complex experimental designs, but to just say, I guess I see papers that say, "Oh, these bacteria increased or decreased, and they're butyrate producers." It's like, "That tells you nothing." In those same papers, you can see that people are saying, "We want to increase these butyrate producers because butyrate apparently does all these good things." In that same paper, they then measure short chains and they're like, "Well, there was no difference between them." You can of course go through the math and in your mind of, "Okay, well, if we had increased production but also increased absorption, that might make it look like nothing actually changed. You would still be left with the same number." That's kind of the problem with these static numbers. Which, we're just all limited by that, so it's kind of a wimpy answer to say, "Oh, it's more complicated than that."

To your original point, yeah, a lot of this stuff is really overlooked. People researching this in livestock animals, like poultry and swine, probably don't care as much about what human people are researching, and vice versa. I really subscribe a lot more to the one health, or just that we should be interpreting this with all available sources, not just human work. I feel like maybe, in my head, I've bashed animal research a little bit, even though I came from there, because everything is so controlled. Then you get to the human, and I feel like all bets are off. Animal research is great to figure out the methods, but we're all in our own silos. We could really learn a lot. I haven't even talked about companion animal nutrition, either. I feel like the answers are out there, but it's also just information overload. There's just so many papers on this. I almost have microbiome fatigue. I don't want to see another paper with microbiome in it.

Andrea Wien: Well, I'm sorry to tell you that there's going to be a lot more.

Stephen Fleming: I know, I know. From myself anyway, too. We're doing it, too.

Andrea Wien: You had mentioned, I had asked you for some talking points on this, and you had brought up exogenous and endogenous short chain fatty acids from fermentation, and how those are two different things. So I want to get into that a bit, but I think first, we need to just define the terms exogenous and endogenous for people.

Stephen Fleming: Yeah. I think we sort of got into that a little bit already, but I just mean exogenous as it came from outside the body. Like fermented food, right? If you eat a pickle, that was exogenous to you. What I meant by endogenous is, I meant that those fermentative metabolites, those short chains came from the fermentation of something in the body. Maybe I could keep running with this pickle analogy. If you eat a pickle, it's pickled, so there's acetate in there. Actually, I think this is going to backfire on me. Let's pick something else. Let's just pick a fiber, psyllium husk or something like that. There's really not a lot, or I don't think any, short chains that are present in that ingredient, but once it's fermented, there are short chains there. I would consider those endogenous. Then if you had drinking vinegar or something like that, I would consider that exogenous.

Andrea Wien: Okay, that's helpful. Yeah. I always like to ask this question to kind of wrap up, because I think you're the one that's done the research, you're the one that's looked at the studies. How have you changed or not changed your behavior based on what you've learned around short chain fatty acids?

Stephen Fleming: Oh man. I'm the worst. I haven't changed at all. I had someone to ask this to me, too, because they said, "Why is it that all these nutrition professors are out of shape? Do they not believe in their own research?" It was an argument with another grad student. They were like, "I feel like your whole field is bunk because if you guys believed in your research, you should all be super fit, eating super well all the time."

Andrea Wien: Right. It's like going to the dermatologist with bad skin. You're like, "Why should I trust you?"

Stephen Fleming: Yeah, I know. Right? Okay, on the simplest level, I know what they are now. I guess I did used to be like, "I don't want to go to that aisle with the laxatives because then people are going to think something's wrong with me." There's maybe a stigma like that. Now it's like, "No, this stuff is totally normal." Maybe I'm more exploratory in foods or supplements, but I'm also trying to be a lot more critical. If I see a supplement and they've got some wild claims on there, it's like, "All right, what's going on here? What are you trying to sell to me?" Then on the reverse, if nothing is said about it, it's like, "What's the benefit of this?"

Andrea Wien: Right. To your point earlier, it doesn't necessarily behoove us to be increasing these for the sake of just increasing them, because we don't actually know if that's good or bad, what levers that will pull. It's really, so boring, we always talk about, "Just go back to the basics. Eat a diverse range of foods, make sure you're getting an adequate amount of fiber, stay hydrated." You know, everything kind of in moderation rule.

Stephen Fleming: I am not a dietician, so I will make zero recommendations. I did learn that anyone can call themselves a nutritionist, though. I thought that was interesting.

Andrea Wien: It depends on the state, I will say. There's some rules around states, but yes.

Stephen Fleming: Yeah. Well, I guess it's good that there's some rules in place. I did my bachelor's in psychology, so I always come back to the behavior aspect of it. I know personally, when I try to change everything at once, I fail at all of them. If I'm trying to exercise more, eat better, and get on a sleep schedule, it's just overwhelming to me. Small habits add up. Those are the types of recommendations I would make, rather than you should eat this or that. I feel like a lot of us know we shouldn't be eating things sometimes. There's of course scientific debate on like how much of XYZ macronutrient should we have, but there were times in grad school where I'm like, "I could probably have less McDonald's." I think it's fairly safe to say it would be good to have less.

Andrea Wien: Yeah. I think there was a whole documentary on that.

Stephen Fleming: Maybe. Maybe.

Andrea Wien: Maybe. Some guy named Morgan. I don't know. All right. Well, Stephen, thank you so much for hopping on with us. This has been great. Of course, this will be a developing area of research. So, as much as you don't want to see the research, it will be coming out. Maybe we'll have you back on as things progress and we know a little bit more.

Stephen Fleming: Excellent. Looking forward to it.

Andrea Wien: Thanks so much. Bye. Thanks for listening. To check out the show notes for this episode, including a link to Stephen's article on short chain fatty acids for Traverse Science, visit our show notes at Don't forget, BIOHM is B-I-O-H-M. You'll also find a link to the show notes in the description for this show. The Microbiome Report is powered by Biome Health. If you have an idea for an episode, or just want to send me a note, you can find me on Instagram @dreeats, D-R-E eats, and by email at I'm Andrea Wien, and I will catch you next time.


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