The Gut Health Podcast

Feed Your Gut: The Fiber Deficit Most of Us Don’t Know We Have

• Kate Scarlata and Megan Riehl • Episode 28

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Fiber isn’t one-size-fits-all and for some people, more isn’t better. In this episode, we explore why most people under-eat fiber, why certain fibers can worsen symptoms, and how to personalize intake in a way your body can actually tolerate. Dr. Heather Armstrong shares emerging insights on fiber function, microbiome capacity, and practical strategies for going low and slow. We also unpack new science explaining why fiber supports gut health in some individuals, while triggering issues in others with reduced fermentative activity. 

In this episode, we discuss:
• The fiber gap, health risks, and minimum intake targets
• How solubility, viscosity, and fermentability guide fiber choice
• Matching fiber types to IBS, diarrhea, and constipation
• Why whole foods matter more than isolates
• Citrus peel pectin and simple kitchen hacks
• Why “low and slow” dosing reduces gas and pain
• How long microbiome changes and symptom relief actually take
• When fiber supplements help (and when they don’t)
• Individualized fiber needs in IBD (and implications for IBS, MS, and liver disease)
• Why dietitians are essential for precision nutrition

This episode is especially relevant if you’ve been told to “just eat more fiber”—and it didn’t go well.

Learn more about Dr. Heather Armstrong's novel research:

Gut feeling: new test and precision diet could boost health for people with IBD. U of A research team in clinical trials for their innovative AI-powered tool that could reduce inflammation by “rewiring” the gut microbiome.

References:

Ramezani F, Pourghazi F, Eslami M, et al. Dietary fiber intake and all-cause and cause-specific mortality: An updated systematic review and meta-analysis of prospective cohort studies. Clin Nutr. 2024

Chang SC, Cassidy A, Willett WC, Rimm EB, O'Reilly EJ, Okereke OI. Dietary flavonoid intake and risk of incident depression in midlife and older women. Am J Clin Nutr. 2016 

Armstrong HK, Bording-Jorgensen M, Santer DM, et al. Unfermented β-fructan Fibers Fuel Inflammation in Select Inflammatory Bowel Disease Patients. Gastroenterology. 2023

Armstrong H, Mander I, Zhang Z, Armstrong D, Wine E. Not All Fibers Are Born Equal; Variable Response to Dietary Fiber Subtypes in IBD. Front Pediatr. 2021

Gao J, Lee AA, Abtahi S, et al. Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols Diet Improves Colonic Barrier Function and Mast Cell Activation in Patients With Diarrhea-Predominant Irritable Bowel Syndrome: A Mechanistic Trial. Gastroenterology. 

This episode is sponsored by Activia.

Learn more about Kate and Dr. Riehl:

Website: www.katescarlata.com and www.drriehl.com
Instagram: @katescarlata @drriehl and @theguthealthpodcast

Order Kate and Dr. Riehl's book, Mind Your Gut: The Science-Based, Whole-body Guide to Living Well with IBS.

The information included in this podcast is not a substitute for professional medical advice, examination, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider before starting any new treatment or making changes to existing treatment.

Kate Scarlata, MPH, RDN:

This podcast is sponsored by Activia.

Dr. Megan Riehl:

Hello, friends, and welcome to the gut health podcast. We are your hosts. I'm Dr. Megan Riehl, a GI Health Psychologist.

Kate Scarlata, MPH, RDN:

And I'm Kate Scarlata, a GI dietitian. What if I told you there was one nutrient that only about 10% of Americans are actually getting enough of? And it's one of the most powerful for gut health, heart health, and longevity. It's true. It's fiber. Us gut-loving fiber people, we do love our fiber, don't we, Dr. Riehl? We sure do. Fiber, fiber, fiber. That's right. It deserves way more attention than it gets. The truth is, we're living in a fiber deficit. The Institute of Medicine recommends that women have about 21 to 25 grams per day. That's adult women, and about 30 to 38 grams of fiber per day for men. But the majority of Americans are falling short. And it really matters because large-scale research shows high fiber intake can reduce the risk of death from all causes, lowers heart disease risk, cancer risk by even 20%. Fiber is our gut microbes' favorite meal. So, what exactly does fiber do? And why is it so powerful? And how can we get more of it? Without overthinking our meals, let's dig in.

Dr. Megan Riehl:

I can't wait because I'm constantly thinking about this concept, and we're all questioning what does it actually mean and how do we do these guidelines? So today we have the perfect guest expert to join us, Dr. Heather Armstrong. She is an associate professor of gastroenterology at the University of Alberta in Canada. She has received numerous national and international awards for her work and over $25 million in research funding in her first three years as a professor. This funding supports her team's work to uncover how changes in the gut microbiota can affect the way the body responds to different environmental and dietary factors. She's also studying the positive and negative effects that result from infancy to adulthood in disease settings such as inflammatory bowel disease, multiple sclerosis, liver diseases, and cancer. We are so excited to have you.

Kate Scarlata, MPH, RDN:

So welcome to The Gut Health Podcast, Dr. Armstrong. Thank you for having me. So we start every episode with a myth buster, and we thought we would love you to bust a myth pertaining to fiber and gut health. Okay.

Dr. Heather Armstrong:

I think I get a little bit of heat for this sometimes, but I think one of the myths that I'd love to bust is the fact that not all fibers are good for us. And it really depends on who you are as an individual and your health status and whether you have a chronic illness or not.

Kate Scarlata, MPH, RDN:

I think that's a huge myth to bust. And I think one that really most people are just not attuned to some of the more recent research. Perhaps you're in tune because you've led some of this research, and we're going to get into it because this is important stuff. You know, I think food interacts with our gut microbiome. It's so obvious, right? So clearly, who's living there, they're going to like certain fibers or have the capacity to break them down, or maybe don't. And that can lead to different things for different people. So fiber should really be individualized, and that's a great way to kick this off. Yes, it is.

Dr. Megan Riehl:

And we're going to start with the basics. So let's break it down to this term we hear. What is dietary fiber? We've mentioned the guidelines in terms of how much men and women should be getting. Can you tell us where do we start there with dietary fiber? And then what's the point? Why do we want to meet those recommendations?

Dr. Heather Armstrong:

Yeah, so you know, I think something that most people don't realize is dietary fibers are actually a type of carbohydrate. And I know, you know, lots of people these days are scared of carbohydrates because they think of the sugars and the other molecules that fall under that term. But dietary fibers are just a type of carbohydrate that are considered largely what's called non-digestible. And so our gut does not digest dietary fibers the way it does other food molecules like proteins and sugars and things like this. Instead, we really have that relationship with the microbes that live in our gut, and the microbes assist us in that breakdown process. And so, you know, when you think about dietary fibers, I think that's kind of the key concept to understand that differs from the other food factors.

Dr. Megan Riehl:

And again, those guidelines of 21 to 25 grams for women and 30 to 38 for men. Where does that come from? Why is that important?

Dr. Heather Armstrong:

Yeah, you know, it's interesting. I think all things in nutrition and medicine, you know, they're based on what we understand today, based on the health of people today and the lifestyles that we live, primarily in, you know, some of the larger first world countries that do a lot of this research. You know, I think the values are a bit of a base minimum. You look at some of the diets that historically people would have had and in some of the other regions of the world that are less studied than where we live. And you're really seeing, you know, upwards of 100 a day in some of those communities. And so I think it's really, you know, a base minimum for guidelines for what we are striving to achieve. And the purpose of that is the studies that have been performed on overall health. In the case of fiber, it's typically cardiometabolic and kind of general obesity, is where the wealth of the data has come from. There's a lot more recently coming out on specific disease settings, but you know, it is the amount of fiber a day that a man or a woman of average size should consume in order to gain the greatest level of benefit. But it's not to say that that's the maximum that you should consume. It's not like a pill or a supplement where we're saying don't consume more than that. We're saying, you know, that is the absolute minimum you should be trying to consume daily.

Kate Scarlata, MPH, RDN:

So crazy because, you know, about 90% of Americans aren't meeting that target, you know. So it's mind-boggling to think of 100 grams of fiber and it's so far from the way we eat, which, you know, clearly is very ultra-processed and terrible. So not all of us.

Dr. Heather Armstrong:

Well, and I do sometimes wonder if benefits more to do with kind of society overall and our education of understanding where these fibers come from and how we can actually access them in easy nutrition and kind of just fresh fruits, vegetables, and grains. And I think a part of that in some of the work that we do with patients here, a part of that comes from, you know, lettuce is not, you know, even it's the our favorite thing to put in salads and vegetable mixes, lettuce is not, you know, a great source of dietary fiber. And so you may be eating a lot of plant, but that doesn't mean that you're actually eating a lot of dietary fiber. And so I think, you know, trying to communicate with the public which plant-based foods actually have the highest source and the greatest breadth of types of dietary fibers is kind of something that we as a community need to be doing a better job of.

Kate Scarlata, MPH, RDN:

Could not agree more.

Dr. Megan Riehl:

Yeah, we see this a bit in how food impacts mental health too. And again, clarifying kind of where things are coming from. And there was a large study that followed about 82,000 nurses for a decade. And they found that women who consumed more polyphenols, which are a type of natural compound that can be found in fiber-rich foods, like oranges and grapefruits, and that those women that had more of that had lesser rates of depression. And so there have been other studies that have looked at polyphenols specifically. And we're not necessarily saying that, like, well, if you eat oranges, you won't have depression, or it's the treatment for depression, but it does speak to the individuality of what we're eating, how we're eating it, the diversity of our fibers and different nutrients, and that it can have a profound impact on both our physical and our emotional health, potentially.

Dr. Heather Armstrong:

Yeah, and I think it's every little bit helps because at the end of the day, I think the real take-home for most people is you know, you need food to survive. Your microbes also need food to survive, and their primary food source is these fibers, these carbohydrate molecules. And so if you feed them correctly, they will be your best friend. And I think, you know, there's this underappreciation in the public for the fact that the gut microbes are responsible for the vast majority of the production of dopamine in your body and all of these happy hormones that are directly involved in brain chemistry, serotonin, and other pathways. So, you know, this appreciation for keeping the gut microbiome healthy and they will keep us healthy, but not to starve them by avoiding carbohydrates and plant-based foods.

Kate Scarlata, MPH, RDN:

Yeah. Exactly. And just, you know, we're talking about fiber, but the polyphenols also can act like prebiotics, you know, when we're talking about food for our gut microbiome that promote some kind of health effect for the human host. So, you know, the plant foods, just like when we think about fiber in foods, we're not just getting one type of fiber, we're getting a variety of different things. And it's one of the reasons why I really like food first, of course, as a dietitian, you know, you're getting so much more than just isolated fiber.

Dr. Heather Armstrong:

Polyphenols is something that's really stepping into the limelight on more lot more recently. You know, when we used to think of polyphenols, we saw olive oil. Right. And now more and more I think there's this appreciation that the polyphenols often come bound to the dietary fibers. And so during this fermentation process and they get they're released and they go about their activities as well. So I think it's something that I typically like to highlight is that getting your fibers from whole food with those polyphenols, with those proteins, with those other nutrients, is so important compared to trying to supplement your dietary fibers in with a very chemically isolated version of fiber entirely by itself, devoid of any of these other beneficial nutrients. So I think it's one of the reasons why so many of us in this industry really lean on, you know, if we're going to get fiber, let's try our best to get it from Whole Foods because it comes with all of these other very beneficial nutrients, like the polyphenols.

Kate Scarlata, MPH, RDN:

Yes, absolutely. So, you know, when I was back in school a million years ago, we talked about solubility and insolubility of fiber, and then we stopped there. And obviously, you know fiber is much more complicated than solubility and insolubility. But can we start there and just describe what those differences are in those types of fibers and how they might impact our health?

Dr. Heather Armstrong:

Yeah, so I mean we try to categorize fibers based on their functions, right? And so there's kind of these three key terms. One is the solubility of the fibers. So does it readily solubilize or dissolve in a liquid? So one example people think of is when you buy those supplements, can you dissolve it in water and does it actually turn into a liquid properly? But another example of that is in the gut. So obviously, our gastrointestinal system is filled with different liquids, saliva and whatever fluids we've drank, water, things like that. So, do they break down and dissolve? And so, are they going to have their effect through, you know, dissolving and interacting with the microbes and interacting with us? Or are they not going to solublise and so they are going to instead contribute to bulking, which is kind of turning stool into something that's a bit more of a solid substance? You know, there's other versions of this. So solubility is one way of separating the types of dietary fiber, and then viscosity is another. So does it form that gel gum? An example in the food industry is, you know, when you put pectin and some of these fibers into a liquid solution, are you going to get a jam at the end of that? And are you going to kind of create this nice viscous substance? Again, that's kind of lending to how is it going to impact us or is it going to impact the bulking of the stool as it passes through our body? Is it going to help with water absorption and some of these other things that happen as we pass through the bowel? And the third most common is fermentability. So, you know, there are the fibers are not readily digestible. We don't do much with them. But even when you talk about what do our microbes do with them, there are some fibers that are very easy for a broad variety of our microbes to ferment and break them down. And there are some types of fibers that are largely not very well fermented by a human gut. They may be in a cow or a ruminant that has multiple stomachs and multiple spaces in the gut, or they, you know, cellulose is a great example. It makes up our celery and our lettuce and these kind of structurally solid parts of our plant-based foods. There are microbes that live in the dirt in the forests that can ferment these types of fiber, but in our gut, that fermentation isn't very successful. So there's kind of these different categories that we use to try to identify what these fibers do for us in our gut.

Kate Scarlata, MPH, RDN:

Do you think those characterizations of looking at fermentability, viscosity, insolubility, etc., is that enough?

Dr. Heather Armstrong:

We can say are there other ways to look at these, but eventually we hit a point where it's, you know, I think we almost need to look at every individual fiber and ask, you know, what is our goal? Is it kind of general overall health? Or are we dealing with a different health condition that requires, you know, maybe you've got a patient who suffers from diarrhea or a very fast transit time in the bowel? And so you're looking more at bulking. And so is there a definition of that that we want to focus on? And so, you know, we could keep tossing out different definitions forever, I think, because these fibers are so complex. But I think at the end of the day, it's really trying to ask ourselves, do we understand what the different fibers do? And can we apply those to the patient or the person sitting in front of us?

Dr. Megan Riehl:

Exactly. And our patients hear that, right? So they see their gastroenterologist and they get oftentimes a blanket eat more fiber. And then they walk out and they go, okay, what does that mean? Hopefully they're gonna listen to this episode. But also, you know, if you had to like quickly give up, like, how do you deliver that eat more fiber to your patient in in the moment, if a listener is like, yeah, I've heard that and I have diarrhea or I have constipation.

Dr. Heather Armstrong:

Yeah, and I think that's it. I think you've got to ask, you know, what is the problem that we're facing up front? So if the individual sitting in front of you has no real clinical concerns, but they're interested in adding more fiber to their diet to improve longevity or performance or mental acuity, now you're trying to just balance out how you eat a nicely balanced diet. It's going to have a combination of different types of fibers. Whereas if you've got someone with, you know, inflammatory bowel disease or someone with constipation or an emptying issue, now you're starting to ask, well, there are specific fibers that help us in this setting. Some are safer than others. In this setting, your microbiome may be unhealthy, so we need to account for that. Our team's in the middle right now of the final phase clinical trial to develop a precision carbohydrate diet, is what we're calling it, where essentially we use the microbiome and different human biomarkers to essentially define for that individual what's the optimal carbohydrates. And that's not just dietary fibers, but resistant starches as well, which kind of sit in a similar family to the dietary fibers. The microbes really utilize them and for the benefit of their health. And so the tool is set to use these biomarkers to define for the individual sitting in front of us what is the best combination and the best concentration of these carbohydrates to use to improve your health, be it disease or otherwise. So hopefully 2027-2028, we'll have this tool clinically available. At the moment, it's complex, it kind of depends on who the individual is. Typically, if we're dealing with someone who has a GI condition, I would be recommending not to avoid certain types of fibers altogether. So inulin and fructooligosaccharides (fos), they're kind of the beta- fructan fibers. They're the most common ones you'll see if you look for a dietary fiber supplement, and they're kind of the most famous two for nutritional interventions. They're great if your microbiome can use them, but if you're struggling or you're experiencing any symptoms, gas, pain, bloating after taking them, we'll typically say just take a small amount, let your microbes handle it, gives them the time to adjust to this, give those microbes time to grow and flourish so that your gut can handle these types of fibers. One of our favorite types of fiber at the moment is the pectins. You've mentioned citrus, obviously, and the polyphenol load that comes with them. You know, a lot of the work that we've been doing has identified that the type of pectin, the source and the polyphenols all together is what gives us that benefit. But I think something that a lot of our patients kind of are surprised by when we explain this is that it's not eating the flesh of the citrus fruit, which is so common for most people in the United States and the UK and things like this. It's actually the peel, it's the skin of the citrus fruits, primarily mandarins and naval oranges that have the pectin and the polyphenols and all of those goodies. So we typically recommend that patients peel the orange and use it almost like a bell pepper or capsicum and cut it up. You can put it in smoothies, you can put it in salads, you can put it in stir fries. It's a bit like a green pepper, and then it's a little bit better, but it mixes really well the same way a green pepper would. So if you kind of use it the same way, you'll be getting access to those really beneficial polyphenols and fibers. So even in our patients who are sensitive, that's kind of our top choice for getting fiber back in their diet.

Kate Scarlata, MPH, RDN:

That is awesome. I love that. I've never heard of that. And I'm a huge smoothie person. So I in, you know, I'll throw anything in that smoothie. So, you know, that's a great way to do that.

Dr. Megan Riehl:

And just over the break, my six-year-old was holding their orange and asked, "Can I eat this like an apple?" And my husband and I both kind of looked at each other. We're like, I mean, you could try it. It's not gonna hurt you. We usually peel that, but maybe he was on to something, clearly. Yeah. Yeah, exactly. All right. So you heard it here.

Kate Scarlata, MPH, RDN:

Put those orange peels on the salad or eat them like a pepper. That's right. And I just want to just dial back a bit because I think you mentioned so much important stuff here. And I love the precision direction of, you know, figuring out fiber for individuals based on their gut microbiome and other factors. That's amazing. I think, you know, just as a reminder, especially working with a dietitian or a gastroenterologist, someone that is knowledgeable about fibers and your health, there are ways to modify, you know, a good psyllium husk. Fiber, for instance, is a great way to help with constipation and diarrhea. So in those IBS patients with a mixed presentation, that might be something I might start with. Or you may find, you know, certain patients with high cholesterol, and we'll look for those viscous fibers because they slow down digestion, grab the bile acid, help with cholesterol levels. So there's all these physiological things happening with different types of fibers in the gut. And we're not just getting one kind of soluble viscous fiber and you know, one type of food or vegetable. There's a mix of fibers and all of these things. But some foods will be higher sources of these viscous fibers. So well, pectin is in the skin, right? That you just mentioned. But don't we see pectin also in apples in the flesh?

Dr. Heather Armstrong:

Yeah, we do. Although apples are a really neat one too, because most of the pectin is actually in the seed. Yeah. So I mean, it's funny. I mean, growing up, I grew up in rural New Zealand, and so we were a little bit more feral than some of the apples that are bringing, maybe. So we'd eat our kiwis hole and our citrus hole and the whole apple coronal. So, you know, your parents would tell you, you know, don't eat too many of the seeds, all of the cyanide concerns, but the amount of seeds you'd have to eat to actually get it at the cyanide, and you typically have to crush the seeds to get the cyanide out of them, which doesn't happen in our gastrointestinal tract very efficiently. So, you know, we have patients who ask about that, they're a bit concerned about, well, can I eat the seeds? But that is one of the big sources and apples of sin. And so it is interesting that, you know, what we typically consume isn't always the high fiber bet, and it's, you know, even the beta-glucans, which have, you know, so much wealth behind them for this cardio metabolic effect and helping with obesity and cholesterol and things like this. You know, the source really matters, and it's it's so interesting to watch the course of dietetics history that you know, we're really going for oats and wheats and whole grains and your breads and things like that lately. And I think we've still really lost this connection that we used to have with foods like barley. Right. You know, you used to use barley in your soups and in your breads and all of these bakings, and it's quite uncommon these days to see barley as a food source, but it's another one of those foods that has a fantastic effect as a viscous fiber and a fiber that really helps with kind of overall cardiac health and blood sugar, blood sugar, yeah, all of that.

Kate Scarlata, MPH, RDN:

So barley's good and oats, oat brands are some options there for some of the viscous effects. So you mentioned kiwi skin, and it's funny because you know, people are like that furry skin, but I use it in again in my smoothies. We just wash those kiwis, chop them up, freeze them. Don't freeze a whole kiwi because it just bounces around your blender if you're gonna do that. It's not a good idea. But anyway, just chopping them up and throwing them in the blender. Is the skin, I know it has some insoluble fiber. Does it have beneficial fibers that I'm unaware of?

Dr. Heather Armstrong:

Yeah, a kiwi skin is fairly limited bulk compared to the kiwi fruit. But again, there's some polyphenols and insoluble fibers that can be quite beneficial. And you know, the fur is you'll see people who don't like a peach versus a nectarine as well because of the fluffy outside. You know, getting rid of that fluff with just kind of a scrub brush or something while you're washing it can remove some of that fur. Because there are some people who will experience kind of you know digestive issues or kind of some gas or bloating just from like the little furries that come on the kiwi fruit as well. So, you know, it's something Kevin Whelan and some of the team at London College of Medicine and their dietetics group have always kind of leaned into this. Don't be afraid of the peels, don't be afraid of the skins of the foods, because that's where a lot of the nutrient content can come from. And sometimes it's fiber, sometimes it's polyphenol, sometimes it's other vitamins and nutrients.

Kate Scarlata, MPH, RDN:

That's interesting. I don't know how I feel about the apple seeds and like cyanide, though. I don't know. That's just not going to be probably a big record. You might get a little cyanide. We'll see.

Dr. Heather Armstrong:

Yeah. I will say I don't think I often eat the whole core of the effort-living these days every time at least, but I'm not afraid to if it's I mean, you survived and you're doing pretty well.

Dr. Megan Riehl:

I know.

Kate Scarlata, MPH, RDN:

Yeah. Yeah. So give it a go. Give it a go. Oh gosh. So I think we've talked a little bit about intrinsic fibers versus natural fibers and the difference. But do you see a role for these in some ways to fill that fiber gap in some instances?

Dr. Heather Armstrong:

Yeah, you know, I think at the end of the day, it's not strike fear and say that these supplements are all bad. It's just being mindful of, you know, the volume that some of these supplements recommend is fairly unnatural. And we are really starting to see work out of not just my team others globally, that if you go too high of a dose with anything, you might see a negative effect. And so just being wary that not your entire fibres source should be coming from a single supplement of a single fiber in isolation. But I certainly, you know, getting people to change their lifestyle and diet is complicated. And sometimes it's convenience, sometimes it's cost. There's all kinds of different reasons for why. And so if at the end of the day, including a supplement in the best version of a whole food diet that individual can use, I'm not afraid to get them to use these different supplements, be it psyllium, like you mentioned, or or these beta- fructans like inulin and fos, they're beneficial. I just think everything in moderation and being mindful of if you can get that food from a whole food diet, then that's probably best. I will say, my opinion, you know, we have people ask quite often, the beta-fructans are a great example. If you can get your hands on a chicory root powder, which you can find at a lot of supplements and health food stores these days, if you can get your hands on a chicory root powder, it's only two tablespoons a day. It is equivalent to the amount of beta-fructan that you'd be trying to get from those same supplements. And the cost will typically be lower, and you'll be getting it as a whole food. It's a bit of astronaut food because it's often been dried or pulsed, but it is still the whole food, it's still the whole chicory root rather than being a chemically isolated supplement. So there are kind of still ways of going about this that I think it's best to still use a whole food source, even if it is powdered, rather than running straight to a supplement.

Dr. Megan Riehl:

I think that's really fair that based on where you're starting, we want to give people an opportunity to have as much variety and options financially access. It's a lot to consider, and we don't also want to overwhelm people with these goals.

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Dr. Megan Riehl:

That kind of brings me to my next question here in terms of a lot of times it requires low and slow. Because if you go from very low fiber to very high fiber, tell us a little bit about what you've heard happens in the clinic as well as it basically can cause some GI distress.

Dr. Heather Armstrong:

That's right. Yeah, I mean, I think it's it's the same as anything. So you need the microbes in place to be able to utilize these fibers. And if you haven't been eating much for dietary fibre to date, they're probably still there, but in in very low numbers. And so you need to go low and slow in the sense that you need to give those microbes time to flourish. You need to give them time to say, well, this is my favorite food source, but I can only handle little bits of the time. And so the more you continue to eat, the more those microbes will grow. But you need to give them time to do that. So, you know, going from zero to 150 overnight, you don't have the microbes in place to be able to utilize those dietary fibers yet. And so you may be feeding the whole ones, or you may end up with kind of unfermented fiber present in the gut, which our group and others have now shown can actually stimulate inflammation or pain and distress in the gastrointestinal system. So taking it slow and starting with kind of small amounts, did you handle it? Are you still feeling okay? Okay, double it tomorrow. See kind of see what your threshold is. And trying a variety of different fibers, I think, is really the key too, rather than just, you know, one supplement, one fiber type. Because that's still only going to feed a subgroup of bugs as well in your gut. It's not going to feed a broad array of microbes.

Kate Scarlata, MPH, RDN:

Yeah, I kind of made that mistake with fiber one bars and like grabbed these very high fiber bars with chicory root extract, you know, take them to work, have one on the way, one at midday, and then you're like, oh my gosh. Yeah, not good. So, you know, I think we need diversity of fibers to feed the diversity of the gut microbes. We want diversity in our colonic environment. So, you know, with this variety is really helping us hopefully create more of a diverse environment of microbes.

Dr. Heather Armstrong:

I think even if we look at the clinical trials that have been run introducing either supplements or whole foods, increasing fiber, you know, typically what you see is you start quite low dose for a week, and then you scale up, and slowly but surely you'll see these changes start to happen in the gut microbiome, and people start to feel better. I also say typically in our clinical trials, we've noticed it can take as much as two months to start to see that real significant shift in the gut microbiome. So giving yourself some grace and taking it slow can be quite important because these aren't it's not going to happen in 24 hours. It's not a magic, well, and it's not a magic pill.

Dr. Megan Riehl:

About how long should people expect it to take to kind of maybe see some health improvements in in their fiber? And I get that this is probably again very individualized to what's going on. So you tell me if there's a little bit of an answer there.

Dr. Heather Armstrong:

Yeah, it completely depends on who you're dealing with. So I think like the average population, we've done studies and kind of typically otherwise healthy people like firefighters and community members and studies like that. And you know, if you don't have a lot of health problems to start with, it will probably take a couple of months before you start to notice yourself saying, Oh, I feel a bit more awake in the morning, I feel a bit more focused. We've had individuals come back saying, you know, I was on statins for cholesterol and now I'm not anymore, or you've you've lowered your dose, so cholesterol is just looking better. I'd say kind of expecting that two to six months period to see a real significant clinical change is quite normal. But normally in clinical trials, we say it takes a year really to see a meaningful clinical impact in a disease setting. You want to be kind of pursuing that 12-month mark. And the reason I say that is there are interestingly these clinical trials that have taken measurements quite early on every couple of weeks, and immediately they see, oh well, we saw these fantastic shifts at two weeks, but then as they continue out to the six and 12-month mark, the individual actually returns back to baseline. And so sometimes you can see these shifts simply by changing something about your environment or your diet, and they're not sustainable changes because maybe you're not doing enough, maybe it's not enough for a bit yet, you're not at your tipping point yet. But just being mindful that, you know, sometimes seeing these immediate changes isn't something that we're striving for. We're really looking for that long-term health benefit.

Kate Scarlata, MPH, RDN:

And most of the studies are just not going out that far. And I know it's costly to run a lot of these studies, so you know, that makes a limitation in advancing the science, right?

Dr. Heather Armstrong:

Yeah. Well, one of the bigger issues we often see in nutritional clinical trials is that on average, people will stop adhering or will quit a clinical trial after as little as two to four weeks. And so I think it's a struggle of balance between, you know, yes, the cost of running a study for sure and the the goal of completing it, but people's willingness to actually engage in these clinical trials and complete them and adhere to them and not want to quit at the first vacation or family event or birthday that comes up. Yeah. It's a real struggle when you're running these types of studies for sure.

Kate Scarlata, MPH, RDN:

Absolutely. So we kind of debroached on this significantly to some degree. You know, 70% of our microbes in our body live in our gut. They're interfacing with any food, particularly that those that are not digested and arrive in the colon. And different bodies react to that differently. And what do we do with that? Or what do we know about how to do, you know, other than listening to your body and saying, oh, dial it back? Are there other things that we need to pay attention to applying fiber recommendations in different populations?

Dr. Heather Armstrong:

It's amazing. I really like I think a lot of the work that we've done has come off the backs of what dietitians already do. Dieticians are phenomenal at being able to listen to what's going on, try different subtle changes in nutrition, listen again. Is it making a difference and make changes just based on what's happening for that individual? And it's incredible how little of that has actually been grounded in real scientific knowledge of what's happening and why. It's really rooted in experience, expertise, and kind of an understanding of if you try this and it doesn't work, try this. And so, you know, that experience from dietitians is really what led us to say, well, can we understand then the and why so that we can identify much earlier in an individual how to intervene based on real biomarkers instead of this dietetics experience, which is phenomenal, how well dietitians have been able to do this, but really understanding why and in who I think can help us better streamline these guidelines. So, yeah, like I said, I think you know, we are trying our best, and many others out there, many research groups out there are doing similar and trying to understand how does nutrition benefit the individual rather than having kind of streamlined guidelines for all. But at the moment, I think it's a bit of exactly that, just listening to your body. If something's not working, don't quit the first time because maybe you had a bad sleep. Maybe you did something else, maybe you're identifying that food incorrectly. So stress was high. Stress was high. There's all kinds of things that can change our physiology in our gut, and it doesn't have to be blame placed on the food that you ate that day. So give yourself a rest, try again in a week's time, see if you can come back around to that and give it a go again and and really kind of hone in on listening to your body. But I think that diversity is probably the biggest key. If you can take small amounts of diverse different types, I mean, some people say try to get all the colours of the rainbow on your plate when you're dealing with plants. And I think that's probably a great way to go about it because now you're dealing with diversity of plants and therefore diversity of not only fibers but many types of nutrients, and kind of trying that approach because diversity is key to our health and our microbiome's health. So I think it's probably the best approach that we have at the moment. And if you are really struggling, that dietitian is probably the end or be all. I don't think even most gastroenterologists are adequately trained in nutritional advice unless they have experience in it. So I think dietitians probably actually your first best bet.

Kate Scarlata, MPH, RDN:

And we have more time. You know, it's like I did a survey study with the American College of Gastroenterologists providers, the gastroenterologists and advanced practice providers. And 77% of them were spending 10 minutes or less on nutrition. That's fine. It's excellent that they're even broaching it, but it's not enough to talk about these complex diet-related symptoms and adjustments and personalization. So yeah.

Dr. Megan Riehl:

For what people spend on supplements or probiotics or, you know.

Dr. Heather Armstrong:

Well, exactly that. Save on the supplements and ask the dietitian how to get that food naturally by changing which foods you're eating. I think you'd be best off spending your money there because they'll be able to help identify what's missing or what you may be eating too much of or where those symptoms are coming from.

Dr. Megan Riehl:

Huge plug for Kate and all of our GI dietitian colleagues. We love you. We love you.

Dr. Heather Armstrong:

We need you. We need you. We wouldn't make it without dietitians, that's for sure.

Kate Scarlata, MPH, RDN:

Yeah, no, it's, you know, finally getting its little day in the sun because I've been doing this for a long time. And it was like, why do you want to be a dietitian? And I'm like, I'm just interested. I think this is going to be a really cool career, and it has been. So I'm glad I hung in there. You know, you've got some very interesting research looking at particular fibers in inflammatory bowel disease and its potential, you know, maybe less beneficial effects in a subset of them. Can you talk a little bit about the studies that you've done looking at beta fructans and IVD?

Dr. Heather Armstrong:

Yeah, for sure. So, you know, we've got a study that was even just released on multiple sclerosis showing really similar. And I think there's two big take-homes from a lot of what we've found so far is that, like we've said, Lowens flow seems to still be relatively safe, even in IVE patients and people whose gut microbiome is relatively unhealthy. But I think that's probably step one is we are dealing with people who have significant changes in their gastrointestinal system, significant changes in the composition and functionality of their gut microbiome. So you can even have the correct microbes present in the gut. But if the house is on fire and the pH is off and there's huge amounts of inflammation present in that environment, even the correct microbes won't be doing anything other than trying to survive. They're not going to be functioning correctly. They're not going to be producing those neurotransmitters like dopamine and serotonin. They're not going to be breaking down food, they're just going to be trying to survive. And so, you know, this is a very unique scenario where you've got patients with a lot going on. And what we've started to identify, and others have done so since our study was released, is who is this happening and why. And so, yes, you can have these changes that happen in the microbiome where the microbes aren't efficiently capable of fermenting beta fructans in some of these dietary fiber molecules. But another aspect of this seems to come down to what's changing in the gut itself, in the human cells that make up the gut. And so, you know, there is an aspect of this that relates to you've also got a patient with a disease sitting where the cells of the gut like to create inflammation. They are primed to create damage. And so, you know, I don't think even if you have these changes that happen in a healthy individual, I don't think these inflammatory effects of beta-fructane are going to be as significant. You may still experience gas and bloating and pain, some of these other effects, but I don't think it's going to be as equivalent as an inflammatory bowel disease patient where the cells of the gut are just ready to wreak havoc. And so that's what we're really trying to understand because it's not even all IBD patients. Some IBD patients, their immune system is primed in different ways. It doesn't seem to mind so much this engagement with unfermented dietary fibers, or their microbiome remains healthy enough to still utilize these fibers. And so they gain a benefit from eating these foods. And so that's what we're really trying to get at is based on you, your gut microbiome, and your own individualized gut and everything that makes it up. What is the best, most optimal types of carbohydrates for you to be eating to gain that benefit, that anti-inflammatory effect, that healing effect that we see in the gut? And so it's certainly complicated. I can't say what those biomarkers are. We're still identifying them in this final phase clinical trial and testing that this really works. But it really is partly the microbes, how they function, what is their fermentation success look like, and partly the human and what is your likelihood of either having a beneficial response if you see these unfermented fibers or having a negative response.

Kate Scarlata, MPH, RDN:

So I have a follow-up question. So, and you may or may not be able to answer it. I'm not sure how this relates to what you're looking at in your study. But so for the individuals that appear to not ferment these fibers have some kind of negative reaction from an inflammatory pathway activation scenario. Are they feeling symptoms when they're eating? Like, is there a clear correlation with symptoms? Symptoms seem to be the number one.

Dr. Heather Armstrong:

Okay. The symptoms seem to come first. There's some individuals where we see the symptoms progress to gut damage, ulcerations. We even see in some individuals there seems to be a pathway that shows up that looks like it's involved in progression to colon cancer and these IBD patients that's affiliated with this, but it's rare. It's not all patients. And it really begs the question of would they have to consume this and be in this FLIR state their entire life for this to actually culminate in colon cancer? Or is this something that is urgent and concerning in a small percentage of these individuals? And is there a different pre-bodic we should be focusing on in these people? And so those are questions that we're still trying to understand. But I think that's it, is the fact that the first thing we see is symptoms. And so again, kind of coming back to listening to your body if you are experiencing pain, distress, worsened diarrhea. We had a patient come in recently, and it was hard to keep a straight face and not laugh about this idea that they've said, Well, I drink poppy now because it has inulin added into it, and that's supposed to be good for me. And as soon as I drink it, I get the worst diarrhea I've ever experienced in my life. So it's obviously working. And I think to her, that can't possibly be the goal. It's widespread diarrhea that is unconsoled is probably not the goal that we are looking for when you're consuming this. And so I think that's exactly it is that is not the desired effect of consuming dietary fibre, is this gruesome diarrhea that's unconsolable and prevents you from going to work in the morning. That's that's not what fiber is meant to do for you. It's supposed to regulate you and make you feel healthy. One to two bowel movements a day is normal, not 10 plus liquid diarrhea. Liquid diarrhea. That's not the goal. And so I think it's just it's quite interesting that sometimes people measure success as an effect, whether it's good or not. And I think we need to get away from that. You know, you should feel healthy, you should feel well, your bowel movements should be normal, and that's our goal. And if you're experiencing anything other than that, I think this low and slow approach that Megan's mentioned is really important. That's where we need to kind of scalp back and say this is possibly a bit too much or possibly the wrong kind of fiber that we're focusing on.

Dr. Megan Riehl:

Exactly. Well, God bless her. She was trying, but it, you know, it speaks to our messaging and also how society is targeting people, right? Like, oh, well, I'm drinking prebiotic soda, that's better than regular soda.

Dr. Heather Armstrong:

And we're it's a great marketing scheme, and I think that's frankly all it is, and it excuses me. You know, it's another version of all grains are bad for you because pollutants bad, and it's hard to listen to, it's hard to watch patients go through this because they are just trying to get information and make sense of everything. And I think if they took the time to just sit down with a dietitian, they'd learn a lot more in that half hour to an hour than they would trying to scour the ends of the depths of Dr. Google, and it's just yeah, you know, getting this chemically isolated Enilin in a soda pop. It's sort of getting it from Whole Foods is just it's concerning.

Dr. Megan Riehl:

Well, and we hope that people will continue to tune into our podcast because we're science-based here. And, you know, to not be too political, but there are some doctors in the United States right now that are touting a lot of confusing messages to people, and it's a lot to sift through.

Dr. Heather Armstrong:

I think it's the struggle when we try to simplify things into something that works for everybody too. And I think that's you know, politicians are always going to have things they do well and things that they don't at the end.

Kate Scarlata, MPH, RDN:

Don't get us going. Don't get us going.

Dr. Heather Armstrong:

I think it just comes down to the messaging though, you know, like what worked for an individual. And I think this kind of politicians aside, it comes back to kind of social media and everything that the communication that we have with people right now, following someone who doesn't have the same health as you, didn't live in the same region as you, didn't have the same upbringing as you, and having them say, Well, this worked for me, so this will work for everyone. It's just not how the human body works, unfortunately. And so, you know, trying to see either a professional who has experience working with someone who's in your shoes when experiencing what you're experiencing is much more important at the end of the day, I think is trying to get access to that precision approach to health is probably more important than trying to get a one size fits all approach, because I just don't think it's possible.

Kate Scarlata, MPH, RDN:

Exactly. And just to kind of reiterate, you know, severe abdominal pain after eating, diarrhea, violent diarrhea, probably not what we're going for for adding fiber. You will have an uptick of gas, though. You might have slight bloating with a little bit of fiber too. And those are normal. It's if the bloating's painful, the gas is trapped in painful. You know, those are different stories, but don't expect that you're not going to have a little uptick in gas because you you will have a little uptick in gas. Sorry.

Dr. Heather Armstrong:

Yeah, and it's being mindful too, because I think you know, when people think of gas, I think that's something that people can be quite confused about too. So, you know, the microbes produce gases like carbon, we're not saying things like this when they're when they're going through this process of fermentation. So it's, you know, your microbes will produce gas as a part of this fermentation process. But things to be wary of is, you know, exactly that if you are jumping from zero to a hundred overnight and you're experiencing gas that's excessive and very smelly, and these are gases that are being produced by microbes that are perhaps sulfur-producing microbes. And some of the microbes that we don't want to see benefiting from what we're eating, they're microbes that we like to kind of keep at bay. Their existence is important, but in small numbers. So kind of backing it up and going a little bit more slowly to allow those other microbes time to flourish and kind of keep some balance in the gut microbiome is is really key. So, you know, smell and volume of gas, I guess. Yes. I think it's just be mindful of. If it's excessive, back it up, take it slow. Yeah.

Kate Scarlata, MPH, RDN:

Yeah, we don't want smelly gas. That's well, you know, kick happens, right?

Dr. Megan Riehl:

It's all your microbes, flamey microbes. That's right. Healthy microbes, hopefully. Not with smelly ones. Yeah. Oh, that's right. That's well, are you saying that that I mean, come on, parts are gonna smell. Parts are gonna smell.

Dr. Heather Armstrong:

It's a guess. At the end of the day, it's a guess.

Dr. Megan Riehl:

And I guess it's also a subjective about how smelly it is. Yeah.

Dr. Heather Armstrong:

Exactly. It's very subjective. But yeah, if you feel like you're struggling, low and slow is the key.

Kate Scarlata, MPH, RDN:

Low and slow. That's the main message. Personalization.

unknown:

Okay.

Dr. Megan Riehl:

Is there any condition where a high fiber diet may not be helpful? I'm thinking like dysynergic defecation or or any dysbiosis. Any cues there?

Dr. Heather Armstrong:

There's certainly certain conditions where, from a dietetics perspective and a gastrointestinal perspective, we certainly try to limit the types of plants that people are consuming or the volume. And that really, I think that has to be guided by a healthcare professional. So I don't want to kind of just sit here and name the list of conditions because I don't want people to run away and be like, well, I have this, so I should stop eating plants. I think that really has to be guided by a dietitian and a gastroenterologist. But there are certainly select disease settings where we do have to be very mindful. These are typically going to be gastrointestinal diseases that involve blockage of the bowel or thickening of the bowel wall or fibrosis of the bowel. And essentially the reason why I say it can be concerning is that you don't want to overbulk the stool and get to a point where the stool can't pass through the intestine safely anymore. And so you risk hemorrhaging the bowel or you risk causing damage, or you risk just constipation to the point where you can't pass the stool. Those are kind of some of the dangerous settings where we want to limit the types, certain types of fibers that are involved as these bulking agents. Other fibers are still fine, they can be fermented, broken down, that's all okay. But any of the fibers like psyllium and some of these fibers that we would typically use to battle diarrhea and some of these others that help bulk the stool and thicken it. You've got to be careful with those in certain disease settings for sure.

Kate Scarlata, MPH, RDN:

Yep. Not one size fits all. I think we got that message today. That's right. That's right. Yeah. Should we move to the speed round?

Dr. Megan Riehl:

I love the speed round and it has been so much fun to talk with you. So I'm excited to hear your answers.

Kate Scarlata, MPH, RDN:

Exactly. We get to know a little bit about you and we love learning, you know, outside of research, which again, I'm gonna link a lot of Dr. Armstrong's research and we have other research we'll be linking. If there's any papers you want to share with us, Dr. Armstrong, feel free to if I haven't read them already, because I'm a huge fan. But we're gonna just ask quick questions, quick answers to get to know you a little bit better. So I'll start. What is your favorite high fiber food that actually tastes amazing?

Dr. Heather Armstrong:

I really love the citrus peels. I mix them in pretty much anything. I love them, mix them in smoothies, mix them in any kind of baking or stir fries and things like that. I just I have IBD myself and I find that it it makes a world of difference with my gut health. So it's my favorite go-to.

Dr. Megan Riehl:

That is an episode takeaway. I'm gonna eat one like a pepper. I swear I'm excited about this. Yeah. How about your morning routine? Coffee first or fiber first?

Dr. Heather Armstrong:

I have IBD, so I don't actually eat coffee. I avoid a lot of caffeine products, just it's not a friend of my digestive treatment, an IVD patient. But yeah, it's interesting because we've got this clinical trial going on right now and trying to get kind of higher beta fructane into patients. The beta fructan that comes from chicory root, chicory root has this really interesting kind of coffee duck chocolate flavor to it. And so I actually tell our patients to mix chicory root powder into their coffee in the morning to get a little bit of both. Amazing.

Kate Scarlata, MPH, RDN:

That's a really good tip. Okay. What is your favorite way to relax after a long day at work? I have three dogs at home.

Dr. Heather Armstrong:

So when I get home, they always want to run around a bit and go for a walk. And you know, my job as a professor involves a lot of sitting sometimes. And so, you know, getting out for a walk with them at the end of the day and then just having a cuddle and a relax is kind of my go-to when I'm done a day awake.

Kate Scarlata, MPH, RDN:

I'm with you, girl. I'm with you, girl. I have a chocolate lab, and it's like she's only two and we're just constantly walking. Oh yeah. She's a busy girl. That Mabel, Mabel June, very busy girl. I love that.

Dr. Megan Riehl:

And what's a small thing that made you smile recently?

Dr. Heather Armstrong:

Oh, we actually had a patient finish a clinical trial this morning, and they emailed saying, thank you, thank you, thank you. This has made such a world of difference. They're gonna keep going with it, and they can't wait to see this publicly available in the clinic. And I think, you know, that is everything that we are going for, is not only that our research is interesting and we figure out the watch and the why, but this actually has an impact for people. So it was just a great way to start the morning.

Kate Scarlata, MPH, RDN:

That's awesome. You made us smile too. Yeah. You know, that's why we're in healthcare, and it's so nice when you can make a difference in someone's life. I mean, what a gift. Yeah. So is it music, movement, snacks, or naps?

Dr. Heather Armstrong:

I'll put music and movement together. I'm definitely one of those people that just likes to put the music on. And, you know, in my office, I've typically got some music and a foot chatting, if nothing else, or dancing around the kitchen at home. Well, yeah, that's my go-to combo for sure. I love that.

Dr. Megan Riehl:

Well, we appreciate your time, your research, your mind, and all that you're contributing to really the healthcare world. So thank you for joining us today. And we look forward to having another conversation at some point in the future.

Dr. Heather Armstrong:

Absolutely. Yeah, thanks for having me. We'll maybe come back when we've got this tool launched and we can talk more about it publicly. All right. We will look forward to that.

Kate Scarlata, MPH, RDN:

Definitely. All right. Well, thank you very much for listening. And to our audience, please subscribe, share, and give love to the GutHelp podcast.

Dr. Megan Riehl:

Thank you for joining us as we grow this gun help community. We hope you enjoyed this episode, and don't forget to subscribe. We leave us a comment. Also follow us on social media. We'd love for you to share it. Thanks for tuning in.

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Kate Scarlata

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Megan Riehl

Host