Podcast: Gut Health, Fiber, and the Microbiome, Explained

Dr. Zylberberg: Fiber helps regulate digestive movement. I think there's a lot of misconceptions about fiber. People will say, "You only need fiber if you're constipated," or, "You only need fiber if you have diarrhea," but actually it works in both ways. 

Courtney: Welcome to Health Matters, your biweekly dose of the latest in health and wellness from NewYork-Presbyterian. I'm Courtney Allison. 

This season on Health Matters, we're covering your health from A to Z, asking our experts to break down the health topics and wellness trends we're all curious about. Today, we're at the letter F and G, talking about fiber and gut health. 

Courtney: And what is the gut-brain connection? To explore these questions and more, we spoke to Dr. Haley Zylberberg, a gastroenterologist at NewYork-Presbyterian and Weill Cornell Medicine. We talked about how the gut works, how to know when something's off, and what we can do to protect our gut health. And in recognition of Colorectal Cancer Awareness Month, Dr. Zylberberg shares the importance of colorectal screening. 

Courtney: Dr. Zylberberg, thank you so much for joining us today. 

Dr. Zylberberg: Thanks so much for having me. 

Courtney: So we hear so much about the gut these days, the gut-brain connection, the microbiome. So let's start with the basics. What exactly is the gut? What does that encompass? 

Dr. Zylberberg: Yeah. That's a great question. The gut is composed of a few different organs that work together, and so you can think of the gut as a long tube that starts with the mouth, goes down the esophagus, which is the food pipe, into the stomach. Then there's the small intestines, the large intestines, and then of course, you know, everything needs to come out through the end, so that's the rectum and the anus. 

Courtney: And what is the gut's role in our body? 

Dr. Zylberberg: So the gut has a few roles, actually. I think we all know that's the place where we break down food and digest food, and then the food, once it's digested into nutrients and vitamins and water and different electrolytes, all need to get absorbed. And so that's why the lining of the gut, specifically the small intestines, is so long, because you're absorbing all these nutrients so that the body can have energy and have all the building blocks it needs to function and be healthy. And then of course, you need to dispose of it, so that's the waste system, and food needs to move down, and nutrients need to move down through the tube, and so there's the motility component, the movement component. Super important. 

Courtney: And so why is the gut so important to our overall health? 

Dr. Zylberberg: We need vitamins, micronutrients, electrolytes, water in order to have our body function, right? We need energy, so sugars are broken down into energy. We need different vitamins and micronutrients for the proteins and the enzymes in our body to be processed. Really the only way for all of our organs to do the things they need to do is through the gut, is through digestion. 

Courtney: Thank you so much for that. It's interesting to hear how everything works together to power our bodies. And so something else we hear a lot about is the microbiome. Can you explain what the microbiome is and the role it plays in our gut health?

Dr. Zylberberg: You can think of it as a community of organisms that live in the colon or the large intestines, and it's mostly bacteria, but there are some viruses and fungi. And there are tons of them, right, living there, different species, and that's totally normal. You know, we hear about good bacteria, we hear about bad bacteria, but these are mostly the good bacteria. And we need them because they help break down fiber and also produce different compounds like short chain fatty-acids. And so we rely on them to live and break down different products that enter our body. 

Courtney: Can we talk about the balance between the good bacteria and the bad bacteria? 'Cause I kind of picture, like, a microscopic war happening in our guts. Is that true? 

Dr. Zylberberg: Definitely there are times when bad bacteria enter, right? You have a stomach bug, gastroenteritis, norovirus, bad bacteria, bad viruses that enter and can cause havoc. Also, certain bacterial species are associated with certain disease states, but we don't wanna wipe out the bacteria and the viruses and the fungi. We wanna sometimes treat with antibiotics if there's definitively a bad bacteria, but otherwise we wanna make sure that these foreign beings are there to help us. 

Courtney: Okay. So we kinda want them to coexist. 

Dr. Zylberberg: Yes. We definitely want them to coexist. A lot of work being done in figuring out what are the good species and the bad species, and still more that needs to be done to really figure that out. 

Courtney: So what are some signs of a healthy gut? How do we know everything's kinda moving along well? 

Dr. Zylberberg: Every once in a while, having some bloating or pain or gas, that's not abnormal, but on a regular basis, you shouldn't really have those sorts of symptoms. Digestion should be easy. You should have a good appetite, feel hungry, process your food without feeling pain, without feeling bloating. A healthy gut means different things to different people. Nobody's gut is exactly the same. And so it's really about knowing what is regular and predictable and normal for you. So one person may have a bowel movement every day, and that's their normal. Another person may have a bowel movement every couple of days, and that's their normal. So it's important to recognize what your normal is and compare yourself to you, and not to compare yourself to anyone else. 

Courtney: Right. So it sounds like everybody's different, and it's good to know your own body. So are there certain foods that can help support our gut? 

Dr. Zylberberg: Definitely. Eating foods that are-fermented can be very helpful. Things like yogurt, kimchi, sauerkraut, miso that have been known to sort of help the good bacteria. Bacteria need fiber because they break it down, so fermentation is just the process of breaking it down, and it helps aid in our digestion. So the bacteria need it to survive, and we need it because it helps our digestive processes move well. 

Courtney: Say more about fiber. We hear a lot about that. What is the role of fiber, and can you elaborate on how eating more foods with fiber can improve our gut health? 

Dr. Zylberberg: Fiber helps regulate digestive movement. There's a lot of misconceptions about fiber. People will say, "You only need fiber if you're constipated," or, "You only need fiber if you have diarrhea." But actually it works in both ways because it helps with diarrhea because it can help absorb water, and it can help with constipation because it can actually help stimulate motility in the digestive system and also add some bulk to the stool so that it's softer. And so you can think of it as a digestive aid that helps with movement and helps with having healthy, normal bowel patterns in general. 

Courtney: What is a good amount of fiber to aim for? How much fiber should we be getting every day? 

Dr. Zylberberg: The best amount would be between 20 to 30 grams a day. We definitely do not eat enough fiber. Foods that are high in fiber are things like whole grains, oatmeal, beans, lentils, vegetables, fruits, nuts, and seeds. I think a big misconception is people will eat, like, a big salad and say, "Oh, yeah, I had a lot of fiber 'cause I just had a big salad." But depending on what's in the salad, there actually may not be as much fiber because romaine lettuce, for example, really doesn't have that much fiber. 

Courtney: What are some other good ways to get more fiber in our diets? 

Dr. Zylberberg: Chia seeds in, like, your oatmeal, that is a ton of fiber. Just some berries as a snack can also be a lot of fiber. But what's very important about fiber is going very slowly. Something that I frequently encounter, and I'm sure others do too, is people will say, "Oh, I tried fiber, but that made me feel worse. I was very bloated and gassy, so I stopped." And that's usually a sign of doing too much fiber too quickly. Because if your body isn't used to 30 grams of fiber, well, 

Dr. Zylberberg: yes, if you eat 30 grams of fiber, your bacteria in your colon are gonna be working, working, working, and producing a lot of gas, and that may be uncomfortable. So you know, about five grams every couple of days. Make sure to drink a lot of water with foods that have fiber because that helps as well, so it's always recommended to increase fiber slowly. 

Courtney: So I'd love to also ask you about probiotic supplements. I take one from time to time just hoping it helps me, but it sounds like the jury's still out. So I'm wondering your take on probiotic supplements. Do they help? 

Dr. Zylberberg: Yeah, that's a great question and something I get asked all the time as well. So probiotics one can think of as sort of food for the good bacteria that live in our colon, so you are talking about feeding them with fiber but also feeding them with these probiotics. And so there's the natural probiotics, foods that are fermented, and then there's a probiotic supplement. And the jury is still out. It's not really recommended in guidelines for most conditions. That being said, I do find that sometimes patients find them helpful, so while I don't necessarily recommend them for everybody, they also in most cases won't really hurt. Other supplements that sometimes are helpful for people who have GI symptoms are actually peppermint oil supplement or drinking peppermint tea because peppermint relaxes the lining, you know, the muscles in the gut and can bring relief to people who are having cramping and bloating. So that's something that I also frequently recommend to people. But any time that anyone is considering starting a supplement that isn't just a daily multivitamin, I think it's great practice to speak to your primary care doctor or your gastroenterologist because sometimes supplements can actually cause problems. Some of them can cause diarrhea, constipation, can cause liver damage, kidney issues, so very important to speak to your healthcare team. 

Courtney: Something else I hear a lot about is the gut-mind connection. What is the link or relationship between the gut and the brain? 

Dr. Zylberberg: We have this idea that there's a gut-brain interaction or gut-brain axis and that there is a two-way communication between the gut and the brain. And so if one is stressed, well, that can worsen gut symptoms and vice versa. If someone has gut symptoms for different reasons, that can worsen stress, and so it's this sort of cycle. And it is backed by science. Um, there are nerve connections. So for example, there's the vagus nerve, which is one of the largest nerves in the body that directly go from the gut to the brain and send signals. Immune signals travel, hormonal signals, and so there's a lot of ways that the gut and the brain interact. For some GI conditions, there's evidence that doing meditation or hypnosis or cognitive behavioral therapy can actually help improve GI symptoms by stress relief. So these things are, are very linked together, but exactly how, uh, is still being worked out. 

Courtney: So it sounds like there's kind of like an information superhighway between the gut and the brain. 

Dr. Zylberberg: I think that's a great way to think of it. Yes, there's nerves that innervate the entirety of the gut, and that's important for motility. It's important for immune function. It's important for the signaling in general. And all of these things need to work and coordinate together to make, to make the gut work and to make the gut move.

Courtney: So we've spent some time talking about signs of a healthy gut, what we can do to improve our gut health. Can we also spend some time on signs of an unhealthy gut? What's some signs that your gut might be off? 

Dr. Zylberberg: So there definitely are some red flag signs that no one really should have, like blood in the stool, so red blood or black, tarry, sticky stools, that can be a sign of digested blood, maybe bleeding in the GI tract that then moves down. Unintentional weight loss. If someone suddenly has a poor appetite, they're not eating as much as they used to, they don't feel hungry. If you're having a lot of pain, bloating, gas, heartburn, or symptoms interfering with your ability to eat or just to feel well. All things that every once in a while is fine. If you have a few days where things aren't totally right or totally your normal, that's fine. But if that change is lasting a while and something doesn't feel right, well, maybe something isn't right. 

Courtney: So it's March, Colorectal Cancer Awareness Month. Could we talk about the importance of colorectal cancer screening? 

Dr. Zylberberg: I think if there's one takeaway from this podcast, it should be that knowing your gut, knowing what's normal for you, and any changes or what we call red flag symptoms in the gut could suggest cancer, right? That's why we say it's important to know about how your gut functions and to make sure you're not having any of these red flag symptoms. And screening for colon cancer specifically is very important and worthwhile to do because colorectal cancer is preventable. Screening can detect polyps, which are pieces of tissue that can become cancer, and if one gets screened with a colonoscopy, we can remove those polyps. Frequently, we detect cancer at very early stages where a surgery can sometimes be enough to totally remove the cancer. So if y- we detect cancer early or detect pre-cancer, the prognosis is really, really good. 

Courtney: What are the general guidelines? When should we get screened? 

Dr. Zylberberg: So for people who have no family history of colon cancer, screening starts at 45. So mark your calendars. If someone has a family history of cancer, then it becomes either age 40 or 10 years younger than the age that the relative had cancer. If there are no polyps or precancerous polyps, then your next colonoscopy is 10 years. And while colon cancer, colorectal cancer, definitely more common in older people, younger people are being diagnosed with cancer more frequently now. Just because you're in your 20s, if you're seeing blood in your stool, that isn't normal. You should go speak to one of your doctors about it and see if maybe you need to be screened. 

Courtney: That's a really important message, especially about younger people. Dr. Zylberberg, thank you so much for joining us today and talking about all things gut health and how it impacts our overall health. I learned so much talking with you. 

Dr. Zylberberg: It was great to be here, and hopefully this will be a resource for everybody listening. 

Courtney: Our many thanks to Dr. Haley Zylberberg. I'm Courtney Allison. Health Matters is a production of NewYork-Presbyterian. The views shared on this podcast solely reflect the expertise and experience of our guests. To learn more about Dr. Zylberberg's work with patients, check out the show notes. NewYork-Presbyterian is here to help you stay amazing at every stage of your life. Join us next time when we discuss what to know about hay fever and managing allergies. That's in two weeks, right here on Health Matters. So you don't miss it, be sure to follow and subscribe on Apple Podcasts, Spotify, or wherever you get podcasts.