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Kousha Navidar: It's The Brian Lehrer Show. I'm Kousha Navidar, filling in for Brian today here on WNYC. Hey, how's your poop? Don't be uncomfortable. Everyone does it. You know what helps? Eating fiber, but you're probably not getting enough of it. According to Harvard Medical School, American adults eat, on average, 10 to 15 grams of total fiber per day, while the USDA's recommended daily amount for adults up to age 50 is actually 25 grams for women and 38 grams for men.

That might help explain the new diet trend that's been filling up my feed, my TikTok feed that is. It's a trend called "fibermaxxing." I'm not saying "proteinmaxxing." That was 2016. Fibermaxxing is about getting as much fiber as you can in your diet, and the trend is going mainstream. Listeners, this really hits home for me. As a younger guy, I have friends diagnosed with type 2 diabetes or who passed away from colon cancer.

I myself have Crohn's disease. A lot of younger people are starting to focus on fiber, but how much focus is enough and how much is too much? Are we missing anything else? To help us digest the fibermaxxing trend, I'm pleased to be joined by Dr. Trisha Pasricha, a gastroenterologist, the author of the Ask A Doctor column for The Washington Post, and the author of the new book You’ve Been Pooping All Wrong: How to Make Your Bowel Movements a Joy. Dr. Pasricha, welcome to the show.

Dr. Trisha Pasricha: Thank you so much for having me. Glad to be here.

Kousha Navidar: Glad to have you. Listeners, are you on the fibermaxxing trend? Why? Maybe you don't adhere to any trends, but you still have a favorite source of fiber. If so, what is it? Give us a call, or send us a text. We're at 212-433-WNYC. That's 212-433-9692. Dr. Pasricha, this is a serious, important subject, but fun is fun and good. We just want to let you know. We got a text that says, "I'm pooping right now."

[laughter]

Kousha Navidar: People are ready. I want to ask you, when's the first time you saw fibermaxxing as a trend, and why do you think it's becoming a bigger thing among young people?

Dr. Trisha Pasricha: Yes, I probably saw it a couple of months ago, also on my social media feed. I became immediately obsessed. I don't say that about a lot of social media trends. I don't say it lightly. I don't say it often, but fibermaxxing is so important and exciting that we're making fiber cool again because, yes, proteinmaxxing, that was so last year.

Kousha Navidar: Right.

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Dr. Trisha Pasricha: As a gastroenterologist, I think about fiber all the time. Just to take a step back, I think when I talk about fiber to my patients, people think fiber is just a gut health thing, right? Actually, the reason we eat fiber and reason we should eat more fiber than we all are is not because it's feeding us. The whole point of fiber is to feed the microbes living in our microbiome.

We cannot digest fiber. You eat fiber to feed those microbes, which then, in turn, produce these beneficial anti-inflammatory compounds that are not just great for your gut, but they're linked to better brain health, to better heart health, to lower risk of, as you said, type 2 diabetes. This is a whole health problem, and we shouldn't think about it just as a gut health issue. This is really something that all of us would benefit from.

Kousha Navidar: You start one section of your book talking about how, and I love this line, fiber has the best PR. You say there are other critical foods that catalyze reactions in our guts. Since you just brought that up about the biome and those critical foods don't get the same media attention, what are we missing?

Dr. Trisha Pasricha: [chuckles] Yes, I am obsessed with fiber, probably more than the average bear because I'm a gastroenterologist. I do think that if you go to any cookbook about plant-based eating or healthy eating, people talk a lot about fiber, and for good reason. I will say there are other kinds of foods that impact our gut that we're not talking about as much. For example, one thing I talk about in my book is spicy foods.

Spicy foods, as we all know, because we live this experience, they have a really important impact on our gut. If you've ever eaten hot chicken in Nashville, which is where I went to med school, you will know that if not that same day, certainly by the next morning, you're going to have fiery diarrhea for a reason. Spicy foods, the capsaicin in those foods, actually can be beneficial to your gut, even though it's like, "Wait a minute, but this is speeding things up. It's giving me fiery diarrhea." Nobody loves that.

Kousha Navidar: No, they don't.

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Dr. Trisha Pasricha: It can actually help improve pain signaling because the capsaicin acts on the same receptors in your gut that are responsible for pain signaling, as well as this perception of heat. There's a lot of different types of foods that I feel like we don't think as much about in different micronutrients. Ultimately, when the fibermaxxing trend came on board, I was completely here for it because I don't think enough people are bringing fiber into their diet. It can be really hard, especially in this age, where 60% to 80% of our food intake is coming from ultra-processed foods, which is notoriously low in fiber.

Kousha Navidar: Full disclosure. Especially as somebody with Crohn's disease, fibermaxxing is a thing that I've been paying a lot of attention to.

Dr. Trisha Pasricha: Love it.

Kousha Navidar: Yes, this is part of the reason why I was so excited for this segment, but I want to look at the "maxxing" part of that because everything seems to be maxxing today like, proteinmaxxing, looksmaxxing. Obviously, things can be taken too far. Does it worry you that fibermaxxing might be part of that?

Dr. Trisha Pasricha: Well, I don't think that you can ever overdo your fiber, but you can increase the amount of fiber you're taking incorrectly in a way that's going to make you feel ill. I've actually seen that happen numerous times, where people will be like, "I saw fibermaxxing. The next day, I went out. I bought a fiber supplement. I ate a bunch of Brussels sprouts, cruciferous vegetables, kale salads, and I felt horrible. Within 24 hours, I was like, 'This is not the right trend for me. Let me give up.'" Okay, so I never want that to happen to anyone. The biggest mistake you can make with fibermaxxing is going from 0 to 100 in a short period of time.

Again, the reason why this is not so great for you is because what fiber is doing, it is feeding different kinds of species of microbes in your gut. Well, you have to give your microbiome time to adjust to this change. There are some studies that show that these microbes, some changes can occur within a couple of days. For the most part, it's going to take weeks, like on the order of two to three months. I don't tell people like when you're fibermaxxing, suddenly, if you're eating 10 grams of fiber a day, jump up to 30 the next day. I think you're going to feel bloated and ill and gassy if you do that.

Kousha Navidar: It's not so much about the worry of the fiber itself. It's the process of ramping up your body to accept the fiber is what I'm hearing. Fibermaxxing sounds a little bit different than these other trends. I let you say that if it's like more fiber is good fiber. Is that fair to say?

Dr. Trisha Pasricha: Yes. Again, it's not something that you're not absorbing fiber. You're not digesting it. Like protein, you are breaking down and absorbing. Ultra-processed foods, you're breaking down and absorbing. Fiber, the whole goal and point is that you don't digest it. The worst-case scenario of fibermaxxing is you go too hard, too fast. You feel bloated and gassy. That's not going to kill you, but it is going to be really uncomfortable, or--

Kousha Navidar: Okay, I'm so sorry about that. Oh, sorry. No, go ahead. Go ahead. I don't mean to interrupt you. Please go ahead.

Dr. Trisha Pasricha: I was going to say, oh, well, the other possibility is that you eat so much fiber that you start pooping. You end up saying, "Wait a minute. Do I have diarrhea?" because your stool is just so soft. Then, I would say, "Okay, maybe peel back a little bit," but it is in truth. I see this in my clinic all the time. When people start meeting their fiber goals, they end up going two or three times a day, and that actually just can be normal.

Kousha Navidar: Right. I was going to say, you said going too hard too fast. Because if you do, it might get too hard too fast. I'm sorry, listeners. We got to have fun about our health as much. We have a question here for you. It says, "To the fiber doctor, I know fiber is very important, and most of us don't get enough, but I've heard it can impede the absorption of some nutrients. Can the doctor talk in detail about how much of a concern that ought to be, and with what nutrients it's relevant? Thank you." Very interesting question. What do you think, Doctor?

Dr. Trisha Pasricha: Yes, it depends a little bit. If you're meeting your fiber goals through your diet, I wouldn't worry too much about this. Any kind of fruit or vegetable that you're going to encounter in the wild, in the grocery store, it's going to have a mix of different kinds of fibers, meaning different soluble fibers, different insoluble fibers in some ratio. That won't interfere with any kind of medications or other micronutrients in the foods that you're eating.

Some fiber supplements, though, there is a little bit of concern that you may want to consider spacing them out from other medications you're eating, not other foods you're eating. I'm talking about soluble fiber supplements, which are actually the kind that I take myself. I do. I fibermaxx so hard, but I take a soluble fiber supplement even when I know I'm going to meet my dietary fiber-intake goals just because I want that extra fiber in my life.

Kousha Navidar: Is it psyllium husk? Is that what you take?

Dr. Trisha Pasricha: Yes. How did you know?

Kousha Navidar: Come on, everyone with fibermaxxing knows about psyllium husk?

Dr. Trisha Pasricha: Yes, once you know, you know.

Kousha Navidar: Once you know, you know.

Dr. Trisha Pasricha: Yes. Just to be clear, I've made this mistake. For psyllium is spelled with a P. P-S, it's psychology. It's not selenium or something like that. Yes, psyllium husk is great because it's a soluble fiber. Soluble means that it's going to dissolve in water, and it's going to turn into a gel. That's where this concern about, "Okay, does this gel somehow maybe absorb other medicines that you've been taking or interfere with that?" The data on whether it does that is actually pretty weak. You can always run it by your doctor.

I wouldn't worry about, "Is this going to somehow interfere with the absorption of other foods?" All it's going to do is slow things down to some extent. That's actually a good thing. It gives you more time to digest, and you get some benefit from the soluble fiber, both in terms of whether you have constipation because it loosens things up. Soluble fiber also helps if things are too loose because it can bind those looser pieces together in that gel. It's a shape-shifter, and it's a really wonderful, gentle, easy-to-take fiber.

Kousha Navidar: I'm so happy that you brought up psyllium husk, Doctor, because I was going to go to a caller, which we're going to skip for now, but Maurice just want give you a call out in Clifton, New Jersey, that you asked, what's the difference between psyllium husk and fiber? I would still like to go to Edward in Manhattan if we could, though. Edward, Hi, welcome to the show.

Edward: Yes, I'm here. Can you hear me?

Kousha Navidar: Yes, hi.

Edward: Yes. Well, about a year and a half ago, I was told by my doctor that I needed to have a stent implanted in my heart, I'm 66, which they did. I had to drag my LDL cholesterol, bad cholesterol, way down. It was up at 100, and that I should go on a very low-saturated fat diet, I've practically eliminated it, and eat mass quantities of fiber. Every day, I have oatmeal in the morning with tons of fruit. Every afternoon, I have a big tablespoon of psyllium fiber husk in cold water, which is I'm now completely used to. Of course, aside from bringing my LDL cholesterol down from about 100 to about 39, it's just made my regularity very regular.

Kousha Navidar: Edward, that's wonderful, and then I think you had a question about kimchi, right? Oh, sorry.

Edward: I have a question. My question is this. They told me that eating fiber, along with reducing saturated fat, would reduce LDL cholesterol. I've never quite understood how that works. Does fiber absorb saturated fat from your blood, or why does it help to bring your LDL cholesterol down?

Kousha Navidar: Wonderful. Thank you for calling, Edward. Doctor, go ahead.

Dr. Trisha Pasricha: Okay, I love this question. First of all, I'm so glad you brought this up, because this is, I think, one of the lesser-known benefits of psyllium husk in particular. The cardiologists were all over psyllium well before the gastroenterologists like myself were, and here's why. Psyllium reduces cholesterol levels. It actually reduces LDL cholesterol, ApoB, which is this other marker that can help determine your heart disease risk.

The reason it does that is because, remember, psyllium, as a soluble fiber, it turns into a gel. When it does that, it traps bile acids that are just moving along through your small intestine. When it does that, your liver is forced to use up the cholesterol in your bloodstream to produce more bile acids because you're trapping them. You need those bile acids to digest. It uses the cholesterol in your bloodstream to do that, thereby effectively lowering the amount of cholesterol remaining in your blood.

Kousha Navidar: There is this other question that I think a lot of people are probably wondering right now. The text just reads, "How many times a day should I poop?" What do you think about that?

Dr. Trisha Pasricha: [laughs] A classic question. I don't think a week goes by that I don't get this question in my clinic. Everybody right now is thinking, "It's got to be one, right? One is the holy number." It's not. You can go anywhere from up to three times a day to once every three days, and that would be within the range of normal as determined by your fellow Americans in this large analysis they did of people who consider themselves normal in America. It's a big range.

For me, I actually don't really ever worry too much about the number. I just want people to poop. However many times a day is comfortable, effortless, and doesn't disrupt your social life. For some people, every other day is fine. For someone else, three times a day is fine. It really depends on you. It's going to be determined, yes, by how much fiber you're eating, how stressed you are. Are you traveling? How much are you exercising? All of things are going to shift that day to day. If not week to week, month to month.

Kousha Navidar: This has been such a great conversation for me. Listeners, I see all of the texts coming through. They're all great. Maybe we should do a Fiber Friday segment. I don't know.

Dr. Trisha Pasricha: [laughs]

Kousha Navidar: I'm just saying. I don't know, but we'll have to leave it there. My guest has been Dr. Trisha Pasricha, a gastroenterologist, the author of the Ask A Doctor column for The Washington Post. The new book you've got is You’ve Been Pooping All Wrong: How to Make Your Bowel Movements a Joy. Thanks, Doctor.

Dr. Trisha Pasricha: Thank you for having me.

Kousha Navidar: All right, folks, that's it for today. I'm Kousha Navidar, and this is The Brian Lehrer Show. Hey, stick around. Listen to All Of It, and we will see you here on Monday. Be well.

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