The world changes every hour. So do we on NPR News Now, the podcast that brings the latest headlines in five minutes, with new episodes posted at the top of every hour. Clear, fact-based, and ready when you are. Listen to NPR News Now on the NPR app or wherever you get your podcasts. You're listening to Shortwave from NPR. Short Ravers, some people on our team are very online. I'm actually not one of them, but I have been alerted to this phenomenon on social media known as maxing. Whether that's looks maxing, gym maxing, protein maxing, or fiber maxing. I'm tired of not getting enough fiber in, so welcome to day one of becoming a fiber maxer. I'm fiber maxing hard. Fiber is officially scared of me now. Just for anybody trying to diet, quit protein maxing, bro, and fiber max. I will say, I've looked at some of these videos now, and fiber maxers are right about one thing. Over 90% of people in the U.S. don't get enough fiber. The standard American diet, or the Western diet in general, actually is very depleted of fiber. This is Berkeley Limkekai. He's a gastroenterologist at UCLA, and he says most Americans are fiber deficient because, well, we're eating a lot of other stuff. We do like our refined carbohydrates, the sweets. We do love our fried and fatty foods. We do love our ultra-processed foods, which are intentionally created to be more attractive, tasty. And unfortunately, ever since being little children, folks don't really like eating their broccolis as much. The average person eats 10 to 15 grams of fiber per day. But the recommended daily average is more than double that number. And usually, the place that makes itself known is the porcelain throne, the lavatory, the toilet. When they don't consume enough fiber, they tend to have more constipation. And as such, they could actually experience more straining when having bowel movements. They can feel like they're not completely evacuated after each toilet session. They could feel that the feeling of having a bowel movement is more extended over time, or the interval between bowel movements may be longer. So those are some of the initial telltale signs of not having enough fiber intake. I know what you're thinking. You're listening to this and saying, shortwave, you already did an episode on your pooping all wrong and now you're telling me I'm fibering all wrong? Maybe. I'm saying you're fibering perhaps not enough. And we have answers for you. Especially in the United States, increasing fiber is generally a good thing. Too much of any good thing can lead to detriments to your health or your well-being. but in general, yes, fiber is your friend. Today on the show, we're tackling fiber. We speak to a gastroenterologist to parse the science of how little is too little, how much is too much, and like Goldilocks, how do you know what's just right? I Emily Kwong and you listening to Shortwave the science podcast from NPR Okay, I'm here with Berkley Limke-Kai, a gastroenterologist, to talk about fiber. Fiber is a carb that our bodies cannot digest. Berkley, can you talk about some of the benefits of fiber? So I guess the way I look at fiber and its potential benefits are, on one hand, the mechanical aspects of its effects, which leads to changes in bowel habits. And the other way is looking at it from the functional effects. So that's where, on one hand, it's able to shape the gut microbiome and at the same time serve as nutrients or raw materials for the microbiome to generate these anti-inflammatory molecules. Wow, it does a lot, actually, fiber. It does. And do all forms of fiber do all the things? Because I know there's like soluble fiber versus insoluble fiber, and then there's prebiotic fiber. So like what are all those types and what does what? There are many different forms of fiber. There are nuanced differences between them that then actually leads to a differential effect on the types of bacteria that they promote and in terms of the types of molecules that they tend to be converted into. And there are also some types of fibers that, when consumed in diseased states, may actually be detrimental to the body or actually be pro-inflammatory, paradoxically. Yeah, and can you explain what is the difference between soluble and insoluble fibers? Yeah, so soluble fibers are the types of fibers that, as the name implies, it dissolves in liquid. And so they can actually help form a gel of the stool or help kind of produce a stool mass. And these are more helpful for individuals who tend to have looser stools or more diarrhea. By contrast, insoluble fibers are not as well digested as they pass through the gastrointestinal tract. They tend to draw more liquid into the intestines, thus leading to a more liquefaction of the stools. And so these are more helpful for individuals who tend to have a more constipation-like bowel habit. What a power couple, that insoluble-insoluble fiber. And then where does prebiotic fiber fit into this? So the term prebiotic and dietary fibers are actually almost synonymous. Oh, okay. One could even theoretically consider them interchangeably. There are some nuanced differences, but the predominant form of prebiotics actually come in the form of plant fibers. Interestingly, not all plant fibers are dietary because there are leaves and trees outside your building or home that you do not necessarily— That we cannot eat. Exactly, exactly. Yeah. So prebiotics are just plant fibers and some are soluble and some are insoluble? In general, yes. Okay Okay Cool Complicated Well then in that case I want to know how people can increase their fiber safely What the best way to do that Yeah One of the best ways to increase fiber in their diet is actually to increase the proportion of fruits and vegetables that they incorporate into their meals. And the reason for this is because on one hand, you know, there is the benefit of actually getting the fiber in these fiber-rich foods. But at the same time, these particular food types actually also have these molecules called polyphenols that have anti-inflammatory, anti-oxidative, and anti-cancer effects. In addition to that, we would actually also recommend eating the colors of the rainbow. And that is you have different colored vegetables or fruits throughout the week. And the reason for that is because there are also other types of micronutrients and vitamins that actually then help balance out your diet and your micronutrient intake if you actually have this kind of diversity of foods. Awesome. So yeah, eating lots of fruits and vegetables, eating the rainbow. What about whole grains? Does switching entirely to whole grains help with fiber intake? Very much so. Whole grains are actually very rich in fiber and have a lot of beneficial, money on saturated fats. So there are also other potential benefits from whole grains themselves. Another way some people are trying to get fiber or fiber max is with supplements. There's also foods with fiber additives. What do you think of all that? Yeah, so fiber supplements are actually beneficial and a good source of fiber intake. In clinic, we oftentimes recommend fiber supplements for our patients. The supplements is an easy way of boosting daily fiber intake. Gotcha. The potential disadvantage of consuming a fiber supplement is that while it is a great source of fiber, it does not contain all those other nutrients or beneficial molecules that natural fiber in whole foods contains. There is a benefit to the whole foods approach. And it's interesting because fiber, at least on the business side, like food brand watchers are saying fiber is going to be the next thing. There's a booming prebiotic soda market. So what do you think of these sodas? Are they a medically sound way of getting fiber or is it a scam? It's a great question. One could use these different nutrients and add them to virtually any product and use that to increase the attractiveness of their product and maybe the health benefit profile of those products. However, if in totality or if the other components of such product actually does the complete opposite, then it's not really that beneficial to consume in the first place, even if there's something that is said to be potentially beneficial. So this kind of brings us back to fiber maxing, where people on social media are just trying to consume as much fiber as possible. Like the number is the point, 70 or 80 grams. Yes. At the end of the day, what do you think about people eating that much fiber? Is it ever a good thing? So 70 to 80 grams or even 90 or even beyond that of fiber per day is not unprecedented. If you look at other cultures where they consume predominantly fruits and vegetables or in those who are vegan they already routinely consume a very high consumption of fiber per day However someone who is not really accustomed or adapted to consuming that high of a fiber intake, and then suddenly ramps up to 70 to 90 grams per day, could along the way experience a lot of kind of adverse effects from such high fiber intake. Alterations in their bowel habits, maybe disruption of the gut microbiome, potentially could also cause a compromise in certain micronutrient intakes, such as calcium, iron, and zinc, and also can lead to some degree of malnutrition. Yeah. So what is the best way to increase your fiber intake, but responsibly? If one actually wanted to increase their fiber intake, I would actually recommend that they meet with a dietician or nutritionist so they can actually look at kind of the overall balance of their diet to make sure that while, yes, they're increasing dietary fiber consumption, that they're not compromising then on other nutrients. You know, start low and ramp up, stay within the recommended guidelines initially. And if one is able to then tolerate that amount of fiber, one could theoretically increase it thereafter. While keeping in mind that along the way, you know, if one were to develop, let's say, changes in their bowel habits or increased abdominal cramping, discomfort or pain, or even feeling more bloating and distension, that it may be a sign to kind of down throttle kind of the increase in fiber, at least temporarily. That sounds like very good advice because I feel like everything I'm learning from you is that moderation and intention are really important in diet and especially with fiber because it is such a delicate balance. And also so much depends on the individual. What works for you might not work for your friend. Is that the overall message for you? Very much so. Life is a balance and too much of any good thing can actually sometimes be harmful. While one can still aim for increasing fiber intake. You also need to do that in a judicious, kind of intentional and strategic manner so that while optimizing your health in one area, you don't actually compromise your health in other areas. Very important advice. Dr. Berkley Limket Kai, thank you so much for talking to me about fiber and how to, you know, find that Goldilocks middle with it. Well, thank you very much for the invitation. It was a great pleasure chatting with you today. shortwavers we've been doing a lot of health questions lately if you have a question write to us our email is shortwave at npr.org we'd love to look into it and while you're at it follow us on whatever app you're listening to this episode was produced by hannah chin it was edited by rebecca ramirez tyler jones checked the facts robert rodriguez was the audio engineer i'm emily Kwong, thank you for listening to Shortwave from NPR.
