Should I take a probiotic? And other gut questions, answered

Research shows that our gut microbiome -- the trillions of microbes that populate our intestines -- isn't just involved in digestion. It's intimately linked to our immune systems, mental health, cognition and more. If you want to improve the health of your gut microbiome, there are specific best practices that can help. This episode, NPR health correspondent Will Stone shares tips on probiotic supplements, microbiome tests, and the most important factor -- your diet. Follow us on Instagram: @nprlifekit https://www.instagram.com/nprlifekit/?hl=en Sign up for Life Kit's skincare newsletter: http://npr.org/skincare Have an episode idea or feedback you want to share? Email us at [email protected] mailto:[email protected] Support the show and listen to it sponsor-free by signing up for Life Kit+ at plus.npr.org/lifekit http://plus.npr.org/lifekit Saccharomyces boulardii CNCM I-745 and Lactobacillus rhamnosus GG are two examples of probiotic strains that have considerable evidence from randomized controlled trials. Saccharomyces boulardii CNCM I-745 for travelers' diarrhea and antibiotic-associated diarrhea and Lactobacillus rhamnosus GG for antibiotic-associated diarrhea for children and adults, and also for upper respiratory tract infections. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This message comes from the Southern Environmental Law Center. No one voted for dirty air and water. That's why S E L C is fighting back to defend the healthy environment everyone depends on. Because it's not political, it's fundamental. Learn more at S E L C dot org.

• 0:19Marielle Segarra?

  At NPR, there's a little something for everyone. If you need advice for that big life change, try listening to Life Kit. If you want to know more about that new TV show, check out Pop Culture Happy Hour. And if you want to dive deeper into your favorite podcasts and enjoy perks like bonus episodes, archive access, and more, check out NPR Plus. Find out more and support the shows you love at plus.npr.org.

• 0:54Speaker 02

  Scientists know that our microbiome, it's not just involved in digestion. It's intimately linked with so much of our overall health. It influences our immune system, our mental health, our cognition, and much, much more. Some of these links are only beginning to be fully revealed.

• 1:12Marielle Segarra?

  You're listening to Life Kit. I'm Mary El Segarra. And that was NPR health correspondent Will Stone. The gut microbiome is a way of describing the literally trillions of microbes that populate our intestines.

• 1:26Speaker 02

  A lot of these are bacteria, but we also have other organisms in there, fungi and viruses. So you want to picture this packed, dense ecosystem that's alive within you.

• 1:37Marielle Segarra?

  Now, given what scientists are discovering, that the microbiome is important to our health, people want to hack it. They want to have the very best, healthiest microbiome possible.

• 1:49Marielle Segarra?

  Will says the problem is the science hasn't come quite that far yet.

• 1:53Speaker 02

  Scientists haven't quite figured out how to even define what is a healthy microbiome. There's a lot of variability when you look around the world, depending on where you live, your diet, all kinds of things. And so unless you are acutely ill and, you know, are having symptoms, it's hard to pin down what is healthy.

• 2:14Marielle Segarra?

  We do have some clues, though. It seems that the more diverse your gut bacteria are, the better. Also, if your microbiome bounces back well from disruption, like antibiotic use, that's a good sign.

• 2:26Speaker 02

  And another area that scientists can look at are the different groups of bacteria that are present in your microbiome. And we know that some are associated with better health. When you look around the world, you see this.

• 2:41Marielle Segarra?

  On this episode of Life Kit, best practices for your gut microbiome. I talked to Will about probiotic supplements, microbiome tests, and what you eat, which is still the most important factor here.

• 3:02Speaker 03

  Stay tuned for the following announcements and messages from our sponsors.

• 3:07Speaker 04

  The 2026 midterm elections are upon us. On November 3, voters will determine what the next two years of their local leadership and the balance of national government will look like. Listen to the NPR News Now podcast for all the updates you need ahead of and after November 3 from NPR News.

• 3:29Speaker 05

  American journalist Austin Teis vanished in Syria over a decade ago. For years, we've been searching for him, and now we finally have some answers. This is the prison that Austin was in. Oh, my God. We found Austin's file. Listen to Where Is Austin Teis from NPR's Embedded and BBC Radio 4, on the NPR app, or wherever you get your podcasts.

• 3:54Speaker 06

  Election season feels messier than ever. Attack ads, misinformation, AI. NPR is your antidote. Our network of real, human journalists keeps you focused on the facts. And with NPR Plus, you directly support journalists on the ground, asking questions in service to the public. As a thank you, you get dozens of podcasts sponsor-free. Sign up today at plus.npr.org.

• 4:19Marielle Segarra?

  It's easy to feel overwhelmed by skincare advice. Somewhere along the way, skincare got complicated and started to feel like a job. But what products and treatments will actually lead to healthier skin? Life Kit made a special newsletter series to answer that question. Sign up at npr.org/skincare, or find the link in the description for this episode.

• 4:46Marielle Segarra?

  Well, there's a huge market for gut microbiome tests. Are any of these worth spending money on?

• 4:51Speaker 02

  The short answer is generally no, at least when you look around the huge variety of products out there. And that's because they tend to overstate the science and be way ahead of the evidence. So just to run through, you know, a couple of these, you have these gut microbiome tests that you can buy. They're quite popular. And this isn't a test that your doctor orders because they think you have some illness. This is a test you would get commercially, a couple hundred dollars to try to maybe optimize your microbiome or figure out what's wrong with it on your own. They'll give you hundreds of different measurements and it looks pretty legit. I talked to Dr. Alexander Koritz about them.

• 5:34Speaker 02

  He's a GI specialist and researcher at the University of Minnesota. He says he'll get patients who are worried about their gut health, maybe they'll have some symptoms, and they'll send him their results.

• 5:44Speaker 05

  It usually comes as an entire book, colorful, with many, many entries of different bacterial species, fungal species, different metabolites. And I think the message the patient gets, well, gee, my doctor never did this kind of testing, this amount of information. This is, this looks very impressive. It must mean something. And the reality is, unfortunately, it's not very informative at all.

• 6:15Speaker 02

  And the fundamental problem is one we already discussed, which is we don't have a definite consensus on what even is a healthy microbiome. But beyond that, we've also seen research that's shown the same patient with the same sample can send it to different companies and they get very different results. So it's not just interpretation, it's also kind of the reliability and variability you can get when you go out onto the market.

• 6:41Marielle Segarra?

  Okay. So don't bother with the tests. And what about supplements, like probiotics, for instance?

• 6:49Marielle Segarra?

  If you walk into a health food store, there'll be shelves of many different probiotic capsules you can choose from.

• 6:56Speaker 02

  Yeah, and it can be pretty confusing, you know, to figure out, is any of this worth my money? Now, probiotics can be helpful in specific circumstances. So, for example, there's good evidence they can be beneficial for reducing the risk of diarrhea associated with antibiotic use, also for preventing traveler's diarrhea, or for preterm infants who are at risk of complications. These are a few examples where we have better data. But beyond that, the idea that most people who are otherwise healthy should be taking a probiotic daily to support their gut health, it's really not backed by science yet. There may be a day where we actually have more targeted probiotics that can help people, but we are just not at that point yet.

• 7:42Marielle Segarra?

  And for the cases that you mentioned, it's only certain strains that help with those things, right? Like, you need to pay attention to which strain you're using if you want to, for instance, prevent traveler's diarrhea.

• 7:56Speaker 02

  That's right. Certain strains have been tested in high-quality trials and been shown to be effective. One point that was made to me was you'll see sometimes marketing on these probiotics saying clinically tested. That didn't say they were effective. It just said they were tested. So you have to be mindful about what's actually being promised here and then what can be delivered by the evidence. I spoke to Hannah Holsher about this. She's at the University of Illinois Urbana-Champaign, and she pointed me to a website called USProbioticGuide.com. That outlines, in a very simple way, the levels of evidence for each strain that's been studied and for which conditions.

• 8:35Marielle Segarra?

  Okay. So what can people do, if anything, to try to optimize their gut microbiome?

• 8:44Speaker 02

  Yeah, the first place to start and how you can make the most difference by far isn't any special gut hack or magic solution. It's simple stuff that all of us already know we should be doing for our overall health. And that's because our gut microbiome evolved with us. And when we are healthy and thriving, so do our gut bacteria. Take a listen to Dr. Fergus Shanahan. He's at the National Institute of Ireland in Cork and a longtime researcher in gut health. Like, good sleep, plenty of exercise.

• 9:15Speaker 06

  Exercise, fresh air, good food, good food, meaning real food and not lots of low fiber, ultra processed foods. Your mother probably told you all these things in different language, but all the things you were ever told, they're all good for your microbiome as well. There isn't any need for some health guru to come along and say, oh, I've got some major potion now that's going to impugn your microbiome.

• 9:38Speaker 02

  Basically, he's like, the gut researchers don't have some secret that they've been keeping from us that we all should know. It's just not the case yet.

• 9:48Marielle Segarra?

  Any specifics that you learned about diet, what we should be eating?

• 9:52Speaker 02

  Yeah. Number one, without a doubt, fiber. And folks may have heard this, but most of us do not get enough fiber, just in the general kind of Western diet that most of us have. So you want to aim for anywhere from about 20 grams a day to 40, depending on your age and sex. 35 grams is a generally a good target. And it's not only the quantity of fiber, you want to make sure you're eating different types of fiber, because this diversity in your diet ends up really supporting the microbes in your gut. I spoke to Hannah Holsher about this, and here's the advice she gave.

• 10:26Speaker 07

  If you picture the rainbow of types of foods that you can eat, fruits, vegetables, whole grains, nuts and legumes, you're going to see all of these different colors of the rainbow. And that means these foods have different phytonutrients in them, and they have different fibers. And just like an apple tastes very different from an orange and tastes different from an avocado or broccoli, you know, they have different fibers in them and different phytonutrients and different microbes can go in and use those fibers as energy sources.

• 10:57Speaker 02

  Hannah has spent a lot of time doing well-controlled trials where they feed people different foods and then see how that can influence your gut microbiome. One example, they did a trial with walnuts and they found that it enriched a bacteria called roseburria, which is beneficial and linked to positive health. We do have some data showing that fermented food in particular can be pretty beneficial for lowering inflammation and overall

• 11:25Speaker 02

  Gut microbiome diversity in health. So these are things like sauerkraut, kimchi, yogurt. But you want to look and see whether the yogurt has live cultures of bacteria in it, not highly processed kinds of yogurt with sugar and that they don't actually have bacteria in it. Those are a couple of examples of like beneficial probiotics that you can get from your food.

• 11:49Marielle Segarra?

  Okay. And then is there anything that people should avoid to help their gut microbiome?

• 11:55Speaker 02

  Yeah, so probably no big surprise here unless you really need it. Antibiotics tend to be overused, over prescribed. So try to avoid those when not necessary. Beyond that, Hannah and others brought up some of the usual culprits we hear when we talk about other issues with our health. Foods like highly refined, sugary, that are low in fiber, sometimes called ultra-processed foods. You want to try to keep those to a minimum. And, you know, she's an advocate of moderation, you know, doesn't really think people need to be extreme here, but she says as much as you can. Unfortunately, alcohol is not great for our gut. And, you know, best to avoid that if you're concerned about supporting your gut microbiome.

• 12:39Marielle Segarra?

  Will Stone, thank you so much.

• 12:41Speaker 02

  Thanks for having me. It was fun.

• 12:47Marielle Segarra?

  All right, time for a recap. Don't bother spending money on a gut microbiome test. They overstate the science and they're way ahead of the evidence. Some probiotic supplements have been shown to help with particular problems like traveler's diarrhea and diarrhea associated with antibiotic use. But the idea that most people who are otherwise healthy should be taking a probiotic daily to support their gut health is not backed by science yet. We'll drop the names of a couple of strains that are well studied in the show notes. And you can also check out a website called USprobioticguide.com, which outlines the levels of evidence for each strain that's been studied and for which conditions. Now, the researchers who study the gut say the best thing you can do for your gut microbiome

• 13:31Marielle Segarra?

  is eat enough fiber a day. That's about 20 to 40 grams a day, depending on your age and sex. Eat fermented foods like kimchi and yogurt. Cut down on ultra-processed foods and alcohol. And only take antibiotics when you really need them. Also, get enough sleep and exercise.

• 13:52Marielle Segarra?

  All right, that's our show. By the way, your phone is full of distractions. Make sure it's full of good tips and practical advice, too. The NPR app gives you access to world-class reporting, like what we have on Life Kit, without a paywall. And with our push notifications, we'll keep you up to date to the second. Download the NPR app today.

• 14:13Marielle Segarra?

  This episode of Life Kit was produced by Margaret Serino. It was edited by Megan Cain, Carmel Roth, and Lauren Gonzalez. Our digital editor is Malika Gharid, and our visuals editor is CJ Riechel. Our production team also includes Andy Tako, Claire Marie Schneider, and Sylvie Douglas. Engineering support comes from Peter Alena. Fact checking by Andrea Lopez-Cruzado. I'm Mary El Segarra. Thanks for listening.

• 14:41Speaker 03

  Stay tuned for the following announcements and messages from our sponsors.

• 14:45Speaker 02

  This week on Up First, we're in the final days before the midterm elections. And this is one of the wonderful things about politics, one of the wonderful things about humanity. We have all this data, we have all this information, and nobody really knows what's gonna happen. We're gonna follow it day by day, through Election Day and beyond. And you can listen to Up First every morning on the NPR app or wherever you get your podcasts.

• 15:10Speaker 07

  Midlife brings a lot of changes. Your Turn with Alison Aubrey is a new podcast to help you navigate the twists and turns. From health and relationships to creativity and purpose, we can help steer your next chapter with Your Turn with Alison Aubrey. Find it on the NPR app or wherever you get your podcasts.