A Gastroenterologist’s Take on Gut-Health Myths

Search #guthealth on social media and you’ll find millions of posts from people promising to fix bloating, repair your microbiome and more. And while you might find some posts from actual experts on the topic, many are from creators on social media claiming to be gut-health experts. With so much content out there, it can be hard to tell what’s fact or fiction. 

To clear up some of these trending topics and claims, we spoke with Will Bulsiewicz, M.D., MSCI, aka Dr. B—a renowned gastroenterologist and author. In this exclusive interview, we asked him to weigh in on several gut-health trends to help us separate myth from reality. Read on for his take on everything from castor oil to probiotic sodas.  

EatingWell: Lots of people turn to social media for advice on all sorts of medical conditions. Do you think this is helpful or harmful for folks looking to learn more about gut health? 

Dr. B: Am I allowed to say both? I think it’s a little bit of both. I do believe that access to information is at an all-time high and there is value to that. The challenge is that there’s so much information and there’s no gatekeeping whatsoever on it. Many times we assign expertise or respect for an opinion based upon how many followers an individual has, which can be rather disconnected from actual qualifications and expertise. So this is how we get ourselves into a little bit of a mess. And [social media] algorithms quite clearly prioritize controversy. It’s wonderful that we have access to this information so that you can learn and be empowered. That’s the beauty of it. But we also have a personal responsibility to curate our experts and not accept everything that we hear as the truth.

EatingWell: OK, so let’s dig into some of the common themes we see on social media when people talk about gut health. First up, apple-cider vinegar: fact or fiction?  

Dr. B: Mostly fact, but a little bit of excessive hype. So when you get apple-cider vinegar with the mother [existing living bacteria from previous fermentations], it is a fermented food. [Not all apple-cider vinegar is sold that way.] A study out of Stanford University showed that adding fermented food to our diet can actually enhance the diversity within our gut microbiome. So I like to start my morning with a tall glass of water with a splash of apple-cider vinegar. Not so much that it’s really acidic, but just enough so that I can taste it.

EatingWell: OK, next topic: castor oil. Fact or fiction?  

Dr. B: Oh dear. I’m going to go with fiction on this. I believe we have an epidemic of constipation in the United States. I think that there are a lot of people who don’t even realize that they’re constipated, and that’s the reason why they get bloated every time they eat. And people are trying to address their constipation by consuming castor oil or other remedies. But I think that we can find better ways to relieve constipation, and I don’t think castor oil should be our main strategy.

EatingWell: So what about prebiotic sodas: fact or fiction?

Dr. B:  I’m going with fiction. Here’s the reason why: you absolutely can enjoy carbonated beverages—I do myself—and you absolutely can take prebiotic supplements if you want to or get your prebiotics from diet or both.

But to me, the idea of paying a substantial amount of money for a soda that basically is just a carbonated drink with an added supplement inside of it is a little bit silly, particularly because of the forms of fiber that they use. The [fiber in the] prebiotic sodas are often the types that produce the most gas. And when you combine that with carbonation, you’re setting yourself up for bloating in a bad way. There’s better ways to get our prebiotics.

Don’t get me wrong, I want to address the fiber crisis that we have in the United States where 95% of people are deficient in fiber. But drinking two or three cans of prebiotic soda per day is not the way that we should be addressing this.

EatingWell: Let’s talk about fasting: fact or fiction? 

Dr. B: I’m going to say [fasting is] mostly fact. Sometimes the claims get a little bit out of control as if it’s going to cure all of our problems and it’s not. But fasting—specifically time-restricted eating—can be a strategy that allows us to take some control over the way that we consume our food during the day. I feel like the modern approach of just kind of eating around the clock has taken us away from that. We do know that when people follow a time-restricted eating dietary pattern, it helps them to control their caloric intake. So when you achieve energy balance, there are benefits that come from that.

I think that the other thing about time-restricted eating is that there’s a fixation on the number of hours [you should fast]. What is the magic number of hours? I think an intuitive approach is absolutely the right way to handle that. But the more important part (from my perspective) is the understanding that your ability to metabolize food actually is different at different times during the day. And it’s the worst that it’s going to be late in the day. So really, it’s more of an argument for not having late-night snacks, not having late-night alcohol and giving your body a break when the sun goes down, like after about 8 p.m. 

EatingWell: There’s a lot of buzz around probiotic supplements. What do you think about them? 

Dr. B:  I’m going to go with fact, when appropriately used. The issue that I take as a gastroenterologist is that the marketing by probiotic supplement companies would lead you to believe that the solution to gut-health problems is with a probiotic. And I don’t believe that to be true. That being said, I have seen thousands of patients who take a probiotic because they have digestive health problems, and they may improve those digestive health problems. But that should not be the principal approach to addressing those issues.

We really need to start with a food-first approach, and focus on diet and lifestyle. Get those things aligned, and supplements can help us to achieve our goals. They can be a part of that equation, but they should not be the primary approach that we take. 

To me, one of the big questions that exists is prebiotics versus probiotics. Prebiotics are food for the microbiome. Probiotics are living microbes that have been proven to be beneficial for humans. And the message that I would love to get across to people is that I favor prebiotic [supplements] because you already have the probiotics living inside you and when you take a probiotic capsule, you just don’t know whether that’s going to work at all for your unique microbiome. But when you take prebiotics, whether that be in food or in a supplement, it’s definitely going to feed the bacteria and enrich the probiotics that you have living inside you already.

The Bottom Line 

We couldn’t agree more with Dr. B about how a food-first approach that is intuitive and aligns with your lifestyle is the best way to support a healthier gut. And remember, little changes—like staying hydrated or trying to eat your last meal of the day a little earlier—can really add up with time. If a trend on social media (like castor oil) feels too good to be true, the chances are it probably is. Instead, focusing on science-backed tips like eating a greater variety of plants and including fermented foods, is a better bet. 

Editor’s Note: This interview has been edited for clarity and length.