A leading researcher shares the biggest misconceptions surrounding the gut microbiome and what’s necessary to support it.
Compared to other scientific research areas, the gut microbiome — the collection of microbes and their genetic material that lives in your G.I. tract — is still relatively young. And that means there are many more questions than there are answers, says Suzanne Devkota, Ph.D., an associate professor in the Cedars-Sinai Division of Gastroenterology and the director of the Cedars Human Microbiome Research Institute.
“A lot of microbiome research is a lot of associations: This microbe goes up when you have this disease,” says Devkota. “It's missing the deep science, the mechanistic ‘Why does it happen?’ That's the biggest gap. We probably know 10 percent, and the other 90 percent is in the mechanism. We don't know how this happens."
Despite the vast lack of knowledge on the topic, false claims continue to spread. Here, Devkota breaks down the biggest misconceptions people have about gut health — and what the current research actually shows.
Myth #1. You Can Have a Healthy Gut without Eating Vegetables.
According to Devkota, the “craziest” claim she hears time and again is that people who eat solely meat — not a lick of fiber-rich plant foods — have the healthiest guts. “I don't believe that for a second,” she says.
For one, your gut microbiome is as unique as a fingerprint, so the diet that seems to work best (read: reduces bloating, eases constipation) for one person isn’t necessarily going to have the same impact on the next, says Devkota.
The current research also disproves this idea. Gut microbes like dietary fiber, the indigestible part of plant-based foods, and as they break it down via bacterial fermentation, they create beneficial byproducts that keep your gut healthy, says Devkota. Essentially, you need to eat fiber-rich foods — whole grains, fruits, veggies, beans — to feed your gut microbiome, she notes.
With a carnivorous diet, “the gut microbiome probably becomes so simplified and so non-diverse, and diversity is a marker of health,” she explains. “The fundamental principle is the more diverse your diet is, the more diverse different kinds of bacteria you have, and that's what you want. So through eating one type of food, you're going to have like one type of bacteria. And so there's no way that that can ever be healthy in the long term.”
Your gut houses a plethora of different bacteria, many of which perform the same functions in your body. If you take an antibiotic or medication that wipes out an entire class of bacteria — but you eat a diverse diet — your gut will be equipped with another type of bacteria that can compensate in the meantime, explains Devkota. “The less diversity you have, you lose those compensatory abilities, so if you do something to your microbiome, you can completely lose the ability to do some important function” she adds. “You want a lot of redundancy in your gut, and the only way to do that is to have different kinds of bacteria.”
Myth #2. Sugar and Artificial Sweeteners Are Inherently Bad for Your Gut Microbiome.
Devkota often sees people claiming that sugar and all artificial sweeteners have a harmful effect on the gut microbiome — but that’s not entirely true, she says.
Sugar is absorbed high up in your G.I. tract, shortly after it makes its way through your stomach, she explains. But there aren’t many microbes in this part of your system. “Most of your microbes are in your colon, and sugar doesn't get absorbed in your colon,” says Devkota. “It’s likely that high-sugar diets don't have much impact on the gut microbiome, [though] they have an impact on our bodies — our pancreas and our liver.”
Artificial sweeteners are a bit more complex. There is some data suggesting they may negatively impact the gut microbiome. For instance, a 2021 study found that the artificial sweeteners saccharin, sucralose, and aspartame increased the pathogenicity (specifically, the ability of the bacteria to adhere to, invade, and kill gut epithelial cells) of model gut bacteria E. coli and E. faecalis. And a 2019 review of experimental studies and clinical trials found that saccharin and sucralose were the only artificial sweeteners to change the composition of gut microbiota. “There might be some impact, but there's a lot of dialogue around all artificial sweeteners being bad, bad, bad, but the data actually shows that there are differences between artificial sweeteners — some are worse than others,” says Devkota.
Researchers also haven’t yet found a mechanism to explain the reason why artificial sweeteners may have this effect, says Devkota. “Is it a direct effect, the artificial sweeteners getting all the way down there in the gut and the bugs are doing something with it?” she adds. “Or is it an indirect effect, where it's altering your metabolism and that changes the environment where the microbes live?”
Compounding the problem: There aren’t many other alternatives. Consuming high quantities of sugar is linked with diabetes and metabolic syndrome, and recently developed artificial sweeteners have been viewed as a healthier alternative to satisfy your sweet tooth. “Now, there’s data saying, ‘Oh, well, maybe artificial sweeteners are bad, too,’” says Devkota. “So what's the recommendation there? Go back to eating sugar? Often people make these claims that this is bad and this is good but give no recommendation or suggestion as to what to do then.”
Myth #3. You Need to Take a Probiotic or Prebiotic Supplement.
Probiotics — live microorganisms that are intended to have health benefits when consumed via food or supplements — have long been recommended to repopulate your gut microbiome, particularly after taking an antibiotic, says Devkota. But it wasn’t clear if they were truly beneficial, she adds.
In 2018, new research suggested that taking probiotics after an antibiotic can delay the normal recolonization of your gut, she says. In certain populations, taking a probiotic could cause an inflammatory reaction. “I actually don't recommend probiotics,” says Devkota. “I think there will be a future for them in terms of custom probiotics, tailored to the individual and what the individual actually needs, but we're not there yet.”
On the same token, prebiotic supplements aren’t necessary. Prebiotics are technically fibers that stimulate microorganism growth or activity. But Devkota and her colleagues define them as anything you eat that can alter the microbiome in a favorable way, coaxing the probiotics you have naturally living in your gut to become more abundant. “For prebiotics, that's just eating whole foods, eating a diversity of foods,” she explains. “There's no real pill you need to take. People want to make it rocket science, but it really isn't.”
Postbiotics are the metabolites that bacteria produce in response to prebiotics, says Devkota. “They’re taken up by your gut cells, going into your body, interacting with your immune cells in a positive way,” she says. “It's like a local bioreactor, and that's the system you want to support.”
Some companies have tried to isolate postbiotics and deliver them via a pill, and while there is some legitimacy to it, some of the supplements simply don’t work, she notes. “Sometimes you actually need that reaction to occur natively in the gut — you can’t just give it a postbiotic,” says Devkota. “We're still trying to understand, scientifically, which products can be delivered orally and which ones need to be produced locally in the gut. We don't have all the answers, but I do think that the products that the bacteria produce are more important than the bacteria themselves.”
The Bottom Line
Despite the claims you hear on the internet and in your social circle, supporting your gut health doesn’t need to be so complicated, despite it being one of the most complex organs in your body, says Devkota. “The reality is that what you put in your mouth goes into your gut. And that's the thing your gut was adapted to do: to break down food and metabolize what you eat and your gut evolved with these bugs to be the most efficient it can be to do that process.”
To care for your microbiome, simply eat a diverse diet, with plenty of fermented foods (which are rich in postbiotics), and stay on top of your fiber intake, aiming to consume at least 25 grams a day, says Devkota. Also important: Listening to your body. “I think we all know that if we have a bad gut day, it can affect our whole day, our whole mood,” she adds. “I think people are actually kind of naturally pretty in tune with their gut and they know when something's off or when something's working.”