Why Prebiotics May Do Your Gut Health More Harm Than Good

Photo: Thinkstock/Lprogressman
When it comes to living your healthiest life ever, the conversation always seems to come back to gut health. Besides the obvious digestive-related problems that can spring up when your microbiome's out of balance (from annoying bloating to more serious leaky gut or irritable bowel syndrome), it's also linked to your mood, immunity, and preventing serious diseases.

But while the, er, gut instinct might be to do everything you can to make your microbiome happy by loading up on probiotics, prebiotics, and fiber, it turns out there can be too much of a good thing.

Here's the thing: Probiotics and prebiotics sound similar, but they're completely different (confusing, I know). What makes it even more confusing is that the scientific community hasn't agreed upon one set definition of what they are.

Probiotics are live bacteria that help keep your gut in balance by staving off harmful bacteria that may reside there. And according to Nick Bitz, a licensed, board-certified naturopathic doctor and the supplement brand Youtheory’s chief scientific officer, prebiotics (short for prebiotic fiber) are non-digestible carbohydrates that the bacteria in the large intestine break down into small-chain fatty acids. In layman's terms: "Prebiotics feed all the bacteria and the cells that line the intestinal track and giving them food for energy," Dr. Bitz says. But the The Scientific Association for Probiotics and Prebiotics specifies that the bacteria must target good bacteria in the gut to be considered a prebiotic.

On the surface, therefore, it seems like using prebiotics to feed the probiotics in your digestive tract would be the key to finding gut-health harmony. But, as Dr. Bitz points out, that's not exactly how it works.

Keep reading to see why you might want to proceed with caution when taking prebiotics.

Why prebiotics may harm your gut
Photo: Stocksy/Margaret Vincent

Why prebiotics could harm your gut health

The downside to prebiotics, Dr. Bitz says, is that they feed both the good and bad bacteria in your system.

The Probiotic Cure author and Healthy by Nature radio host Martie Whittekin, CCN, agrees. "Prebiotics increase the amount of bacteria," in your gut, she says, "but not the diversity, which is really what you want. Having a diversity of bacteria in the gut is important because the various strains all do something different for the body."

"Studies do show that prebiotics increase the flora in the gut, but there haven't been any studies that show the benefits of that change," Dr. Bitz says. "So you may be changing the [makeup in your gut], but what's it really doing for you?"

Both experts say that prebiotics can actually cause gas and bloating—two symptoms that may lead you to turn to prebiotics in the first place.

not all prebiotics are the same
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Not all prebiotics are created equal

Before you jump to the conclusion that all prebiotics are bad, Raja Dhir, the co-founder and co-CEO of the new microbiome startup Seed, launching next month, says not all prebiotics are the same. "One of the most exciting new developments in microbiome research is looking at novel non-fermentable prebiotics and how they are converted into health-promoting compounds (metabolites) by the gut microbiota," he says.

This new class of prebiotics unfortunately doesn't include fermentable prebiotics like FOS, GOS, and inulin, which are the most common ones you'll see on labels when supplement shopping. Instead, Dhir says, keep an eye out for dietary polyphenols.

prebiotic capsule
Photo: Twenty20/Byunio

The key to giving your gut some support

So what do you do? Whittekin says to focus on the variety of bacteria strains to really up the diversity in the gut. Dr. Bitz agrees doing this—through probiotics—is a good route to take, but recommends doing it slowly. "I don't like this canned approach of throwing everything we can into a supplement, take it every day, cross our fingers, and hope we get better," he says.

"Start with a probiotic with one strain," Dr. Bitz recommends instead. "Slowly ramp up and see how your body does with just with that. Then, add layers one by one and see how you react." He adds that taking the same approach when adding fiber to your diet is a wise, too, rather than drastically and suddenly upping your veggie intake.

This is one relationship where moving slowly is key. And when you do, hopefully you and your gut will live happily ever after.

FYI: There are other causes of bloating besides food. And here's how to calm your gut in less than 5 minutes.

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