Are Prebiotic Sodas Really Good for Your Gut?

Research suggests fiber additives in functional foods may harm some people’s health.

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Kristina Telhami started drinking prebiotic sodas because she thought they were tasty and healthy for her gut health.

“I figured, ‘Oh my gosh, it’s not soda. It must be healthier. It has prebiotics, and it’s marketed as gut healthy,’” she told The Epoch Times. “I think the marketing got to me at the time.”

Prebiotics come from fiber, which is food for the microbes that live in our gut. Telhami inadvertently put the product to the test on herself, drinking one prebiotic soda nearly every day. Eventually, she realized corresponding bloating and other uncomfortable gastrointestinal (GI) symptoms were related to her new habit.

Once Telhami quit drinking the trendy beverage, her gut calmed down. Formerly a pharmacist, she is now a functional medicine specialist and integrative health practitioner, and she warns her clients that prebiotic sodas aren’t for everyone. She said she’s had many miserable clients who think they are increasing their fiber in a healthy way by drinking them and eventually realize they may be causing or exacerbating GI problems.

Prebiotic sodas typically have 2 to 9 grams of fiber per serving, often sourced from inulin, a plant-based fiber that gels and slows digestion. Fiber has a complex relationship with gut health and is often believed to be universally safe and good for digestion, though, for some, it can worsen GI symptoms.

‘Gut Pop’ Popularity

Besides being low in “net carbs,” meaning fiber offsets sugar, prebiotic sodas are low in sugar, with 2 to 5 grams per serving. Compare that to the about 40 grams of sugar in a 12-ounce soda. The American Heart Association recommends no more than 25 grams of sugar for women and 36 grams for men daily. For perspective, a 12-ounce Coke contains 39 grams of sugar—the equivalent of nearly 10 teaspoons.

Telhami isn’t the only one attracted to prebiotic sodas as an alternative to typical ones. The U.S. probiotic and prebiotic soda market is expected to grow 8.2 percent to reach $766.1 million in 2030, attributed to consumers wanting functional beverages for better immune function, digestion, and overall well-being.

Whether the drinks have true benefits is muddied. Poppi—a prebiotic soda made of inulin, fruit juice, and apple cider vinegar with 5 grams or less of sugar—is settling a combined lawsuit for misleading gut-healthy claims. Still, PepsiCo, Inc. announced on March 17 that it is acquiring poppi for $1.95 billion.

“Everything that’s marketed as healthy or low-sugar or zero-sugar or prebiotic does not mean it’s healthy,” Telhami said. “They’re just marketing it really well.”

The Epoch Times reached out to poppi and Olipop, the leading prebiotic soda brands, to ask about the research that goes into creating their sodas. Neither responded before publication.

Olipop devotes a section on its website to digestive health, saying it aims to help consumers increase fiber with its blend of chicory root inulin, cassava root fiber, Jerusalem artichoke inulin, acacia fiber, and guar fiber.

“Sure, we could have used just one prebiotic fiber in OLISMART, but the reason we use three in each blend is because different bacterial species in your gut like different foods, so OLISMART aims to feed a diverse population of microbes with these different prebiotics,” the company wrote.

Inulin as an Additive

Inulin is naturally found in fruits and vegetables such as bananas, asparagus, chicory root, leeks, onions, wheat, and Jerusalem artichokes. It’s also gained popularity as an additive to health foods, often marketed as gut-healthy. It’s added to some dairy products, used as a sweetener substitute in baking recipes, and suggested for coffee, tea, and smoothies for a smoother texture and fiber boost.

As an additive, inulin is refined through various methods, such as being heated, cooked, dried, or ground into a concentrated form. Prebiotic sodas and many other foods are enriched with inulin, usually chicory root, which is particularly rich in fiber and affordable.

Adding inulin to processed foods is similar to efforts in the 1940s to “enrich” flour and bread with vitamins and iron to assist people with nutrient deficiencies in meeting daily requirements—particularly if they were mainly eating processed foods.

Americans fall far short on fiber. The federal government recommends eating about 28 grams of fiber daily as part of a 2,000-calorie diet. The most recent national data revealed that Americans are getting an average of 8.1 grams of fiber for every 1,000 calories or 16.2 grams for a 2000-calorie daily diet.

However, Telhami is bothered by the idea that we would address our fiber shortage crisis through sodas.

“I just recommend people don’t get these prebiotic fibers and prebiotic-rich foods from processed foods in general,” she said. “Also, too much fiber isn’t good for you. Some people are overdoing their fiber. Everybody processes fiber differently. Sometimes, fiber can constipate you. It’s really about finding a balance that works for you.”

Inulin is a fructan, a type of FODMAP, an acronym for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are short-chain carbohydrates poorly absorbed by the small intestine.

Some people may have fructan intolerance caused by an imbalance of gut microbes, including a lack of bacteria able to digest carbohydrates. That can cause excessive fermentation in the gut, causing gas, bloating, pain, and changes in bowel movements, such as diarrhea or constipation.

Unique Fiber Reactions

Some experts are concerned that inulin added to food or taken as a supplement could be feeding both good and bad microbes and that boosting inulin doesn’t offer a one-size-fits-all fix to America’s fiber shortfall.

One study, published in Cell Host and Microbe, on dietary fiber supplementation found that inulin increased the healthy bacteria Bifidobacterium—though at a high dose of 30 grams. It was also associated with increased inflammation. Three trial participants had to stop taking inulin when liver enzymes rose to dangerous levels, raising concerns of cholestasis—impairment in the flow of bile from the liver.

Two other types of fiber—another single fiber source and a mix of fibers—were also tested in the study. All 18 participants had unique responses to each type of fiber, though overall microbiome diversity fell during fiber supplementation. A diverse microbiome is associated with better health.

“Overall, our findings show the benefits of fiber are dependent on fiber type, dose, and participant—a landscape of factors resulting from interactions between fiber, the gut microbiome, and host. These results have important implications in personalized response and interventions,” the authors wrote.

Telhami said that anyone dealing with gut issues is better off refraining from prebiotic sodas, and carbonation in general, which can also cause GI discomfort. Though lower in sugar than traditional sodas, prebiotic sodas may also contain sugar and other ingredients that could irritate gut health.

It’s best to get fiber from including fruits and vegetables in your diet, she said.

“Do I think you can have them on occasion? Absolutely. Having them once in a while is great, but I don’t think people should be drinking them every day and specifically for gut health purposes,” Telhami said.

Cancer Concern?

Inulin expert Andrew Gewirtz heard of prebiotic sodas only a few weeks ago at a conference, yet he has concerns beyond just uncomfortable GI issues.

A biomedical science professor at Georgia State University, he began studying inulin in mice, convinced of the benefits of fiber supplementation. He told The Epoch Times that an early study found considerable benefits, particularly in mice fed an obesogenic diet—that is, a diet that mimics eating fast food, sugary drinks, unhealthy fats, and added sugars.

However, the mice on the obesogenic diet began to develop cholestatic liver cancer, reported in a follow-up study. Genetic defects were ruled out, Gewirtz said. Further research revealed that mice with colitis—GI inflammation that can cause pain, diarrhea, cramping, and rectal bleeding— were vulnerable to worsened symptoms with inulin in their diet.

A few reasons why inulin may be problematic for some, he suggested, include:

• A diet that’s generally unhealthy. Mice fed a standard diet didn’t get sick.
• The individual’s gut microbiota. They may not have the right mix of bacteria to digest the fibers.
• Immune system makeup. Inulin may dampen the immune system, which would benefit some conditions such as chronic inflammatory diseases, while being harmful if someone has colon polyps.

“Inulin will certainly be utilized by intestinal bacteria, but the outcomes may not always be beneficial,” Gewirtz said. “The short message would be that using these prebiotic fibers could be a powerful means to improve health, but it needs to be done carefully, and it could have negative consequences, too.”

A Cautionary Tale

Lowell Parker said he believes inulin led to his developing colon cancer. Parker had no known family history of any cancer, ate a diet rich in organic vegetables, and had no risk factors such as obesity, tobacco, or alcohol use. He had a clear colonoscopy at age 57 and returned for another in seven years to learn he’d developed a 4- to 5-centimeter tumor.

The only change he had made was taking one tablespoon of inulin with his coffee two years before his second colonoscopy.

“I thought I was doing something good for my body,” Parker told The Epoch Times. “I knew it was acting directly on my colon because there was a period of time when in the afternoon I’d have a lot of gas. I thought, ‘OK, it’s doing what it’s supposed to do. It’s being fermented in the colon by native bacteria that live there, and that’s all great and wonderful for you.’”

Gewirtz and other researchers wrote about Parker’s situation in a case study published in Gastro Hep Advances. The authors wrote that while Parker’s cancer could be unrelated to inulin, it’s concerning enough to warrant more research and a consumer warning that it’s best to get fiber directly from food sources and not in refined states.

Having an occasional prebiotic soda is unlikely to be harmful, Gewirtz said, adding that it’s not a great idea to drink them as a means to promote your health.

“I’m not declaring them dangerous, but I’m just not confident and comfortable that they’re harmless,” he said. “I think if you’re drinking these, you might be basically becoming an experiment.”