Prebiotic soda sugar and fiber levels raise questions about gut-health claims
A UNC analysis of 108 U.S. prebiotic sodas found about 5 grams each of sugar and fiber per can, complicating gut-health marketing claims.
By Tom Brennan · Health & Medicine Correspondent
3 min read
Prebiotic soda sugar fiber levels are closer than many shoppers may expect, according to a new analysis from researchers at the University of North Carolina at Chapel Hill. The findings matter because these drinks are often sold with gut-health messaging, while their overall nutrition profile can include sugars and nonnutritive sweeteners.
Carlos R. Soto Díaz, an MPH and Ph.D. candidate at UNC-Chapel Hill, said many products carry nutrition or function claims that can make them seem healthier than their labels show. He said some drinks advertise “no added sugar” while still containing about 10 grams of total sugars from ingredients such as juice.
Soto Díaz is scheduled to present the research at NUTRITION 2026, the American Society for Nutrition’s annual meeting, held July 25-28 in National Harbor, Maryland. He conducted the work with Lindsey Smith Taillie, a professor at UNC-Chapel Hill.
How much sugar and fiber is in prebiotic soda?
The researchers reviewed 108 prebiotic sodas introduced in the United States from 2021 through 2025, using the Mintel Global New Products Database. They defined the category as carbonated drinks that contain fiber and use “prebiotic” in the product name, package claims or ingredient lists.
On average, the drinks had about 35 calories, 5 grams of sugar and 5 grams of fiber in a 12-ounce, or 355 mL, can, according to the analysis. Their fiber content ranged from about 2 grams to 9 grams per can.
The team compared those products with regular sodas, diet sodas, fruit drinks and flavored sparkling waters launched over the same period. Prebiotic sodas had fewer calories and less sugar than regular soda and fruit drinks, but more than diet soda and flavored sparkling water, according to the researchers.
The category has grown quickly, with U.S. sales estimated at $777 million in 2025, according to the American Society for Nutrition’s summary of the research.
What does prebiotic mean on a soda label?
A prebiotic is an ingredient, often a type of fiber, intended to support beneficial gut microbes. In the U.S. market, the word “prebiotic” is not linked to a required minimum amount of fiber, according to the researchers.
That means shoppers cannot assume a soda provides a meaningful fiber dose just because it uses the term. Soto Díaz said certain prebiotic fibers have been associated with gut-health support, but it remains unclear whether the amounts found in these beverages provide meaningful benefits.
The analysis also found that nearly two-thirds of prebiotic sodas contained nonnutritive sweeteners such as stevia. For comparison, more than 90% of diet sodas used nonnutritive sweeteners, while the share was below 28% for fruit drinks, 16% for flavored sparkling waters and 12% for regular sodas.
Soto Díaz said consumers should read the Nutrition Facts panel rather than relying on front-of-package claims. He said any possible benefit should be weighed against calories, sugars and nonnutritive sweeteners.
The researchers said the value of switching to prebiotic soda depends on what a person usually drinks. Someone replacing sugary beverages could cut sugar and calories, while someone who normally chooses low- or no-calorie drinks may see less benefit.
The team also cautioned that sodas should not be treated as a main source of dietary fiber. The analysis did not report clinical testing of the drinks’ gut-health effects.
This story draws on original reporting from Medical Xpress.