Researchers conducted the randomized, double-blind, placebo-controlled trial to test how Nutriose, Roquette’s branded, soluble dietary fiber supplement, affected the gut microbiota of 124 healthy adult men aged 18–60 with either low or high habitual fiber intake.
The study found that Nutriose was effective at modulating the gut microbiota, with a particularly pronounced effect in the high fiber group.
“These results further document the potential of prebiotic supplementation with a soluble fiber to shape the gut microbiota as part of a preventive strategy to promote health,” they wrote in the journal Frontiers in Nutrition.
Fibermaxxing trend highlights growing awareness of widespread fiber deficiency
Dietary fibers are notoriously under-consumed across high-income countries, and low fiber intake contributes to metabolic, cardiovascular, gastrointestinal and mental health issues, largely through its effects on the gut microbiota.
Despite new trends and social media movements to ‘fibermax’, people often fail to meet fiber needs. Soluble fiber supplements, e.g., resistant dextrins (RDs) like Nutriose, can often be used to address the fiber gap.
Previous research shows that RD supplementation can increase beneficial bacteria like Lactobacilli and Bacteroides, raise enzyme activity linked to carbohydrate breakdown, lower fecal pH, and reduce harmful bacteria such as Clostridium perfringens. RD intake has also been linked to improved blood glucose control, better satiety, improved digestion and steadier energy release.
“Several studies have further confirmed the health benefits of RD driven by microbiota shifts in blood glucose management, satiety, digestive health, and sustained energy release,” the researchers wrote. “Collectively, these results show that RD meets the ISAPP requirements for defining a prebiotic, i.e., “a substrate that is selectively utilized by host microorganisms conferring a health benefit”, susceptible to claim for various health benefits.”
They set out to determine whether the effects of RD on gut microbiota depend on a person’s baseline dietary fiber intake.
High-fiber diet enhances response to Nutriose supplement
The researchers classified participants into low-fiber (≤15 g/day) or high-fiber (≥25 g/day) groups using food diaries and then randomly assigned them to receive either 15 g/day of Nutriose or a placebo for four weeks. Participants maintained their usual diet and lifestyle, recorded bowel habits and provided stool samples before, during and after the intervention, followed by a two-week washout period.
The researchers analyzed stool samples to measure changes in microbiota composition and function, including short-chain fatty acids, pH, immune markers and microbial diversity. They focused on changes in the abundance of the genus Parabacteroides as the primary outcome, while also examining other bacterial groups and metabolic markers.
After four weeks of supplementation, Nutriose caused an increase in the abundance of Parabacteroides, rising from about 1.4% at baseline to 5.5% at the end of treatment. No change occurred in the placebo group, and levels returned to baseline after the two-week washout. This effect appeared in both high- and low-fiber groups but was slightly stronger in high-fiber participants.
Nutriose also increased specific Parabacteroides species (especially P. distasonis) and shifted other bacterial groups, with some increases and decreases across members of the Bacillota phylum. However, most of these microbial changes were transient and disappeared after supplementation stopped.
Nutriose also altered gut microbial function by increasing genes linked to carbohydrate breakdown, particularly in high-fiber participants.
“Supplementation with RD is not just about increasing the global amount of fiber ingested; it provides a specific quality of fiber that results in modifying the microbiota from a taxonomic and functional perspective,” the researchers wrote.
They also noted that baseline fiber intake matters, as while both high- and low-fiber groups responded to RD, participants who already consumed more fiber show stronger and more frequent microbiota changes.
“This study provides evidence that supplementation with RD stimulates the Parabacteroides genus within the gut microbiota, no matter the level of dietary fiber intake, but with a stronger effect shown in high fiber consumers,” the researchers concluded.
They added that the study included only healthy men, relied on self-reported fiber intake, did not distinguish fiber types, and used maltodextrin as a placebo that may have minor microbiota effects, suggesting next steps for future research.
Source: Frontiers in Nutrition. doi: 10.3389/fnut.2026.1810842. “Resistant dextrin promotes beneficial fecal bacteria in high and low fiber diet populations: a randomized, double-blinded, controlled pilot study.” Authors: Perreau, C. et al.
