Soluble Oat Fiber Demonstrates Low GI Side Effects in Clinical Trial

A new clinical study published in Frontiers in Nutrition evaluates the gastrointestinal (GI) tolerance and metabolic impacts of a novel, depolymerized short-chain oat fiber (scOat fiber) in healthy adults.¹ For nutraceutical manufacturers navigating the technical challenges of standard fiber inclusion, such as high viscosity, grittiness, and poor digestive tolerance, the trial results may offer a highly soluble, functional alternative.

"Existing fiber supplements aren't good enough,” explains Matt Amicucci, PhD, Cofounder and Chief Science Officer of one.bio, the manufacturer of the oat fiber used in the study.² “They taste and feel bad. one.bio's 01 fiber is flavorless, scentless, colorless, water-soluble, and gentle on the gut. It's an 'invisible' functional fiber that removes a huge barrier to not just getting more fiber in people's diets, but getting more of the right fiber for the desired health goal."

What Are the Main Findings?

The 14-day, prospective, open-label trial evaluated 63 healthy adult participants distributed across three daily oral dosing groups: 5 g, 10 g, and 20 g of scOat fiber (commercially manufactured as one.bio Oat Fiber). The primary objective was to evaluate GI tolerability via the Gastrointestinal Symptom Rating Scale (GSRS). Secondary and exploratory endpoints included continuous glucose monitoring (CGM) to track glycemic responses during standard rice challenges and standardized questionnaires to measure changes in mood, appetite, energy, and sleep.

The study demonstrated significant GI tolerability across all tested doses.

• Total GSRS scores did not increase and remained in the low to mild range throughout the 14-day period.
• The 5 g/day and 10 g/day groups experienced significant reductions in total GSRS scores, which were observed after one week and maintained through the end of the study.
• Sub-category analysis revealed significant decreases in both abdominal pain and constipation within the 5 g/day and 10 g/day cohorts.

Regarding metabolic benefits, the fiber modulated glucose dynamics.

• A subgroup of 38 participants monitored via CGM demonstrated reduced postprandial glucose responses. The 20 g/day cohort experienced a significant reduction in peak glucose levels during the post-supplementation rice challenges.
• Both the 10 g/day and 20 g/day doses correlated with distinct improvements in glycemic metrics, yielding lower mean glucose levels, fewer glycemic excursions, and increased overall time-in-range.
• Exploratory data also suggested potential improvements in concentration and mental health among participants presenting who had elevated baseline symptoms.

Overall, the researchers highlighted that the oat fiber’s tolerability at high doses offered potential in formulations that include fiber, and noted the potential to address the “fiber gap” in Western diets. “Given the global underconsumption of fiber and its implication in health, the development of tolerable and functional fibers represents a significant opportunity to improve public health,” they concluded.

What Are the Study Limitations?

While the results are promising, several limitations must be noted for an objective assessment:

• Study Structure: The trial used an open-label, non-randomized design and lacked a parallel placebo control group, which limits the ability to rule out potential placebo effects.
• Duration: The 14-day study period represents a short duration, meaning long-term safety, tolerance, and metabolic efficacy profiles require further verification.
• Sample Size: The small sample size (63 total participants, with only 38 included in the CGM glycemic subgroup) warrants larger, powered validation trials.

What Are the Implications for the Nutraceutical Industry?

For supplement and functional food manufacturers, this research addresses an obstacle in fiber product development. Traditional oat β-glucans form highly viscous gels that disrupt the mouthfeel and stability of ready-to-drink beverages and liquid formulations. Conversely, alternative prebiotic fibers like inulin frequently trigger undesirable GI side effects, such as bloating, gas, and abdominal pain, at functional doses.

"Even though it would be ideal for everyone to get their fiber entirely from whole foods, it's often unmanageable. one.bio is providing a gut-friendly, extremely practical option that works with, not against, the modern lifestyles of people desperate for a solution they can stick to,” Amicucci stated.

This article was created with assistance from AI. The content has been reviewed and edited by Erin McEvoy, Associate Editor. For more information on the extent and nature of AI usage, please contact us.

References

1. Marcobal AM, Ng KM, Drexler RA, McConnell BR, Amicucci MJ. Short-chain oat fiber improves gastrointestinal tolerance and regulates glucose metabolism: a two-week open-label study in healthy adults. Front Nutr. 2026;13:1745303. doi:10.3389/fnut.2026.1745303
2. one.bio. one.bio Soundbites. Accessed June 12, 2026. https://cdn.prod.website-files.com/6976593539125ff397b2be9a/6a2a6bb7514df6df3fac6f64_one.bio%20Soundbites_26.pdf