Short-chain oat fiber improves gastrointestinal tolerance and regulates glucose metabolism: a two-week open-label study in healthy adults.

Introduction: Fiber intake is the most common nutritional inadequacy in the Western diet, with most adults consuming less than half of the recommended intake and only 5% meeting the RDI. A novel, short-chain β-glucan derived from oats (scOat fiber), with improved solubility, low viscosity and enhanced palatability compared to conventional oat fibers, was investigated for its benefits as a source of fiber supplementation. Methods: A 14-day pilot study evaluated the gastrointestinal tolerance and functional benefits of scOat fiber in 63 healthy adults assigned to receive 5, 10 or 20 g daily doses. The primary outcome, gastrointestinal tolerability, was assessed using the Gastrointestinal Symptom Rating Scale (GSRS). Secondary outcome included glycemic response during rice challenges, evaluated in a subgroup of 38 participants using continuous glucose monitoring (CGM). CGM was also used to explore overall glucose dynamics. Additional exploratory outcomes (mood, energy, appetite and sleep) were assessed via validated questionnaires. Results: scOat fiber was exceptionally well tolerated across all doses, with no increase in GSRS scores, which remained in the low to mild range. Significant reductions in total GSRS scores were observed, with benefits evident after 1 week at 5 g/day and maintained over time at both 5 and 10 g/day groups. Evaluation of GSRS sub-categories revealed that the 5 g/day and 10 g/day dose groups experienced significant reductions in abdominal pain symptoms. Both dose groups also demonstrated a significant decrease in constipation at the end of the study. Postprandial glucose responses were attenuated following product use, with a significant reduction in peak glucose during rice challenges after 2 weeks in the 20 g/day group. Both 10 and 20 g/day doses were associated with significant improvement in glycemic metrics, including reductions in glucose mean, all glycemic excursions, and an increase in time-in-range. Exploratory analysis suggested that scOat Fiber may improve mental health and concentration in participants with elevated baseline symptoms. Conclusion: Despite the lack of a placebo control and short duration, the dose-dependent nature of the results supports the potential of scOat Fiber as a well-tolerated and functional source of fiber with benefits including glycemic control, digestive health and mental health. Clinical trial registration: https://clinicaltrials.gov/study/NCT06739941, Identifier: NCT06739941.