A Diverse Fiber Mixture, Reflective of a Nutritionally Balanced Diet, Is Well Tolerated by Healthy Adults

Adequate fiber intake is associated with health benefits and reduced disease risk. It is hypothesized that consuming a mixture of fiber types with distinct (physico)chemical characteristics, reflective of those naturally present in a nutritionally balanced diet, may help bridge the known "fiber gap" in many populations. However, good gastrointestinal (GI) tolerance of such a mixture of fiber types is essential to reach adequate fiber intake.

To evaluate GI tolerance of a diverse fiber mixture in healthy adults.

In an open-label, single-arm, single-center study, healthy adults (45‒69 y) consumed 6 g/d of a diverse fiber mixture (FM) (2 × 3 g/d) for 4 wk alongside their habitual diet. FM comprised arabinoxylan, β-glucan, pectin, and resistant starch in proportions similar to those typically consumed in a nutritionally balanced diet. GI tolerance symptoms were assessed weekly using the Gastrointestinal Symptom Rating Scale (GSRS), along with fecal transit type and frequency, digestion-associated quality of life [Digestion Associated Quality of Life Questionnaire (DQLQ)], compliance, safety, and dietary intake.

Of 41 enrolled participants, 38 participants completed the study without major protocol deviations. Changes in GSRS dimensions remained below their respective minimal important differences, a measure of clinical relevance, except for the indigestion dimension from baseline to week 1, with a least-square mean and standard error of 0.4 ± 0.2, where the upper 95% confidence interval (0.0, 0.7) reached the minimal important differences of 0.7. GSRS scores remained otherwise stable over time. Weekly fecal frequency significantly increased from baseline to week 1 with least-square mean ± standard error of 1.4 ± 0.4 and 95% confidence interval (0.5, 2.3). No significant changes were observed in fecal frequency (week 4), fecal transit type, and the digestion-associated quality of life questionnaire.

Daily consumption of 6 g FM for 4 wk was well tolerated by healthy adults.This trial was registered at clinicaltrials.gov as NCT06115057.