(P03-018-23) Effects of Fermentable Fiber and Polyphenol Supplementation on Gastrointestinal Permeability and Symptoms Following Rapid Ascent to Simulated High Altitude

Objectives: Whether nutrition interventions affecting gastrointestinal (GI) health can mitigate increases in GI permeability (GP) and symptoms that may occur upon ascent to high terrestrial altitude (HA) is unknown. This study aimed to determine the effects of dietary supplementation with a blend of fiber and polyphenol sources on GP and GI symptoms following rapid ascent to simulated HA.

Methods: Healthy adults (n = 33, 21 ± 3 yr) participated in a randomized, double-blind, crossover study consisting of three 2-wk study phases separated by ≥1 wk. Two (week 1) and four (week 2) placebo (PL) or fermentable fiber- and polyphenol-containing (FP) snack bars were consumed daily during each phase. Each FP bar contained 1.25 g oligofructose-enriched inulin, 1.25 g galacto-oligosaccharide, 5 g high amylose corn starch, and ~500 mg gallic acid equivalents total phenolics from cocoa seed, green tea leaf, cranberry and blueberry. During the final 2 d of each phase participants resided in a hypobaric hypoxia chamber (~36hr) simulating low altitude (LA; 500 m) or HA (4300 m) to create three conditions: PL+LA, PL+HA, FP+HA. During chamber residence GP was measured by circulating LPS-binding protein (LBP) and 0-5 hr and 5-24 hr urinary sucralose (S) and erythritol (E) excretion. GI symptoms were measured throughout each phase using modified GI Quality of Life Index (GIQLI; range = 0 [severe symptoms] to 40 [no symptoms]) and Irritable Bowel Syndrome (IBS)-Symptom Severity Score questionnaires. Analyses included the 26 and 10 participants who completed ≥1 (modified intention-to-treat, mITT) and all 3 (complete case, CC) chamber residences, respectively.

Results: During HA, 0-5 hr S and E excretion (mITT and CC analyses) and the S:E ratio (CC analysis only) were 15-30% lower in FP versus PL (p < 0.05), while 5-24 hr measures and LBP did not differ. GIQLI scores were ~4 points (~12% ) lower during FP+HA than during both PL conditions (mITT and CC analyses; p < 0.05), but did not differ at other timepoints. IBS scores did not differ between conditions.

Conclusions: Findings suggest this fermentable fiber and polyphenol-rich intervention may reduce permeability within the small and proximal large intestine while marginally increasing GI symptoms following rapid ascent to HA.

Funding Sources: Supported by DHP JPC-5. Opinions expressed are those of the authors and do not reflect those of the United States Army.