(P19-037-25) The Impact of Yeast Mannan Supplementation on Microbial Diversity and Short Chain Fatty Acids

Objectives: This analysis tests the effect of a potential prebiotic yeast mannan preparation on gut microbial diversity and selected fecal metabolites in healthy older adults.

Methods: This is a secondary analysis of a 3-week open-label trial of yeast mannan (ManOliSa®) in adults over 50; comparing stool samples from baseline and intervention. Fecal metabolites were measured by LC-MS/MS. Stool DNA from the same samples was processed by V3V4 amplicon sequencing and reads by DADA2 in QIIME2. Alpha diversity was calculated using the Shannon diversity and baseline vs. intervention was compared by paired t-tests. Beta-diversity was assessed using the Bray-Curtis index, and baseline vs. intervention compared using adonis2. Alpha diversity and fecal metabolite level correlation were assessed with Spearman’s. Selected fecal metabolites were compared between baseline and intervention with paired t-tests. Differences in beta-diversity (Bray-Curtis) by fecal metabolites were completed separately for baseline and intervention using adonis2.

Results: Yeast mannan supplementation showed no differences in alpha or beta diversity between baseline and intervention. Metabolites identified were similar at both time points, without significant correlation with alpha diversity (number of taxa). However, beta diversity (identity of taxa observed) at baseline was found significantly correlated to fecal metabolites (p=0.003), with butyric acid (p=0.047), indolelactic acid (p=0.016), isovaleric acid (p=0.028), and lactic acid (p=0.046) showing significant associations. During the intervention, significant correlations were also identified for these parameters (p=0.038), with lactic acid (p=0.043) and malonic acid (p=0.038) significantly associated with beta diversity.

Conclusions: As yeast mannan, thought to be consumed only by specific taxa, may exhibit a precision prebiotic effect, it did not disrupt alpha or beta diversity of the microbiota of generally healthy older adults. However, supplementation may have changed the specific components of beta diversity associated with fecal metabolites.

Funding Sources: Lallemand Bio-Ingredients, a division of Danstar Ferment A.G. and the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS).