Effects of Yeast Mannan Which Promotes Beneficial Bacteroides on the Intestinal Environment and Skin Condition: A Randomized, Double-Blind, Placebo-Controlled Study.

Reiko Tanihiro,Kohji Ohki,Chikako Nakamura,Hiroshi Sugiyama,Katsuhisa Sakano,Shunsuke Oba,Shukuko Ebihara,Tatsuhiko Hirota,Yasunori Nakamura

doi:10.3390/nu12123673

Abstract

Yeast mannan (YM) is an indigestible water-soluble polysaccharide of the yeast cell wall. In vitro fecal fermentation studies showed that YM could exhibit a notable prebiotic effect. The aim of this randomized, double-blind, placebo-controlled study was to assess the efficacy of YM intake on the intestinal environment and skin condition. One hundred and ten healthy female subjects aged 30–49 years were supplemented with YM or placebo for eight weeks. Skin dryness was set as the primary endpoint. No side effects were observed during the study. Microbiota analyses revealed that YM intake selectively increased the relative abundance of Bacteroides thetaiotaomicron and Bacteroides ovatus compared to that by placebo. Feces and urine analyses showed that YM intake lowered the concentration of fecal p-cresol, indole, and skatole, and elevated urinal equol levels compared to those in placebo. Furthermore, YM supplementation ameliorated subjective skin dryness. This study suggests that YM intake could promote beneficial Bacteroides and improve the intestinal environment and skin condition.

Highlights

Yeast has long been consumed as an ingredient in a large variety of fermented foods and beverages such as bread, beer, and wine
Most prebiotics selectively increase the abundance of gut microbes at the genus level, but few studies have reported on prebiotics that selectively increase the abundance of gut microbes at the species level in humans
Our findings suggest that Yeast mannan (YM) might represent a new prebiotic, which can be further developed into products that might benefit women’s wellbeing [16,17,18]

Summary

Introduction

Yeast has long been consumed as an ingredient in a large variety of fermented foods and beverages such as bread, beer, and wine. Yeast mannan (YM) is a water-soluble, low-viscosity, indigestible polysaccharide derived from the yeast cell wall and has rarely been used as a food ingredient It is composed of a highly branched mannose polymer with a molecular weight of 20–200 kDa [1]. It includes a linear α-1,6-mannoside backbone branched with α-1,2-mannoside and α-1,3-mannoside bonds in mono-, di-, tri-, and tetramer forms [1,2]. We reported that YM was utilized by fecal microbiota and selectively increased the relative abundance of Bacteroides thetaiotaomicron and Bacteoroides ovatus in two types of in vitro assay systems [4,5] This is explained by the distinctive gene apparatuses in these two Bacteroides species: mannan-specific polysaccharide utilization loci contributed to α-mannan partial

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Conclusion