Impact of Dietary Isoflavone Supplementation on the Fecal Microbiota and Its Metabolites in Postmenopausal Women.

Lucía Guadamuro,M Andrea Azcárate-Peril,Baltasar Mayo,Susana Delgado,Rafael Tojo

doi:10.3390/ijerph18157939

Abstract

Isoflavones are metabolized by components of the gut microbiota and can also modulate their composition and/or activity. This study aimed to analyze the modifications of the fecal microbial populations and their metabolites in menopausal women under dietary treatment with soy isoflavones for one month. Based on the level of urinary equol, the women had been stratified previously as equol-producers (n = 3) or as equol non-producers (n = 5). The composition of the fecal microbiota was assessed by high-throughput sequencing of 16S rRNA gene amplicons and the changes in fatty acid excretion in feces were analyzed by gas chromatography. A greater proportion of sequence reads of the genus Slackia was detected after isoflavone supplementation. Sequences of members of the family Lachnospiraceae and the genus Pseudoflavonifractor were significantly increased in samples from equol-producing women. Multivariable analysis showed that, after isoflavone treatment, the fecal microbial communities of equol producers were more like each other. Isoflavone supplementation increased the production of caproic acid, suggesting differential microbial activity, leading to a high fecal excretion of this compound. However, differences between equol producers and non-producers were not scored. These results may contribute to characterizing the modulating effect of isoflavones on the gut microbiota, which could lead to unravelling of their beneficial health effects.

Highlights

Diet modulates the composition of the intestinal microbiota [32] and, in turn, gut microbiota metabolism can determine the final metabolites produced, and the corresponding effects on human health
With the aim of identifying changes in gut microbiota composition associated with the ingestion of isoflavones, and related to the equol-producing metabotype, we selected and made use of fecal samples from eight menopausal women receiving daily isoflavone supplementation over one month
This study allowed the changes in fecal microbial communities caused by isoflavone supplementation for one month to be monitored in a group of menopausal women

Summary

Introduction

A growing body of studies exists, the mechanisms underlying these processes are complex and not entirely understood. In this context, isoflavones-plant-derived polyphenols found at a relatively high concentration in soy and soy-derived products have been related to diverse health benefits such as the prevention of chronic diseases, including hormone dependent cancer, cardiovascular diseases, osteoporosis, and postmenopausal syndrome [3]. There is scientific evidence of the beneficial effects in counteracting symptoms like hot flushes and vasomotor reactions in menopausal women [4], the European Food Safety Authority (EFSA) has refuted health claims about the role of isoflavones in body functions [5]. The clinical effectiveness of ingested isoflavones might be due to their ability to be converted

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