Characterizing the gut microbiota in females with infertility and preliminary results of a water-soluble dietary fiber intervention study Original paper

What was studied?

This original study investigated gut microbiota infertility PHGG by comparing the fecal microbiome of fertile women and women experiencing infertility, then evaluating whether supplementing partially hydrolyzed guar gum (PHGG), a prebiotic soluble fiber, could modulate dysbiosis and improve pregnancy outcomes during assisted reproductive technology. Using 16S rRNA V3–V4 sequencing, the research assessed structural diversity, taxonomic differences, and genera associated with successful conception. The study also explored whether baseline microbial signatures could predict pregnancy response following PHGG-supported embryo transfer. All analyses were corroborated by visual data, including the beta-diversity plots and genus-level bar charts of the uploaded paper.

Who was studied?

The study enrolled 18 fertile controls and 18 infertile women matched for age and BMI. All participants were recruited from the HORAC Grand Front Osaka Clinic between 2017 and 2018. In a second phase, 12 infertile women proceeded with embryo transfer plus PHGG supplementation (10 g/day for 4 weeks). Fecal samples were collected before treatment and during follow-up. No significant differences in diet type or lifestyle were reported, allowing microbiome comparisons to focus primarily on infertility status and PHGG response.

Most important findings

The study identified distinct microbial signatures differentiating fertile and infertile women. Beta-diversity plots showed structural separation, while genus-level data revealed decreased Stenotrophomonas, Streptococcus, and Roseburia, alongside increased Unclassified Barnesiellaceae and Phascolarctobacterium among infertile participants. The phylum Verrucomicrobia—primarily Akkermansia muciniphila—was elevated in infertility, though not significantly. Notably, Roseburia and Blautia, both short-chain fatty acid (SCFA) producers, were lower in infertility, implicating impaired SCFA-mediated mucosal and immunologic regulation. In the PHGG intervention, pregnancy occurred in 58.3% (7/12). Pregnant participants showed rising Bifidobacterium abundance at 2 and 4 weeks, while non-pregnant participants exhibited rising Bacteroides instead. Baseline predictors of successful pregnancy (Figure 6) included lower Paraprevotella and Blautia, paired with a higher tendency toward Bifidobacterium—a genus strongly responsive to PHGG fermentation and well-known for SCFA production, immune modulation, and epithelial support.

Key implications

This study strengthens the clinical relevance of gut microbial profiles in reproductive health. Reduced SCFA-producing genera and elevated Verrucomicrobia may represent microbial features associated with infertility. PHGG’s ability to enrich Bifidobacterium aligns with mechanistic links between fiber fermentation, mucosal immunity, and endometrial receptivity. The findings suggest that individualized microbial signatures could inform adjunctive nutritional strategies in ART. The strong heterogeneity in Bifidobacterium abundance across individuals underlines the importance of personalized microbiome-based reproductive interventions.

Citation

Komiya S, Naito Y, Okada H, et al. Characterizing the gut microbiota in females with infertility and preliminary results of a water-soluble dietary fiber intervention study.J Clin Biochem Nutr. 2020;67(1):105-111. doi:10.3164/jcbn.20-53