Characteristics of the gut microbiota in women with premenstrual symptoms: A cross-sectional study Original paper

What was studied?

This cross-sectional study investigated the gut microbiota in women with premenstrual symptoms, with an explicit aim to identify microbiome signatures linked to premenstrual disorders (PMDs). The focus keyphrase gut microbiota and premenstrual symptoms is central here, because the analysis centers on whether distinct taxonomic shifts in gut bacteria correlate with symptom severity measured by a validated Premenstrual Symptoms Questionnaire (PSQ). Using 16S rRNA sequencing of stool samples, the authors explored microbial diversity, taxonomic differences, and associations between bacterial abundance and symptom burden. They also measured inflammatory markers—C-reactive protein, soluble CD14, and LPS-binding protein—to evaluate whether systemic inflammation or endotoxemia accompanies PMDs. The study’s structural framework compared women with PMDs to controls, seeking specific genera that may serve as potential microbial biomarkers relevant for a microbiome signatures database.

Who was studied?

Fifty-six Japanese women aged 20–45 years were included, all with regular menstrual cycles and free from confounding medications such as antibiotics, antidepressants, probiotics, or drospirenone-containing contraceptives. From this cohort, 21 women met criteria for PMDs based on moderate-to-severe PSQ symptoms with interference in social functioning, while 22 asymptomatic women served as controls. None had gastrointestinal diseases, diabetes, or prior gastrointestinal surgery. Blood and stool samples were collected without cycle-standardization; however, the groups were otherwise comparable in demographic and lifestyle factors. Symptom severity in the PMDs group was substantially higher, as confirmed by PSQ scores and menstrual pain ratings.

Most important findings

The study found no differences in systemic inflammatory markers, suggesting PMDs are unlikely to involve endotoxin-driven inflammation, unlike major depressive disorder (MDD). Alpha diversity was similar between groups, but beta diversity differed, indicating distinct community structures. A key phylum-level finding was the reduced abundance of Bacteroidetes in the PMDs group. At the genus level, several butyrate-associated or neuroactive taxa were reduced, while one genus increased. These associations, although some lost significance after FDR correction, were supported by LEfSe analyses.

The positive correlation between Anaerotaenia and PSQ scores, and the negative correlations for Parabacteroides and Extibacter, suggest metabolite-linked or neuroactive pathways may influence symptom expression.

Key implications

This study suggests that PMDs may involve functional microbial alterations, particularly affecting butyrate-producing and GABA-modulating taxa. The consistent decrease in Parabacteroides and Megasphaera—each with plausible neuroactive roles—raises the hypothesis that microbial metabolites affecting the gut–brain axis may contribute to symptom severity. While causality cannot be inferred from this design, these taxa offer promising leads for future biomarker development, mechanistic studies, or therapeutic modulation via diet, probiotics, or microbiome-targeted interventions. The findings also highlight potential similarities between PMDs and other hormone-linked mood disorders, such as postpartum depression, where similar taxonomic shifts have been observed.

Citation

Takeda T, Yoshimi K, Kai S, Ozawa G, Yamada K, Hiramatsu K. Characteristics of the gut microbiota in women with premenstrual symptoms: A cross-sectional study.PLoS One. 2022;17(5):e0268466. doi:10.1371/journal.pone.0268466