Japan—A preliminary study may have found a link between gut microbiota and female fertility.

The study, published in theJournal of Clinical Biochemistry and Nutrition,states that “fertility depends on a receptive state of the endometrium and hormonal adaptations as well as the immune system. Local and systemic immunities are greatly influenced by the microbiota.” The study is therefore aimed at comparing the gut microbiota in infertile patients with the gut microbiota in fertile patients, and to evaluate the effect of prebiotic supplementation on gut dysbiosis and the outcome of pregnancy in patients treated with assisted reproductive technology (ART). The prebiotic in question was 10g/day of partially hydrolyzed guar gum, branded Sunfiber, provided by Taiyo Kagaku Co., which provided a collaboration research fund to help support the study.

18 infertile women and 18 fertile women as a control group took part in the study. 12 patients in the infertility group were given prebiotic supplementation for four weeks in addition to embryo transfer therapy. The findings: Infertile patients had lessStenotrophomonas, Streptococcus,andRoseburiabacteria, and morePhascolarctobacteriumthan fertile patients. In terms of phylum, infertile patients had more Verrucomicrobia than fertile patients. Verrucomicrobia was represented solely byAkkermansia muciniphila, a species thought to have an anti-inflammatory effect in humans, as well as to affect glucose and lipid metabolism. The researchers were unable to explain the reason for the increase in this bacteria in infertile subjects, and suggested that large-scale controlled trials would be needed in the future.

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The pregnancy rate for the patients treated with prebiotics was 58.3% (7/12). A registry study for the Japan Society of Obstetrics & Gynecology reported that the pregnancy rate for the ART treatment was 36.2%, indicating that the results for treatment in this study were relatively high. In the patients that successfully conceived following prebiotic treatment, the abundance ofParaprevotella andBlautiadecreased andBifidobacteriumincreased.

While noting that this is a very small study, the researchers stated that it “showed the differences in the abundance of gut microbiota between fertile and infertile female groups, and that [Sunfiber] supplementation helped improve gut dysbiosis and the success of pregnancy in females with infertility.”

“These preliminary results are very encouraging but need additional study to confirm the findings,” said Scott Smith, VP, Taiyo International, in a press release. “It’s fascinating to continue learning about the importance of gut microbiome health. It’s only been a few years since conversations began about the gut/brain connection, fueling interest in whatever else may be influenced by gut health. We’re not surprised that researchers are now associating the gut microbiome with fertility. Coping with infertility can be very costly, stressful and emotional. This is definitely an area worthy of future study.”