Association Between Sex Hormone Levels and Gut Microbiota Composition and Diversity-A Systematic Review

Goals/Background: Animal studies have highlighted how the microbiota acts in a sex-specific manner with sex hormones demonstrating an association with the composition and diversity of the microbiota. This systematic review aimed to gather the available scientific evidence to explore the association between sex hormones and gut microbiota composition and diversity, in humans. Study: Four bibliographic databases were searched in July 2020 using terms related to microbiota, microflora, sex hormones, testosterone, and estrogen. Human studies that investigated the correlation between sex hormones and the microbiota composition or diversity using next-generation sequencing were included. Results: A total of 10,468 records were screened with 13 studies included in this review. In healthy women, higher estrogen levels were found to be associated with a higher abundance of Bacteroidetes, a lower abundance of Firmicutes, the Ruminococcaceae family and increased diversity. In healthy men, raised testosterone levels positively correlated with Ruminococcus, Acinetobacter, and an increased microbial diversity. Escherichia and Shigella spp. were correlated with raised testosterone in healthy women whereas Ruminococcus spp. was negatively associated with elevated testosterone levels. Women with altered testosterone/estrogen profiles (such as in polycystic ovary syndrome), had a differing gut microbiota compared with healthy women. Conclusions: The findings gathered highlight an association between sex hormones and the gut microbiota composition/diversity and may contribute to the sex-based variations observed in disease pathogenesis. Factors such as age and medical conditions are implicated in the associations observed and should be accounted for in future studies. As the understanding of the complex symbiotic relationship between humans and their gut microbiota increases, microbiota modulation could be an attractive option for the prevention and treatment of gastrointestinal disorders.

Automated summary

This systematic review explores the association between sex hormones and gut microbiota composition and diversity. The findings suggest that estrogen levels in women are associated with the abundance and diversity of the gut microbiota, while testosterone levels in men are correlated with specific bacterial species and increased diversity. Women with hormonal disorders, such as polycystic ovary syndrome, have altered gut microbiota compared to healthy women. These findings contribute to our understanding of disease pathogenesis and highlight the potential of microbiota modulation for gastrointestinal disorders.