The Circulating Dihydrotestosterone/Testosterone Ratio Is Increased by Gut Microbial 5α-Reductase Activity in Females

This study, involving 7,235 participants from the Swedish CArdioPulmonary bioImage Study, found that women have a 194% higher circulating dihydrotestosterone/testosterone (DHT/T) ratio than men, potentially due to gut microbiota (GM) 5α-reductase activity. The research identified a positive association between microbial genes for 5α-reductase type 1 and the DHT/T ratio in women, with specific bacteria like Odoribacter splanchnicus and Parabacteroides distasonis contributing to this effect. Experiments in mice supported these findings, showing higher DHT/T ratios in female mice with normal gut microbiota. The study suggests that GM acts as an endocrine organ influencing androgen levels in females, highlighting the need for further research on its role in men and the health implications of the DHT/T ratio.