The circulating dihydrotestosterone/testosterone ratio is increased by gut microbial 5α-reductase activity in females
Abstract
BACKGROUND: Dihydrotestosterone (DHT), the most potent ligand to the androgen receptor, is synthesised from testosterone (T) by 5α-reductase type 1 and 2. While type 1 is expressed in several non-reproductive tissues in both sexes, men also express high levels of the high-affinity type 2 isoform in reproductive tissues; yet women have a higher circulating DHT to T (DHT/T) ratio than men. We hypothesised that the high DHT/T ratio in women is caused by high gut microbiota (GM) 5α-reductase activity or altered β-glucuronidase-induced androgen reabsorption from the gut.
METHODS: We used a large cross-sectional subsample of the Swedish CArdioPulmonary bioImage Study (2897 women and 4338 men, 50-65 years of age) with GM composition and functionality determined by metagenome sequencing and circulating androgens determined by liquid chromatography-tandem mass spectrometry.
FINDINGS: We confirmed that women had higher (+194%) circulating DHT/T ratio than men. The relative abundance of microbial genes for 5α-reductase type 1 (P = 3 × 10-4), but not β-glucuronidase, was positively associated with the DHT/T ratio in women. In women, the GM relative abundances of Odoribacter splanchnicus and Parabacteroides distasonis were positively associated with the relative abundance of microbial genes for 5α-reductase type 1 (P < 2 × 10-149) and the circulating DHT/T ratio (O. splanchnicus P = 3 × 10-6; P. distasonis P = 5 × 10-5). In mechanistic studies, we observed very high DHT/T ratio in…
How strong is the evidence?
Evidence Hub reads this as a cross-sectional, done in people. Its evidence level is 4 of 5 (Low · observational). Observational designs can show an association but not prove cause. Reported size: 4,338 participants or records.
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