Industrialization increases the estrogen-recycling capacity of the gut microbiome

Comparing gut metagenomes across industrialized and non-industrialized populations, the authors found that industrialization is associated with a higher microbial capacity to recycle estrogens — more bacterial beta-glucuronidase genes and greater predicted estrogen reactivation. They note that up to 65% of estradiol and 48% of estrone are excreted in bile while only 10–15% of estrogens are recovered in feces, implying substantial host reabsorption. Formula feeding and industrialized lifestyles emerged as factors shaping this recycling capacity, with implications for estrogen exposure, reproductive biology, and estrogen-linked disease risk.