Low-Fiber Diets have altered our gut microbiome so drastically that it can now recycle oestrogen more efficiently https://www.newscientist.com/article/2522701-modern-living-may-be-causing-big-changes-to-our-oestrogen-levels/ Lack of fiber prompts gut bacteria to feed on the gut's mucus lining, breaking down inactive hormones & allowing them to re-enter circulation. Broad-spectrum antibiotics can also disrupt the microbiome, affecting how the body metabolizes and eliminates excess estrogen