This preclinical review from 2023 provides insights into how lactic acid in the gut can transform soy isoflavones and their impact on health. Many lactic acid bacteria (LAB) can transform the methylated and glycosylated forms of isoflavones naturally present in foods into more bioavailable aglycones, such as daidzein, genistein and glycitein.
Rietjens IMCM, Louisse J, Beekmann K. The potential health effects of dietary phytoestrogens. Br J Pharmacol. 2017;174(11):1263-1280. doi:10.1111/bph.13622 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5429336/