# Soy Isoflavones and PCOS: Role in Hormonal and Metabolic Mechanisms
## 4 Polycystic Ovary Syndrome and Soy Isoflavones
### Gut Microbiota
On one hand, isoflavnes may modulate the composition of the gut microbiota by promoting the growth of anti-inflammatory bacteria and limiting the proliferation of potentially pathogenic species. One possible explanation for the beneficial effects of isoflavnes lies in their potential prebiotic properties. In an in vitro study using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME), [PERSON] et al. [186] found that soy isoflavnes (daidzein, daidzin, genistein, and glycitin) supported the growth of probiotic bacteria such as _Bifidobacterium bifidum_ DNG6, _Lactococcus lactis_ St66, _Lactobacillus plantarum_ 10960, and _Lactobacillus_ L8. Furthermore, isoflavnes may enhance the production of anti-inflammatory and antimicrobial compounds by these bacteria. When optimal concentrations of isoflavnes were applied--40 mg/mL for _L. lactis_ St66, 20 mg/mL for _L. plantarum_ 10960, 30 mg/mL for _L. rhamns_ L8.8, and 40 mg/mL for _B. bifidum_ DNG6--the most pronounced zones of inhibition against pathogenic bacteria such as _Escherichia coli_ and _Staphylococcus aureus_ were observed [186]. This antimicrobial effect is likely mediated by the production of organic acids, bacteriostatic peptides, and bacteriocins by the probiotic strains [187]. Moreover, genistein has been shown to inhibit DNA topoisomerase IV activity, thereby potentially disrupting the function of pathogenic bacteria [188]. [PERSON] et al. [186] also demonstrated a synergistic effect between isoflavnes and probiotics, resulting in enhanced antimicrobial efficacy. Pathogen-induced dysbiosis of the colonic microbiota led to a significant reduction in beneficial bacteria, such as _Bifidobacterium_, _Bacteroides_, _Lactobacillus_, and _Weissella_, and a concomitant increase in pathogens, including _Klebsiella_, _Pseudomonas_, _Acinetobacter_, _Escherichia-Shigella_, and _Staphylococcus_ (_p_ < 0.05). Treatment with isoflavnes restored microbial balance by significantly reducing pathogenic bacterial counts and increasing populations of beneficial bacteria (_p_ < 0.05). In addition, isoflavnes have been shown to stimulate the production of SCFAs by intestinal bacteria [186]. SCFAs are known not only to play a vital role in glucose homeostasis, lipid metabolism, and appetite regulation but also to exhibit anti-inflammatory and antimicrobial effects. SCFAs are known to play a vital role not only in glucose homeostasis, lipid metabolism, and appetite regulation but also in exerting anti-inflammatory and antimicrobial effects [189]. Inoculation with pathogens resulted in a significant reduction in SCFA concentrations in the colon, from approximately 124-126 mmol/L to 106-108 mmol/L in different segments (_p_ < 0.05). Isoflavone supplementation significantly increased SCFA concentrations (_p_ < 0.05) [186],On the other hand, a well-functioning microbiota enhances the host's capacity to convert isoflavones into their bioactive forms, such as equal, potentially amplifying the beneficial metabolic and hormonal effects in women with PCOS [17]. The gut microbiota primarily influences the bioavailability and bioactivity of isoflavones through enzymatic activity, including \(\beta\)-glucosidase. This enzyme catalyses the hydrolysis of glycosidic isoflavons forms to their aglycone forms, which are characterised by higher bioavailability. This enzyme is found in many probiotic bacteria, particularly in the _Bifidobacterium_ and _Lactobacillus_ genera [33; 34; 65]. Additionally, certain intestinal bacterial strains demonstrate the capacity to further metabolise daidzein into equal, a compound exhibiting stronger oestrogen-like effects and greater bioactivity. These \"equol producers\" primarily include bacteria from the _Coriobacteriaceae_ family, though selected strains of beneficial bacteria from the _Lactobacillus_, _Lactococcus_, and _Bifidobacterium_ genera also demonstrate this ability [67].