# Soy Isoflavones and PCOS: Role in Hormonal and Metabolic Mechanisms
## 4 Polycystic Ovary Syndrome and Soy Isoflavones
### Gut Microbiota
Therefore, the ability to produce equol is closely linked to a state of microbial equilibrium characterised by adequate species richness, commensal bacterial dominance, and low levels of potentially pathogenic microorganisms [190]. In the context of PCOS, microbiota disorders (dysbiosis), which are commonly observed in female patients, may limit this metabolic potential. Therefore, interventions that restore eubiosis, such as dietary changes, prebiotics, and probiotics, may enhance the effectiveness of isoflavure therapy. In a mouse study conducted by [PERSON] et al. [191], it was observed that switching from a phytoestrogen-deficient diet to one rich in soy isoflavones increased gut microbial diversity and modulated the expression of genes involved in LPS biosynthesis, thereby reducing pro-inflammatory responses. Notably, when the diet was changed from isoflavure-rich to isoflavure-deficient, genes responsible for equol production were lost within just seven days. Reintroduction of the isoflavure-rich diet led to the reappearance of these genes in some mice. This finding suggests that the presence of equol-producing bacteria may depend on dietary composition and can dynamically respond to its changes. During a three-day dietary intervention, involving women with PCOS, it was found that the participants' gut microbiota began to resemble that of healthy women after just three days of isoflavone consumption [17]. Such a rapid microbiota response suggests that isoflavones may promote the growth of equol-producing bacteria. This indicates that even women with PCOS who are not equol producers may still benefit from isoflavue intake. However, in equol-producing individuals, these effects may be particularly pronounced. Scientific reports also suggest that improvements in diet quality may positively affect both the conversion of daidzein to equol and equol's bioavailability. A diet high in carbohydrates appears to play a key role, as carbohydrate fermentation products--hydrogen and SCFAs--support the activity of bacteria involved in daidzein conversion [192; 193]. In contrast, a high-fat diet has been shown to negatively correlate with bacterial equal synthesis capacity [194]. Despite the growing body of literature on gut microbiota in women with PCOS and the known health benefits of soy isoflavure consumption, there remains a lack of studies that comprehensively analyse the relationships between gut microbiota composition, isoflav metabolism, and endocrine-metabolic symptoms in PCOS. Selected available studies are presented in Tables 5 and 6. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Authors, Year** & **Study Design,** & **Characteristics of the** & **Intervention/Aim** & **Main Results** & **Conclusions** \\ Year & **Duration** & **Study Group** & **of the Study** & **Main Results** & **Conclusions** \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Overview of preclinical studies evaluating the effects of soy isoflavones and probiotics on gut microbiota and endocrine-metabolic symptoms in PCOS. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Authors, Year** & **Study Design,** & **Characteristics of the Study** & **Intervention/Aim** & **Main Results** & **Conclusions** \\  & **Duration** & **Study Group** & **of the Study** & **Main Results** & **Conclusions** \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Overview of clinical trials evaluating the effects of soy isoflavones on gut microbiota and endocrine-metabolic symptoms in PCOS.