# Soy Isoflavones and PCOS: Role in Hormonal and Metabolic Mechanisms
## 4 Polycystic Ovary Syndrome and Soy Isoflavones  
Polycystic ovary syndrome is a disease that is one of the most common causes of female infertility [80]. It is estimated that PCOS affects 10-13% of women of reproductive age if the diagnosis is based on the Rotterdam criteria, and the incidence rate is steadily increasing [1; 2; 3; 4; 5]. PCOS, frequently, in addition to hormonal and typically related to the reproductive system, can be accompanied by numerous metabolic and systemic disorders, such as tissue insulin resistance (IR), cardiovascular diseases (CVD), chronic inflammation, dermatological and psychological symptoms, and intestinal dysbiosis [1; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54; 55; 56; 57;  
International Evidence-Based Guideline for the Assessment and Management of Polycyclic Ovary Syndrome 2023 (extended Rotterdam criteria 2003) allows us to distinguish four basic phenotypes of PCOS, with phenotypes A and B not differing significantly in terms of endocrine or metabolic characteristics [1,89] (see Figure 4). According to the 2014 consensus of the European Society of Endocrinology (ESE) and other researchers, it is possible to change from one phenotype to another, especially in the transition from ovulatory to anovulatory cycles, which is associated, among other things, with weight gain, poor diet, and low physical activity [90, 91, 92, 93].  
Experts from all over the world strongly recommend implementing a healthy lifestyle that combines a healthy diet and physical activity [1]. Both women trying to get pregnant and those who are not planning to do so in the near future will benefit from this solution. The main advantages include the following: improvement of general health, body composition, and quality of life. An additional, and for many women key, advantage of lifestyle changes is weight control, including maintaining weight, preventing weight gain, or achieving controlled weight reduction [1,94].  
Figure 4: PCOS phenotypes in adult women based on International Evidence-Based Guideline for the Assessment and Management of Polycystic Ovary Syndrome 2023 (extended Rotterdam criteria 2003) [1]. ✓—indicates the presence of a symptom; �—indicates the absence of a symptom.  
Figure 3: The characteristic PCOS features and associated disorders of the various systems [17, 18, 19, 20, 21, 22, 23, 24, 80, 81, 82, 83, 84, 85, 86, 87, 88].  
Although the pathogenesis of polycystic ovary syndrome is still unclear, it has been proven that inflammation deteriorates its course [95; 96; 97; 98]. Therefore, improvement can be achieved by following diets with high anti-inflammatory potential, while the Western diet worsens the condition of patients [94; 96]. Significant benefits in both the prevention and management of PCOS and its metabolic and hormonal complications are also seen in functional foods, particularly soy isoflavones [17; 19; 25; 26; 27; 99]. Nutritional models in which soy products or legumes play an important role are primarily plant-based diets, e.g., the portfolio low-carbohydrate diet or the Mediterranean diet, which also have high anti-inflammatory potential [96; 99]. The benefits of using plant-based models containing soy isoflavones, in addition to their potential to affect oestrogen receptors in PCOS, may also have other benefits. These include a low degree of food processing and the associated lower caloric content of the diet, which can facilitate the reduction of excessive body weight or maintain it at a healthy level [100]. The effect of individual soy isoflavones on various mechanisms occurring in PCOS is discussed in the following chapters of this article.