Adherence to the Mediterranean Diet, Dietary Patterns and Body Composition in Women with Polycystic Ovary Syndrome (PCOS) Original paper

What was studied?

This cross-sectional, case-controlled study investigated the relationship between adherence to the Mediterranean diet (MD), dietary intake patterns, body composition, and clinical severity of polycystic ovary syndrome (PCOS) in treatment-naïve women. The primary aim was to determine whether the quality of dietary intake, specifically adherence to the MD, was associated with hyperandrogenism, insulin resistance (IR), inflammation, and altered body composition in women with PCOS compared to BMI- and age-matched controls. Using validated methods, including the PREDIMED score and seven-day food records, the study examined the dietary quality and macronutrient composition, while bioelectrical impedance analysis (BIA) was employed to assess body composition, including phase angle (PhA) as a marker of cellular health and inflammation.

Who was studied?

The study involved 112 treatment-naïve women with PCOS and 112 healthy, age- and BMI-matched controls, all recruited from the same geographical region in Italy. Inclusion criteria limited the population to premenopausal women aged 18–40 with BMIs up to 39.9 kg/m². Participants had no other endocrine or metabolic diseases, had not followed any special diet or taken nutritional supplements in the preceding three months, and had not taken medications affecting metabolism. Dietary assessments were conducted via face-to-face interviews using seven-day food records and the PREDIMED questionnaire, while hormonal, inflammatory, and metabolic parameters were evaluated through fasting blood draws.

What were the most important findings?

Women with PCOS exhibited significantly lower adherence to the Mediterranean diet, consuming less extra-virgin olive oil, fish, legumes, and nuts compared to controls, despite similar total caloric intake. Their diets were higher in simple carbohydrates and saturated fatty acids (SFA), and lower in complex carbohydrates, fiber, monounsaturated fatty acids (MUFA), and omega-3 polyunsaturated fatty acids (n-3 PUFA). These nutritional differences were directly associated with higher serum testosterone levels, increased CRP (a marker of inflammation), higher HOMA-IR values, and worse anthropometric profiles, including increased waist circumference. Body composition analysis revealed significantly lower fat-free mass, phase angle (PhA), and intracellular water, and higher fat mass and extracellular water in PCOS patients, indicating poorer cellular health and hydration status.

From a microbiome perspective, the Mediterranean diet’s high content of fiber, polyphenols, and MUFA promotes the growth of beneficial microbes such as Faecalibacterium prausnitzii, Bifidobacterium spp., and Lactobacillus spp., which are known to produce short-chain fatty acids (SCFAs) like butyrate. SCFAs enhance insulin sensitivity, reduce systemic inflammation, and improve gut barrier function. In contrast, diets high in SFA and simple sugars promote dysbiosis and increase pro-inflammatory taxa such as Proteobacteria. This study indirectly supports the role of microbiota in mediating the diet-PCOS relationship through the systemic metabolic and endocrine improvements associated with MD adherence.

What are the implications of this study?

This study underscores the central role of dietary quality, particularly adherence to the Mediterranean diet, in modulating the severity of PCOS. It provides strong evidence that beyond caloric intake, the types of fat and carbohydrates consumed significantly impact inflammation, insulin sensitivity, and androgen levels. The findings establish a direct link between poor MD adherence and more severe hyperandrogenemia and inflammatory status. Clinically, this reinforces the necessity of nutritional counseling as a first-line intervention in PCOS management. The Mediterranean diet offers a microbiome-friendly strategy, rich in fiber and MUFA, capable of reducing systemic inflammation and potentially improving microbiota composition. Furthermore, phase angle (PhA) emerges as a promising biomarker of PCOS severity and nutritional status. For clinicians and researchers, these findings support incorporating nutritional pattern assessments and body composition analysis into standard PCOS evaluation, emphasizing the gut–diet–hormone axis as a therapeutic target.