Background/Objectives: Low semen quality and male infertility are critical global health issues. Emerging research highlights that nutritional factors could play a significant role in determining reproductive outcomes. Understanding and optimizing these dietary influences, including the role of polyphenols, is crucial for developing targeted strategies to improve male fertility. We aimed to explore the relationship between the intake of different classes of polyphenols and semen quality indicators in a cohort of healthy young males. Methods: This is a secondary analysis involving 106 male individuals, aged 18–35 years, from the FERTINUTS trial. Dietary intake was assessed using 3-day dietary records, and semen quality parameters were analyzed. Multivariable linear regression analysis was employed to evaluate the associations between dietary polyphenol consumption and semen quality indicators. Results: Our findings revealed both positive and negative associations between polyphenol consumption and sperm morphology parameters. A higher intake of total polyphenols was associated with a lower percentage of abnormalities in sperm heads but a higher rate of abnormalities in the principal piece. Similar results were observed for lignan and flavonoid intake. Additionally, a higher intake of flavonoids was also associated with a greater percentage of normal sperm forms. In contrast, a higher dietary intake of stilbenes was associated with a higher percentage of combined abnormalities. Conclusions: Higher intake of polyphenols, particularly flavonoids and lignans, was associated with improved sperm head morphology but also with increased tail abnormalities, although no associations with motility or vitality were observed. These results suggest that specific polyphenol classes may have both beneficial and adverse effects on sperm structure, warranting consideration of compound type and dosage in dietary recommendations. Further studies are needed to determine whether these morphological changes impact fertilization outcomes and reproductive potential.

Background/Objectives: Low semen quality and male infertility are critical global health issues. Emerging research highlights that nutritional factors could play a sig-nificant role in determining reproductive outcomes. Understanding and optimizing these dietary influences, including the role of polyphenols, is crucial for developing targeted strategies to improve male fertility. We aimed to explore the relationship between the intake of different classes of polyphenols and semen quality indicators in a cohort of healthy young males. Methods: This is a secondary analysis involving 106 male individuals, aged 18–35 years from the FERTINUTS trial. Dietary intake was as-sessed using 3-day dietary records, and semen quality parameters were analysed. Multivariable linear regression analysis was employed to evaluate the associations between dietary polyphenol consumption and semen quality indicators. Results: Our findings revealed both positive and negative associations between polyphenol con-sumption and sperm morphology parameters. A higher intake of total polyphenols was associated with a lower percentage of abnormalities in sperm heads but a higher rate of abnormalities in the principal piece. Similar results were observed for lignan and fla-vonoid intake. Additionally, a higher intake of flavonoids was also associated with a greater percentage of normal sperm forms. In contrast, a higher dietary intake of stil-benes was associated with a higher percentage of combined abnormalities. Conclu-sions: While these results suggest that higher intake of polyphenols, particularly fla-vonoids and lignans may protect sperm head integrity by supporting DNA and acro-some function, we also observed an increase in tail abnormalities, without significant effects on motility or vitality. As fertility relies on multiple factors, such morphological changes could influence reproductive success. These findings highlight the need to consider both type and dosage of polyphenols to better understand its implications for reproductive health.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline. MicroRNAs (miRNAs) have emerged as promising regulators of AD-related pathways and potential minimally invasive biomarkers. However, existing meta-analyses have yielded inconsistent results, and whether miRNA signatures are conserved across biological fluids remains unclear. The present work aimed to systematically review studies performing miRNA discovery or multi-candidate profiling in blood and CSF during the last 15 years, in order to identify miRNAs showing significant and consistent differential expression across independent studies. By systematically comparing the direction and consistency of miRNA dysregulation across independent studies and biological sources, we identified 80 miRNAs consistently dysregulated in both blood and CSF, revealing a reproducible cross-fluid signature of AD-associated molecular alterations. Notably, miR-451a and miR-16-5p emerged among the most consistently dysregulated miRNAs across fluids. In contrast, several miRNAs displayed divergent or compartment-specific patterns, highlighting that blood and CSF may capture distinct aspects of AD-related molecular changes. Among these, miR-484, miR-3200-3p and miR-598 were identified as novel CSF candidates, while miR-20a-5p, miR-363-3p and miR-5006-3p represented novel blood-specific candidates. Furthermore, a substantial proportion of detected miRNAs was associated with extracellular vesicle/exosomal fractions, supporting their potential stability and biological relevance. Overall, our findings demonstrate that AD-associated miRNA dysregulation comprises both conserved and biofluid-specific signatures. From a clinical perspective, the current evidence primarily supports further evaluation of miRNAs as diagnostic/discriminative biomarkers rather than validated tools for early detection, disease monitoring, or prognosis. Their clinical translation remains limited by biofluid and methodological heterogeneity and requires harmonized cross-cohort and longitudinal validation.