Association Between Dietary Polyphenol Intake and Semen Quality: Insights from the FERTINUTS Study

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.