Dietary Glycemic Index and Load and Semen Quality: A Cross-Sectional and Prospective Analysis within the FERTINUTS Trial.

Purpose: Infertility is a global health issue and nutrition plays a significant role in fertility outcomes. We aimed to investigate the cross-sectional and prospective associations of glycemic index (GI) and glycemic load (GL) with semen quality parameters in a cohort of healthy young men.

Materials and methods: The study included 106 men aged 18-35 years from the FERTINUTS trial. Dietary intake was estimated through 3-day dietary records and several semen parameters were assessed. Multivariable linear regression analysis with the Least Absolute Shrinkage and Selection Operator (LASSO) approach was employed.

Results: The cross-sectional analysis revealed positive associations between GI and GL and total sperm count, sperm concentration, and total motility. In the prospective analysis, baseline GI was associated with increases in pH, vitality, immotile sperm or abnormal midpiece and decreases in total sperm count and motility. Conversely, GL was positively associated with changes in vitality and total sperm count.

Conclusions: While these findings suggest that GI may have adverse effects on several sperm quality parameters, the results were not consistently observed in the cross-sectional analysis. However, GL was consistently associated with better sperm quality in both analyses. The impact of carbohydrate quality and quantity on fertility remains uncertain and larger prospective studies are needed.