Mediterranean Diet, ultra-processed food consumption and semen quality in healthy young men

Abstract Background Diet quality can have beneficial effects on male reproductive health, although studies are still limited, and little is known on the potential impact of ultra-processed foods (UPFs) on semen quality parameters. Methods A cross-sectional analysis was run on 126 participants (mean age 20.0 ± 1.2 y) from the FAST randomized controlled trial in 2018-2019. Food intake was assessed through a FFQ. UPF was defined following the Nova classification and calculated as the ratio (weight ratio) between UPF (g/d) and total food (g/d). Adherence to the Mediterranean Diet (MD) was ascertained by the Mediterranean Diet Score (MDS). The semen analyses were performed using a microscope for optical evaluation with a Makler counting chamber and two automated semen analysers. The primary outcomes were sperm volume, concentration, motility and morphology. A hierarchical mixed model approach was utilized to accommodate the within-subject correlation arising from the triple temporal repetition of measurements. Results Highest UPF consumption (Q4), compared to lowest (Q1), was associated with lower sperm concentration (β=-54.1×106 spz./ml; 95%CI: -92.9 to -15.4; p-trend=0.002 across quarters), and progressive motility (β=-14.2%; 95%CI: -28.2 to -0.09; p-trend=0.036). The percentage of cells with normal morphology tended to be reduced in young men consuming more UPF compared to lowest intake (β=-2.93%; 95%CI: -6.22 to 0.37; p-trend=0.071). The MDS was not associated with any of the parameters under study. Conclusions A larger dietary share of UPF was inversely associated with sperm concentration and progressive motility in young men of reproductive age. MD adherence was not associated with semen quality parameters, and this is possibly due to the low variability of MD adherence in this sample. Dietary recommendations for improving sperm health should prioritize limiting UPF in the diet. Key messages • Ultra-processed food (UPF) intake was unfavourably associated with semen quality parameters amongst young men. • Dietary recommendations for improving sperm health should recommend limiting UPF.