Ultra-processed food consumption and semen quality parameters in the Led-Fertyl study

STUDY QUESTION Is ultra-processed food (UPF) consumption associated with semen quality parameters? SUMMARY ANSWER Higher UPF consumption was inversely associated with total sperm count, sperm concentration, and total motility in men of reproductive age. WHAT IS KNOWN ALREADY The consumption of UPF, which has been rising during the last decades, has been demonstrated to be positively associated with several chronic diseases such as diabetes or cardiovascular diseases. However, the scientific evidence on its potential impact on semen quality remains notably limited. STUDY DESIGN, SIZE, DURATION A cross-sectional analysis was conducted using data from 200 healthy men (mean age 28.4 ± 5.5 years) enrolled in the Led-Fertyl (Lifestyle and Environmental Determinants of Seminogram and Other Male Fertility-Related Parameters) study between February 2021 and April 2023. PARTICIPANTS/MATERIALS, SETTING, METHODS UPF consumption (% of energy from UPF) was estimated according to the NOVA classification system using a validated 143-item semi-quantitative food frequency questionnaire. Total sperm count, sperm concentration, sperm vitality, total motility, progressive motility, and normal sperm forms were set as the main outcomes. Microscopic parameters were analyzed using a phase-contrast microscope and a computer-assisted sperm analysis (CASA) system. Semen samples were collected and tested according to World Health Organization 2010 standards. Multivariable linear regression models were fitted to estimate the associations between UPF tertile and semen quality parameters. MAIN RESULTS AND THE ROLE OF CHANCE Sperm concentration (β: −1.42 × 106 spz./ml; 95% CI: −2.72 to −0.12) and motility (β: −7.83%; 95% CI: −15.16 to −0.51) were lower in participants in the highest tertile of UPF compared to the lowest. A similar association was observed for sperm count when UPF was analyzed per 10% increment of energy from UPF consumption (β: −1.50 × 106 spz.; 95% CI: −2.83 to −0.17). Theoretically replacing 10% of energy from UPF consumption with 10% of energy from unprocessed or minimally processed food consumption was associated with a higher total sperm count, sperm concentration, total motility, progressive motility, and normal sperm forms. LIMITATIONS, REASONS FOR CAUTION Cross-sectional studies do not permit the drawing of causal inferences. Measurement errors and reporting bias cannot be entirely ruled out. WIDER IMPLICATIONS OF THE FINDINGS This work suggests that consumption o