Influence of body mass index on semen quality: Examining sperm DNA fragmentation, protamine deficiency, and hormonal profiles

Objective: To investigate whether differences exist in DNA fragmentation levels and protamine deficiency in the sperm of obese men compared to those of overweight and proven fertile, normal weight men and evaluate the alterations related to reproductive hormones, semen parameters and their association with body mass index (BMI). Methods: Participants in this observational study were divided into three groups based on their BMI: proven fertile, normal weight men ( n =200); overweight men ( n =200); and obese men ( n =200). After 3 days of abstinence, seminal fluid was collected from all participants and analyzed. Blood samples were also collected on the same day for hormonal analysis. Sperm DNA fragmentation and protamine deficiency were also assessed. Results: A total of 600 men with a mean age of (34.3±7.9) years were included in the study. Obese males (BMI 30 kg/m 2 or higher) exhibited significant reductions in semen volume, sperm concentration, total sperm motility percentage, progressive motility, non-progressive motility, and levels of total testosterone, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) compared to overweight (BMI 25 to 29.9 kg/m 2 ) and normal weight males (BMI 18.5 to 24.9 kg/m 2 ) ( P <0.001). Conversely, obese males showed a significant increase in prolactin level, sperm DNA fragmentation, and protamine deficiency compared to overweight and normal weight males ( P <0.001). Significant negative correlations were demonstrated between BMI and sperm concentration, motility, total testosterone, FSH and LH ( P <0.001), whereas prolactin, sperm DNA fragmentation and protamine deficiency were positively correlated with BMI ( P <0.001). Conclusions: This study provides clear evidence that obesity contributes potentially to male infertility by inducing sperm DNA fragmentation and protamine deficiency, as well as negatively impacting reproductive hormones and semen quality.