Association between obesity and alteration of sperm DNA integrity and mitochondrial activity

Abstract

Study Type – Prognosis (cohort) Level of Evidence 3a What's known on the subject? and What does the study add? The relationship between high levels of BMI and changes in altered standard semen analysis parameters are described in the literature. However, the functional characteristics of the sperm are essential to complete the evaluation of male infertility. Thus, this study provides important information about the functionality of the sperm of men with different levels of BMI. OBJECTIVE: To assess the effect of obesity on semen analysis, sperm mitochondrial activity and DNA fragmentation. MATERIALS AND METHODS: A transversal study of 305 male patients, presenting for clinical evaluation, was carried out. The patients were divided into three groups according to body mass index (BMI) as follows: eutrophic (BMI < 25 kg/m 2 , n = 82), overweight (BMI ≥ 25 kg/m 2 and <30, n = 187) and obese (BMI ≥ 30 kg/m 2 , n = 36). The variables analysed were semen analysis, rate of sperm DNA fragmentation and sperm mitochondrial activity. Groups were compared using one‐way analysis of variance followed by a least significant difference post‐hoc test. A P ‐value of <0.05 was considered to indicate statistical significance. RESULTS: No differences were observed in age, ejaculatory abstinence, ejaculate volume, sperm vitality, morphology or round cell and neutrophil count among the groups. The eutrophic group had a higher percentage of sperm with progressive motility ( P = 0.001). Mitochondrial activity was lower in the obese group ( P = 0.037) when compared to the eutrophic, and the percentage of sperm with DNA damage was higher in the obese group ( P = 0.004) than the other two groups. CONCLUSION: Increased BMI values are associated with decreased mitochondrial activity and progressive motility and increased DNA fragmentation.