Impact of Manganese Levels on Sperm Functional Characteristics Among Men Investigated for Infertility in Benin, Nigeria

Background: Manganese (Mn) is absolutely necessary for several biological functions in the body, but higher concentrations may be extremely harmful to male reproductive health. Objectives: This study aimed to determine Mn, zinc (Zn), and copper (Cu) levels in serum and seminal plasma and correlate their concentrations with sperm quantity and quality among men investigated for infertility. Methods: A total of 70 infertile males in the age range of 25-45 years and 50 control subjects were evaluated in this study. The semen samples were analyzed by the microscopic technique, while Mn, Zn, and Cu were analyzed using an atomic absorption spectrophotometer. Socio-demographic parameters were obtained using a semi-structured questionnaire. Then, unpaired Student’s t test and chi-square test were used to compare the discrete data between infertile males and controls and categorical data, respectively. Finally, Pearson’s correlation coefficient was employed to correlate measured elements with sperm induces. Results: The sperm count, sperm motility, viability, and serum/seminal plasma Zn and Cu levels were significantly lower (P<0.001), while the Mn and Cu/Zn ratios were significantly higher (P<0.001) among infertile men than control subjects. Serum/seminal plasma Mn levels were inversely correlated with the sperm count (r=-0.279, P=0.02), motility (r=-0.279, P=0.02), and morphology (r=-0.275, P0.04), while Zn levels were positively correlated with sperm motility (r=0.238, P=0.04) and morphology (r=0.258, P<0.03). Eventually, Cu was inversely correlated with motility (r=-0.237, P=0.04) and morphology (r=-0.235, P=0.04). Conclusion: Overall, high levels of Mn in the serum and seminal plasma may have an adverse effect on sperm quantity and quality, and thus, there is a need for routine Mn determination as part of the investigation in the evaluation of infertile males irrespective of the occupation of subjects