The effect of oxidative stress on male fertility: A review

Male fertility is critical around the world, including in Nigeria, where infertility rates range between 20% and 30%. Male infertility is caused by a variety of factors, including genetics, lifestyle, and environmental pollutants, which frequently involve oxidative stress and reactive oxygen species (ROS). ROS imbalance is linked to idiopathic male infertility, which has no clear cause. Understanding the complexities of these issues is critical for diagnosis and treatment. Internal (endogenous) and external (exogenous) sources generate reactive oxygen species (ROS). External factors include pollutants, ultraviolet (UV) radiation, heavy metals, and smoking. Sources within the body include mitochondria, nicotinamide adenine dinucleotide phosphate oxidase (NAPDH oxidase; NOX) enzymes, and immune cells. Controlled ROS production serves signaling pathways, but imbalance can damage cellular components, leading to cell death. Reactive oxygen species (ROS) negatively affect sperm via both internal and external pathways. External factors such as psychological stress, exercise, heat stress, smoking, and poor diet increase ROS production. Psychological stress raises norepinephrine and cortisol, intensifying ROS. Exercise, especially vigorous, generates excessive ROS, potentially harming sperm. Heat stress from various sources elevates ROS through hormonal disruptions. Smoking, alcohol, and unhealthy foods also contribute to ROS production, damaging sperm health. Reproductive tract infections and immature spermatozoa, along with conditions like varicocele, leukocytes, inflammation, and cytokines, further exacerbate oxidative damage to sperm internally. In conclusion, oxidative equilibrium is essential for preserving the health of sperm. Male infertility can result from oxidative stress, which drastically reduces the quality of sperm. It has been demonstrated that antioxidant therapy has positive impacts on sperm characteristics and pregnancy outcomes. Maintaining oxidative balance is therefore crucial for male reproductive health, and antioxidant supplementation may be a helpful tactic to enhance sperm quality in situations of male infertility.