ABSTRACT
About 13–15% of couples worldwide are infertile, which is defined as the inability to achieve pregnancy within 12 months of regular sexual intercourse. Male factors account for 40–50% of the causes of infertility. Recent reports identified oxidative stress as a likely cause of male infertility development, although the mechanisms have not been fully clarified. An excessive amount of reactive oxygen species (ROS) caused by alcohol consumption, cigarette smoking, varicocele, and obesity, among other factors, results in lipid peroxidation in the sperm membrane, DNA damage, and apoptosis, decreasing the sperm viability and motility. Therefore, enhancement of the antioxidant capacity to protect sperms from oxidative stresses could present a major opportunity for improving male infertility. Many clinical studies have been conducted on the possible beneficial effects of treatment with antioxidants on male infertility.
Lycopene is a red pigment found in fruit and vegetables, including tomatoes, watermelon, and apricots, and is reportedly one of the most efficient singlet oxygen quenchers and potent peroxyl radical scavengers. Moreover, lycopene has been reported to be highly concentrated in the testes, where sperms are produced. Therefore, lycopene and lycopene-rich foods, such as tomatoes, are expected to improve male infertility by enhancing the antioxidant capacity of sperm, and this hypothesis has prompted few animal and clinical trials. In this review, we summarize the known mechanism by which ROS causes male infertility, major reports that examined the effects of lycopene and tomato on male infertility in animal and clinical trials, and existing knowledge about their mechanisms.
