Many studies have focused on male infertility. There is limited evidence about the influence of nutrition on quality of semen. Approximately, 30-80% of infertility cases are caused by oxidative stress and decreased level of seminal total antioxidant capacity. This study was aimed to review the effects of oral antioxidant supplements on improving major semen parameters such as sperm concentration, motility, morphology, DNA damage, and fertility rate. Data were extracted from PubMed and Google scholar database by using the terms "antioxidant", "multivitamin", "carnitine", "CoQ10", "vitamin C", "vitamin E", "zinc", "folic acid", "N-acetyl cysteine" and "selenium" combined with "male infertility", "semen", and "sperm" to generate a set of relevant citations. Supplements such as CoQ10 and alpha-tocopherol significantly improve sperm count. Also, carnitine has positive effects on sperm motility and morphology. Simultaneous administration of vitamin E and vitamin C reduces the sperm DNA damage. However, in some studies, one or more factors have not changed substantially. In most of the studies, antioxidant supplementation improved the number, motility, morphology and sometimes DNA integrity of sperm. The present study showed that antioxidant supplements, especially a combination of antioxidants such as vitamin C, vitamin E, and CoQ10 intake can effectively improve semen parameters in infertile men.
Keywords: Antioxidants; Carnitine; Coenzyme Q10 (CoQ10); Male infertility; Semen; Vitamins.