TABLE 2.

Positive and negative impacts of various parameters on sperm and male fertility

Parameter	Positive impact	Negative impact	References
Obestatin	Increases testosterone secretions Ameliorates testicular functions	–	İrez et al. (2019)
Omega−6 fatty acids	Induces inflammation of a slight intensity, atherosclerosis, dysfunction of the endothelium, and oxidative stress	Cause a deterioration in testicular endocrine function Reduce the concentration levels of free and total testosterone Decrease the testicular volume	Mínguez‐Alarcón et al. (2017)
Saturated fats	–	Decrease the sperm concentration in semen Lower semen count
Fish oil supplements	Improve semen parameters in response to omega‐3	Affect sperm fatty acid
Grape seed Para–amino‐benzoic acid Red clover	Fertility‐enhancing dietary and nutritional supplement compositions	–	Andrews and Grunebaum (2015)
Amino acids (D‐Aspartic acid, arginine [Arg], glutamate, tyrosine, tryptophan)	Effective primary defense for protection of the sperm membrane structure Amino acids–deficient diet decreases sperm counts by ca. 90% and increases the percentage of nonmotile sperm approximately 10‐fold Amino acid supplements increased sperm counts by 18% and sperm motility by 7.6%	–
Seminal plasma amino acids (Alanine, serine, valine, glycine, L‐proline, L‐glutamine)	Cause post‐thaw viability Enhance the live sperm, total motility, and maintain higher functional membrane and acrosomal integrity by reducing lipid peroxidation	–	Kocabaş et al. (2019)
Smoking	–	Induces oxidative stress in the testes Reduces sperm concentration Increases abnormal morphology Decreases motility and vitality Enhances DNA fragmentation and seminal leukocyte concentration Reduces capacitation and acrosome reactions	Martin et al. (2016)
Alcohol	–	Causes poor fertility Affects negatively spermatogenesis and semen parameters, including sperm motility, morphology, and concentration	Karmon et al. (2017)