In addition, we used the modified McMaster methodological quality assessment tool and the Cochrane risk of bias assessment tool to ensure that all selected records met the minimum quality criteria and included several outcomes commonly used in sports nutrition research. NAC could act as a neutraliser of exercise-induced OS by protecting erythrocyte membranes , which would result in an increase in Hb and Hct values compared with non-supplemented subjects. The increase in EPO secretion is mediated by an increase in hypoxia-inducible factor 1-alpha (HIF-1α), directly by NAC supplementation, or by plasma thiols that stabilise HIF-1α; for example, by acting on the hydroxylation of its proline residues . The immunomodulatory properties of NAC at high doses (2400 mg/day) could increase GSH levels in lymphocytes and modulate neutrophil functions during the development of SARS-CoV-2 infection, but NAC does not enhance immune response . The immunomodulatory properties of NAC at high doses (2400 mg/day) could elevate GSH levels in lymphocytes and modulate neutrophil functions during the development of SARS-CoV-2 infection, [shqkxh.org](http://shqkxh.org:3000/arnetteharms5) but NAC does not increase functions in the immune response . However, there was no clear evidence of beneficial effects of NAC supplementation on haematological markers, inflammatory response, and muscle behaviour. Participants supplemented with NAC showed significant improvements in exercise performance, antioxidant capacity, [http://61.190.74.90:9900/wuladolph1665](http://61.190.74.90:9900/wuladolph1665) and glutathione homeostasis. Overall, most of the trials reported beneficial effects of NAC supplementation and no serious adverse events were reported. Original articles published up to 30 April 2023 with a controlled trial design comparing NAC supplementation with a control group were included. Using the Preferred Reporting Items for Systematic Reviews and [git.randomhack.com](https://git.randomhack.com/walterskeyhill) Meta-Analyses (PRISMA) guidelines, we systematically reviewed studies indexed in the Web of Science, Scopus, and PubMed to assess the effects of NAC on physical performance, laboratory biomarkers, and adverse effects in adult men. Also, publication bias could change the effects of NAC on E2 levels and endometrial thickness. A comparison of two meta-analyses with the subjects of NAC and l-carnitine supplementation on inflammatory and oxidative stress biomarkers revealed that NAC had better effects than l-carnitine(Reference Faghfouri, Zarezadeh and Tavakoli-Rouzbehani6,Reference Fathizadeh, Milajerdi and Reiner44) . Other mechanisms proposed for [feleempleo.es](https://feleempleo.es/employer/mens-hormone-therapy-in-atlanta-ga/) the effects of l-carnitine on FSH and LH levels could be attributed to the regulation of lipid peroxidation and activity of antioxidant enzymes(Reference Rezaei, Mardanshahi and Shafaroudi43). Therefore, [http://47.103.159.168](http://47.103.159.168:10012/florentinatimm) a definite interpretation of more decreasing effects of NAC on E2 levels than metformin needs more studies. Study location, treatment duration and type of control were detected as sources of heterogeneity following subgroup analysis (Table 2). Thus, trim and fill analysis was conducted with five imputed studies. Sensitivity analysis determined that no particular study likely affected the pooled results. The type of control and study location were identified as sources of high heterogeneity following subgroup analysis. This study was conducted as a randomized, blinded clinical trial. Comhaire et al. also found that NAC improved sperm concentration and acrosome reaction while reducing ROS and oxidation of sperm DNA . At the same time, antioxidants, which protect the cell from excessive ROS-induced lipid peroxidation, are also present in the ejaculate . Spermatozoa are susceptible to oxidative damage because their plasma membranes are rich in polyunsaturated fatty acids and have low concentrations of scavenging enzymes . In infertile men’s semen, leukocytes and immature or abnormal spermatozoa are often the two main sources of ROS . Therefore, scavenging excess ROS is essential [testosterone for sale](http://101.37.147.115:3000/jenifertinline/git.gasshog.fr2011/wiki/How-to-Do-Cupping-Therapy:-What-It-Is%2C-Benefits-and-Risks) normal spermatogenesis and fertilization . Increased pathological ROS generation leads to sperm dysfunction (lipid peroxidation), [https://jobcop.uk/employer/testosterone-for-sale-buy-testosterone-online-legally](https://jobcop.uk/employer/testosterone-for-sale-buy-testosterone-online-legally/) decreased semen quality and sperm DNA damage . The small-study effect was evaluated by the formal tests of Egger’s and Begg’s. To detect potential sources of heterogeneity, subgroup analyses were performed according to the predefined variables, including duration of the intervention, NAC dosage, [https://git.nulldirect.com/preston62c4097](https://git.nulldirect.com/preston62c4097) study location and the type of control. If heterogeneity was not significant, the fixed-effects model was employed to estimate the overall effect size. Risk bias assessments were conducted independently by two reviewers. If the study contains a methodological defect that may affect its findings, the study was given a ‘high risk’ score; if there was no defect for that domain, a ‘low risk’ score; if the information was insufficient to determine the effect, an ‘uncertain risk’ score. The tool consists of seven domains, including random sequence generation, allocation concealment, [http://60.205.162.59:3000/ruebenrobert49](http://60.205.162.59:3000/ruebenrobert49) performance bias, reporting bias, detection bias, attrition bias and other sources of bias. The amino acid NAC can modulate OS through its actions as a cysteine donor in maintaining glutathione homeostasis and through a direct knockdown of ROS . In these cases, the administration of exogenous antioxidants seems necessary to alleviate oxidative damage . These factors can be considered oxidative risk co-factors, [unpourcent.online](https://unpourcent.online/@helenephx13192) as they increase the risk of damage and OS due to their cumulative effect on the ROS sources of exercise . In addition, there are extrinsic factors to exercise that can increase and trigger more OS in the body or impair the effectiveness of the antioxidant defence system, [124.223.89.168](http://124.223.89.168:8080/philomenafetty/philomena1984/wiki/The-Largest-Online-Healthcare-Clinic-in-North-America%2C-Affordable-Pricing%2C-Enjoy-Increased-Energy-%26-Focus%21) such as environmental conditions and the athlete’s diet . After NAC treatment, patients’ sperm count and motility increased significantly whereas abnormal morphology, DNA fragmentation and protamine deficiency showed significant decreases compared to pre-treatment levels (P P P This study investigated the effects of supplementation with N-acetyl-cysteine (NAC) on the sperm quality, chromatin integrity and levels of oxidative stress in infertile men. In a meta-analysis study, beneficial effects of NAC supplementation on IL-8, malondialdehyde and homocysteine levels have been shown.
In addition, we used the modified McMaster methodological quality assessment tool and the Cochrane risk of bias assessment tool to ensure that all selected records met the minimum quality criteria and included several outcomes commonly used in sports nutrition research. NAC could act as a neutraliser of exercise-induced OS by protecting erythrocyte membranes , which would result in an increase in Hb and Hct values compared with non-supplemented subjects. The increase in EPO secretion is mediated by an increase in hypoxia-inducible factor 1-alpha (HIF-1α), directly by NAC supplementation, or by plasma thiols that stabilise HIF-1α; for example, by acting on the hydroxylation of its proline residues . The immunomodulatory properties of NAC at high doses (2400 mg/day) could increase GSH levels in lymphocytes and modulate neutrophil functions during the development of SARS-CoV-2 infection, but NAC does not enhance immune response . The immunomodulatory properties of NAC at high doses (2400 mg/day) could elevate GSH levels in lymphocytes and modulate neutrophil functions during the development of SARS-CoV-2 infection, [shqkxh.org](http://shqkxh.org:3000/arnetteharms5) but NAC does not increase functions in the immune response . However, there was no clear evidence of beneficial effects of NAC supplementation on haematological markers, inflammatory response, and muscle behaviour. Participants supplemented with NAC showed significant improvements in exercise performance, antioxidant capacity, [http://61.190.74.90:9900/wuladolph1665](http://61.190.74.90:9900/wuladolph1665) and glutathione homeostasis. Overall, most of the trials reported beneficial effects of NAC supplementation and no serious adverse events were reported. Original articles published up to 30 April 2023 with a controlled trial design comparing NAC supplementation with a control group were included. Using the Preferred Reporting Items for Systematic Reviews and [git.randomhack.com](https://git.randomhack.com/walterskeyhill) Meta-Analyses (PRISMA) guidelines, we systematically reviewed studies indexed in the Web of Science, Scopus, and PubMed to assess the effects of NAC on physical performance, laboratory biomarkers, and adverse effects in adult men. Also, publication bias could change the effects of NAC on E2 levels and endometrial thickness. A comparison of two meta-analyses with the subjects of NAC and l-carnitine supplementation on inflammatory and oxidative stress biomarkers revealed that NAC had better effects than l-carnitine(Reference Faghfouri, Zarezadeh and Tavakoli-Rouzbehani6,Reference Fathizadeh, Milajerdi and Reiner44) . Other mechanisms proposed for [feleempleo.es](https://feleempleo.es/employer/mens-hormone-therapy-in-atlanta-ga/) the effects of l-carnitine on FSH and LH levels could be attributed to the regulation of lipid peroxidation and activity of antioxidant enzymes(Reference Rezaei, Mardanshahi and Shafaroudi43). Therefore, [http://47.103.159.168](http://47.103.159.168:10012/florentinatimm) a definite interpretation of more decreasing effects of NAC on E2 levels than metformin needs more studies. Study location, treatment duration and type of control were detected as sources of heterogeneity following subgroup analysis (Table 2). Thus, trim and fill analysis was conducted with five imputed studies. Sensitivity analysis determined that no particular study likely affected the pooled results. The type of control and study location were identified as sources of high heterogeneity following subgroup analysis. This study was conducted as a randomized, blinded clinical trial. Comhaire et al. also found that NAC improved sperm concentration and acrosome reaction while reducing ROS and oxidation of sperm DNA . At the same time, antioxidants, which protect the cell from excessive ROS-induced lipid peroxidation, are also present in the ejaculate . Spermatozoa are susceptible to oxidative damage because their plasma membranes are rich in polyunsaturated fatty acids and have low concentrations of scavenging enzymes . In infertile men’s semen, leukocytes and immature or abnormal spermatozoa are often the two main sources of ROS . Therefore, scavenging excess ROS is essential [testosterone for sale](http://101.37.147.115:3000/jenifertinline/git.gasshog.fr2011/wiki/How-to-Do-Cupping-Therapy:-What-It-Is%2C-Benefits-and-Risks) normal spermatogenesis and fertilization . Increased pathological ROS generation leads to sperm dysfunction (lipid peroxidation), [https://jobcop.uk/employer/testosterone-for-sale-buy-testosterone-online-legally](https://jobcop.uk/employer/testosterone-for-sale-buy-testosterone-online-legally/) decreased semen quality and sperm DNA damage . The small-study effect was evaluated by the formal tests of Egger’s and Begg’s. To detect potential sources of heterogeneity, subgroup analyses were performed according to the predefined variables, including duration of the intervention, NAC dosage, [https://git.nulldirect.com/preston62c4097](https://git.nulldirect.com/preston62c4097) study location and the type of control. If heterogeneity was not significant, the fixed-effects model was employed to estimate the overall effect size. Risk bias assessments were conducted independently by two reviewers. If the study contains a methodological defect that may affect its findings, the study was given a ‘high risk’ score; if there was no defect for that domain, a ‘low risk’ score; if the information was insufficient to determine the effect, an ‘uncertain risk’ score. The tool consists of seven domains, including random sequence generation, allocation concealment, [http://60.205.162.59:3000/ruebenrobert49](http://60.205.162.59:3000/ruebenrobert49) performance bias, reporting bias, detection bias, attrition bias and other sources of bias. The amino acid NAC can modulate OS through its actions as a cysteine donor in maintaining glutathione homeostasis and through a direct knockdown of ROS . In these cases, the administration of exogenous antioxidants seems necessary to alleviate oxidative damage . These factors can be considered oxidative risk co-factors, [unpourcent.online](https://unpourcent.online/@helenephx13192) as they increase the risk of damage and OS due to their cumulative effect on the ROS sources of exercise . In addition, there are extrinsic factors to exercise that can increase and trigger more OS in the body or impair the effectiveness of the antioxidant defence system, [124.223.89.168](http://124.223.89.168:8080/philomenafetty/philomena1984/wiki/The-Largest-Online-Healthcare-Clinic-in-North-America%2C-Affordable-Pricing%2C-Enjoy-Increased-Energy-%26-Focus%21) such as environmental conditions and the athlete’s diet . After NAC treatment, patients’ sperm count and motility increased significantly whereas abnormal morphology, DNA fragmentation and protamine deficiency showed significant decreases compared to pre-treatment levels (P P P This study investigated the effects of supplementation with N-acetyl-cysteine (NAC) on the sperm quality, chromatin integrity and levels of oxidative stress in infertile men. In a meta-analysis study, beneficial effects of NAC supplementation on IL-8, malondialdehyde and homocysteine levels have been shown.