Abstract
Study question
Does oral antioxidant supplementation improve sperm quality in infertile men with varicocele who have not undergone surgical repair?
Summary answer
Oral antioxidant supplementation improves sperm concentration and motility in infertile men with varicocele who have not undergone surgical repair. What is known already: Benefit from oral antioxidant supplementation has been shown in infertile men with varicocele following surgical repair. Similarly, oral antioxidant supplementation has been suggested in infertile men with varicocele who have not undergone surgical repair. However, its effect currently remains controversial.
Study design, size, duration
A literature search was performed until January 2021 aiming to identify prospective studies evaluating the use of oral antioxidant supplementation alone or in combination in men with varicocele who have not undergone surgical repair.
Participants/materials, setting, methods
Seven prospective studies were identified, published between 1987 and 2018, including 278 infertile men with varicocele who had not undergone surgical repair. The number of patients included ranged from 20 to 65. Sperm analysis, evaluating sperm concentration, motility and morphology was performed in these studies before and after oral antioxidant supplementation. Meta-analysis of weighted data was performed using random effects model. Results are reported as weighted mean difference (WMD) with 95% confidence interval (CI).
Main results and the role of chance
Seven studies were included in the systematic review. Oral antioxidant supplementation was performed by a combination of pentoxifylline, zinc and folic acid (single study), a combination of l-carnitine, fumarate, acetyl-l-carnitine, fructose, CoQ, vitamin C, zinc, folic acid and vitamin B12 (single study), a combination of L-Carnitine, vitamin C, coenzyme Q10, vitamin E, vitamin B9, vitamin B12, zinc , and selenium, l-carnitine (single study), or sole treatment with acetyl-l-carnitine (single study), L-Carnitine (single study), Coenzyme Q10 (single study) or zinc sulfate (single study). For the purpose of meta-analysis, the effect of oral antioxidant supplementation was evaluated after three months of treatment.
Oral antioxidant supplementation significantly increased sperm concentration (WMD +5.65x106/ml 95% CI: +1.11 to + 10.12 p = 0.01, random effects model) and motility (WMD +4.30%, 95% CI: +0.86 to + 7.74 p = 0.01, random effects model) in infertile men with varicocele who had not undergone surgical repair.
On the other hand, no significance difference was observed in sperm morphology (WMD +3.9%, 95% CI: –0.16 to + 8.04 p = 0.06, random effects model) and volume (WMD +0.53ml, 95% CI: 0.0 to + 1.0 p = 0.052, random effects model).
Limitations, reasons for caution
The number of relevant trials and that of patients included is small to allow for solid conclusions to be drawn. Moreover, although different oral antioxidants have been administered in infertile who had not undergone surgical repair, subgroup analysis was not feasible.
Wider implications of the findings: Currently, limited evidence supports the use of oral antioxidants in the treatment of men with varicocele, who have not undergone surgical repair. Although the benefit in sperm concentration and motility appears to be modest, it might be important regarding achievement of pregnancy in these men.
Trial registration number
Not applicable
Effects of Periconceptional Multivitamin Supplementation on Folate and Homocysteine Levels Depending on Genetic Variants of Methyltetrahydrofolate Reductase in Infertile Japanese Women
