2. Outcomes and conclusions from all included studies.
| Study ID | Design, population | Outcomes described in methods section | Outcomes reported on in results | In meta‐analysis Y or N | Results |
Conclusions + = positive effect ‐ = negative or no effect |
| Akiyama 1999 | Cross‐over, head‐to‐head Infertile men, high ROS levels N = 10 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Ethylcystein did not improve sperm density and motility but "sperm function" increased and ROS levels decreased, compared to vitamin E | + Ethylcysteine shown to be effective for improvement of sperm parameters when compared to vitamin E |
| Attallah 2013 | Parallel, no treatment Idiopathic athenozospermia, IUI N = 30 Conference abstract |
Sperm parameters, chemical and clinical pregnancy | Sperm parameters, chemical and clinical pregnancy | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical |
NAC increased sperm concentration and motility Clinical pregnancy was not significantly different between the groups |
+ NAC improves semen quality and improves pregnancy rates prior to IUI, no improvement of pregnancy rate |
| Azizollahi 2013 | Multiple arm trial Men post‐varicocelectomy N = 160 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical |
Mild improvement in sperm parameters with the use of antioxidants zinc, folic acid or both | + Co‐administration of zinc and folic acid improved sperm parameters and increased varicocelectomy outcomes, only zinc an improvement in pregnancy rate |
| Balercia 2005 | Multiple arm, placebo Infertile men N = 60 |
Sperm parameters | Sperm parameters, pregnancy rate | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical Y ‐ live birth |
Improvement in motility in LAC group. | + Long‐term carnitine is effective in increasing sperm motility. No evidence of increased live birth or clinical pregnancy. |
| Balercia 2009 | Parallel, placebo Infertile and unexplained N = 60 |
Sperm parameters | Sperm parameters, pregnancy rate | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical |
Co enzyme Q10 increased sperm motility. | + Q10 effective in improving sperm kinetic features in asthenospermia. No evidence of increased live birth or clinical pregnancy. |
| Barekat 2016 | Parallel, no treatment Subfertile men with varicocele N = 40 |
Sperm parameters, DNA fragmentation | Sperm parameters, DNA fragmentation, clinical spontaneous pregnancies | Y ‐ sperm parameters Y ‐ DNA fragmentation Y ‐ pregnancy rate, clinical (SEs converted to SDs) |
Sperm parameters significantly improved after surgery compared to before surgery in both the NAC and control groups. NAC might have an additional value by improving sperm motility post‐varicocelectomy | + The results of this study revealed that NAC improved chromatin integrity and pregnancy rate when administered as adjunct therapy post‐varicocelectomy |
| Biagiotti 2003 | Multiple arm, no treatment Severe idiopathic oligoasthenospermia N = 42 Conference abstract |
Sperm parameters | Sperm parameters | N ‐ no data available | A significant improvement in morphology concentration, motility in the carnitine group No side effects |
+ Quality of semen is positively associated with fertilisation and implantation rates in assisted reproduction |
| Blomberg Jensen 2018 | Parallel, placebo Infertile men with impaired semen quality N = 307 |
Sperm parameters, reproductive hormones, live birth rate | Sperm parameters, reproductive hormones, live birth rate | Y ‐ sperm parameters Y ‐ live birth rate |
Vitamin D was not associated with changes in semen parameters, although spontaneous pregnancies tended to be higher in couples in which the man was in the treatment group | ± Vitamin D did not improve semen quality. The positive impact of vitamin D supplementation on live birth rate and serum inhibin B in oligozoospermic and vitamin D–deficient men may be of clinical importance and warrant verification by others. |
| Boonyarangkul 2015 | Multiple arm, placebo, tamoxifen excluded Men with abnormal semen analysis N = 68 |
Sperm parameters, DNA damage (Comet assay) | Sperm parameters, DNA tail length | Y ‐ sperm parameters | Folate alone significantly decreased DNA tail length at 3‐months. Sperm motility was significantly increased after 3‐months Folate alone. | + Our study indicated that folate in combination with Tamoxifen citrate could improve sperm quality including semen parameters and sperm DNA integrity |
| Busetto 2018 | Parallel, placebo Infertile men with OAT, 50% included with varicocele N = 104 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical |
Sperm concentration, total sperm count, progressive and total motility were significantly increased in supplemented (Proxeed Plus) patients. Increased pregnancy rate | + Supplementation with metabolic and antioxidant compounds could be efficacious when included in strategies to improve fertility |
| Cavallini 2004 | Multiple arm, placebo Idiopathic OAT men with varicocele N = 325 |
Sperm parameters, pregnancy rate, adverse events | Sperm parameters, pregnancy rate, adverse events | N ‐ sperm parameters, only medians given in full text. Means in conference abstract but no data given for placebo group and data for group 3 (carnitine + cinoxacin) versus group 2 (carnitines) unable to be used as 3 includes cinoxacin an anti‐inflammatory drug. Analysis 1.12; Analysis 1.14; Analysis 1.24; Analysis 1.26 N ‐ pregnancy rate, unclear if clinical Table 2 Y ‐ adverse events |
Significant increase in sperm parameters for carnitines when compared to placebo. Carnitine groups had a significantly higher pregnancy rate than placebo group |
+ The antioxidant plus anti‐inflammatory group was more effective in improving sperm parameters and pregnancy than those of carnitines alone or placebo however carnitines alone were more effective than placebo |
| Conquer 2000 | Multiple arm, placebo Asthenozoospermic men N = 28 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters (SEs converted to SDs) |
DHA showed no effect on sperm motility or concentration | ± DHA supplementation increased DHA levels in the sperm but not motility or concentration |
| Cyrus 2015 | Parallel, placebo Infertile men with varicocele N = 115 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Vitamin C was not effective on sperm count but improved sperm motility and morphology significantly | + Ascorbic acid can play a role as adjuvant treatment after varicocelectomy in infertile men |
| Dawson 1990 | Multiple arm, placebo Men with sperm agglutination N = 30 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters (SEs converted to SDs) |
The group receiving 1000 mg of AA showed more improvement in parameters than the 200mg group and the placebo | + Vitamin C can improve sperm parameters, especially dosage of 1000 mg. |
| Deng 2014 | Head‐to‐head Men with idiopathic oligoasthenozoospermia N = 86 |
Sperm parameters, adverse reactions, pregnancy rate | Sperm parameters, adverse reactions, pregnancy rate | Y ‐ sperm parameters Y ‐ clinical pregnancy rate |
Vitamin D is a safe option for the treatment of idiopathic oligoasthenozoospermia and can effectively improve the semen quality especially the progressive sperm motility |
+ Vitamin D can improve forward movement sperm number and percentage, improve the woman's clinical pregnancy rate, and is well tolerated |
| Dimitriadis 2010 | Multiple arm, no treatment, vardenafil/sildenafil arms excluded Men with oligoasthenospermia N = 75 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | An improvement in sperm concentration with carnitine versus no treatment | + Enhancement of Leydig cell secretory function may increase sperm concentration and motility |
| Ener 2016 | Parallel, no treatment Infertile men with varicocele N = 56 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, unknown if clinical Table 2 |
The administration of vitamin E increased all of the parameters; however not statistically significant | ‐ Vitamin E supplementation does not improve the sperm parameters after varicocelectomy |
| Eslamian 2013 | Parallel, placebo Asthenoszoospermic men N = 50 |
Sperm parameters | sperm parameters, sperm membrane and serum fatty acids | N ‐ sperm parameters, data not usable, no continuous data but categories from 'significantly improvement' to 'worsened' | Sperm parameters improved with DHA + vitamin E supplementation | + Sperm parameters improve with DHA + vitamin E supplementation |
| Exposito 2016 | Parallel, placebo Normozoospermig, oligozoospermic and asthenozoospermic men N = 113 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | N ‐ sperm parameters N ‐ pregnancy rate Both not included because data included normospermic men |
50% of oligozoospermic men improved sperm concentration and sperm count to normozoospermic levels. This trend was also observed in asthenozoospermic men, but nog significantly | + Vitamin E treatment by oral administration improves semen parameters |
| Galatioto 2008 | Parallel, no treatment Men with persistent oligospermia after embolisation of varicocele N = 42 |
Sperm parameters, pregnancy rate, adverse events | Sperm parameters, pregnancy rate, adverse events | N ‐ sperm parameters, only medians given N ‐ pregnancy, unclear if clinical Table 2 N ‐ adverse events |
Significant difference in sperm count in combined antioxidant group but not in motility. One pregnancy in the NAC group No significant adverse effects |
± NAC does not improve pregnancy rate, no significant adverse events, but do significantly increase sperm count |
| Gamidov 2017 | Multiple arm, no treatment Men with varicocele N = 114 |
Sperm parameters, DNA fragmentation, adverse events | Sperm parameters, DNA fragmentation, adverse events | N ‐ sperm parameters, only medians with IQR Analysis 1.18; Analysis 1.24; Analysis 1.24 N ‐ DNA fragmentation, only medians with IQR Analysis 1.10 Y ‐ adverse events |
SpermActine (SA) resulted in a 22.3% decrease in the level of sperm DNA fragmentation at 3 months. SA + vitamin complex resulted in a 27% increase in the sperm concentration at 3 months. There were no side effects of pharmacotherapy. | + Antioxidant therapy leads to an improvement in the basic sperm parameters (sperm concentration and motility) and a decrease in the level of sperm DNA fragmentation in the short term. There were no side effects |
| Gopinath 2013 | Multiple arm, placebo Idiopathic OAT men N = 138 |
Sperm parameters, pregnancy rate, adverse events | Sperm parameters, pregnancy rate, adverse events | Y ‐ sperm parameters N ‐ pregnancy rate, not clinical Table 2 Y ‐ adverse events |
Combined antioxidant significantly improved sperm count and total motility in both treatment arms (1 vs 2 tablets). Mild adverse events were reported, no severe. | + Exogenous administration of fixed dose combination of antioxidants is safe and effective therapy in improving the male subfertility regarding sperm parameters. Only mild adverse events when using combined antioxidants |
| Greco 2005 | Parallel, placebo Infertile males with high DNA fragmentation N = 64 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | No significant difference in concentration or motility however DNA fragmentation was significantly reduced in the vitamin C + E when compared to placebo | + A short oral treatment of Vitamin C + E can reduce DNA fragmentation |
| Haghighian 2015 | Parallel, placebo Men with idiopathic asthenozoospermia N = 48 |
Sperm parameters, adverse events | Sperm parameters, adverse events | Y ‐ sperm parameters N ‐ adverse events, reported "none", however not clear which side effects they aimed for |
Sperm parameters were significantly higher in ALA group. No side effects due to the oral administration of ALA were observed in any participants. | + Medical therapy of asthenoteratospermia with ALA supplement could improve quality of semen parameters |
| Haje 2015 | Multiple arm, placebo, tamofixen arms excluded Infertile men with idiopathic OAT N = 128 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | N ‐ sperm parameters, range of treatment 3 ‐ 6 months and not divided N ‐ pregnancy rate, unclear if pregnancy and no numbers but percentage |
L‐carnitine no improvement of sperm count or motility. Only tamoxifen or tamofixen + L‐carnitine improved pregnancy rate, not significantly. | ± Administration of tamoxifen or L‐carnitine can improve sperm parameters and ICSI outcomes. Combining those result in maximum therapeutic effect |
| Kessopoulou 1995 | Cross‐over, placebo Male infertility N = 30 |
Sperm parameters, adverse events, live birth | Sperm parameters, adverse effects, live birth | N ‐ sperm parameters, only medians given Analysis 1.12; Analysis 1.24 Y ‐ pregnancy rate, clinical Y ‐ live births Y ‐ adverse events |
No differences in sperm outcomes were seen between the groups. 1 pregnancy in the vitamin E group and nil in the placebo (first phase data) | + No difference in semen parameters. There is evidence of increased live birth and clinical pregnancy rate. |
| Kumamoto 1988 | Multiple arm, placebo Men with abnormal sperm count or motility N = 396 |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, only scales given | No statistical difference in sperm outcomes in vitamin B 12 groups or placebo | ‐ No improvement in sperm parameters after use of vitamin B12 |
| Lenzi 2003 | Cross‐over, placebo Infertile men with OAT N = 100 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, no definition of pregnancy given see Table 2 |
The patient groups showed no differences in sperm outcomes between therapy (carnitine) and placebo groups. Six pregnancies in the carnitine group and nil in the placebo (first phase) |
+ The pregnancies obtained during the carnitine therapy period could suggest that carnitines may also lead to improvement in sperm function and fertilisation |
| Lenzi 2004 | Parallel, placebo Infertile men with OAT N = 60 |
Sperm parameters, pregnancy rate, adverse events | Sperm parameters, pregnancy rate, adverse events | Y ‐ sperm parameters N ‐ pregnancy rate, no definition of pregnancy given Table 2 N ‐ adverse events |
Four participants taking carnitine induced a pregnancy in their partner and nil in the placebo | + No evidence of improved sperm parameters |
| Li 2005 | Head‐to‐head Infertile men with OAT N = 150 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, no definition given Table 2 |
L‐carnitine and acetyl carnitine more effective than vitamin E + vitamin C for pregnancy, sperm parameters and no evidence of adverse events | + L‐carnitine and acetyl carnitine more effective than vitamin E + vitamin C for pregnancy, sperm parameters and no evidence of adverse events |
| Li 2005a | Head‐to‐head Infertile men with OAT N = 80 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Statistical significance for carnitines over vitamin E + C | + Improvement of sperm parameters for carnitines compared to vitamin E + C |
| Lombardo 2002 | Cross‐over Infertile men with OAT N = 100 Conference abstract |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, no data available | Sperm parameters (concentration, motility) carnitines versus placebo | + Improvement of sperm parameters |
| Martinez 2015 | Multiple arm, placebo, SG1002 arm excluded Men with idiopathic OAT N = 54 |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, no SDs given | Resveratrol treatment did not significantly affect any of the parameters. | ‐ Resveratrol treatment did not significantly affect any of the parameters. SG1002 may reverse oligoasthenozoospermia. It seems to be more potent antioxidant than resveratrol |
| Martinez‐Soto 2010 | Parallel, placebo Infertile men N = 50 Conference abstract + manuscript from author |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | No differences were found in traditional sperm parameters or lipid composition of the sperm membrane after DHA treatment, only reduction in the percentage of spermatozoa with DNA damage | + Positive effect only on DNA fragmentation |
| Mehni 2014 | Multiple arm, placebo, pentoxifylline arms excluded Infertile men with OAT N = 235 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | L‐carnitine only improved sperm motility, combined with pentoxifylline it improves all sperm parameters. | + Positive effect only sperm motility |
| Micic 2017 | Parallel, placebo Men with OAT N = 175 Conference abstract |
Sperm motility | Sperm motility | N ‐ sperm motility, data given in medians with IQR Analysis 1.18 | Proxeed Plus significantly improved progressive sperm motility | + Proxeed Plus significant improvement in percentage of progressive sperm motility after six months of therapy and also underlines the importance of duration of therapy (3 and 6 months) |
| Morgante 2010 | Parallel, no treatment Infertile men with idiopathic asthenospermia N = 180 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Significant improvement in sperm motility. | + Improvement of sexual satisfaction Significant improvement in sperm motility |
| Nadjarzadeh 2011 | Parallel, placebo Men with Idiopathic OAT N = 60 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Non‐significant changes in semen parameters of CoQ10 group. | ‐ CoQ10 further evidence suggesting that supplementation is associated with alleviating oxidative stress, although it does not show any significant effects on sperm concentration, motility and morphology |
| Nozha 2001 | Head‐to‐head Men with OAT N = unclear, 20? |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, no data available | Vitamin E + selenium significantly improves sperm motility | + Vitamin E + selenium associated with improved sperm motility when compared with vitamin B |
| Omu 1998 | Parallel, no treatment Men with asthenozoopermia N = 100 |
Sperm parameters | Sperm parameters, pregnancy, live birth |
N ‐ sperm parameters, only % increase or decrease, not usable Y ‐ pregnancy rate, clinical Y ‐ live birth |
Significant improvement in sperm quality by zinc therapy | + Zinc has a role in improving sperm parameters. Significant increase in pregnancy, not live birth |
| Omu 2008 | Multiple arm, no treatment Men with asthenozoospermia N = 100 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Zinc therapy alone, in combination with vitamin E or with vitamin E+C were associated with comparably improved sperm parameters and less sperm DNA fragmentation | + Zinc therapy reduces asthenozoospermia |
| Peivandi 2010 | Cross‐over, placebo Infertile men N = 30 |
Sperm parameters | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, no defined as clinical Table 2 |
Significant improvements in mean sperm concentration and progressive sperm motility upon two months of L‐carnitine intake but no significant changes were found in sperm volume or morphology. | + Sperm outcomes and biochemical pregnancies. L‐carnitine intake effectively improved the mean sperm count and progressive sperm motility |
| Pourmand 2014 | Parallel, no treatment Men with male factor infertility and varicocele N = 100 |
Sperm parameters, DNA fragmentation, adverse events | Sperm parameters, DNA fragmentation, adverse events | N ‐ sperm parameters, no SD given
N ‐ DNA fragmentation, no SD given Y ‐ adverse events |
No statistical difference between the two groups (varicocelectomy with L‐carnitine or with no adjuvant therapy). | ‐ Addition of 750 mg of L‐carnitine orally daily to standard inguinal varicocelectomy does not add any extra benefit in terms of improvement in semen analysis parameters or DNA damage |
| Poveda 2013 | Multiple arm, placebo Infertile men N = 60 Conference abstract |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, data not available | L‐carnitine significantly improves sperm concentration, Spermotrend and Maca improve sperm motility. | + Sperm concentration with L‐carnitine and motility with combined antioxidant Spermotrend |
| Pryor 1978 | Cross‐over, placebo Men with severe oligozoospermia N = 64 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | N ‐ sperm parameters, bar graph of % patients showing an increase in motility and density N ‐ pregnancy rate, not clear if clinical. Included in biochemical analysis Table 2 |
Arginine was no more effective than placebo for sperm parameters and biochemical pregnancy rates | ‐ There was no difference in the conception rates of the wives or changes in the quality of the semen during each period of treatment |
| Raigani 2014 | Multiple arm, placebo Men with proven male factor infertility N = 83 |
Sperm parameters, DNA fragmentation | Sperm parameters, DNA fragmentation | N ‐ sperm parameters, data provided in medians with IQR Y ‐ DNA fragmentation (mean with SD) |
Sperm concentration, DNA fragmentation not significantly improved in either group | ‐ Zinc sulphate and folic acid supplementation did not ameliorate sperm quality in infertile men with severely compromised sperm parameters, OAT |
| Rolf 1999 | Asthenospermia (N = 33) |
Sperm parameters, pregnancy rates, adverse events | Sperm parameters, pregnancy rate, adverse events | Y ‐ sperm parameters N ‐ pregnancy rate, not stated as clinical pregnancy N ‐ adverse events, not clear which side effects aimed for |
No adverse events or pregnancies in either group | ‐ Overall no difference vitamin E + C versus placebo |
| Safarinejad 2009 | Multiple arm, placebo Men with idiopathic OAT N = 468 |
Sperm parameters, adverse events | Sperm parameters, adverse events | Y ‐ sperm parameters N ‐ adverse events, not specified which adverse events aimed for |
All semen parameters significantly improved with selenium and N‐acetyl‐cysteine treatment. Administering selenium plus N‐acetyl‐cysteine resulted in additive beneficial effects. Zero adverse events | + Supplemental selenium and N‐acetyl‐cysteine improve semen quality. Zero adverse events |
| Safarinejad 2009a | Parallel, placebo Men with idiopathic OAT N = 212 |
Sperm parameters, adverse events | Sperm parameters, adverse events | Y ‐ sperm parameters N ‐ adverse events, not specified which adverse events aimed for |
Significant improvement in sperm density and motility after coenzyme Q10 therapy. Zero adverse events | + Coenzyme Q10 supplementation resulted in a statistically significant improvement in certain sperm parameters. Zero adverse events |
| Safarinejad 2012 | Parallel, placebo Infertile men N = 228 |
Sperm parameters | Sperm parameters | Y ‐ sperm parameters | Sperm parameters improved significantly after coenzyme Q10 | + Coenzyme Q10 was significantly effective in men with unexplained oligoasthenoteratozoospermia for improving sperm density, sperm motility and sperm morphology |
| Scott 1998 | Multiple arm, placebo Men with subfertility and low sperm motility N = 69 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, not usable due to pooling of data in the two intervention groups Table 2 |
Sperm motility increased in both selenium‐treated groups, only significant if both treatment groups were combined. Sperm density unaffected | ± Selenium supplementation in subfertile men with low selenium status can improve sperm motility and the chance of successful conception. However, not all patients responded; 56% showed a positive response to treatment |
| Sharifzadeh 2016 | Parallel, placebo Idiopathic subfertile men N = 114 |
Sperm parameters, adverse events | Sperm parameters, adverse events | Y‐ sperm parameters Y ‐ adverse events |
Significant increase in concentration in zinc group | + Normal sperm percentage and total sperm concentration increased after zinc sulphate treatment |
| Sigman 2006 | Parallel, placebo Infertile men with low sperm motility N = 26 |
Sperm parameters, pregnancy rate | Sperm parameters, pregnancy rate | Y ‐ sperm parameters N ‐ pregnancy rate, biochemical Table 2 |
No statistically significant or clinically significant increase in motility or total motile sperm counts between baseline, 12 week, or 24 weeks in the carnitine or placebo arms. | ‐ Carnitine supplementation demonstrated no clinically or statistically significant effect on sperm motility or total motile sperm counts. No difference in pregnancy rate |
| Sivkov 2011 | Parallel, placebo Men with chronic prostatitis and infertility N = 30 |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, no SD given Analysis 1.12 | One‐month course of therapy produced no side effects, had a positive effect on low fertility of ejaculate. | + Selenium + zinc improve |
| Sofikitis 2016 | Multiple arm, no treatment, Avanafil excluded Oligoasthenospermic infertile men N = 39 Abstract only |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, no data available | No significant difference in L‐carnitine group regarding sperm parameters | ‐ No direct conclusion made about L‐carnitine. From result section concluded: no impact on sperm parameters after use of L‐carnitine |
| Suleiman 1996 | Parallel, placebo Asthenospermic men N = 110 |
Sperm parameters | Sperm parameters, pregnancy rate, live birth, miscarriage | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical Y ‐ live birth Y ‐ adverse events: miscarriage |
Vitamin E significantly decreased the MDA concentration in spermatozoa and improved sperm motility. Significant increase pregnancy/live birth rate | + Vitamin E increases sperm motility, pregnancy rate and live birth rate compared to placebo |
| Tremellen 2007 | Parallel, placebo Male factor infertility N = 60 |
Pregnancy rate, adverse events | Pregnancy rate, adverse events, live birth provided by author | Y ‐ pregnancy rate, clinical Y ‐ live birth Y ‐ adverse events |
Antioxidant group recorded a statistically significant improvement in viable pregnancy rate. Side‐effects on the Menevit antioxidant were rare (8%) and mild in nature. | + Menevit antioxidant appears to be a useful ancillary treatment that significantly improves pregnancy rates in couples undergoing IVF‐ICSI treatment. Side‐effects on the Menevit antioxidant were rare (8%) and mild in nature. |
| Wang 2010 | Head‐to‐head Infertile men with asthenozoospermia N = 135 |
Sperm parameters, pregnancy rate, adverse events | Sperm parameters, pregnancy rate, adverse events | Y ‐ sperm parameters N ‐ pregnancy rate, not clear if clinical Table 2 N ‐ adverse events, zero found, however not clear which they aimed for |
Significant increase in L‐carnitine + vitamin E group for sperm motility, no difference for sperm density and morphology. Pregnancy rate significantly higher in L‐carnitine + vitamin E group | + L‐carnitine (+vitamin E) significantly improves sperm motility and pregnancy rate |
| Wong 2002 | Multiple arm, placebo Fertile and subfertile men N = 103 |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, only medians provided Analysis 1.14; Analysis 1.26; Analysis 2.5; Analysis 2.12 | Subfertile men demonstrated a significant 74% increase in total normal sperm count and a minor increase of 4% abnormal spermatozoa | + Total normal sperm count increases after combined zinc sulphate and folic acid treatment in both subfertile and fertile men |
| Zalata 1998 | Head‐to‐head, pilot Men attending andrology clinic N = 22 Conference abstract |
Sperm parameters | Sperm parameters | N ‐ sperm parameters, only before and after median data given | No significant difference in sperm parameters after treatment (acetyl‐cysteine or DHA). DNA damage measured by oh8dG (fmol/ug) was significantly decreased after supplementation | ‐ No improvement of sperm parameters |
| Zavaczki 2003 | Parallel, placebo Men with idiopathic infertility N = 20 |
Sperm parameters, clinical pregnancy, adverse events | Sperm parameters, clinical pregnancy, adverse events | Y ‐ sperm parameters Y ‐ pregnancy rate, clinical Y ‐ adverse events |
No significant changes in sperm characteristics were detected | ‐ Magnesiumt neither leads to a significant improvement of sperm variables nor does it increase the pregnancy rates |
DHA: docosahexaenoic acid; IUI: intrauterine insemination; NAC: N‐acetylcysteine; OAT:oligoasthenoteratozoospermia; ROS: reactive oxygen species