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Antioxidants for male subfertility.

Overview of attention for article published in Cochrane database of systematic reviews, December 2014
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  • In the top 5% of all research outputs scored by Altmetric
  • High Attention Score compared to outputs of the same age (97th percentile)
  • High Attention Score compared to outputs of the same age and source (88th percentile)

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2 news outlets
3 blogs
20 tweeters
2 Facebook pages
1 Wikipedia page

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Antioxidants for male subfertility.
Published in
Cochrane database of systematic reviews, December 2014
DOI 10.1002/14651858.cd007411.pub3
Pubmed ID

Showell MG, Mackenzie-Proctor R, Brown J, Yazdani A, Stankiewicz MT, Hart RJ, Showell, Marian G, Mackenzie-Proctor, Rebecca, Brown, Julie, Yazdani, Anusch, Stankiewicz, Marcin T, Hart, Roger J, Marian G Showell, Rebecca Mackenzie-Proctor, Julie Brown, Anusch Yazdani, Marcin T Stankiewicz, Roger J Hart


Between 30% to 80% of male subfertility cases are considered to be due to the damaging effects of oxidative stress on sperm and 1 man in 20 will be affected by subfertility. Antioxidants are widely available and inexpensive when compared to other fertility treatments and many men are already using these to improve their fertility. It is thought that oral supplementation with antioxidants may improve sperm quality by reducing oxidative stress. Pentoxifylline, a drug that acts like an antioxidant, was also included in this review.   This Cochrane review aimed to evaluate the effectiveness and safety of oral supplementation with antioxidants for subfertile male partners in couples seeking fertility assistance. We searched the Cochrane Menstrual Disorders and Subfertility Group Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO and AMED databases (from inception until January 2014); trial registers; sources of unpublished literature and reference lists. An updated search was run in August 2014 when potentially eligible studies were placed in 'Studies awaiting assessment'. We included randomised controlled trials (RCTs) comparing any type or dose of antioxidant supplement (single or combined) taken by the subfertile male partner of a couple seeking fertility assistance with a placebo, no treatment or another antioxidant. Two review authors independently selected eligible studies, extracted the data and assessed the risk of bias of the included studies. The primary review outcome was live birth; secondary outcomes included clinical pregnancy rates, adverse events, sperm DNA fragmentation, sperm motility and concentration. Data were combined, where appropriate, to calculate pooled odds ratios (ORs) or mean differences (MD) and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I(2) statistic. We assessed the overall quality of the evidence for the main outcomes using GRADE methods.   This updated review included 48 RCTs that compared single and combined antioxidants with placebo, no treatment or another antioxidant in a population of 4179 subfertile men. The duration of the trials ranged from 3 to 26 weeks with follow up ranging from 3 weeks to 2 years. The men were aged from 20 to 52 years. Most of the men enrolled in these trials had low total sperm motility and sperm concentration. One study enrolled men after varicocelectomy, one enrolled men with a varicocoele, and one recruited men with chronic prostatitis. Three trials enrolled men who, as a couple, were undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) and one trial enrolled men who were part of a couple undergoing intrauterine insemination (IUI). Funding sources were stated by 15 trials. Four of these trials stated that funding was from a commercial source and the remaining 11 obtained funding through non-commercial avenues or university grants. Thirty-three trials did not report any funding sources.A limitation of this review was that in a sense we had included two different groups of trials, those that reported on the use of antioxidants and the effect on live birth and clinical pregnancy, and a second group that reported on sperm parameters as their primary outcome and had no intention of reporting the primary outcomes of this review. We included 25 trials reporting on sperm parameters and only three of these reported on live birth or clinical pregnancy. Other limitations included poor reporting of study methods, imprecision, the small number of trials providing usable data, the small sample size of many of the included studies and the lack of adverse events reporting. The evidence was graded as 'very low' to 'low'. The data were current to 31 January 2014.Live birth: antioxidants may have increased live birth rates (OR 4.21, 95% CI 2.08 to 8.51, P< 0.0001, 4 RCTs, 277 men, I(2) = 0%, low quality evidence). This suggests that if the chance of a live birth following placebo or no treatment is assumed to be 5%, the chance following the use of antioxidants is estimated to be between 10% and 31%. However, this result was based on only 44 live births from a total of 277 couples in four small studies.Clinical pregnancy rate: antioxidants may have increased clinical pregnancy rates (OR 3.43, 95% CI 1.92 to 6.11, P < 0.0001, 7 RCTs, 522 men, I(2) = 0%, low quality evidence). This suggests that if the chance of clinical pregnancy following placebo or no treatment is assumed to be 6%, the chance following the use of antioxidants is estimated at between 11% and 28%. However, there were only seven small studies in this analysis and the quality of the evidence was rated as low.Miscarriage: only three trials reported on this outcome and the event rate was very low. There was insufficient evidence to show whether there was a difference in miscarriage rates between the antioxidant and placebo or no treatment groups (OR 1.74, 95% CI 0.40 to 7.60, P = 0.46, 3 RCTs, 247 men, I(2) = 0%, very low quality evidence). The findings suggest that in a population of subfertile men with an expected miscarriage rate of 2%, use of an antioxidant would result in the risk of a miscarriage lying between 1% and 13%.Gastrointestinal upsets: there was insufficient evidence to show whether there was a difference in gastrointestinal upsets when antioxidants were compared to placebo or no treatment as the event rate was very low (OR 1.60, 95% CI 0.47 to 5.50, P = 0.46, 6 RCTs, 429 men, I(2) = 0%).We were unable to draw any conclusions from the antioxidant versus antioxidant comparison as not enough trials compared the same interventions. There is low quality evidence from only four small randomised controlled trials suggesting that antioxidant supplementation in subfertile males may improve live birth rates for couples attending fertility clinics. Low quality evidence suggests that clinical pregnancy rates may increase. There is no evidence of increased risk of miscarriage but this is uncertain as the evidence is of very low quality. Data were lacking on other adverse effects. Further large well-designed randomised placebo-controlled trials are needed to clarify these results.

Twitter Demographics

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Mendeley readers

The data shown below were compiled from readership statistics for 241 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Spain 1 <1%
Ethiopia 1 <1%
Chile 1 <1%
United Kingdom 1 <1%
Brazil 1 <1%
Canada 1 <1%
Unknown 235 98%

Demographic breakdown

Readers by professional status Count As %
Student > Master 52 22%
Researcher 40 17%
Student > Bachelor 30 12%
Student > Ph. D. Student 28 12%
Student > Doctoral Student 20 8%
Other 71 29%
Readers by discipline Count As %
Medicine and Dentistry 118 49%
Agricultural and Biological Sciences 44 18%
Unspecified 25 10%
Nursing and Health Professions 12 5%
Psychology 10 4%
Other 32 13%

Attention Score in Context

This research output has an Altmetric Attention Score of 50. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 31 May 2018.
All research outputs
of 11,411,629 outputs
Outputs from Cochrane database of systematic reviews
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Outputs of similar age
of 252,892 outputs
Outputs of similar age from Cochrane database of systematic reviews
of 251 outputs
Altmetric has tracked 11,411,629 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 97th percentile: it's in the top 5% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 9,089 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 20.6. This one has done particularly well, scoring higher than 91% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 252,892 tracked outputs that were published within six weeks on either side of this one in any source. This one has done particularly well, scoring higher than 97% of its contemporaries.
We're also able to compare this research output to 251 others from the same source and published within six weeks on either side of this one. This one has done well, scoring higher than 88% of its contemporaries.