The lack of evidence behind over-the-counter antioxidant supplements for male fertility patients: a scoping review

The Effect of Dietary Supplements on Male Infertility in Terms of Pregnancy, Live Birth, and Sperm Parameters: A Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

The aim of this systematic review and meta-analysis was to investigate the effect of dietary supplements on male infertility.

METHODS

PubMed, Embase, and CENTRAL were searched from inception to May 2024. Randomized controlled trials with treatment durations of ≥12 weeks investigating the effect of dietary supplements on male infertility compared to placebo were included. Primary outcomes were pregnancy and live birth, while secondary outcomes were sperm concentration, sperm count, total motility, progressive motility, normal morphology, and DNA Fragmentation Index. Risk of bias was assessed using the revised Cochrane risk of bias (RoB2) tool. Data were meta-analyzed using random effects-restricted maximum likelihood models. Certainty of evidence was evaluated using the grading of recommendations, assessment, development and evaluation (GRADE) approach.

RESULTS

Of the 3137 articles identified, 50 were included. No effect on pregnancy and live birth was found. Different supplements improved single sperm parameters: Zinc and folic acid and ≥3 substance dietary supplements improved sperm concentration, selenium, carnitine, and coenzyme Q10 improved motility and alpha-lipoic acid improved normal morphology. Vitamin D, vitamin E, and omega-3 fatty acids showed no improvement in sperm parameters. The majority of studies had some concerns or high risk of bias, and certainty of evidence was generally low or very low.

CONCLUSIONS

This study found no convincing evidence of an effect of any dietary supplements on male infertility. Larger and more well-conducted randomized controlled trials focusing on specific supplements and considering pregnancy outcomes are needed.

Current drawbacks and future perspectives in the diagnosis and treatment of male factor infertility, with a focus on FSH treatment: an expert opinion

PURPOSE

Infertility is defined as the inability to conceive after 1 year of unprotected intercourse, affecting approximately 15-20% of couples in Western countries. It is a shared problem within the couple; when the main issue lies with one of the partners, it is preferable to refer to "male factor" or "female factor" infertility rather than simply male or female infertility. Despite male factor infertility accounting for half of all couple infertility cases, the clinical approach to the male partner is not uniformly standardized across international guidelines.

METHODS

To provide an expert overview, we have comprehensively reviewed and critically analyzed the most up-to-date literature on this sensitive topic, leading to the development of a proposal for tailored assessment of the diagnostic-therapeutic pathway and preventive strategies. The diagnostic approach also considers that infertile men are objectively less healthy than their fertile counterparts of the same age and ethnicity.

RESULTS

This article discusses the diagnostic flow, the classification of male factor infertility, the definition of idiopathic infertility, the involvement of general health, and treatment recommendations, emphasizing follicle-stimulating hormone treatment in selected groups of patients.

CONCLUSION

We provide expert opinion on current drawbacks and future perspectives in this field, with practical advice for the clinical practice of general practitioners and expert in reproductive medicine.

The Effect of Antioxidant Administration on Semen Quality in Men with Infertility: A Randomized Placebo-Controlled Clinical Trial

A randomized, placebo-controlled, quadruple-blind trial was performed to evaluate the effect of oral administration of the antioxidant combination Spermotrend® for three months on semen quality in infertile men with at least one abnormal variable in semen analysis. Eighty men were randomized between 2019 and 2022, receiving either the antioxidant combination Spermotrend® (n = 40, spermotrend-group) or placebo (n = 40, placebo-group). Although a total of 80 patients were enrolled in the study, the final data is only from 70 patients. The primary outcome measure was sperm motility (rapid progressive, progressive, and total motility). The values of primary and secondary outcomes between treatment initiation and treatment completion were compared within groups. Moreover, their changes between treatment initiation and treatment completion were compared between the placebo- and the spermotrend-groups. Sperm rapid progressive motility significantly increased in infertile men treated for three months with antioxidant combination Spermotrend® (+1.0%, 95% CI: 0.0 to +2.0, p = 0.04), while this increase was not observed in the placebo-group. Sperm progressive motility significantly increased in infertile men treated for three months with antioxidant combination Spermotrend® (+3.0%, 95% CI: 0.0 to +15.1, p = 0.02), while this increase was not observed in the placebo-group. Similarly, DFI was significantly decreased in infertile men treated for three months by antioxidant combination Spermotrend® (-3.2%, 95% CI: -5.8 to -0.5, p = 0.02). However, no statistically significant differences were observed in the changes of pre- and post-treatment values between the spermotrend- and the placebo-group regarding sperm progressive motility, concentration, normal morphology, DFI, and formation of 8-OH-dG. The antioxidant combination Spermotrend® appears to exert limited benefit on sperm motility and DFI in infertile men with at least one abnormal variable in semen analysis.

Effectiveness of exercise interventions on sperm quality: a systematic review and network meta-analysis

Background

Infertility affects about 10% to 15% of the world's population, thus making it a global concern. Although there are a large number of studies to develop treatment for infertility in men, there are no studies to illustrate the effect of exercise on male sperm treatment in a well rationalized and aggregated manner, therefore the aim of this study was to validate the comparative effectiveness of different exercise interventions for treating sperm quality in men by using a network Meta-analysis.

Methods

All randomized clinical trials (RCT) were obtained from PubMed, Cochrane Library, EMBASE, Web of Science, CNKI, Wanfang, and VIP databases, and network meta-analysis was used to assess the effectiveness of exercise interventions on sperm quality.

Results

Fourteen studies with 1079 subjects were finally included in this study. Compared with the physical inactivity group, indoor aerobic, outdoor aerobic, and resistance training significantly reduced sperm density (P<0.05); indoor aerobic, outdoor aerobic, and resistance training significantly reduced the number of necrotic spermatozoa and the number of active spermatozoa (P>0.05).Outdoor aerobic[MD=1.84,95%CI:(1.56,2.14),P<0.05], multi-component motion [MD=1.37,95%CI:(0.85,1.89),P<0.05],competitive sports[MD=1.04,95%CI:(0.46,1.60),P<0.05],indoor aerobic [MD=0.32, 95%CI:(0.21,0.44), P<0.05], effectively enhanced sperm volume; other sports [MD=9.49,95%CI:(6.17,12.84),P<0.05], indoor aerobic[MD=4.43,95%CI:(3.12,5.74),P<0.05],resistance training [MD=3.93, 95%CI:(0.49,7.37), P<0.05], competitive sports [MD=5.44,95%CI:(0.10,10.79), P<0.05], and bicycle aerobics[MD=27.29,95%CI:(22.45,32.06),P<0.05], significantly enhanced sperm motility; other sports [MD=17.20,95%CI:(3.12,31.19), P<0.05], effectively enhanced total sperm count;resistance training[MD=10.90,95%CI:(8.44,13.36), P<0.05],other sports [MD=1.97,95%CI:(1.41,2.54),P<0.05], indoor aerobic [MD=2.43,95%CI:(1.13,3.73), P<0.05],and bicycle aerobic [MD=12.18, 95%CI:(10.19,14.18),P<0.05], significantly enhanced sperm morphology; bicycle aerobic (MD=18.87, 95%CI:11.70,25.86, P<0.05), and indoor aerobic (MD=9.53, 95%CI:8.97,10.09, P<0.05),effectively enhanced sperm concentration.

Conclusion

In conclusion, outdoor aerobics had a significant effect on improving sperm volume in infertile patients; other sports had a significant effect on enhancing sperm motility and total sperm count in infertile patients; resistance training had a significant effect on enhancing sperm morphology in infertile patients, and bicycle aerobic has a significant impact on improving sperm concentration in infertile patients.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#myprospero, identifier CRD42024534582.

Can nutraceuticals counteract the detrimental effects of the environment on male fertility? A parallel systematic review and expert opinion

INTRODUCTION

Male fertility relies on a complex physiology that may be negatively influenced by lifestyle, diet, and environment. The beneficial effect of nutraceuticals on male fertility is a debated claim. The aim of this study was to assess if the positive effect of nutraceuticals can counteract the negative effects of the environment on male fertility.

EVIDENCE ACQUISITION

PubMed®/MEDLINE®, Embase and Cochrane Database were searched (September-October 2023), along with crosschecking of references and search for ongoing studies of the effects of the environment and nutraceuticals on male fertility, in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

EVIDENCE SYNTHESIS

Several environmental factors such as microplastic and other endocrine-disrupting chemicals and climate changes may affect the sperm quality in terms of reduction of sperm count number, mobility and altered morphology and thereby reduce male fertility. On the other hand, new evidence demonstrates that a balanced diet rich in antioxidants and essential nutrients, together with minimized exposure to environmental toxins, may improve male fertility and reproductive health. Several nutraceutical compounds proved a protective role against negative environmental effects on male fertility.

CONCLUSIONS

Available evidence confirms that the environment may negatively impact male fertility, and this impact is estimated to rise in the forthcoming years. On the other hand, new data indicate that nutraceuticals may have a protective role against the negative impact of environmental factors on male fertility. The need for future studies to monitor and explore these aspects of men's health cannot be underestimated.

The dual nature of micronutrients on fertility: too much of a good thing?

OBJECTIVE

To study the effects of generally considered safe doses of antioxidant micronutrient supplementation on semen parameters, systemic redox balance, sperm DNA structural integrity, and fertility.

DESIGN

Given ethical limitations in human studies, this dose escalation study examined the effects of common water-soluble antioxidant micronutrients (vitamin C, zinc, folate, and carnitine) on semen parameters, redox status, DNA integrity, and fertility outcomes in healthy male mice over one spermatogenic cycle. The study was partially repeated at the highest carnitine dose for pregnancy outcomes and comparatively assessed in subfertile, oxidatively stressed mice.

SUBJECTS

"Fertile/healthy" (CD1) and "Subfertile/oxidatively stressed" (gpx5-/-) mice.

EXPOSURE

Water-soluble micronutrients (vitamin C, zinc, folate, and carnitine).

INTERVENTION

N/A MAIN OUTCOME MEASURES: Sperm parameters included count, motility, viability, and acrosome integrity. Systemic redox status was evaluated in blood, measuring malondialdehyde, thiol levels, and total antioxidant capacity. Sperm DNA parameters were examined for oxidation (8-OHdG staining), fragmentation (TUNEL), and decondensation (toluidine blue). Pregnancy outcomes were also assessed in CD1 mice fed carnitine.

RESULTS

In healthy mice, increasing doses of individual micronutrients had minimal effects on semen parameters. However, high doses of all four micronutrients significantly disrupted the redox balance in blood plasma and compromised sperm DNA integrity in an ingredient-specific manner. Moderate to high doses of carnitine caused severe DNA fragmentation, a finding confirmed in a subsequent experiment using the highest carnitine dose. In this follow-up experiment, male mice supplemented with carnitine and mated with females showed decreased pregnancy rates and fewer total pups born. Conversely, in oxidatively stressed mice, high-dose carnitine had the opposite, beneficial effect of improving sperm DNA integrity.

CONCLUSIONS

At high doses, antioxidants can induce reductive stress, damaging vital molecular components of sperm cells such as DNA. Although strong evidence supports the use of preconception antioxidants to boost semen quality, healthcare professionals should assess oxidative stress levels when possible and recommend personalized antioxidant doses to avoid reductive stress and prevent adverse reproductive outcomes.

Effect of Micronutrients and L-Carnitine as Antioxidant on Sperm Parameters, Genome Integrity, and ICSI Outcomes: Randomized, Double-Blind, and Placebo-Controlled Clinical Trial

The evaluation of sperm DNA integrity is recommended in the sixth edition of the 2021 World Health Organization guidelines. Oxidative stress has been identified as a crucial factor leading to genome decay, lipid peroxidation, and nucleoprotein oxidation. This double-blind, placebo-controlled clinical trial aimed to assess the effect of oral antioxidant treatment (Fertilis), which contains L-carnitine and some micronutrients, in the improvement of conventional sperm parameters, sperm DNA integrity and in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) outcomes. A total of 263 participants were enrolled and randomly divided into two groups: 131 participants received the antioxidant treatment, while 132 participants received a placebo. The male partners in both groups underwent the antioxidant treatment or the placebo for a duration of three months. For each participant, we performed a hormonal test, an infectious test, a spermogram, a TUNEL assay for sperm DNA fragmentation, a toluidine blue staining for sperm DNA decondensation, and an IVF/ICSI procedure. Sperm characteristics analysis (volume, count, motility, and vitality), sperm DNA fragmentation, and sperm DNA decondensation were assessed and compared to the results preceding the antioxidant treatment. The study outcome revealed a significant decrease in the DNA fragmentation index and a significant increase in sperm motility after 3 months of treatment (p = 0.01 and p = 0.02, respectively). Additionally, a significant improvement in clinical pregnancy rate (p = 0.01) and life birth rate (p = 0.031) was observed. No significant changes were observed in conventional sperm parameters (volume, count, and vitality) or sperm DNA decondensation (SDI). Antioxidant therapy has a beneficial impact on achieving pregnancy, whether through spontaneous conception or assisted reproductive procedures (ART).