The impact of vitamin E supplementation on sperm analysis in varicocelectomy patients: a triple-blind randomized controlled trial

Abstract

Objective

To evaluate the impact of vitamin E supplementation on sperm analysis results in patients post-varicocelectomy.

Martials and method

This single-center, triple-blind, randomized controlled trial was conducted at Imam Reza Hospital, Mashhad, Iran. Ninety male patients, aged 15–25 years, with infertility and varicocele grade 2 or 3, were randomized into two groups. The intervention group received 400 units of vitamin E daily for 3 months, while the control group received a placebo. Sperm analysis was conducted before and 3 months after the intervention. Statistical analyses were performed using SPSS version 23, with significance set at P < 0.05.

Results

A total of 90 patients were enrolled and equally randomized into two groups (n = 45 per group). The mean age was 30.68 ± 6.31 years. Post-intervention, the improvement in sperm motility was significantly higher in the vitamin E group compared to the placebo group (P = 0.03). Both groups showed significant improvements in sperm motility, count, and morphology from pre- to post-intervention (P < 0.001).

Conclusion

Vitamin E supplementation post-varicocelectomy is associated with improved sperm parameters, suggesting potential benefits in the management of male infertility related to varicocele. However, varicocelectomy alone also results in significant improvements.

Trial registration

This study is registered at the Iranian Registry of Clinical Trials (IRCT20200911048689N1). Registered on October 10, 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-025-08740-x.

Introduction

Infertility is a prevalent issue, affecting approximately 15% of couples worldwide, with male factors contributing to about half of these cases [1].

Varicocele, a condition characterized by the abnormal dilation and elongation of the veins within the scrotum [2], is a significant cause of male infertility [3]. It is associated with impaired spermatogenesis, leading to reduced sperm count, motility, and altered morphology [4]. Varicocelectomy, a surgical procedure to correct varicocele, is commonly performed to improve these parameters and enhance fertility outcomes [5].

Despite the established benefits of varicocelectomy, not all patients experience significant improvements in sperm parameters post-surgery [6]. This inconsistency has prompted the exploration of adjunctive therapies to enhance outcomes. Oxidative stress is a key factor in the pathogenesis of varicocele-related infertility [7], and antioxidants like vitamin E have shown promise in mitigating oxidative damage to spermatozoa [8]. Vitamin E, a lipid-soluble antioxidant found in plant oils [9], protects cell membranes and spermatozoa from oxidative stress [10].

This study aims to evaluate the effect of vitamin E supplementation on sperm analysis results in patients undergoing varicocelectomy. By comparing the outcomes of vitamin E supplementation with a placebo, we seek to determine whether adjunctive antioxidant therapy can improve the efficacy of varicocelectomy in treating male infertility.

Martials and methods

Study design

This study was a single-center, triple-blind, randomized controlled trial conducted at Imam Reza Hospital, Mashhad, Iran, in 2021.

Ethics

The study protocol was approved by the Research Ethics Committee of Mashhad University of Medical Sciences (code IR.MUMS.MEDICAL.REC.1399.309). The trial was registered at the Iranian Registry of Clinical Trials (code IRCT20200911048689N1). All participants provided written informed consent after the study protocol was explained to them.

Participants

Male participants aged 15–40 years, diagnosed with infertility related to grade 2 or 3 varicocele, were recruited. Inclusion criteria included infertility related to varicocele and body weight between 50 to 100 kg. Exclusion criteria included azoospermia, history of chronic diseases, smoking, addiction, routine use of supplements, sensitivity to vitamin E, and testicular atrophy. Demographic information was recorded for all participants.

Randomization and blinding

Participants were randomly assigned to the intervention or placebo group using a computer-generated randomization sequence. The randomization sequence was prepared in blocks of 4–6 to ensure balance between groups. Allocation concealment was maintained by using sealed, opaque, sequentially numbered envelopes. The envelopes were prepared by a third party not involved in the study to ensure that investigators, participants, and outcome assessors remained blinded to group assignments throughout the trial. This triple-blind design ensured that neither the participants nor the researchers had knowledge of the group assignments, minimizing the risk of selection or performance bias.

Intervention

The intervention group received 400 units of vitamin E daily for three months, while the control group received a placebo identical in appearance and administered in the same manner.

Pre-intervention assessment

Prior to varicocelectomy, sperm analysis was conducted to confirm infertility. Physical examinations were performed in a warm room using the Valsalva maneuver while the patients stood. Color Doppler ultrasound (CDU) was utilized to measure the diameter of the largest vein in the pampiniform plexus and detect retrograde flow. Semen samples were obtained through masturbation after 3–4 days of sexual abstinence.

Follow-up assessments

Three months after varicocelectomy, a repeat sperm analysis was conducted. The results were compared within and between the two groups.

Statistical analysis

Quantitative data were presented as mean ± standard deviation or median (interquartile range). Comparisons between the two groups were conducted using the independent sample t-test or Mann–Whitney U test, depending on the normality of the distribution. The Wilcoxon test was used to compare before-and-after changes within each group. Statistical analyses were performed using SPSS software version 23 (SPSS Inc., Chicago, Illinois, USA). Statistical significance was defined as P < 0.05.

Results

Participant flow

A total of 90 patients were assessed for eligibility, and all met the inclusion criteria and agreed to participate. The participants were equally randomized into two groups: 45 were allocated to the intervention group (vitamin E supplementation) and 45 to the control group (placebo) (Fig. 1). There were no dropouts or exclusions during the study, and all participants completed the trial and were included in the final analysis.

Fig. 1.

The CONSORT flowchart

Baseline characteristics

The mean age of participants was 30.68 ± 6.31 years. There were no statistically significant differences in baseline characteristics, including age and pre-intervention sperm analysis parameters, between the intervention and control groups. Specifically, the mean age was 30.37 ± 6.18 years for the intervention group and 31.0 ± 6.49 years for the control group (P = 0.64) (Table 1).

Table 1.

Comparison pre-intervention sperm analysis features between two groups

Sperm analysis parameters	Placebo Median (IQR)	Intervention Median (IQR)	P value*
Movement (%)	26 (19.5–31)	27 (19–30)	0.83
Count (million in milliliters)	30 (19–43)	27 (22–34)	0.56
Morphology (%)	5 (4–5)	4 (3–5)	0.73

IQR interquartile

^*Mann–Whitney U Test

Pre-intervention sperm analysis

Before the intervention, there were no significant differences between the groups in terms of sperm movement, count, and morphology. Sperm movement was 26% (IQR: 19.5–31) in the placebo group vs. 27% (IQR: 19–30) in the intervention group (P = 0.83). Sperm count was 30 million/mL (IQR: 19–43) in the placebo group vs. 27 million/mL (IQR: 22–34) in the intervention group (P = 0.56). Sperm morphology was 5% (IQR: 4–5) in the placebo group vs. 4% (IQR: 3–5) in the intervention group (P = 0.73) (Table 2).

Table 2.

Comparison post-intervention sperm analysis features between two groups

Sperm analysis parameters	Placebo Median (IQR)	Intervention Median (IQR)	P value*
Movement (%)	35 (30–38)	35 (31–39)	0.09
Count (million in milliliters)	35 (26.5–48)	32 (27–40)	0.73
Morphology (%)	5 (4–6)	5 (4–6)	0.30

IQR interquartile

^*Mann–Whitney U Test

Post-intervention sperm analysis

Three months after the intervention, both groups showed improvements in sperm analysis parameters, but the differences between the groups were not statistically significant. Sperm movement was 35% (IQR: 30–38) in the placebo group vs. 35% (IQR: 31–39) in the intervention group (P = 0.09). Sperm count was 35 million/mL (IQR: 26.5–48) in the placebo group vs. 32 million/mL (IQR: 27–40) in the intervention group (P = 0.73). Sperm morphology was 5% (IQR: 4–6) in both groups (P = 0.30) (Table 3).

Table 3.

Comparison the changes in sperm analysis parameters of groups from pre- to post-intervention between study groups

Sperm analysis parameters	Placebo Median (IQR) Mean (SD)	Intervention Median (IQR)/ Mean (SD)	P value*
Movement (%)	6 (3–11.5)	10(5–15)	0.03**
Count (million in milliliters)	4.64 (8.56)	6.95 (9.45)	0.22
Morphology (%)	0.46 (0.89)	0.71 (1.01)	0.22

IQR interquartile, SD standard deviation

^*Independent sample T-test

^**Mann–Whitney U Test

Changes from pre- to post-intervention

The comparison of changes in sperm analysis parameters from pre- to post-intervention showed that the improvement in sperm motility was significantly higher in the intervention group than in the control group. Sperm movement improvement was 10% (IQR: 5–15) in the intervention group vs. 6% (IQR: 3–11.5) in the placebo group (P = 0.03). Sperm count improvement was 6.95 million/mL (SD: 9.45) in the intervention group vs. 4.64 million/mL (SD: 8.56) in the placebo group (P = 0.22). Sperm morphology improvement was 0.71% (SD: 1.01) in the intervention group vs. 0.46% (SD: 0.89) in the placebo group (P = 0.22) (Table 3).

Within-group comparisons

Within each group, all sperm analysis parameters showed significant improvements from pre- to post-intervention. In the placebo group, sperm movement increased from 26% (IQR: 19–31) to 35% (IQR: 30–38) (P < 0.001). Sperm count increased from 30 million/mL (IQR: 19–43) to 35 million/mL (IQR: 26–48) (P < 0.001). Sperm morphology increased from 5% (IQR: 4–5) to 5% (IQR: 4–6) (P < 0.001). In the intervention group, sperm movement increased from 27% (IQR: 19–30) to 35% (IQR: 31–39) (P < 0.01). Sperm count increased from 27 million/mL (IQR: 22–34) to 32 million/mL (IQR: 27–40) (P < 0.01). Sperm morphology increased from 4% (IQR: 3–5) to 5% (IQR: 4–6) (P < 0.01) (Table 4).

Table 4.

Comparison before and after intervention sperm analysis features among each group

Sperm analysis parameters	Placebo Median (IQR)		P value*	Intervention Median (IQR)		P value*
	Before	After		Before	After
Movement (%)	26 (19–31)	35 (30–38)	< 0.001	27 (19–30)	35 (31–39)	< 0.01
Count (million in milliliters)	30 (19–43)	35 (26–48)	< 0.001	27 (22–34)	32 (27–40)	< 0.01
Morphology (%)	5 (4–5)	5 (4–6)	< 0.001	4 (3–5)	4 (5–6)	< 0.01

IQR interquartile

^*Wilcoxon rank test

Discussion

Our study demonstrated that while varicocelectomy alone leads to significant improvements in sperm parameters, the addition of vitamin E supplementation further enhances these outcomes. Specifically, the intervention group, which received 400 units of vitamin E daily for three months, showed a significantly greater improvement in sperm motility compared to the placebo group (P = 0.03). Both groups exhibited significant improvements in sperm count and morphology from pre- to post-intervention, but these changes were not statistically different between groups.

The findings of our study align with previous research on the benefits of antioxidants, particularly vitamin E, in improving sperm quality. Oxidative stress plays a critical role in the pathophysiology of varicocele-related infertility, and antioxidants like vitamin E mitigate oxidative damage to spermatozoa. Studies by Keshtgar et al. [11] and Yousef et al. [12] have reported improvements in sperm motility and overall semen quality with antioxidant supplementation, corroborating our results.

However, our study is among the first triple-blind trials specifically investigating vitamin E supplementation post-varicocelectomy. Previous studies, such as the one conducted by Ener et al. [13], have explored the impact of vitamin E on semen parameters and pregnancy rates post-varicocelectomy, reporting similar beneficial effects. The absence of significant changes in these parameters could be attributed to biological variability in spermatogenesis or limitations in sample size. The differences in dosage and duration of vitamin E supplementation between studies highlight the need for further research to determine optimal treatment protocols.

Our findings align with the meta-analysis by Wang et al. [14], which showed that vitamin E treatment increases total sperm count and improves forward motility with long-term use​​. This meta-analysis included 459 patients across multiple studies, indicating a broader consensus on the positive effects of vitamin E on sperm quality. Our study's results corroborate these findings, showing a significant improvement in sperm motility, an aspect not uniformly observed in all studies within the meta-analysis. Specifically, our study noted a 10% improvement in sperm motility in the intervention group compared to a 6% improvement in the placebo group (P = 0.03).

This study's strengths include its triple-blind design, ensuring unbiased results, and the use of a placebo control, which allows for a clear comparison of the effects of vitamin E supplementation. The study's single-center design and strict inclusion and exclusion criteria enhance the internal validity of the findings. However, the study also has limitations. The follow-up period of three months may not be sufficient to observe long-term effects on fertility and pregnancy outcomes. Additionally, the sample size, while adequate for detecting differences in sperm parameters, may not be large enough to generalize findings to all varicocelectomy patients.

Conclusions

Vitamin E supplementation post-varicocelectomy significantly improves sperm motility, suggesting potential benefits in the management of male infertility related to varicocele. While varicocelectomy alone is effective, the addition of vitamin E appears to enhance these benefits. Further research is warranted to explore the long-term effects and optimal treatment protocols for vitamin E supplementation in this context.

Authors’ contributions

Conceived and designed the experiments: Alireza Akhavan Rezayat; Performed the experiments: Alireza Akhavan Rezayat, Kasra Saeedian; Analyzed the data: Maryam Emadzadeh; Wrote the manuscript: Kasra Saeedian; Final edit of paper: Maryam Emadzadeh, Alireza Akhavan Rezayat.

Funding

This research was funded by the Mashhad University of Medical Sciences, research number 981699.

Mashhad University of Medical Sciences

Data availability

Data are available on reasonable request to the corresponding author.

Declarations

Competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.