Vitamin D and Male Erectile Function: An Updated Review

Sequential administration of febuxostat and vitamin E protects against testicular ischemia/reperfusion injury via inhibition of sperm DNA damage in Wistar rats

The pathway of testicular ischemia-reperfusion injury (TIRI) has been shown to involve reactive oxygen species (ROS) generation in the ischemic phase and later phase of reperfusion. This study was therefore designed to investigate the effect of blockage of ROS in the ischemic and reperfusion phases of TIRI. Thirty male Wistar rats were grouped into five groups (n = 6 rats each): sham, torsion + detorsion (TD), febuxostat (FEB)-administered (TFD) group, vitamin E (V)-administered (TDV) group, and FEB and vitamin E-administered (TFDV) group. Blood samples (for inflammatory and hormonal assay), testicular (for oxidative stress and histopathology), and epididymal (for sperm DNA damage and indices) tissues were collected after 3 days of detorsion. The TFD and TFDV groups showed a significant reduction in XO and MDA (p < 0.001; η2 > 0.7), as well as a concomitant increase in CAT, thiols, and SOD levels when compared with the TD group (p < 0.01, η2 > 0.5). The TFD group significantly reduced all inflammatory markers (p < 0.05; η2 = 0.75). The observed increase (p < 0.05; η2 = 0.92) in LH level, in response to a low level of testosterone in the TD group, was significantly raised in TFD and TFDV groups. The observed decrease (p < 0.001) in inhibin level in the TD group was raised (p < 0.05; η2 = 0.90) in the TDV group only. A significant increase (p < 0.001) in sperm DNA damage in the TD group was significantly reduced (p < 0.05; η2 = 0.88) in all the treatment groups while the reduced sperm viability (p < 0.01) in the TD group was increased (p < 0.05) in the TFDV group only. There was an improvement in the testicular cytoarchitecture in the TFD and TFDV groups. This study showed that sequential administration of febuxostat in the ischemic phase of TT and vitamin E in the later phase of reperfusion protects the testes against TIRI via inhibition of oxidative stress, inflammation, and sperm DNA damage.

Vitamin D deficiency induces erectile dysfunction: Role of superoxide and Slpi

BACKGROUND AND PURPOSE

Epidemiological studies suggest a relationship between vitamin D deficiency and erectile dysfunction (ED). We hypothesized that vitamin D deficiency or vitamin D receptor (VDR) knockout causes ED and analysed the underlying molecular mechanisms.

EXPERIMENTAL APPROACH

Erectile function was assessed in vivo in anaesthetized male mice or rats by evaluating intracavernosal pressure (ICP) and in vitro in male Vdr-/- mice, and rat or human isolated corpora cavernosa (CCs) mounted in a myograph. Bulk RNA-sequencing (RNA-seq) transcriptomic analysis was performed in rat CCs. Vitamin D deficiency was induced in rats fed a vitamin D-free diet for 5 months.

KEY RESULTS

CCs from human donors with low plasma vitamin D exhibited reduced nitric oxide (NO)-dependent erectile function. This ED was also reproduced in vitamin D-deficient rats and VDR knockout mice, in vivo and ex vivo, and is associated with penile fibrosis and reduced response to the phosphodiesterase 5 inhibitor (PDE5i) sildenafil. CCs from deficient rats show increased superoxide levels, and their impaired erectile function was restored by superoxide scavengers. Transcriptomic analysis, real-time polymerase chain reaction (RT-PCR) and Western blot showed down-regulated secretory leukocyte protease inhibitor (Slpi). Moreover, recombinant SLPI prevented superoxide-induced ED, while Slpi gene silencing led to reduced erectile function in a superoxide-dependent manner.

CONCLUSION AND IMPLICATIONS

Vitamin D deficiency or VDR knockout reduces erectile function. We suggest that this effect is mediated by increased superoxide levels and down-regulation of SLPI. Vitamin D deficiency might be an aetiological factor for vascular ED and for the therapeutic failure of PDE5i.

Mendelian Randomization Reveals Serum Copper as a Micronutrient is a Risk Factor for Erectile Dysfunction

The cause and effect between serum micronutrients and erectile dysfunction (ED) is not clear. The purpose of this study was to evaluate the causal relationship between micronutrients and ED by Mendelian randomization (MR) analysis. We used the published genome-wide association study (GWAS) data for two-sample MR analysis. This study utilized inverse variance weighted (IVW), MR egger, weighted median, simple mode, and weighted mode method to assess the causal relationship between serum micronutrients and ED. IVW is considered the standard method for MR analysis. We used Cochran's Q tests to evaluate the heterogeneity. To investigate horizontal pleiotropy, this study employed the MR Egger method. Additionally, leave-one-out analysis was used to evaluate the influence of individual genetic loci on the results. The results showed that there was a causal relationship between serum copper and ED, and it was positively correlated with ED (OR = 1.115, CI = 1.00-1.24, p = 0.014). There was no significant correlation between other micronutrients and ED. Sensitivity analysis results indicated that our findings exhibit no heterogeneity or pleiotropy, thereby strengthening our conclusions. Serum copper is a risk factor for ED, which provides a new idea for the diagnosis and treatment of ED in the future. However, further experiments are needed to elucidate the underlying mechanisms.

Serum 25-hydroxyvitamin D level and erectile dysfunction: a causal relationship? Findings from a two-sample Mendelian randomization study

Background

Serum 25-hydroxyvitamin D level is associated with erectile dysfunction (ED) in observational studies. However, whether there is a causal association between them remains uncertain.

Objective

Conduct a two-sample Mendelian randomization (MR) analysis to investigate the causal effect between serum 25-hydroxyvitamin D level and ED risk.

Method

Genome-wide association study (GWAS) data of serum 25-hydroxyvitamin D levels comprising 6,896,093 single nucleotide polymorphisms (SNP) from 496,949 people of European ancestry were regarded as exposure for the MR analysis. Additional GWAS data involving 9,310,196 SNPs of 6,175 European ED cases and 217,630 controls were used as outcome data. The MR-Egger, inverse variance weighted (IVW) method, weighted median, simple mode, and weighted mode were employed to evaluate causal effects, among which IVW was the primary MR analysis method. The stability of the MR analysis results was confirmed by a heterogeneity test, a horizontal pleiotropy test, and the leave-one-out method.

Result

There were 103 SNPs utilized as instrumental variables (p < 5 × 10-8). The results of MR analysis showed no causal effects of serum 25(OH) D concentration on ED risks (IVW; OR = 0.9516, 95% CI = 0.7994 to 1.1328, p = 0.5772). There was no heterogeneity and pleiotropy in the statistical models.

Conclusion

The present MR study did not support a causal association for genetically predicted serum 25-hydroxyvitamin D concentration in the risk of ED in individuals of European descent.

Mechanisms Suggesting a Relationship between Vitamin D and Erectile Dysfunction: An Overview

Vitamin D deficiency (VDD) and erectile dysfunction (ED) heavily burden the male population. The higher prevalence of both conditions in the elderly suggests a possible relationship between the two conditions. In addition, in vitro, animal, and human studies have revealed several mechanisms that may relate VDD to ED. The main mechanism by which vitamin D might exert its action on sexual function appears to be through the regulation of endothelial function. Indeed, VDD correlates with several markers of endothelial function. The action of vitamin D on the endothelium would be exercised both indirectly through its intervention in inflammatory processes and through the production of oxygen free radicals, and directly through the regulation of vascular stiffness, the production of nitric oxide, and the regulation of vessel permeability. Furthermore, the ubiquitous distribution of the vitamin D receptor in the human body means that this hormone can also exert a beneficial effect on erectile function by interfering with those comorbidities significantly associated with ED, such as hypertension, diabetes mellitus, hypercholesterolemia, chronic kidney disease, and hypogonadism. In this review, we thoroughly and carefully presented the evidence and mechanisms that would appear to relate vitamin D levels to erectile function. Furthermore, we have summarized the meta-analytic evidence for and against this association to provide a true representation of this topic. Data published to date suggest that low levels of vitamin D could contribute to worsening erectile function through several mechanisms. Therefore, vitamin D levels should be measured in patients with ED and maintained at adequate levels by specific supplementation in case of deficiency. However, the low quality and heterogeneity of clinical trials evaluating the effects of vitamin D administration on erectile function and ED-associated comorbidities do not allow for a univocal conclusion, and indicate the need for further studies to analyze these aspects.

Whether Adding Vitamin D to Tadalafil 5 mg Treatment Is Useful in Patients with Erectile Dysfunction and Vitamin D Deficiency?

INTRODUCTION

Numerous factors such as endothelial disease and hormonal disorder cause the development of erectile dysfunction (ED). However, the relationship between vitamin D deficiency (VDD) and ED is unclear. Moreover, the benefit of vitamin D replacement on ED patients with VDD is uncertain. As far as we know, there is no study yet in the literature regarding the addition of vitamin D to phosphodiesterase type 5 inhibitors in the treatment of ED patients with VDD. In this study, we investigated whether adding vitamin D to daily tadalafil treatment would be beneficial in ED patients with VDD.

METHODS

A total of 111 patients with VDD accompanying ED were retrospectively evaluated between January 2016 and December 2019. Patients were divided into 2 groups according to the treatment they received. Group 1 (n = 58) was treated with daily oral tadalafil 5 mg, while group 2 (n = 53) received oral tadalafil 5 mg and 4,000 IU vitamin D3. Total International Index of Erectile Function-15 (IIEF-15) scores and vitamin D levels of the groups were compared at the end of the study.

RESULTS

The mean vitamin D level was increased statistically significant in group 2, but no difference was seen in group 1 (p < 0.001 and p > 0.05, respectively). There was a significant increase in median erectile function, orgasmic function, sexual desire, sexual satisfaction, and overall satisfaction scores in both groups (p < 0.001). However, the increase in median erectile function and sexual desire scores was significantly higher in group 2 compared to group 1 at the end of the study (p = 0.01 and p < 0.001, respectively).

CONCLUSION

We found that adding vitamin D to 5 mg oral daily tadalafil treatment may have an additional positive effect on erectile function and sexual desire in ED patients with VDD.

Low Serum 25-Hydroxyvitamin D Level as a Potential Risk Factor of Erectile Dysfunction in Elderly Men with Moderate to Severe Lower Urinary Tract Symptoms

Purpose

To evaluate the correlation between vitamin D level and erectile dysfunction (ED) in male lower urinary tract symptoms (LUTS) patients.

Materials and Methods

We analyzed data from 534 male patients who were tested for LUTS from 2014 to 2017. LUTS severity was classified into mild (≤7) or moderate to severe (≥8) based on total IPSS scores. Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D [25(OH)D] level of less than 20 ng/mL. The severity of ED was dichotomized into mild (≥17 points) or moderate to severe (≤16 points) depending on total IIEF-5 scores. The association of the serum 25(OH)D level with moderate to severe ED was assessed using logistic regression analysis.

Results

In the entire cohort, moderate to severe ED was significantly associated with age ≥60 years (odds ratio [OR], 1.762; 95% confidence interval [CI], 1.011–3.073) and moderate to severe LUTS (OR, 2.075; 95% CI, 1.134–3.789), but not with serum 25(OH)D level (OR, 1.001; 95% CI, 0.979–1.023). Whereas, in the subgroup consisting of moderate to severe LUTS patients over 60 years (n=223), either low serum 25(OH)D level (OR, 0.944; 95% CI, 0.903–0.986) or vitamin D deficiency (OR, 2.949; 95% CI, 1.118–7.782) was the independent risk factor of moderate to severe ED as a result of each multivariate analysis.

Conclusions

Low vitamin D status closely correlated with moderate to severe ED in elderly men with moderate to severe LUTS.

Is There an Association Between Vitamin D Deficiency and Erectile Dysfunction? A Systematic Review and Meta-Analysis

Erectile dysfunction (ED) is found very frequently in the male population, in particular in its arteriogenic form, which also represents an important predictor of cardiovascular diseases (CVDs). Some evidence suggests that vitamin D could play a role in cardiovascular risk prevention thanks to its ability to reduce endothelial damage, oxidative stress, the production of inflammatory cytokines, and dyslipidemia. Since ED and CVDs have pathogenic mechanisms in common, numerous studies have evaluated a possible association between vitamin D deficiency (blood concentrations of 25-hydroxyvitamin D < 20 ng/mL) and ED, but with conflicting results. This meta-analysis was therefore performed to clarify the discrepancy of the data so far published. To achieve this, articles have been searched extensively in the Pubmed, MEDLINE, Cochrane, Academic One Files, Google Scholar, and Scopus databases from the first day they were created until January 2020. The search strategy included pertinent Medical Subjects Headings (MeSH) terms. Of the 431 items retrieved, only eight observational studies were included, resulting in a total sample size of 4055 patients. It was found that 25-hydroxyvitaminD (25(OH)D) levels did not show any significant difference between patients with and without ED. However, when patients with vitamin D deficiency only were taken into account, the international index of erectile function (IIEF) score for erectile dysfunction was significantly worse than in controls. This association remained significant even when eugonadal-only patients were considered. Finally, we found that eugonadal patients with severe ED have lower 25(OH)D₃ levels than patients with mild ED. In conclusion, this meta-analysis suggests an association between vitamin D deficiency and the presence of severe forms of ED, independent of testicular function.