Impact of vitamin D deficiency on mouse sperm structure and function

Joint and individual associations between multiple vitamins and sperm quality in adult men

Background

Several studies have suggested that a healthy diet is associated with improved male fertility outcomes. However, the joint and individual associations between the status of multiple vitamins and sperm quality remain unclear.

Objectives

This study aimed to investigate the associations between serum vitamin levels and sperm quality parameters in adult men.

Methods

A cross-sectional study was conducted among 156 adult men seeking fertility care at a reproductive center from December 2023 to June 2024. Blood and semen were collected on the same day to determine the concentrations of nine kinds of vitamins (B1, B2, B6, B9, B12, C, A, D, E) and five parameters of sperm quality [total sperm number, sperm concentration, progressive motile sperm, morphologically normal rate, and DNA fragment index (DFI)]. The joint and individual associations between vitamin levels and sperm quality were analyzed using multiple linear regression and Bayesian kernel machine regression (BKMR) models.

Results

Increased tertiles of vitamin B1 and 1,25-dihydroxyvitamin D3 [1,25-(OH)2-D3] in serum were associated with higher sperm quality (all P for trends < 0.10). Compared with the lowest tertiles, the highest tertiles of vitamin B12 had β: 3.0 (95% CI: 0.8, 5.2) increasing in DFI, and vitamin A was negatively associated with progressive sperm motility (P for trends = 0.05). We generally found null results between multiple vitamin levels and the parameters of sperm quality in the BKMR models.

Discussion

These research findings imply that vitamins could have a dose-dependent dual effect on sperm quality. More specifically, the impact of vitamins varies according to their dosage levels and types. Personalized vitamin supplementation may be more effective than taking multivitamins in improving sperm quality.

Relationship between serum vitamin D concentration and parameters of gonadal function in infertile male patients

Background

Vitamin D (vitD) deficiency could affect male reproductive function. Our objective was to investigate the relationship between serum vitD concentrations and hormonal and seminal parameters in infertile patients and to compare the results with those in healthy controls.

Materials and methods

Infertile patients (n = 29) and normozoospermic healthy donors (n = 27) were recruited for the study. Serum concentrations of vitD, total testosterone, estradiol, and sex hormone-binding globulin were determined using chemiluminescence assays, and free testosterone concentration was determined by radioimmunoassay. Semen analysis was performed as suggested by the World Health Organization. Statistical analysis was conducted using Student's t test, contingency tables, and linear regression studies.

Results

VitD concentrations were lower in patients than in controls (p < 0.001). A significant association (p < 0.001) was observed between vitD concentrations <20ng/mL and infertility. In the control group, significant correlations were reported between vitD concentrations >30 ng/mL and the concentrations of testosterone (p < 0.05), free testosterone (p < 0.01), and estradiol (p < 0.05). A direct correlation was found between vitD concentration and percentage of sperm vitality (p = 0.01). VitD also positively correlated with the percentage of progressive sperm motility (p <0.05) and sex hormone-binding globulin concentrations (p < 0.01).

Conclusions

VitD may affect male reproductive parameters, and its deficiency could be associated with infertility.

Calcium and vitamin D homoeostasis in male fertility

Calcium and vitamin D have well-established roles in maintaining calcium balance and bone health. Decades of research in human subjects and animals have revealed that calcium and vitamin D also have effects on many other organs including male reproductive organs. The presence of calcium-sensing receptor, vitamin D receptor, vitamin D activating and inactivating enzymes and calcium channels in the testes, male reproductive tract and human spermatozoa suggests that vitamin D and calcium may modify male reproductive function. Functional animal models have shown that vitamin D deficiency in male rodents leads to a decrease in successful mating and fewer pregnancies, often caused by impaired sperm motility and poor sperm morphology. Human studies have to a lesser extent validated these findings; however, newer studies suggest a positive effect of vitamin D supplementation on semen quality in cases with vitamin D deficiency, which highlights the need for initiatives to prevent vitamin D deficiency. Calcium channels in male reproductive organs and spermatozoa contribute to the regulation of sperm motility and capacitation, both essential for successful fertilisation, which supports a need to avoid calcium deficiency. Studies have demonstrated that vitamin D, as a regulator of calcium homoeostasis, influences calcium influx in the testis and spermatozoa. Emerging evidence suggests a potential link between vitamin D deficiency and male infertility, although further investigation is needed to establish a definitive causal relationship. Understanding the interplay between vitamin D, calcium and male reproductive health may open new avenues for improving fertility outcomes in men.

The role of the transsulfuration pathway in spermatogenesis of vitamin D deficient mice

Vitamin D deficiency is a global health problem and has been linked to defective spermatogenesis and male infertility. In this study, we aimed to investigate the main enzymes involved in the transsulfuration pathway of 1-carbon metabolism, and spermatogenesis function. Therefore, sixteen male C57 mice were addressed to a control (standard diet) or vitamin D deficient (VDD) diet for 14 weeks. The results show that compared to the standard diet, VDD increased final body weight and reduced sperm quality, caused damage to the testicular structure, and decreased the serum levels of testosterone. In addition, serum concentrations of homocysteine, vitamin B12, and sperm oxidative stress markers increased. In testicular tissues, the CBS and CSE protein levels were down-regulated whereas HO-1 was up-regulated at both mRNA and protein expression levels. Within a mice deprivation model, VDD deeply suppressed testosterone and impaired spermatogenesis with oxidative stress-mediated mechanisms. The effects of the deprivation appeared to be at least in part independent of genomic and receptor-mediated vitamin D actions and suggest a specific impairment of the alternative transsulfuration pathway.

Overlapping sperm damages from vitamin B or D deficiency in mice: Insights into the role of clinical supplementations

In this study, the effect of 14 weeks of standard diet (controls) or folate and vitamin B12-free diet (VBD group) or vitamin D-free diet (VDD group) were assessed on mice testicular function, and sperm function. Vitamin D deprivation caused increased body weight with no effect from VBD confirming the calcium-independent role of vitamin D on body weight homeostasis. The two deprivations caused convergent damages including decreased testosterone, worsened Johnson scores, tubular differentiation index and spermatogenesis index, and serious worsening of sperm parameters and of sperm functional tests (DNA methylation, protamination, DNA damage and lipid peroxidation). From a metabolic point of view, the damage from both models converged on the one carbon cycle (methylations) and the transsulfuration pathway (GSH and antioxidant defences) and increased circulating homocysteine, although with different mechanisms: VBD appeared to hamper methylations due to lower ability to regenerate homocysteine to methionine whereas VDD appeared to interfere with homocysteine transsulfuration to cysteine and, thereafter, GSH. VDD also caused a huge paradox increase of vitamin B12, which was likely in a non-functional form and warrants further investigation. These findings strongly endorse the potential benefit of combined folate/B12 and vitamin D supplementation in infertile patients.

Vitamin D and calcium, together and separately, play roles in female reproductive performance

Vitamin D (VD) deficiency reduces the chances of successful fertilization; however, it remains to be validated whether this effect is dependent or not on calcium. To address this question, we generated several situation using a mouse model in which VD content was either increased or decreased in a normo or hypocalcemia context. After the measurement of serum 25-hydroxyvitamin D₂, calcium and phosphorus levels, an analysis was carried out in terms of oocytes maturation as well as reproductive performance. VD overdose, despite the fact that it resulted in an increased number of mature oocytes, reduced developmental competence and offspring survival. VD deficiency (VDD), on the contrary, reduced the number and percentage of mature oocytes, blastocyst rate, as well as fertility rate and offspring survival. Hypo-calcemia when VD levels were normal, had a similar effect than VDD. The effects of VDD were reversed by a diet that corrected calcium level. Therefore, both VD overdose (in a context of normal calcium level) VD deficiency as well as hypo-calcemia have an effect on female reproductive function. In conclusion, although closely related, VD and calcium act in part independently of each other in defining the “optimum” for female reproductive performance.

Relationship between Serum Vitamin D in Male, Sperm Function and Clinical Outcomes in Infertile Men Candidate for ICSI: A Cohort Study

Background

Today, vitamin D deficiency (VDD) is one of the major health issues around the world and VDD is associated with several diseases. This study was conducted to find the relationship between vitamin D status in male's serum with sperm function and clinical outcomes in infertile men candidate for intracytoplasmic sperm injection (ICSI).

Materials and Methods

In this cohort study, different parameters of male fertility such as sperm parameters, oxidative stress, and sperm chromatin status were evaluated in sperm samples of 30 infertile couples candidate for ICSI. Clinical outcomes like fertilization, embryo quality, and implantation were also assessed. Data were analyzed using SPSS Statistics 25.0 software. Besides, assessment of the correlation between aforementioned parameters with the level of serum vitamin D, in this study, ICSI candidates were divided into three groups [individuals with sufficient vitamin D levels (>30 ng/ml), insufficient vitamin D levels (between 20-29 ng/ml), and VDD (<20 ng/ml)]. The aforementioned parametesr were also compared between these study groups.

Results

Analysis of all the data revealed a significant correlation between the level of vitamin D with sperm concentration (P=0.000, r=0.5), sperm count (P=0.03, r=0.31) and sperm reactive oxygen species (ROS) level (P=0.000, r=-0.77). Moreover, comparing clinical outcomes within study groups showed a significant difference in implantation rate between sufficient and other groups (insufficient and deficient) (P=0.02).

Conclusion

Considering the association between sperm concentration and level of ROS with vitamin D and, higher implantation rate in individuals with vitamin D sufficient group compared to other two groups, our data call for vitamin D supplementation as part of male infertility treatment. But considering our sample size, further research is needed to verify these findings.