Associations between testosterone, bone mineral density, vitamin D and semen quality in fertile and infertile Chinese men

Dietary trends and the decline in male reproductive health

Over the twentieth century, male reproductive health has suffered a substantial decline, as evidenced by decreases in sperm counts and testosterone levels and increases in reproductive pathologies. At the same time, the prevalence of chronic diseases such as obesity, diabetes, and metabolic syndrome has risen dramatically. Metabolic and reproductive health are highly interconnected, suggesting that their respective trends are intertwined and, given the timeframe of such trends, environmental and not genetic factors are most likely to be the primary causes. Industrialization, which began in Europe in the mid-eighteenth century, has resulted in profound changes to our diet, lifestyle, and environment, many of which are causal factors in the rise in chronic diseases. Industrialization results in a nutrition transition from an agricultural unprocessed to a modern processed diet, incorporating increases in sugar, vegetable oils, ultra-processed foods, linoleic acid, trans-fats, and total energy. This dietary shift has incurred numerous adverse effects on metabolic and reproductive health, characterized by chronic inflammation, oxidative stress, and insulin resistance. Moreover, these effects appear to multiply across subsequent generations via epigenetic inheritance. Men's fertility is markedly affected by obesity and diabetes, with an increase in total energy via processed food intake arguably being the key factor driving the diabesity pandemic. In contrast, wholefoods rich in micronutrients and phytonutrients support male fertility and a healthy body weight. Therefore, men wanting to maximize their fertility should consider making positive dietary changes, such as replacing processed foods with unprocessed foods that support metabolic and reproductive health.

Vitamin D supplementation for improving sperm parameters in infertile men: A systematic review and meta-analysis of randomized clinical trials

Objective

Vitamin D has been hypothesized to have a potential role in altering sperm motility and metabolism. However, experimental studies have demonstrated inconsistent results between vitamin D and sperm parameters. This study aims to investigate the role of vitamin D supplementation to improve sperm parameters in infertile men.

Methods

This is a systematic review and meta-analysis study. We comprehensively conducted a search on ClinicalTrials.gov, IRCT.ir, Europe PMC, and PubMed and collected published studies on vitamin D supplementation and sperm parameters for infertile men. The risk of bias was assessed by using Risk of Bias version 2 (RoB v2) and the statistical analysis was performed by using Review Manager 5.4 software.

Results

Five trials with a total of 648 infertile men were included. Our meta-analysis showed that supplementation with vitamin D may significantly improve total sperm motility [mean difference 4.96 (95% CI 0.38, 9.54), p = 0.03, I2 = 69%], progressive sperm motility [mean difference 4.14 (95% CI 0.25, 8.02), p = 0.04, I2 = 89%], and normal sperm morphology [mean difference 0.44 (95% CI 0.30, 0.57), p < 0.00001, I2 = 0%] better than placebo in infertile men. However, total sperm count (p = 0.15), sperm concentration (p = 0.82), and semen volume (p = 0.83) did not differ significantly between two groups.

Conclusions

Vitamin D supplementation may improve sperm motility, progressive sperm motility, and morphology in infertile men. Vitamin D supplementation may be considered in managing male fertility issue.

Differential effects of vitamin D on upper and lower body fat-free mass: potential mechanisms

Vitamin D insufficiency is a global health concern and low vitamin D status is regularly associated with reduced muscle mass and sarcopenia in observational research. Recent research using Mendelian randomization (MR) has highlighted the potentially causal positive effect of serum vitamin D (25(OH)D) on total, trunk and upper body appendicular fat-free mass (FFM). However, no such effect was found in lower body FFM, a result that mirrors the outcomes of some vitamin D intervention studies. Here we review the current literature on vitamin D, muscle mass and strength and discuss some potential mechanisms for the differing effects of vitamin D on upper and lower body FFM. In particular, differences in distribution of the vitamin D receptor as well as androgen receptors, in the upper and lower body musculature, will be discussed.

The Association between Vitamin D and the Components of Male Fertility: A Systematic Review

OBJECTIVE

Previous systematic reviews of the effects of vitamin D on the components of male fertility have been inconclusive. This article systematically reviews the latest research to examine the relationship between vitamin D, semen quality parameters, and sex hormones production.

METHODS

MEDLINE, Cochrane, and Web of Science databases were searched using the appropriate keywords.

RESULTS

Observational studies indicate significant correlation between vitamin D levels and sperm parameters, with a particular emphasis on sperm motility, and partially suggest a relationship between higher serum testosterone and vitamin D levels. Additionally, interventional studies confirmed that vitamin D supplementation has a positive effect on sperm motility, especially progressive. However, most randomized clinical trials indicate that vitamin D treatment does not have any significant effect on testosterone or other hormone levels.

CONCLUSIONS

Although our findings add to the discussion regarding the effect of vitamin D on male fertility, there is still no solid evidence to support the use of vitamin D supplementation to improve the outcomes of patients with impaired sperm parameters and hormonal disorders. Additional dedicated clinical studies are needed to clarify the relationship between vitamin D and male fertility, along with its components.

Vitamin D levels and human sperm DNA fragmentation: a prospective, cohort study

Background

Intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of couples with male factor infertility but results remain suboptimal and suggest the need for further investigation into the molecular biology of spermatozoa. Vitamin D has been implicated in spermatogenesis and sperm function. Hypovitaminosis D has been associated with abnormal testicular function, including elevated sperm DNA fragmentation in a murine model. This study’s objective was to evaluate if there is a correlation between Vitamin D sufficiency and human spermatozoa DNA fragmentation index % (DFI%) in infertile couples.

Results

A prospective cohort study using a consecutive, convenience sample of subjects with infertility. The primary endpoint was the effect of Vitamin D sufficiency on human spermatozoa DFI%, and secondary outcomes included Vitamin D’s effect on moderate DFI%, high DFI%, High DNA stainability % (HDS%), sperm density (million/mL), sperm total motility (% total) and sperm strict morphology (% total). Of the 111 participating, 9 were excluded, leaving 102subjects. The subjects were stratified by vitamin D levels: deficient (< 20 ng/mL; n = 24), insufficient (20–30 ng/mL; n = 43),, and sufficient (> 30 ng/mL; n = 35). There were no statistical difference between the categories of serum vitamin D levels and sperm DFI% as well as the secondary outcomes. An increased BMI was associated with low serum vitamin D levels (p = 0.0012).

Conclusion

Vitamin D deficiency was not associated with sperm DFI% or routine sperm parameters. Previous animal and human studies have demonstrated conflicting results between sperm parameters and Vitamin D levels. Redundant pathways in Vitamin D and calcium homeostasis in the human male reproductive tract may maintain essential reproductive processes during Vitamin D insufficiency or deficiency.

Trial registration

Trial Registration Number: MOD00002311 (ClinicalTrials.gov).

Vitamin D and Male Reproduction: Updated Evidence Based on Literature Review

The purpose of this study was to clarify the vitamin D (VD) effect on male infertility. Our research was conducted using the following electronic databases: MEDLINE, Embase, Web of Science, Scopus, ClinicalTrials.gov, and Cochrane Library. Selection criteria included all published randomized controlled trials and non-randomized studies, focusing on vitamin D and male reproductive function. The results showed that the effects of VD on male reproduction has been investigated in three different topics: the molecular mechanism underlying VD effects on semen quality (SQ), the relationship between VD levels and SQ, and the effect of VD supplementation on SQ. Results supported the hypothesis of a relevant interrelation between concentrations of male VD and semen parameters, with particular reference to sperm motility; on the contrary, evidence on the effect of VD on male sex steroid hormone levels was inconclusive. The results of this review hold up the thesis that VD plays a role in male reproduction. Most of the data highlighted a positive effect on semen quality, particularly in sperm motility, both in fertile and infertile men. Additional dedicated studies are required to elucidate the still controversial aspects of this topic.

Is there a relationship between serum vitamin D and semen parameters? A cross-sectional sample of the Iranian infertile men

BACKGROUND

Recent studies suggest that serum vitamin D may be associated with semen parameters. In the present cross-sectional study, we attempted to investigate the association between serum vitamin D levels and semen parameters among Iranian sub-fertile men.

RESULTS

A total of 350 infertile men recruited for this cross-sectional study using a simple random sampling method with a mean age of 34.77 years old, body mass index of 26.67 kg/m², serum vitamin D of 20.17 ng/ml, semen volume of 3.82 mL, sperm count of 44.48 (10⁶/mL), sperm total motility of 38.10 %, and morphologically normal sperm of 7.0 %. After controlling for potential confounders, serum vitamin D was positively associated with semen volume (β = 0.63, 95 % CI: 0.06, 1.20), sperm count (β = 14.40, 95 % CI: 4.56, 24.25), sperm total motility (β = 18.12, 95 % CI: 12.37, 23.86), and sperm normal morphology (β = 1.95, 95 % CI: 1.07, 2.83).

CONCLUSIONS

The present findings suggest that higher serum vitamin D levels are positively associated with higher semen volume, sperm count, sperm total motility, and normal morphology rate. These findings, however, do not specify a cause-and-effect relationship, and there is a need for further research in this area to understand whether vitamin D supplementation can improve semen parameters.

Male fertility as a marker for health

Male reproduction is a complex biological process, and male factor infertility is increasingly recognized as a biomarker for overall male health. Emerging data suggest associations between male reproduction and medical disease (genetic, infectious, chronic comorbid conditions), psychological disease, environmental exposures, dietary habits, medications and substances of abuse, and even socioeconomic factors. There is also evidence that a diagnosis of male fertility is associated with future disease risk including cancer, metabolic disease and mortality. As such, there is a growing view that the male fertility evaluation is an opportunity to improve a man's health beyond his immediate reproductive goals, and also highlights the necessity of a multidisciplinary approach.

Male vitamin D status and male factor infertility

OBJECTIVE

To determine the association between vitamin D levels in the male partner and fertility outcomes in couples with mild male factor infertility.

DESIGN

Secondary analysis of a randomized, controlled trial.

SETTING

Nine fertility centers in the United States.

PATIENT(S)

Men (n = 154) with sperm concentration between 5 and 15 million/mL, motility ≤40%, or normal morphology ≤4% were eligible. Female partners were ovulatory, ≤40 years old, and had documented tubal patency.

INTERVENTION(S)

Men provided semen and blood at baseline for semen analysis and 25-hydroxyvitamin D (25(OH)D) levels. They were randomly assigned to receive a vitamin formulation including vitamin D 2,000 IU daily or placebo for up to 6 months. Couples attempted to conceive naturally during the first 3 months and with clomiphene citrate with intrauterine insemination of the female partner in months 4 through 6.

MAIN OUTCOME MEASURE(S)

Primary: sperm concentration, motility, morphology, and DNA fragmentation at baseline. Secondary: cumulative pregnancy, miscarriage, and live birth rates.

RESULT(S)

Semen parameters and sperm DNA fragmentation were not statistically significantly different between men with vitamin D deficiency and men with 25(OH)D levels ≥20 ng/mL. In addition, clinical pregnancy and live birth rates were similar. Male 25(OH)D level <20 ng/mL was associated with a higher rate of pregnancy loss (adjusted odds ratio 9.0; 95% confidence interval 1.3 to 61.3).

CONCLUSION(S)

Vitamin D deficiency in the male partner did not significantly impact semen parameters or treatment outcomes. Further study is warranted to better characterize the rate of miscarriage in couples with male vitamin D deficiency.

The effects of Vitamin D3 supplementation on Spermatogram and endocrine factors in asthenozoospermia infertile men: a randomized, triple blind, placebo-controlled clinical trial

OBJECTIVE

Evaluate the effects of vitamin D3 (VD3) on sperm parameters and endocrine markers in infertile men with asthenozoospermia.

MATERIALS AND METHODS

This randomized, triple-masking, placebo-controlled clinical trial conducted on 86 asthenozoospermia infertile men with serum 25 hydroxy vitamin D3 (25(OH)VD3) < 30 ng/ml in the infertility clinic of Ahvaz Jahad daneshgahi, Iran. Patients were randomly allocated to groups A and B, who received daily 4000 IU VD3 and matching placebo respectively for 3 months. Demographic data, dietary intake, physical activity, sun exposure, anthropometric indices, serum 25(OH)VD3, luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T), estradiol (E2),, sex hormone-binding globulin (SHBG), free androgen index (FAI = T/SHBG. 100), T/LH and T/E2 ratios, prolactin (PRO), parathyroid hormone (PTH), osteocalcin (OCN), phosphorus and sperm parameters were assessed.

RESULTS

Three months VD3 supplementation with 4000 IU/day had no significant effects body weight, body mass index (BMI), waist circumference (WC), body fat (BF), serum, OCN, LH, FSH, T, E2, SHBG, PRO, T/E2 ratio, FAI, semen volume, sperm count and normal sperm morphology. It increases serum 25(OH)VD3, PTH and phosphorus and seminal and serum calcium, T/LH ratio and total and progressive sperm motility and decreased significantly compared to the baseline and placebo group.

CONCLUSION

VD3 supplementation may affect sperm motility in men with asthenozoospermia and serum 25(OH)VD3 < 30 ng/ml.

TRIAL REGISTRATION

Iran Clinical Trials Registry, ID: IRCT20151128025274N4, registered on 28 March 2018, URL of trial registry record: https://www.irct.ir/trial/29983.

Assessment of serum vitamin D level and seminal vitamin D receptor gene methylation in a sample of Egyptian men with idiopathic infertility

Vitamin D deficiency has been linked with different health problems including male infertility. Its function is mediated by the vitamin D receptor, which acts as a transcription factor. Epigenetic mechanisms such as DNA methylation may affect the vitamin D receptor gene and result in gene silencing. The present study aimed to assess serum vitamin D level and seminal methylation of vitamin D receptor gene in idiopathic male infertility. Blood and semen samples were collected from 60 men with idiopathic infertility and 40 healthy fertile men. Vitamin D levels were detected using enzyme-linked fluorescent assay technique and methylation status was assessed by methylation-specific PCR. Results revealed that serum levels of 25OHD were significantly lower in patients compared to controls. Positive correlation was found between serum level of 25OHD and sperm concentration in patients group and progressive motility in total studied group. Methylation of vitamin D receptor gene was significantly higher in patients compared to control group. Negative correlation was found between methylation of vitamin D receptor gene and both sperm concentration and progressive motility in total studied group. Results of the present study suggest that vitamin D deficiency and vitamin D receptor gene methylation may be involved in aetiopathogenesis of idiopathic male infertility.

Evaluation of the effect of vitamin D supplementation on spermatogram, seminal and serum levels of oxidative stress indices in asthenospermia infertile men: a study protocol for a triple-blind, randomized controlled trial

BACKGROUND

It is suggested that vitamin D may have a beneficial role in male reproduction. The male reproductive system is a target tissue for vitamin D. This study will aim to evaluate the effects of vitamin D supplementation on sperm parameters, seminal and serum levels of oxidative stress and serum endocrine factors in asthenospermia infertile men.

METHODS/DESIGN

This randomized, triple-blind, placebo-controlled clinical trial will be conducted on 86 infertile men with idiopathic asthenozoospermia (the mobility of sperm < 40% and rapid progressive sperm motility < 32%), with serum levels of vitamin D less than 30 ng / ml in the "Infertility Clinic of Ahvaz Jahad daneshgahi", Iran.

MAIN OUTCOMES MEASURE (S)

Demographic data, dietary intake, physical activity, sun exposure, anthropometric indices, serum and seminal levels of MDA (Malondialdehyde), 8-hydroxy-2- Dioxy Guanosine (8-OHDG), Total Antioxidant Capacity (TAC) and calcium, sperm DNA fragmentation index (DFI), serum 25-OHD, luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), free androgen index (FAI = T/SHBG. 100), T/LH and T/E2 ratios, prolactin (PRO), parathyroid hormone (PTH), osteocalcin (OCN), phosphorus and sperm parameters.

DISCUSSION

The deficiency of vitamin D as an antioxidant is common all over the world. Numerous observational studies have shown a positive association between vitamin D levels and semen quality. However, few clinical studies have been conducted in this area. So considering with the high prevalence of this antioxidant deficiency specifically in infertile men, it seems that the supplementation of vitamin D in infertile men with insufficient levels or deficiency may improve the status of oxidative stress and thereby may affect sperm parameters and endocrine factors involved in male fertility.

TRIAL REGISTRATION

Iran Clinical Trials Registry, ID: IRCT20151128025274N4 , registered on 28 March 2018.

Nutrition, genetic variation and male fertility

Infertility affects nearly 50 million couples worldwide, with 40-50% of cases having a male factor component. It is well established that nutritional status impacts reproductive development, health and function, although the exact mechanisms have not been fully elucidated. Genetic variation that affects nutrient metabolism may impact fertility through nutrigenetic mechanisms. This review summarizes current knowledge on the role of several dietary components (vitamins A, B₁₂, C, D, E, folate, betaine, choline, calcium, iron, caffeine, fiber, sugar, dietary fat, and gluten) in male reproductive health. Evidence of gene-nutrient interactions and their potential effect on fertility is also examined. Understanding the relationship between genetic variation, nutrition and male fertility is key to developing personalized, DNA-based dietary recommendations to enhance the fertility of men who have difficulty conceiving.

Serum vitamin D content is associated with semen parameters and serum testosterone levels in men

The present study aimed to evaluate the influence of serum vitamin D levels on semen quality and testosterone levels. This is a cross-sectional study conducted at Androscience, Science and Innovation Center in Andrology and High-Complex Clinical and Andrology Laboratory in Sao Paulo, Brazil, with 508 male patients, aged 18-60 years, from 2007 to 2017. Seminal parameters and serum sexual hormones were correlated with serum vitamin D concentrations in 260 men selected by strict selection criteria. Patients were divided into normozoospermic group (NZG, n = 124) and a group with seminal abnormalities (SAG, n = 136). Evaluation included complete physical examination, past medical history, habits and lifestyle factors, two complete seminal analysis with sperm functional tests, serum levels of 25-hydroxy-vitamin D3(25(OH)VD3), total and free testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormone-binding globulin (SHBG), total cholesterol, homeostatic model assessment of insulin resistance (HOMA-IR) index, and karyotype. The mean concentration of 25(OH)VD3was significantly lower in the SAG (P < 0.001) and positively correlated with all baseline seminal parameters and total testosterone levels. In addition, serum vitamin D3concentration was found to be positively correlated with sperm concentration (β= 2.103; P < 0.001), total number of spermatozoa with progressive motility (β = 2.069; P = 0.003), total number of motile spermatozoa (β = 2.571; P = 0.015), and strict morphology (β = 0.056; P = 0.006), regardless of other variables. This is the first comparative study to address the issue of serum vitamin D3content between normozoospermic patients and those with sperm abnormalities. It clearly demonstrates a direct and positive relationship between serum vitamin D level and overall semen quality, male reproductive potential, and testosterone levels.

Dietary supplements in the management of varicocele-induced infertility: A review of potential mechanisms

Varicocele is a main cause of lower production of spermatozoon and infertility with multiple pathophysiological mechanisms. In the past decades, the use of dietary supplements has significantly increased due to both the modern lifestyle and the food shortages of the industrialised countries. The purpose of this review paper is to collect scientific evidences from basic and clinical studies which support the use of dietary supplements to define the clinical framework for patients with varicocele. In the present review, we used keywords such as dietary supplements, varicocele, male infertility, oxidative stress, DNA fragmentation, sperm parameters to find the proper articles. The standard search biomedical engines were used for seeking the papers. The use of dietary supplements such as minerals, vitamins and antioxidants has an essential role in the prevention and treatment of varicocele by increasing the levels of antioxidant enzymes (e.g. peroxidase, superoxide dismutase and catalase) and decreasing the levels of inflammatory markers (e.g. tumour necrosis factor-α, interleukin-6 and interleukin-1) in testis. According to the results, the dietary supplements may alleviate the spermatogenesis in varicocele patients through different mechanisms such as suppression of stress oxidative and inflammation in testicular tissue.

Effects of Vitamin D on Apoptosis and Quality of Sperm in Asthenozoospermia

OBJECTIVE

Vitamin D receptor (VDR) is expressed in human spermatozoa. However, the role of vitamin D (VD) in human male reproduction has not yet been clarified. In this study, effects of VD on sperm parameters and its apoptosis in asthenozoospermic and healthy men were evaluated.

METHODS

The study was carried out on discharged semen samples of 80 asthenozoospermic and healthy men. The samples were divided into control and experimental groups (received 20 µMol of VD). This study assessed sperm motility using the Makler chamber, their morphology by Diff quick, apoptosis and necrosis by Annexin-V and TUNEL assays, and their chromatin integrity was assessed by Aniline blue and Toluidine blue staining, according to WHO guidelines.

RESULTS

The results revealed that: 1) the total number of motile sperms was increased by VD in both groups, but it was only significant in the asthenozoospermia group. 2) The progressive motility was increased with significant difference in both groups.3) Morphology of sperm did not show any changes due to VD in any of the groups. 4) Early apoptosis and necrosis of sperms were reduced in both groups, but the results of late apoptosis showed no statistical difference in these groups. 5) The percentage of positive toluidine blue was significantly decreased after using VD in the asthenozoospermia group.

CONCLUSION

VD could improve motility, early apoptosis, and sperm necrosis, especially in asthenozoospermic men and it could be used for therapeutic opportunities.

High serum FSH is not a risk factor for low bone mineral density in infertile men

BACKGROUND

Male infertility is associated with a higher long-term morbidity and mortality risk. However, it is not clear which diseases are contributing to this risk. Osteoporosis is a possible factor, as it is a frequent disease and sex steroids regulate both fertility and bone health. Furthermore, there are data indicating that high FSH levels in women are related to low bone mineral density (BMD), independent of estradiol levels. As infertile men often have increased FSH, already from a young age, this could be a risk factor for impaired bone health in later life.

METHODS

One hundred and thirty-seven men with a history of male factor infertility due to spermatogenic failure (SgF men) as well as a control group of 70 men from couples treated with IVF for female factor infertility (non-SgF men) were included in a long-term follow-up study. Men with explained infertility, including testosterone deficiency, were not included. Data from baseline fertility investigations were retrieved from the patient files of the SgF men. At follow-up hormonal and semen analysis were performed and axial, femoral and total body BMD was measured by dual X-ray absorptiometry in all men. Multiple linear regression was used to assess differences between SgF and non-SgF men and to study associations between FSH levels and BMD.

RESULTS

Median follow-up time was 14.8 years (5th-95th percentile 11.3-18.2) after fertility assessment for SgF men and 15.6 years (12.1-18.5) for non-SgF men (p = 0.033). When comparing the two groups, no significant differences in total T, free T or E2 levels were apparent at follow-up. As expected, LH and FSH were higher in SgF men ((median (5th-95th percentile)) for LH (IU/L): 4.3 (2.2-13.6) for SgF men and 3.0 (1.4-5.8) for non-SgF men (p < 0.001); FSH (IU/L): 9.8 (2.8-35.5) versus 3.7 (1.6-8.7); p < 0.001), and inhibin B and semen parameters were lower in SgF men. There were no differences in BMD between the two groups at follow-up. Furthermore, both groups had median Z-scores close to zero at all sites, indicating that BMD is not different when compared to age-matched healthy men. In SgF men, neither baseline FSH, nor FSH at follow-up, was associated with BMD at the different sites at follow-up.

CONCLUSION

Men with spermatogenic failure are not at increased risk for impaired bone health when middle aged. Furthermore, infertile men with high FSH levels do not have lower BMD.

Effect of serum 25-hydroxyvitamin D levels on sperm quality and assisted reproductive technology outcomes for men of infertile Chinese couples

INTRODUCTION

Vitamin D insufficiency/deficiency is highly prevalent in China, but its effect on sperm quality and outcomes of assisted reproductive technology (ART) in men from infertile couples is not clear. This study aimed to explore the association of serum 25-hydroxyvitamin D (25OHD) levels and semen parameters, as well as ART outcomes for men from infertile couples.

MATERIALS AND METHODS

This study recruited 1308 men from infertile couples who attended the Reproductive Medicine Center of Peking University Third Hospital for first time from February to August 2019 (NCT03804294). Reproductive hormones levels, semen parameters, and clinical outcomes of ART were compared between vitamin D-deficient group (serum 25OHD ≤ 10 ng/mL), insufficient group (serum 25OHD 10-20 ng/mL), and sufficient group (serum 25OHD ≥ 20 ng/mL).

RESULTS

We found 27.7% of participants were vitamin D sufficient, suggesting high prevalence of vitamin D insufficiency/deficiency in China. Reproductive hormone levels were similar between the three groups. The total number of morphologically normal spermatozoa was significantly different between the three groups in all participants, impaired semen quality subgroup, and normozoospermia subgroup (P < .05) with the adjustment of confounders (age, BMI, alcohol consumption, cigarette smoking, and physical exercise). The percentage of normal sperm morphology significantly increased with elevated serum 25OHD levels in all participants and the participants with impaired semen quality (P < .05), and the total sperm count showed significant difference in participants with impaired semen quality (P = .026). For routine in vitro fertilization and intracytoplasmic sperm injection cycles, there were no differences in fertilization rate, top-quality embryo rate, biochemical pregnancy rate, and clinical pregnancy rate between serum 25OHD < 20 ng/mL and serum 25OHD ≥ 20 ng/mL groups.

CONCLUSIONS

Males of infertile couples with higher serum 25OHD levels exhibit better results in sperm morphology, and serum 25OHD levels may contribute to total sperm number in participants with impaired semen quality, but show no effects on the ART outcomes.

The effect of vitamin D on sperm motility and the underlying mechanism

Vitamin D deficiency is a common health issue around the world. We therefore evaluated the associations of semen quality with both serum and seminal plasma vitamin D levels and studied the mechanisms underlying these by incubating spermatozoa with 1,25(OH)₂D in vitro. Two hundred and twenty-two men were included in our study. Vitamin D was detected using an electrochemiluminescence method. Spermatozoa used for in vitro experiments were isolated by density gradient centrifugation. Positive relationships of serum 25(OH)D with semen volume and seminal plasma fructose were identified. Seminal plasma 25(OH)D level showed no relationship with serum 25(OH)D level, while it was inversely associated with sperm concentration and positively correlated with semen volume and sperm kinetic values. In vitro, sperm kinetic parameters increased after incubation with 1,25(OH)₂D, especially upon incubation for 30 min with it at a concentration of 0.1 nmol l⁻¹. Under these incubation conditions, the upward migration of spermatozoa increased remarkably with increasing adenosine triphosphate (ATP) concentration. The concentration of cyclic adenosine monophosphate (cAMP) and the activity of protein kinase A (PKA) were both elevated, and the PKA inhibitor, N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H89) reversed the increase of ATP production. The concentrations of cytoplasmic calcium ions and nicotinamide adenine dinucleotide (NADH) were both enhanced, while mitochondrial calcium uniporter (MCU) inhibitor, Ruthenium 360 (Ru360) did not reverse the increase of ATP production. Therefore, seminal plasma vitamin D may be involved in regulating sperm motility, and 1,25(OH)₂D may enhance sperm motility by promoting the synthesis of ATP both through the cAMP/PKA pathway and the increase in intracellular calcium ions.

Roles of Vitamin D in Reproductive Systems and Assisted Reproductive Technology

Vitamin D, an essential steroid hormone in the human body, plays an important role in not only the regulation of calcium and phosphorus metabolism, but also in various physiological processes, such as cell differentiation and apoptosis, inflammation, and insulin resistance. Vitamin D receptors are widely distributed in male and female reproductive systems, suggesting that vitamin D is essential for fertility. Because vitamin D deficiency is highly prevalent around the world, this review aims to discuss the potential functions of vitamin D in male and female reproductive systems and the associations between vitamin D and assisted reproductive technology (ART) outcomes. Vitamin D is involved in many physiological reproductive processes, including steroidogenesis, spermatogenesis, and acrosome reaction. It is correlated with sperm quality, ovarian reserve, polycystic ovarian syndrome, and endometriosis, among others. Controversial clinical findings on vitamin D levels and ART outcomes were revealed in this review, and demonstrations of efficacy for human fertility in randomized controlled trials of vitamin D supplementation are notably lacking. Thus, further studies are highly required involving molecular mechanisms among different species and human populations, as well as randomized controlled trials.

New insights to guide patient care: the bidirectional relationship between male infertility and male health

Male reproduction is a complex process, and numerous medical conditions have the potential to alter spermatogenesis. In addition, male factor infertility may be a biomarker for future health. In the present review, we discuss the current literature regarding the association between systemic diseases and fertility, which may impact clinical outcomes or semen parameters. A number of conditions that have systemic consequences were identified, including genetic (e.g., cystic fibrosis, DNA mismatch repair alterations), obesity, psychological stress, exogenous testosterone, and a variety of common medications. As such, the infertility evaluation may offer an opportunity for health counseling beyond the discussion of reproductive goals. Moreover, male infertility has been suggested as a marker of future health, given that poor semen parameters and a diagnosis of male infertility are associated with an increased risk of hypogonadism, cardiometabolic disease, cancer, and even mortality. Therefore, male fertility requires multidisciplinary expertise for evaluation, treatment, and counseling.

Investigation of serum vitamin D and ischaemia-modified albumin levels in infertile Turkish men

Our aim was to explore the existence of a possible relationship of sperm motility with serum 25-hydroxyvitamin D3 (25-OH VD) levels and with ischaemia-modified albumin (IMA) levels in infertile Turkish men. A total of 30 men with nonobstructive azoospermia (no spermatozoa in ejaculate), 30 men with oligospermia (total progressive motile sperm count (TPMSC) <15 × 10⁶ /ml) and 33 fertile men with normospermia (with at least one child, as the control group) were enrolled in the study. The mean 25-OH VD levels for groups 1, 2 and 3 were 9.31 ± 6.46, 19.71 ± 12.80 and 30.52 ± 12.49 respectively (p < .05). There was a statistically significant difference in serum IMA levels among the groups (479.32 ± 307.56 vs. 296.37 ± 127.27 vs. 150.04 ± 81.05, respectively; p < .05). A positive correlation between serum 25-OH VD levels and TPMSC, and a negative correlation between TPMSC and serum IMA levels were determined. Infertile men had lower serum 25-OH VD and higher IMA levels than fertile men, with a positive correlation between serum 25-OH VD levels and TPMSC, and a negative correlation between TPMSC and serum IMA levels. Vitamin D supplementation may increase the sperm motility.

The association between serum vitamin D, fertility and semen quality: A systematic review and meta-analysis

PURPOSE

A number of studies have examined the association between vitamin D, fertility and semen quality, however, findings have been inconclusive. Herein, we systematically reviewed available observational studies to elucidate the overall relationship between vitamin D, fertility and semen quality in adult population.

METHODS

PubMed, Cochrane's Library, Science Direct, Scopus, Google Scholar and ISI Web of Science databases were searched until December 2018 for all available studies evaluating the association between vitamin D, fertility and semen quality. The Newcastle-Ottawa Quality Assessment Scale was used to examine the quality of each study.

RESULTS

A total of 18 studies out of 1843 met our inclusion criteria and were included in our systematic review and meta-analysis. Serum 25(OH)D3 was significantly higher in fertile subjects compared to infertile ones (WMD -0.63; 95% CI, -1.06 to -0.21; P = 0.003). Furthermore, there was a significant association between serum 25(OH)D, sperm motility (WMD -5.84; 95% CI, -10.29 to -1.39; P = 0.01) and sperm progressive motility (WMD -5.24; 95% CI, -8.71 to -1.76; P = 0.003).

CONCLUSION

Our findings add to the existing literature supporting the concept that nutrition, especially vitamin D, plays an important role in men's sexual health. It should be noted that because of significant heterogeneity among the included studies, caution is warranted when interpreting the results. Further well-designed prospective cohort studies and clinical trials are needed for better understanding of the relationship between vitamin D and fertility and its components.

Vitamin D status is not associated with reproductive parameters in young Spanish men

BACKGROUND

Relatively low sperm count was reported among young Spanish men in 2013. Several potential culprits have been suggested as explanations for reported trends in sperm counts in Western men, including lifestyles. Although controversial, some studies suggest that semen parameters, such as low sperm motility or abnormal morphology, may be associated with low serum vitamin D levels.

OBJECTIVES

To evaluate associations between semen parameters and reproductive hormones and serum 25-hydroxyvitamin D (25OHD) status in young Spanish men and to examine these associations in relation to dietary intake of vitamin D.

MATERIALS AND METHODS

This cross-sectional study includes 198 university students recruited in 2010-2011 in southern Spain, who provided samples of blood and semen and food frequencies. Semen quality was evaluated by measuring volume, concentration, sperm counts, motility, and morphology, according to the WHO guidelines. Serum samples were analyzed for total 25OHD and reproductive hormones, including FSH, LH, testosterone, inhibin B, and estradiol. Dietary vitamin D intake was assessed using a validated food frequency questionnaire. Associations with semen quality and reproductive hormones were examined using linear regression, adjusting for potential confounders.

RESULTS

Almost all men had adequate levels of serum vitamin D - only three men (1.5%) were vitamin D deficient (<30 nmol/L) and 17% were insufficient (<50 nmol/L). However, dietary vitamin D intakes were relatively low (below recommended 600 IU/day in 99% of men). Neither dietary intake nor serum vitamin D levels were associated with any sperm parameter or any reproductive hormone (all p ≥ 0.09).

DISCUSSION

We did not observe an association between vitamin D status and any reproductive parameter in our study population.

CONCLUSIONS

Our results suggest that serum vitamin D levels are sustained in Spanish men despite low dietary intake and therefore low vitamin D does not explain the poor semen quality previously observed in these young Spanish men.

Vitamin D and Male Fertility: An Updated Review

To date, the key role of vitamin D in male reproductive system has been suggested, since the expression of vitamin D receptors and metabolizing enzymes was demonstrated in the testis and spermatozoa. Nevertheless, a general consensus about the role of vitamin D in male fertility is still debated. The aim of this review is to provide an updated systematic revision of the current available literature, discussing the experimental and clinical evidence on the role of vitamin D in the regulation of testis hormone production, seminal parameters and male fertility. The consequences of vitamin D deficiency on serum levels of testicular hormones have been analysed by several observational and interventional studies, with controversial results. Equally, the experimental researches not were able to state a certain relationship between vitamin D status and testis hormone production. Possible bias, including age, body mass index, and baseline vitamin D status justified the differences among studies. As well as concerning the effect of vitamin D on semen parameters, most of the studies agreed in the possibility that vitamin D might have a positive effect on human male fertility potential, particularly through better sperm motility. Regarding pregnancy outcomes, normal level of vitamin D seems to be related to better pregnancies. However, all the previous studies displayed a wide heterogeneity in study design, population, methodology, and cut off values used for the evaluation of vitamin D status. Future studies are needed to better clarify the exact role of vitamin D on hormonal and seminal panel in both fertile and infertile men.

Vitamin D status among long-term survivors of testicular cancer

A correlation between disturbances in hormone levels and the onset of metabolic disorders has been reported in long-term survivors of testicular cancer (TC).

We evaluated serum vitamin D levels and other biological parameters in a consecutive series of 61 long-term (≥3 years) unilateral TC survivors with a median a follow-up of 4 years and in a cohort of healthy males. Deficient vitamin D levels were observed in 10 (17%) of the 58 long-term unilateral TC survivors but were not reported in healthy males (p=.019, Fisher test). Median vitamin D levels were 18.6 ug/L in 58 assessable TC survivors and 23.6 ug/L in 40 healthy males (p=.031). In univariate logistic regression analysis, TC diagnosis was associated with inadequate levels of vitamin D (p=.047). Vitamin D levels were lower when follow-up was > 10 years, albeit this difference was not statistically significant (p=.074). Long-term (especially > 10 years) TC survivors may have difficulty maintaining optimal vitamin D levels. Larger studies are needed to better characterize vitamin D status and possible correlations with premature hormonal aging reported in long-term TC survivors.

Effects of Vitamin D Supplementation on Semen Quality, Reproductive Hormones, and Live Birth Rate: A Randomized Clinical Trial

CONTEXT

Results of animal models and cross-sectional cohort studies have suggested a beneficial role for vitamin D in male reproduction.

OBJECTIVE

Determine the effect of vitamin D and calcium supplementation on semen quality in infertile men with serum 25-hydroxyvitamin-D (25OHD) levels ≤50 nmol/L.

DESIGN

A single-center, triple-blinded, randomized clinical trial.

PARTICIPANTS

A total of 1427 infertile men were screened to include 330; 1002 men did not meet inclusion criteria and 95 did not wish to participate.

INTERVENTION

The active group received cholecalciferol 300,000 IU initially, then 1400 IU cholecalciferol and 500 mg of calcium daily for 150 days; the other group received placebo.

RESULTS

Serum concentrations of 25OHD and 1,25-dihydroxyvitamin D3 were significantly higher in men in the treatment group compared with the placebo group. Vitamin D supplementation was not associated with changes in semen parameters, although spontaneous pregnancies tended to be higher in couples in which the man was in the treatment group [7.3% vs 2.4%, Δ5.0% (-0.6%; 10.5%)]. Vitamin D treatment in a subgroup of oligozoospermic men increased the chance for a live birth compared with placebo [35.6% vs 18.3%, Δ17.3% (1.6%; 32.9%)]. Moreover, serum inhibin B levels were higher in men deficient in vitamin D who were randomly assigned to receive high-dose vitamin D [193 pg/mL vs 143 pg/mL, Δ49 pg/mL (8; 91 pg/mL)]; however, the increase in sperm concentration was not significantly higher than in the placebo group (P = 0.07).

CONCLUSION

High-dose vitamin D supplementation did not improve semen quality in vitamin D-insufficient infertile men. The positive impact of vitamin D supplementation on live birth rate and serum inhibin B in oligozoospermic and vitamin D-deficient men may be of clinical importance and warrant verification by others.

On the origin of obesity: identifying the biological, environmental and cultural drivers of genetic risk among human populations

Genetic predisposition to obesity presents a paradox: how do genetic variants with a detrimental impact on human health persist through evolutionary time? Numerous hypotheses, such as the thrifty genotype hypothesis, attempt to explain this phenomenon yet fail to provide a justification for the modern obesity epidemic. In this critical review, we appraise existing theories explaining the evolutionary origins of obesity and explore novel biological and sociocultural agents of evolutionary change to help explain the modern-day distribution of obesity-predisposing variants. Genetic drift, acting as a form of 'blind justice,' may randomly affect allele frequencies across generations while gene pleiotropy and adaptations to diverse environments may explain the rise and subsequent selection of obesity risk alleles. As an adaptive response, epigenetic regulation of gene expression may impact the manifestation of genetic predisposition to obesity. Finally, exposure to malnutrition and disease epidemics in the wake of oppressive social systems, culturally mediated notions of attractiveness and desirability, and diverse mating systems may play a role in shaping the human genome. As an important first step towards the identification of important drivers of obesity gene evolution, this review may inform empirical research focused on testing evolutionary theories by way of population genetics and mathematical modelling.

Is immunosuppression, induced by neonatal thymectomy, compatible with poor reproductive performance in adult male rats?

With increasing knowledge that the immune system has a major impact on reproductive ‎health, the potential for cells arising in organs such as the thymus to alleviate oxidative stress ‎has been revealed. This study addresses the impact of neonatal thymectomy on male ‎reproductive function in pubertal and adult animals. Neonatal Sprague Dawley rats were allotted to four treatments consisting of fully thymectomized, partially thymectomized, intact, and sham-operated rats. Half of the rats in each treatment were sacrificed at 40 and the other half at 80 days of age. Testicular volume, ventral prostate and spleen weight, several sperm attributes (concentration, motility, livability, membrane integrity, sperm penetration into mucus, total antioxidant capacity, mitochondrial dehydrogenase activity), plasma superoxide dismutase, glutathione, and testosterone level as well as fertility decreased in thymectomized rats. Adrenal gland weight, sperm malondialdehyde level, indices of oxidative stress, sperm abnormality, testicular and sperm lipid peroxidation, protein carbonylation, and sperm reactive oxygen species generation increased in thymectomized rats. In thymectomized rats, the testes contained high levels of malondialdehyde but low levels of glutathione and ferric-reducing antioxidant power. Epididymal sperm reactive oxygen species, blood lipid peroxidation, and oxidative stress indices ‎‎in blood and spermatozoa were highest in fully thymectomized, intermediate ‎in partially thymectomized, and lowest in both pubertal and mature control rats. Blood levels of superoxide dismutase, lipid peroxidation indices, and ‎testosterone, and mitochondrial adenosine triphosphate and ‎dehydrogenase activities in epididymal spermatozoa were lowest in fully thymectomized, ‎intermediate in partially thymectomized, and highest in both pubertal and mature control rats.‎ The data indicated that increased oxidative stress and mitochondrial dysfunction might play a role in the mechanism of immunosuppression-induced testicular and sperm abnormalities.

Possible influence of vitamin D on male reproduction

Vitamin D is a versatile signaling molecule with an established role in the regulation of calcium homeostasis and bone health. In recent years the spectrum of vitamin D target organs has expanded and a reproductive role is supported by the presence of the vitamin D receptor (VDR) and the vitamin D metabolizing enzymes in the gonads, reproductive tract, and human spermatozoa. Interestingly, expression levels of VDR and the vitamin D inactivating enzyme CYP24A1 in human spermatozoa serve as positive predictive markers of semen quality and are higher expressed in spermatozoa from normal than infertile men. VDR mediates a non-genomic increase in intracellular calcium concentration, sperm motility, and induces the acrosome reaction. Furthermore, functional animal model studies have shown that vitamin D is important for sex steroid production, estrogen signaling, and semen quality. Cross-sectional clinical studies have supported the notion of a positive association between serum 25-hydroxyvitamin D (25-OHD) level and semen quality in both fertile and infertile men. However, it remains to be determined whether this association reflects a causal effect. The VDR is ubiquitously expressed and activated vitamin D is a regulator of insulin, aromatase, and osteocalcin. Hence, it is plausible that the influence of vitamin D on gonadal function may be mediated indirectly through other vitamin D regulated endocrine factors. Recent studies have indicated that vitamin D supplementation may be beneficial for couples in need of assisted reproductive techniques as high serum vitamin D levels were found to be associated with a higher chance of achieving pregnancy. Randomized clinical trials are needed to determine whether systemic changes in vitamin D metabolites can influence semen quality, fertility, and sex steroid production in infertile men. In this review known and possible future implications of vitamin D in human male reproduction function will be discussed.

Reproductive endocrinology of vitamin D

Vitamin D is a versatile hormone with several functions beyond its well-established role in maintenance of skeletal health and calcium homeostasis. The effects of vitamin D are mediated by the vitamin D receptor, which is expressed together with the vitamin D metabolizing enzymes in the reproductive tissues. The reproductive organs are therefore responsive to and able to metabolize vitamin D locally. The exact role remains to be clarified but several studies have suggested a link between vitamin D and production/release of reproductive hormones into circulation, which will be the main focus of this review. Current evidence is primarily based on small human association studies and rodent models. This highlights the need for randomized clinical trials, but also functional animal and human in vitro studies, and larger, prospective cohort studies are warranted. Given the high number of men and women suffering from reproductive problems and abnormal endocrinology research addressing the role of vitamin D in reproductive endocrinology may be of clinical importance.

The role of vitamin D in male fertility: A focus on the testis

In the last decade, vitamin D has emerged as a pleiotropic molecule with a multitude of autocrine, paracrine and endocrine functions, mediated by classical genomic as well as non-classical non-genomic actions, on multiple target organs and systems. The expression of vitamin D receptor and vitamin D metabolizing enzymes in male reproductive system, particularly in the testis, suggests the occurrence of vitamin D synthesis and regulation as well as function in the testis. The role of vitamin D in the modulation of testis functions, including hormone production and spermatogenesis, has been investigated in animals and humans. Experimental studies support a beneficial effect of vitamin D on male fertility, by modulating hormone production through genomic and non-genomic actions, and, particularly, by improving semen quality essentially through non-genomic actions. However, clinical studies in humans are controversial. Indeed, vitamin D seems to contribute to the modulation of the bioavailable rather than total testosterone. Moreover, although an increased prevalence or risk for testosterone deficiency was reported in men with vitamin D deficiency in observational studies, the majority of interventional studies demonstrated the lack of effect of vitamin D supplementation on circulating levels of testosterone. The most consistent effect of vitamin D was reported on semen quality. Indeed, vitamin D was shown to be positively associated to sperm motility, and to exert direct actions on spermatozoa, including non-genomic driven modulation of intracellular calcium homeostasis and activation of molecular pathways involved in sperm motility, capacitation and acrosome reaction. The current review provides a summary of current knowledge on the role of vitamin D in male fertility, by reporting clinical and experimental studies in humans and animals addressing the relationship between vitamin D and testis function.

Comparison of Serum Vitamin D between Fertile and Infertile Men in A Vitamin D Deficient Endemic Area: A Case-Control Study

Introduction

The aim of this study was to compare serum vitamin D between fertile and infertile men in endemic area of vitamin D deficiency. The role of vitamin D in all aspects of human health has attracted a great interest. Vitamin D effect on female fertility and to a lesser extent in men is under investigation. Previous researchers have found meaningful positive relationship between semen quality and serum vitamin D level. However, in endemic area of vitamin D deficiency, this effect is under question.

Methods

Serum 25-OH-Vitamin D was compared between infertile male patients and fertile control group. Infertile cases were from patients of our infertility clinic and fertile controls from healthy cases with at least one child below 5 years of age. SPSS version 19 was used for statistical analysis (Kolmogorov-Smirnov test and Mann-Whitney test).

Results

Between 116 fertile and 114 infertile men who entered the study, serum level of 20 was a critical point, which patients with upper serum level had significantly better spermogram. In addition to it, even in vitamin D deficient patients and controls, fertile controls had higher serum vitamin D.

Conclusions

There is a positive correlation between serum level of vitamin D and spermogram quality, even in vitamin D deficient areas. Fertile people have a higher level of serum vitamin D in comparison to infertile patient in aforementioned areas.

Associations of vitamin D status and vitamin D-related polymorphisms with sex hormones in older men

OBJECTIVE

Evidence regarding relationships of serum 25-hydroxyvitamin D (25(OH)D) with sex hormones and gonadotropin concentrations remains inconsistent. Polymorphisms in vitamin D-related genes may underly these relationships. Our aim was to examine the relationship of vitamin D status and polymorphisms in vitamin D-related genes with sex hormone and gonadotropin levels.

DESIGN AND MEASUREMENTS

We analysed data from the Longitudinal Aging Study Amsterdam, an ongoing population-based cohort study of older Dutch individuals (65-89 years). We included data of men with measurements of serum 25-hydroxyvitamin D (25(OH)D) (n=643) and determination of vitamin D-related gene polymorphisms (n=459). 25(OH)D concentrations were classified into four categories: <25, 25-50, 50-75 and >75nmol/L. Outcome measures were total testosterone, calculated bioavailable and free fraction testosterone, SHBG, estradiol, LH and FSH concentrations. Hypogonadism was defined as a total testosterone level <8.0nmol/L.

RESULTS

Serum 25(OH)D was positively associated with total and bioavailable testosterone levels. After adjustments for confounders, men with serum 25(OH)D less than 25 (n=56), 25-50 (n=199) and 50-75nmol/L (n=240) had lower total testosterone levels compared to men with serum 25(OH)D higher than 75nmol/L (n=148) (β (95% confidence interval): -2.1 (-3.7 to -0.4nmol/L), -0.8 (-1.9 to 0.4nmol/L) and -1.4 (-2.4 to -0.3nmol/L), respectively). For bioavailable testosterone the association was significant only for men with serum 25(OH)D less than 25nmol/L (-0.8 (-1.4 to -0.1nmol/L)) compared to men with serum 25(OH)D >75nmol/L. Serum 25(OH)D was not related to SHBG, estradiol or gonadotropin levels. Hypogonadism (n=29) was not associated with lower serum 25(OH)D. No significant differences were found in hormone levels between the different genotypes of the vitamin D-related gene polymorphisms. Also, the polymorphisms did not modify the relationships of serum 25(OH)D with sex hormones or gonadotropins.

CONCLUSION

Vitamin D status is positively associated with testosterone levels. No association was found between vitamin D-related gene polymorphisms and hormone levels.

Association of vitamin D status with semen quality and reproductive hormones in Iranian subfertile men

Although vitamin D deficiency is one of the most common health problems throughout the world, including Iran, conflicting information exists on the potential association between serum vitamin D levels and semen quality. This study intended to evaluate the association between serum vitamin D [25(OH) D3] with semen quality and hormones in Iranian subfertile men. We also compared mean vitamin D and hormone levels in normospermic men with oligoasthenoteratozoospermia (OAT) men. This cross-sectional study was conducted on 278 men who were referred to Royan Infertility Clinic (Tehran, Iran) from March to September 2014. The participants were categorized into two groups; of 186 normospermic and 92 OAT patients according to World Health Organization 2010 criteria. Each participant provided informed consent prior to launching research. Participants completed two general questionnaires of nutritional status. Blood and semen samples were obtained for assessment, and all data were adjusted for age, body mass index (BMI), and season. Vitamin D levels were classified according to Institute of Medicine guidelines. Vitamin D deficiency, insufficiency, and normal levels were observed in 8.6%, 43.6%, 47.8% of participants, respectively. No association was found between daily dietary intake of vitamin D and calcium with sperm parameters. Serum vitamin D was inversely correlated with PTH (p < 0.045). In normospermic men, serum vitamin D levels categorized were not correlated with semen parameters and reproductive hormones (FSH, LH, testosterone(T), and FT), whereas sperm motility showed a positive correlation with vitamin D categorized in OAT men (rs = 0.131, p = 0.028). In conclusion, there was a high incidence of deficiency and insufficiency 25(OH) D Levels (<20ng/ml) observed in Iranian men (52.2%). Moreover, our findings showed a correlation between vitamin D levels and sperm motility in OAT men, which requires further studies.

Epigenetics in male reproduction: effect of paternal diet on sperm quality and offspring health

Epigenetic inheritance and its underlying molecular mechanisms are among the most intriguing areas of current biological and medical research. To date, studies have shown that both female and male germline development follow distinct paths of epigenetic events and both oocyte and sperm possess their own unique epigenomes. Fertilizing male and female germ cells deliver not only their haploid genomes but also their epigenomes, which contain the code for preimplantation and postimplantation reprogramming and embryonal development. For example, in spermatozoa, DNA methylation profile, DNA-associated proteins, protamine 1:protamine 2 ratio, nucleosome distribution pattern, histone modifications and other properties make up a unique epigenetic landscape. However, epigenetic factors and mechanisms possess certain plasticity and are affected by environmental conditions. Paternal and maternal lifestyle, including physical activity, nutrition and exposure to hazardous substances, can alter the epigenome and, moreover, can affect the health of their children. In male reproductive health, data are emerging on epigenetically mediated effects of a man's diet on sperm quality, for example through phytochemicals, minerals and vitamins, and nutritional support for subfertile men is already being used. In addition, studies in animal models and human epidemiological data point toward a transgenerational effect of the paternally contributed sperm epigenome on offspring health.

High prevalence of hypogonadism and associated impaired metabolic and bone mineral status in subfertile men

OBJECTIVE

It is yet unknown to which degree young subfertile men present with signs of hypogonadism and whether low testosterone concentration, like in older men, is associated with risk of osteoporosis and metabolic derangements in those subjects. The objective was therefore to investigate the prevalence of hypogonadism and its association with metabolic and bone parameters in young subfertile men.

DESIGN

Cross-sectional case-control study.

PATIENTS

Men from infertile couples (n = 192); 18-50 years; sperm concentration <20 × 10(6) /ml and population-based age-matched controls (n = 199).

MEASUREMENTS

Blood sampling, anthropometrics, blood pressure, ankle-brachial index and assessment by dual-energy X-ray absorptiometry were undertaken. Odds ratios of biochemical hypogonadism (total testosterone <8·0 nmol/l and/or luteinizing hormone ≥8·6 IU/l and/or ongoing androgen replacement therapy) were calculated. Serum concentrations of sex hormones, lipids, glucose, insulin and HbA1c were assessed and bone mineral density (BMD) evaluated.

RESULTS

Compared to controls, the risk of hypogonadism was increased among subfertile men (OR 10; 95% CI, 5·1, 22), being highest in those with nonobstructive azoospermia. Hypogonadal men had higher HbA1c concentration (mean diff. 2·8 mmol/mol; 95% CI, 0·64, 4·9; P = 0·011) and lower lumbar spine BMD (mean diff. 0·05 g/cm(2) ; 95% CI, 0·01, 0·10; P = 0·032) compared to eugonadal subfertile men, even more pronounced in subfertile men with subnormal testosterone levels.

CONCLUSION

Young subfertile men have 10 times increased OR of hypogonadism, which is linked to increased HbA1c and decreased bone mineralization. Endocrine assessment and, if needed, measures to prevent metabolic sequelae and osteoporosis should be included in the routine management of men from infertile couples.

Vitamin D status and fertility outcomes during winter among couples undergoing in vitro fertilization/intracytoplasmic sperm injection

OBJECTIVE

To assess the vitamin D status of men and women undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI), and to investigate associations between vitamin D status and fertility variables.

METHODS

A cross-sectional prospective study was undertaken of men and women attending a fertility clinic in Ireland for IVF/ICSI between January and March 2014. Vitamin D status was determined by measurement of serum 25-hydroxyvitamin D (25(OH)D). Questionnaires examined knowledge and practices concerning vitamin D. Fertility variables and pregnancy outcomes were assessed in relation to vitamin D status.

RESULTS

Overall, 73 men and 64 women provided blood samples. Among men, no correlation was found between 25(OH)D and total motility (ρ=0.069, P=0.562), progressive motility (ρ=0.066, P=0.576), count (ρ=0.001, P=0.996), or morphology (ρ=-0.034, P=0.774) of sperm. Additionally, there was no association between 25(OH)D and ongoing pregnancy rates (P=0.158). There was no difference in 25(OH)D between men with and without male factor subfertility issues (P=0.856). Among women, there was no significant correlation between 25(OH)D and anti-Müllerian hormone (P=0.629) or number of collected (P=0.198) and fertilized oocytes (P=0.136). There was no difference in 25(OH)D between women with and without ongoing pregnancy (P=0.222).

CONCLUSION

No correlation was found between fertility variables or pregnancy outcomes and male or female vitamin D status.

Vitamin D and chronic diseases: the current state of the art

The objective was to provide the current state of the art regarding the role of vitamin D in chronic diseases (osteoporosis, cancer, cardiovascular diseases, dementia, autism, type 1 and type 2 diabetes mellitus, male and female fertility). The document was drawn up by panelists that provided their contribution according to their own scientific expertise. Each scientific expert supplied a first draft manuscript on a specific aspect of the document's topic that was subjected to voting by all experts as "yes" (agreement with the content and/or wording) or "no" (disagreement). The adopted rule was that statements supported by ≥75 % of votes would be immediately accepted, while those with <25 % would be rejected outright. Others would be subjected to further discussion and subsequent voting, where ≥67 % support or, in an eventual third round, a majority of ≥50 % would be needed. This document finds that the current evidence support a role for vitamin D in bone health but not in other health conditions. However, subjects with vitamin D deficiency have been found to be at high risk of developing chronic diseases. Therefore, although at the present time there is not sufficient evidence to recommend vitamin D supplementation as treatment of chronic diseases, the treatment of vitamin D deficiency should be desiderable in order to reduce the risk of developing chronic diseases.

Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men

STUDY QUESTION

Are low vitamin D levels linked with semen quality and sex steroids in infertile men?

SUMMARY ANSWER

Infertile men with vitamin D deficiency had lower sperm motility, total numbers of motile sperm, Inhibin B, sex-hormone-binding-globulin (SHBG) and testosterone/estradiol ratio, but higher levels of free sex steroids, than infertile men with normal vitamin D levels.

WHAT IS KNOWN ALREADY

Low vitamin D levels have been associated with decreased sperm motility in healthy men, but a relationship between vitamin D and calcium with semen quality and especially sex steroids has not been sufficiently described in infertile men.

STUDY DESIGN, SIZE, DURATION

This study comprises baseline characteristics of 1427 infertile men screened from 2011 to 2014 for inclusion in a randomized clinical trial, the Copenhagen-Bone-Gonadal Study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total 1427 infertile men, consecutively referred to our tertiary andrological centre for fertility workup, underwent a physical examination and had semen quality assessed based on two samples and blood analysed for serum testosterone, SHBG, estradiol, inhibin B, luteinizing hormone, follicle-stimulating hormone (FSH), 25-hydroxyvitamin D (25-OHD), ionized calcium (Ca(2+)) and karyotype. There were 179 men excluded due to serious comorbidities or anabolic steroid usage, leaving 1248 patients for analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Men with 25-OHD >75 nmol/l had higher sperm motility and 66 and 111% higher total numbers of motile spermatozoa after 45 and 262 min, respectively, than men with 25-OHD <25 nmol/l (all P < 0.05). SHBG levels and testosterone/estradiol ratios were 15 and 14% lower, respectively, while free testosterone and estradiol ratios were 6 and 13% higher, respectively, in men with 25-OHD <25 nmol/l (all P < 0.05). Men with lower Ca(2+) levels had higher progressive sperm motility and inhibin B/FSH ratio but lower testosterone/estradiol ratio (all P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

All outcomes presented are predefined end-points but inferral of causality is compromised by the descriptive study design. It remains to be shown whether the links between vitamin D, calcium, semen quality and sex steroids in infertile men are causal.

WIDER IMPLICATIONS OF THE FINDINGS

The associations between vitamin D deficiency and low calcium with semen quality and sex steroids support the existence of a cross-link between regulators of calcium homeostasis and gonadal function in infertile men.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the Danish Agency for Science, Technology and Innovation, Hørslev Fonden, Danish Cancer Society and Novo Nordisk Foundation. There are no conflicts of interest.

TRIAL REGISTRATION NUMBER

NCT01304927.

DATE OF TRIAL REGISTRATION

25 February 2011.

DATE OF ENROLMENT OF FIRST PATIENT

8 March 2011.

Vitamin D and gonadal function in men: a potential inverse U-shaped association?

Accumulating evidence from animal and human studies suggests that vitamin D, apart from its regulatory effects on musculoskeletal health, is involved in reproductive function in both genders. The basis of the interplay between vitamin D and reproduction lays on the presence of both vitamin D receptor (VDR) and 1α-hydroxylase (CYP27B1) enzyme in reproductive organs. In males, VDR are present in testis, epididymis, prostate, and seminal vesicles. In Sertoli cells, whose secretory activities are ion channel-dependent, vitamin D has been shown to stimulate calcium uptake through a nuclear receptor activity. Epidemiological studies support a positive association between serum 25-hydroxy-vitamin D [25(OH)D] concentrations and sperm motility in both fertile and infertile men In addition, large multi-center, cross-sectional studies from Europe and USA have shown positive, linear association between 25(OH)D and androgen concentrations. On the contrary, there are studies that support an inverse U-shaped association, that is, men with both low and high 25(OH)D concentrations demonstrate poorer gonadal function compared with those with intermediate concentrations. Given the rapid increase in over-the-counter use of vitamin D supplements by men that anticipate advantageous health outcomes, the aim of the present commentary is to provide an overview of the studies that present either U-shaped or linear association between 25(OH)D concentrations and male gonadal function.

Vitamin D and Reproduction: From Gametes to Childhood

Vitamin D is well recognized for its essentiality in maintaining skeletal health. Recent research has suggested that vitamin D may exert a broad range of roles throughout the human life cycle starting from reproduction to adult chronic disease risk. Rates of vitamin D deficiency during pregnancy remain high worldwide. Vitamin D deficiency has been associated with an increased risk of fertility problems, preeclampsia, gestational diabetes, and allergic disease in the offspring. Vitamin D is found naturally in only a few foods thus supplementation can provide an accessible and effective way to raise vitamin D status when dietary intakes and sunlight exposure are low. However, the possibility of overconsumption and possible adverse effects is under debate. The effect of vitamin D supplementation during pregnancy and early life on maternal and infant outcomes will be of particular focus in this review.