Relationship Between Vitamin D and Hormones Important for Human Fertility in Reproductive-Aged Women

Genetic insights into vitamin D deficiency: a case-control study of GC and CYP24A1 gene polymorphism

Despite the sunny climate, vitamin D deficiency is highly prevalent in several parts of the world. Several risk factors are associated with VD deficiency, including single nucleotide polymorphism and post-translational modifications in its transport protein, known as vitamin D binding protein (DBP) or GC and CYP24A1, a protein associated with its degradation. Our study explores the impact of rs4588 and rs7041 in the GC gene, along with CYP24A1 rs4809960 and rs2585428, on serum vitamin D and the risk of vitamin D insufficiency. This study enrolled 114 healthy controls and 239 vitamin D-deficient subjects. SNPs were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The G/T genotype of D432E and the A/A genotype of T436K in the GC gene were observed to be risk factors for vitamin D deficiency. Overall, a significant (P < 0.05) association was observed between the D432E and T436K polymorphism and vitamin D deficiency. Polymorphic genotypes of CYP24A1 rs4809960 and rs2585428 polymorphisms were significantly associated with a higher risk of Vitamin D deficiency. D432E and T436K polymorphisms were associated with decreased vitamin D and increased PTH levels in vitamin D-deficient individuals. Similarly, both CYP24A1 polymorphisms were significantly associated with a higher risk of vitamin D deficiency. Also, a negative association was observed between sufficient serum levels of 25-hydroxyvitamin D and PTH levels.

Nutritional Support of Chronic Obstructive Pulmonary Disease

Background: COPD is a heterogenous disease of the respiratory tract caused by diverse genetic factors along with environmental and lifestyle-related effects such as industrial dust inhalation and, most frequently, cigarette smoking. These factors lead to airflow obstruction and chronic respiratory symptoms. Additionally, the increased risk of infections exacerbates airway inflammation in COPD patients. As a consequence of the complex pathomechanisms and difficulty in treatment, COPD is among the leading causes of mortality both in the western countries and in the developing world. Results: The management of COPD is still a challenge for the clinicians; however, alternative interventions such as smoking cessation and lifestyle changes from a sedentary life to moderate physical activity with special attention to the diet may ameliorate patients' health. Here, we reviewed the effects of different dietary components and supplements on the conditions of COPD. Conclusions: COPD patients are continuously exposed to heavy metals, which are commonly present in cigarette smoke and polluted air. Meanwhile, they often experience significant nutrient deficiencies, which affect the detoxification of these toxic metals. This in turn can further disrupt nutritional balance by interfering with the absorption, metabolism, and utilization of essential micronutrients. Therefore, awareness and deliberate efforts should be made to check levels of micronutrients, with special attention to ensuring adequate levels of antioxidants, vitamin D, vitamin K2, magnesium, and iron, as these may be particularly important in reducing the risk of COPD development and limiting disease severity.

Elucidating the chrononutrition patterns and sleep quality among subfertile patients with different vitamin D levels

Subfertility affects about 10-15% of Malaysians, characterized by difficulty conceiving after 12 months of unprotected intercourse. Emerging research suggests that vitamin D deficiency, influenced by dietary intake and sleep patterns, may contribute to fertility. This study examines the relationship between chrononutrition patterns, sleep quality and vitamin D deficiency in subfertile patients. A cross-sectional study was conducted at two hospitals in Selangor, Malaysia, involving 140 subfertile individuals who fit the inclusion and exclusion criteria. Data were collected through self-administered questionnaires, including food frequency questionnaires (FFQ), the Chrononutrition Profile Questionnaire (CPQ), and the Pittsburgh Sleep Quality Index (PSQI). Serum vitamin D levels were measured through 25-hydroxyvitamin D blood test. Statistical analyses were performed using SPSS version 29. Results revealed a significant difference in mean serum vitamin D levels between male and female participants (p < 0.001), with 76.7% of the females being vitamin D deficient. Most parameters were not significant in males compared to females. Notably, a negative correlation was found between vitamin D levels and both energy and fat intake in females (p < 0.05). Female gender was identified as a significant determinant of vitamin D deficiency (OR 5.186, p < 0.001), while poor evening eating habits were strongly associated with deficiency (AOR 10.553, p < 0.05). These findings highlight the importance of gender and dietary patterns in vitamin D deficiency among subfertile patients. Hence, there is a need for targeted nutritional and lifestyle interventions.

The Contribution of Precision Nutrition Intervention in Subfertile Couples

BACKGROUND/AIM

Subfertility is characterized by a decrease in reproductive efficiency, which can result in delayed pregnancy, and affects one in six individuals during their lifetime. The present narrative review aims to evaluate the contribution of precision nutrition to changes in fertility in subfertile couples.

METHODS

The literature review was carried out through bibliographic research in the PubMed, Scopus, SciELO and Google Scholar databases. The following search criteria were applied: (1) original articles and narrative, systematic or meta-analytic reviews, and (2) the individual or combined use of the following keywords: "genetic variation", "nutrigenetics", "precision nutrition", "couple's subfertility", and "couple's infertility". A preliminary reading of all the articles was carried out, and only those that best fit the themes and subthemes of the narrative review were selected.

RESULTS

Scientific evidence suggests that adherence to a healthy diet that follows the Mediterranean pattern is associated with increased fertility in women and improved semen quality in men, better metabolic health and reduced levels of inflammation and oxidative stress, as well as maintaining a healthy body weight. The integration of different tools, such as nutrigenetics, predictive biochemical analyses, intestinal microbiota tests and clinical nutrition software, used in precision nutrition interventions can contribute to providing information on how diet and genetics interact and how they can influence fertility.

CONCLUSIONS

The adoption of a multidisciplinary and precision approach allows the design of dietary and lifestyle recommendations adapted to the specific characteristics and needs of couples with subfertility, thus optimizing reproductive health outcomes and achieving successful conception.

Hypovitaminosis D in university workers in Southern Ecuador: interactions between gender and lifestyle

Background

Hypovitaminosis D may be common in tropical countries and is linked to disorders of phospho-calcium metabolism, rickets, muscle pain, immune system deficiencies, and increased susceptibility to microbial infections.

Objective

To assess the prevalence of hypovitaminosis D in apparently healthy university workers in Loja, Ecuador.

Methods

A cross-sectional study was completed in a private Ecuadorian university from May 2023 to September 2023, involving 440 participants. Data were gathered using a structured questionnaire created to assess risk factors influencing vitamin D levels. Serum 25-hydroxyvitamin D (25-OH)D concentrations were measured utilizing immunoenzymatic methods. Altered states (insufficiency or deficiency) of vitamin D were defined with serum values <30 ng/mL. Associations between vitamin D status and selected determinants were analyzed with independence tests, with significance set at p < 0.05. Where possible, odds ratios (OR) were calculated using logistic regression.

Results

The sample consisted of 60.9% faculty members and 39.1% administrative staff; 42.7% were men and 57.3% were women, with an average age of 41.9 ± 7.6 years. Only 2.7% of participants were aged 60 years or older. The mean serum 25-(OH)D concentration was 19.5 ± 6.8 ng/mL. Altered 25-(OH)D levels were found in 93.4% of participants, with 94.0% showing decreased serum 25-(OH)D concentrations and 1.6% displaying deficiency states. Hypovitaminosis D was associated with sex (OR = 2.40; 95% CI: 1.3-5.57; p < 0.05) and sunscreen use (OR = 0.36; 95% IC: 0.13-0.99; p < 0.05).

Conclusion

Hypovitaminosis D was almost universal among the apparently healthy university workers studied. The findings suggest that both sex and sunscreen use may independently or jointly contribute to hypovitaminosis D in these individuals. Further studies will be required to clarify this interplay.

Anti-Müllerian hormone: biology and role in endocrinology and cancers

Anti-Müllerian hormone (AMH) is a peptide belonging to the transforming growth factor beta superfamily and acts exclusively through its receptor type 2 (AMHR2). From the 8th week of pregnancy, AMH is produced by Sertoli cells, and from the 23rd week of gestation, it is produced by granulosa cells of the ovary. AMH plays a critical role in regulating gonadotropin secretion, ovarian tissue responsiveness to pituitary hormones, and the pathogenesis of polycystic ovarian syndrome. It inhibits the transition from primordial to primary follicles and is considered the best marker of ovarian reserve. Therefore, measuring AMH concentration of the hormone is valuable in managing assisted reproductive technologies. AMH was initially discovered through its role in the degeneration of Müllerian ducts in male fetuses. However, due to its ability to inhibit the cell cycle and induce apoptosis, it has also garnered interest in oncology. For example, antibodies targeting AMHR2 are being investigated for their potential in diagnosing and treating various cancers. Additionally, AMH is present in motor neurons and functions as a protective and growth factor. Consequently, it is involved in learning and memory processes and may support the treatment of Alzheimer's disease. This review aims to provide a comprehensive overview of the biology of AMH and its role in both endocrinology and oncology.

The role of vitamin D3 in follicle development

Vitamin D3 plays a crucial role in female reproduction. As research progresses, the mechanisms of action of vitamin D3 on follicular development have been widely discussed. Firstly, key enzymes involved in the synthesis and metabolism of vitamin D3 have been discovered in the ovary, suggesting that vitamin D3 can be synthesized and metabolized locally within the ovary. Additionally, the detection of vitamin D3 receptors (VDR) in follicles suggests that vitamin D3 may exert its effects by binding specifically to these receptors during follicular development. Further research indicates that vitamin D3 promotes follicular growth by enhancing the development of granulosa cells (GCs) and oocytes. Currently, the mechanism of action of vitamin D3 in follicular development is becoming increasingly clear. Vitamin D3 promotes oocyte development by regulating molecules involved in meiotic arrest in oocytes. It also enhances granulosa cell proliferation by stimulating steroid hormone synthesis and cell cycle regulation. Additionally, vitamin D3 exerts anti-inflammatory effects by reducing oxidative stress and advanced glycation end-products (AGEs), mitigating the detrimental effects of inflammation on follicular development. These functions of vitamin D3 have clinical applications, such as in treating polycystic ovary syndrome (PCOS), improving female fertility, and enhancing outcomes in in vitro fertilization (IVF). This review summarizes the research progress on the role and mechanisms of vitamin D3 in follicular development and briefly summarizes its clinical applications.

The Key Role of Vitamin D in Female Reproductive Health: A Narrative Review

Vitamin D, besides its crucial role in bone health and immune function, has received increased attention in recent years due to its possible impact on many processes related to female reproductive health. Recent research has tried to explain the role played by vitamin D in maintaining adequate hormonal status, fertility, and pregnancy outcomes. Our aim for this narrative literature review was to highlight and explain the mechanisms through which vitamin D status impacts female reproductive health. We believe this represents a very important subject of research, especially due to the increased incidence of infertility nowadays. Further studies are necessary on the association between vitamin D status and female reproductive health in order to fully understand its effects and to reach a consensus regarding vitamin D supplementation as a method to improve fertility status.

The Impact of Vitamin D and Its Dietary Supplementation in Breast Cancer Prevention: An Integrative Review

Vitamin D deficiency is currently a significant public health issue closely linked to numerous diseases, such as breast cancer. This study aims to determine the estimated optimal serum levels of vitamin D to have a protective effect against breast cancer, in addition to exploring the biological mechanisms and risk factors involved. A literature search of articles published in the last 5 years was conducted, and simple statistical analyses using mean and standard deviation were performed to calculate the average concentration of vitamin D from different available studies. It has been observed that serum levels of vitamin D ≥ 40.26 ng/mL ± 14.19 ng/mL could exert a protective effect against breast cancer. Additionally, various biological mechanisms, such as those related to the immune system, and risk factors like diet implicated in this relationship were elucidated. Consequently, it can be concluded that proper serum levels of vitamin D may have a protective effect against breast cancer, and dietary supplementation may be an appropriate procedure to achieve these optimal vitamin D concentrations.

Seasonal Serum 25(OH) Vitamin D Level and Reproductive or Immune Markers in Reproductive-Aged Women with Infertility: A Cross-Sectional Observational Study in East Japan

Several studies have reported that vitamin D may modify human reproductive functions; however, the results are conflicting. We aimed to comprehensively evaluate serum vitamin D levels and examine the relationship between serum vitamin D levels and ovarian reserve markers, and immune markers of implantation, in reproductive-aged Japanese women with infertility.in reproductive-aged women with infertility. This cross-sectional, single-center study included reproductive-aged women who underwent preconception screening for fertility. Serum vitamin D levels and reproductive and immune markers were measured. Standard and advanced statistical techniques were used. We observed a statistically significant difference in the seasonal and monthly 25(OH) vitamin D levels; the 25(OH) vitamin D level during winter was the lowest among all seasons. However, there was no linear correlation between 25(OH) vitamin D levels and ovarian reserve markers, such as follicle-stimulating hormone and anti-Müllerian hormone, or the Th1/Th2 cell ratio, which is used as an implantation-related immunological marker. In this large-scale study, we evaluated the serum 25(OH) vitamin D concentration in reproductive-aged women with infertility in Japan; however, there was no association between reproductive function and vitamin D levels.

Relationship between Serum 25-Hydroxyvitamin D Levels and Hormonal Status in Infertile Women: A Retrospective Study

(1) Background: Infertility is a prevalent issue that affects 10-18% of couples worldwide, and up to 30% in Eastern Europe. Infertility of unknown etiology is one of the most challenging forms of infertility. Vitamin D has recently been extensively studied and researchers are investigating its possible role in ovulation and pregnancy. While the evidence suggests a positive association between vitamin D and ovulation, more research is needed to understand the role that vitamin D plays in ovulation. (2) Methods: In this study, 86 infertile patients were studied retrospectively in a single center by analyzing their anthropometric (body mass index), biochemical (total cholesterol, insulin resistance) and hormonal data in correlation with their vitamin D status. (3) Results: It was found that the mid-luteal progesterone level was significantly related to the 25-hydroxy vitamin D level in a multivariate linear regression model. An analysis of subgroups of ovulatory and anovulatory patients suggests that serum 25-hydroxy vitamin D levels of approximately 20 ng/mL may be necessary to trigger ovulation or to support progesterone secretion. (4) Conclusions: Vitamin D deficiency should be considered when infertility of unknown etiology and progesterone-related disorders occur.

Vitamin D Status in Women with a History of Infertility and Decreased Fecundability: A Population-Based Study

BACKGROUND

Infertility and fecundability problems have been linked with lower 25-hydroxyvitamin D (25(OH)D) concentrations, but studies conducted with small, heterogenous or selected populations have shown inconsistent results.

METHODS

This study included women at age 31 from prospective population-based Northern Finland Birth Cohort 1966. Serum 25(OH)D concentrations were evaluated between women with or without previous infertility examinations or treatments (infertility group, n = 375, reference group, n = 2051) and time to pregnancy (TTP) of over 12 months (decreased fecundability group, n = 338) with a wide range of confounders. Furthermore, 25(OH)D concentrations were also compared among reproductive outcomes.

RESULTS

The mean 25(OH)D concentration was lower and 25(OH)D < 30 nmol/L was more frequent in women with a history of infertility compared to reference group. Moreover, 25(OH)D > 75 nmol/L was more frequent in the reference group. The mean 25(OH)D concentration was lower in women who had had multiple miscarriages. Both history of infertility (β = -2.7, 95% confidence interval (CI) -4.6, -0.7) and decreased fecundability associated with lower 25(OH)D concentration (β = -4.1, 95% CI -7.4, -0.8) after adjustments. In conclusion, this population-based study demonstrated that previous infertility and decreased fecundability were associated with lower 25(OH)D.

The Role of Inactivated NF-κB in Premature Ovarian Failure

Premature ovarian failure (POF) is defined as deployment of amenorrhea due to the cessation of ovarian function in a woman younger than 40 years old. The pathologic mechanism of POF is not yet well understood, although genetic aberrations, autoimmune damage, and environmental factors have been identified. The current study demonstrated that NF-κB inactivation is closely associated with the development of POF based on the data from literature and cyclophosphamide (Cytoxan)-induced POF mouse model. In the successfully established NF-κB-inactivated mouse model, the results showed the reduced expression of nuclear p65 and the increased expression of IκBα in ovarian granulosa cells; the reduced numbers of antral follicles; the reduction of Ki-67/proliferating cell nuclear antigen-labeled cell proliferation and enhanced Fas/FasL-dependent apoptosis in granulosa cells; the reduced level of E2 and anti-Müllerian hormone; the decreased expression of follicle-stimulating hormone receptor and cytochrome P450 family 19 subfamily A member 1 (CYP19A1) in granulosa cells, which was reversed in the context of blocking NF-κB signaling with BAY 11-7082; and the decreased expressions of glucose-regulated protein 78 (GRP78), activating transcription factor 6, protein kinase R-like endoplasmic reticulum kinase, and inositol-requiring enzyme 1 in granulosa cells. Dual-luciferase reporter assay demonstrated that p50 stimulated the transcription of GRP78, and NF-κB affected the expression of follicle-stimulating hormone receptor and promoted granulosa cell proliferation through GRP78-mediated endoplasmic reticulum stress. Taken together, these data indicate, for the first time, that the inactivation of NF-κB signaling plays an important role in POF.

25(OH)VitD and human endocrine and functional fertility parameters in women undergoing IVF/ICSI

BACKGROUND

Vitamin D plays an important role in reproduction. Evidence shown that free 25-hydroxyvitamin D (25(OH)VitD) was more accurate than total 25(OH)VitD in reflecting the status of 25(OH)VitD during pregnancy. However, the relationship between free 25(OH)VitD and female fertility parameters has not been reported yet. Therefore, this study aims to compare the correlation of free and total 25(OH)VitD with fertility parameters in infertility females undergoing in vitro fertilization and embryo transfer (IVF-ET) or intracytoplasmic sperm injection (ICSI).

METHODS

According to the inclusion and exclusion criteria, 2569 infertility patients who received IVF-ET or ICSI treatment for the first time participated in this study. Five milliliter peripheral blood samples of the patients were collected on the day before embryo transfer (ET). Enzyme linked immunosorbent assay (ELISA) kits was used to detect free 25(OH)VitD and total 25(OH)VitD, and clinical information was collected. Spearman's rho was used to evaluate the association between the variables.

RESULTS

The median (IQR) of free 25(OH)VitD was 4.71 (4.11-5.31) pg/mL and total 25(OH)VitD was 19.54 (16.52-22.83) ng/m. The correlation between them, however, was week (rho=0.311). Compared to total 25(OH)VitD, free 25(OH)VitD was slightly better correlated with basal follicle-stimulating hormone (FSH) (rho=0.041, P=0.036), basal estradiol (E₂) (rho=0.089, P<0.001), anti-Müllerian hormone (AMH) (rho=-0.057, P=0.004), antral follicle count (AFC) (rho=-0.053, P=0.007), E₂ (rho=-0.080, P<0.001), number of oocytes retrieval (rho=-0.079, P<0.001) and progesterone (P)/E₂ on hCG trigger day (rho=0.081, P<0.001).

CONCLUSIONS

Overall, there was only a rather weak correlation of free as well as total 25(OH)VitD with human endocrine and functional fertility parameters in women undergoing IVF/ICSI. Neither free nor total 25(OH)VitD seems to play a major role in human embryo implantation.

Interplay Between mTOR and Hippo Signaling in the Ovary: Clinical Choice Guidance Between Different Gonadotropin Preparations for Better IVF

One of the most widely used types of assisted reproduction technology is the in vitro fertilization (IVF), in which women undergo controlled ovarian stimulation through the administration of the appropriate hormones to produce as many mature follicles, as possible. The most common hormone combination is the co-administration of gonadotropin-releasing hormone (GnRH) analogues with recombinant or urinary-derived follicle-stimulating hormone (FSH). In the last few years, scientists have begun to explore the effect that different gonadotropin preparations have on granulosa cells' maturation and apoptosis, aiming to identify new predictive markers of oocyte quality and successful fertilization. Two major pathways that control the ovarian development, as well as the oocyte-granulosa cell communication and the follicular growth, are the PI3K/Akt/mTOR and the Hippo signaling. The purpose of this article is to briefly review the current knowledge about the effects that the different gonadotropins, used for ovulation induction, may exert in the biology of granulosa cells, focusing on the importance of these two pathways, which are crucial for follicular maturation. We believe that a better understanding of the influence that the various ovarian stimulation protocols have on these critical molecular cascades will be invaluable in choosing the best approach for a given patient, thereby avoiding cancelled cycles, reducing frustration and potential treatment-related complications, and increasing the pregnancy rate. Moreover, individualizing the treatment plan will help clinicians to better coordinate assisted reproductive technology (ART) programs, discuss the specific options with the couples undergoing IVF, and alleviate stress, thus making the IVF experience easier.