Vitamin D deficiency as a risk factor for endometriosis in Iranian women

Vitamin D and Endometriosis: Is There a Mechanistic Link?

Endometriosis is a prevalent chronic gynaecological disorder, but its cause is still unclear, and both genetic and environmental factors may contribute disease aetiology. Prominent amongst the latter is vitamin D which can be obtained either by the action of sunlight on skin or from dietary sources. Serum levels of the main circulating form of vitamin D, 25-hydroxvitamin D (25(OH)D), have been reported to be inversely correlated with endometriosis, suggesting that vitamin D-deficiency may be a risk factor for the disease. Crucially, the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D) is known to exert many functions beyond its established role in the endocrinology of mineral homoeostasis and prevention of rickets. Several of these extra-skeletal effects of 1,25(OH)2D may impact the risk and progression of endometriosis. The following review details the studies that have assessed associations between vitamin D status/supplementation and endometriosis severity and disease progression, but also describes the mechanistic targets for 1,25(OH)2D in endometriosis with specific reference to immunomodulatory responses and effects on angiogenesis. Endometriosis is an under-reported health issue with poor non-invasive options for diagnosis. Given that vitamin D-deficiency may trigger or exacerbate key pathophysiological responses linked to endometriosis, analysis of vitamin D status in women may provide an alternative risk marker for endometriosis. Treatment options for endometriosis are also limited and the review will also consider whether vitamin D supplementation has a role in the management of endometriosis, either in prevention or treatment.

Menstrual Blood as a Non-Invasive Alternative for Monitoring Vitamin Levels

Background/Objectives: Menstrual blood has recently emerged as a novel specimen for diagnostics, offering a non-invasive alternative to traditional blood testing methods. Despite the importance of vitamins and monitoring their levels in preventative healthcare measures, the feasibility of measuring them in menstrual blood has yet to be explored. In this study, we aimed to assess the potential of using menstrual blood for determining vitamin levels by comparing their levels in menstrual blood to those in matched capillary blood samples. Methods: A prospective, monocentric, observational study was conducted with healthy, reproductive-aged voluntary participants. Menstrual blood was collected from 30 participants using a menstrual cup, and the corresponding capillary blood samples were obtained using a finger prick. The samples were transferred to dried blood spot (DBS) cards and analyzed using mass spectrometry to determine vitamin levels. Statistical analyses were performed to compare menstrual blood vitamin A and D levels, and hemoglobin, to those in capillary blood. Results: The vitamin levels could be ascertained from the menstrual blood, and were observed to significantly correlate with those from the capillary blood for both vitamin A (r = 0.77, p < 0.001) and vitamin D (r = 0.66, p < 0.001), despite being statistically different. Conclusions: The results of this pilot study demonstrate the potential utility of menstrual blood in estimating vitamin A and D levels, illustrating the prospect of a non-invasive menstrual blood-based vitamin test following larger clinical and analytical validation studies.

Calcium homeostasis and endometriosis: A Mendelian randomization study

Background

Previous observational studies have investigated the correlation between calcium homeostasis modulator levels and endometriosis risk. Yet, the genetic association between body calcium homeostasis and endometriosis risk remains to be elucidated.

Methods

Four tiers of Mendelian randomization (MR) analysis were conducted, as follows: (1) single univariate MR and (2) multivariate MR to evaluate the correlation between calcium homeostasis regulators and endometriosis; (3) inverse MR to probe the influence of endometriosis on body calcium homeostasis; (4) two-sample MR to scrutinize the connection between calcium levels and endometriosis categories.

Results

The two-sample MR analysis unveiled a robust positive correlation between genetically inferred calcium levels and endometriosis risk (IVW: OR = 1.15, 95 % CI: 1.02-1.29, p = 0.018). The MVMR analysis corroborated that the positive correlation of calcium levels with endometriosis persisted after adjusting for 25(OH)D and PTH. The inverse MR analysis disclosed a significant association between endometriosis and 25(OH)D (β = 0.01, 95 % CI: 0.00-0.02, p = 0.007) and calcium (β = 0.02, 95 % CI: 0.00-0.04, p = 0.035). The two-sample MR analysis further demonstrated that calcium levels were positively linked solely to endometriosis of uterus (i.e. adenomyosis, IVW: OR = 1.23, 95 % CI: 1.01-1.49, p = 0.038), with no evidence of a influence on other endometriosis categories.

Conclusions

This study, employing various types of MR, offers some genetic evidence for the relationship between calcium homeostasis and endometriosis, augmenting the current comprehension of the complex association between the two and suggesting that calcium levels are a risk factor for endometriosis. These findings provide a unique genetic perspective that may spur further investigation and may inform future strategies for managing patients with endometriosis.

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.

Vitamin D evaluation in adenomyosis: A retrospective cross-sectional study

Objective

Adenomyosis is a chronic inflammatory illness that depends on estrogen. In addition to its immune regulatory effects in chronic diseases, vitamin D also plays roles in regulating normal cell growth. In the present study, the purpose was to evaluate the possible relationships between serum 25-OH vitamin D levels and clinical and laboratory parameters in patients who were histopathologically diagnosed with adenomyosis.

Materials and Methods

A total of 168 females with a history of hysterectomy between January 2019 and November 2022 who were histopathologically diagnosed with adenomyosis and 168 women who were not diagnosed with adenomyosis were retrospectively evaluated in the present study. Demographic, clinical, and laboratory data were recorded at the time of admission. Visual analogue scale (VAS) scores were calculated for each patient to evaluate the severity of dysmenorrhea.

Results

There was a significant difference between the groups in terms of VAS: the adenomyosis group scored an average of 6, whereas the control group scored an average of 3 (p<0.001). The average platelet volume value of the patients was 8.6 fL in the adenomyosis group, and that of the control group was 7.2 fL, and it was detected to be significantly elevated in the adenomyosis group (p<0.001). The CA-125 value of the patients was 63.5 U/mL in the adenomyosis group, and that of the control group was 15.6 U/mL and it was detected to be significantly rised in the adenomyosis group (p<0.001). The 25-OH vitamin D level of the patients was 12.6 ng/mL in the adenomyosis group and that of the control group was 19.1 ng/mL and it was detected to be significantly elevated in the control group.

Conclusion

The current investigation provides compelling evidence for the association between low vitamin D levels and adenomyosis, which agrees with other research in the field. The current study's findings agree with other research that suggests vitamin D regulates cellular and signaling networks, including those that control cytokines and gene expression during adenomyosis. However, further studies are needed because data assassing the therapeutic efficacy of vitamin D in adenomyosis are questionable.

Vitamin D and reproductive disorders: a comprehensive review with a focus on endometriosis

Vitamin D is a fat-soluble steroid hormone that was initially known only for regulating calcium and phosphorus levels and maintaining bone health. However, it was later discovered that many organs express vitamin D metabolizing enzymes and have a ligand for vitamin D, which regulates the expression of an extensive assortment of genes. As a result, vitamin D is indispensable for the proper function of organs, and its deficiency is believed to be a critical factor in symptoms and disorders such as cardiovascular diseases, autoimmune diseases, and cancers. The significance of vitamin D in reproductive tissues was recognized later, and studies have revealed its crucial role in male and female fertility, as well as proper reproductive function during pregnancy. Vitamin D deficiency has been identified as a risk factor for infertility, gonadal cancers, pregnancy complications, polycystic ovary syndrome, and endometriosis. However, data investigating the association between vitamin D levels and reproductive disorders, including endometriosis, have encountered inconsistencies. Therefore, the present study aims to review existing research on the effect of vitamin D on proper reproductive function, and the role of deficiency in reproductive diseases and specifically focuses on endometriosis.

25-hydroxyvitamin D and Endometriosis: A bidirectional Mendelian randomization study

Numerous studies have demonstrated a correlation between serum 25-hydroxyvitamin D (25OHD) and endometriosis. However, the precise nature of this association remains elusive. The causal connection between 25OHD and endometriosis remains uncertain, as it is yet to be determined whether one directly influences the other. The objective of our research was to investigate the cause-and-effect connection between 25OHD and endometriosis. The study employed Mendelian randomization (MR) in a bidirectional two-sample investigation to examine the causal relationship between 25OHD and endometriosis. The analysis utilized the most recent publicly accessible statistics from the genome-wide association study (GWAS) encompassing 25OHD, endometriosis, and its five subtypes. The primary analytical approach employed was Inverse-Variance Weighting (IVW), accompanied by supplementary analysis methods including weighted median, MR-Egger, simple mode, and weighted mode. Furthermore, sensitivity analyses were conducted to assess the potential influence of heterogeneity and pleiotropy on the MR outcomes. MR primary analysis showed no significant causal effect of 25OHD on endometriosis (OR = 0.892, 95%CI = 0.745 ~ 1.068, P = 0.213). Similarly, there was no evidence to support a causal relationship of endometriosis on 25OHD (IVW Beta = 0.005, 95%CI = 0.993 ~ 1.018, P = 0.406). However, when conducting MR analysis on different subtypes of endometriosis and 25OHD, we found a positive correlation between endometriosis of ovary and 25OHD level (IVW Beta = 0.012, 95%CI = 1.002 ~ 1.022, P = 0.024). This study indicates that there is no causal relationship between serum 25OHD and endometriosis. However, it is important to note that serum 25OHD levels will increase in patients with endometriosis of the ovary. Further observational studies and clinical trials are indispensable.

Vitamin D-The Iceberg in Endometriosis-Review and Meta-Analysis

(1) Background: Although vitamin D has many known biological effects, very little research has been conducted on how vitamin D may be related or play a role in endometriosis. The aim of our study was to perform an evaluation regarding vitamin D levels and possible implications in endometriosis through a statistical analysis of the data collected from the included studies. (2) Methods: For this review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, and PubMed/Internet portal of the National Library of Medicine databases using several keywords related to our topic. (3) Results: Only nine articles were identified as complete or possessing the capacity to compute all available data. We totalized a number of 976 patients with endometriosis and 674 controls. From the nine studies included in our analysis, three of them claim there is no difference between women with and without endometriosis concerning 25(OH) vitamin D levels; however, the other six studies found significant differences regarding this aspect. (4) Conclusions: Our results underscored the complexity of analyzing the role of the vitamin D complex in a challenging condition like endometriosis and suggest that focusing on the tissue level might be essential to obtain accurate answers to our inquiries.

How Can Selected Dietary Ingredients Influence the Development and Progression of Endometriosis?

Endometriosis is a chronic, hormone-dependent disease characterized by the presence of endometrial tissue in ectopic locations. Since the treatment options for this disease are still limited, and the cure rate is unsatisfactory, the search for ways to treat symptoms and modify the course of the disease is of key importance in improving the quality of life of patients with endometriosis. So far, the literature has shown that nutrition can influence endometriosis through hormonal modification and altering the inflammatory or oxidative response. Since the importance of nutrition in this disease is still a subject of scientific research, we aimed to summarize the current knowledge on the role of dietary modifications in endometriosis. Our review showed that nutrients with anti-inflammatory and antioxidant properties, including most vitamins and several trace elements, may influence the pathogenesis of endometriosis and can be considered as the nutrients preventing the development of endometriosis. However, despite the many discoveries described in this review, further interdisciplinary research on this topic seems to be extremely important, as in the future, it may result in the development of personalized therapies supporting the treatment of endometriosis.

The Role of Selected Dietary Factors in the Development and Course of Endometriosis

Endometriosis is a chronic disease with a complex, heterogeneous pathogenesis that affects about 10% of women of reproductive age, causing pain and leading to infertility. Treatment consists of administering pharmacological agents (resulting in a reduction of estrogen levels and inflammation), as well as the surgical removal of endometriotic lesions. Unfortunately, despite a wide range of available therapies, there is still a high recurrence rate after surgery. Consequently, it is necessary to improve the outcome of patients with endometriosis. In this context, there is growing interest in possible dietary modification to support or complement classic treatment options and even serve as a potential alternative to hormone therapy. In addition, a growing number of studies indicate positive effects of selected dietary factors on the development and course of endometriosis. This review article focuses on the potentially beneficial effects of compounds from the polyphenol group (curcumin, epigallocatechin gallate, quercetin, resveratrol), vitamins, and selected micronutrients on endometriosis. The results indicate the potential of the selected ingredients in fighting the disease. However, most of the studies have been performed on experimental animal models, with a smaller proportion looking at the actual effects of use among women. Therefore, well-designed studies are needed to assess the importance of a well-chosen diet and the effects of specific dietary factors on the health of women suffering from endometriosis.

Effect of active vitamin D on proliferation, cell cycle and apoptosis in endometriotic stromal cells

RESEARCH QUESTION

What is the effect of vitamin D3 (1,25(OH)₂D₃) on proliferation, cell cycle and apoptosis of endometrial stromal cells (ESC) in endometriotic patients?

DESIGN

ESC isolated from 10 women with endometriosis and 10 healthy controls were treated with 1,25(OH)₂D₃. The proliferation of control endometrial stromal cells (CESC), eutopic endometrial stromal cells (EuESC) and ectopic endometrial stromal cells (EESC) was analysed 72 h after the treatment using methyl thiazolyl tetrazolium assay. Propidium iodide staining and flow cytometry were used to determine the cell cycle distribution in ESC. Annexin V/propidium iodide double staining was used to evaluate apoptosis in ESC.

RESULTS

In the presence of oestrogen, 1,25(OH)₂D₃ treatment inhibited the proliferation of ESC from all three origins (P = 0.009 for CESC, P = 0.005 for EuESC and P < 0.001 for EESC). The percentage of S phase cells in EESC was higher than in EuESC and CESC (P = 0.002 and P = 0.001, respectively). The percentage of S phase cells in EuESC was higher than in CESC (P = 0.005). The percentage of G1 phase cells in EESC was lower than that of EuESC and CESC (P = 0.003 and P = 0.002, respectively) and the percentage of G1 phase cells in EuESC was lower than that of CESC (P = 0.007). Moreover, 1,25(OH)₂D₃ inhibited cell cycle regardless of cell type (P = 0.002 in EESC, P = 0.001 in EuESC and P = 0.014 in CESC), but in the absence of oestrogen, inhibited cell cycle only in EuESC (P = 0.012).

CONCLUSIONS

Although 1,25(OH)₂D₃ increased apoptotic and necrotic cells and decreased live cells in the EuESC and EESC, it did not affect apoptosis in CESC and only increased necrotic cells. These findings indicate that 1,25(OH)₂D₃ potentially has a growth-inhibiting and pro-apoptotic effect on ESC from endometriotic patients.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

Changes in MCP-1, HGF, and IGF-1 expression in endometrial stromal cells, PBMCs, and PFMCs of endometriotic women following 1,25(OH)2D3 treatment

1,25(OH)2D3 has anti‐inflammatory and growth inhibitory effects. Our study explored the effect of 1,25(OH)2D3 treatment on the expression of monocyte chemotactic protein‐1 (MCP‐1), hepatocyte growth factor (HGF), and insulin‐like growth factor‐1 (IGF‐1) by peripheral blood mononuclear cells (PBMCs), peritoneal fluid mononuclear cells (PFMCs), endometrial stromal cells (ESCs), and its effect on the proliferation of PBMCs and PFMCs of patients with endometriosis compared with controls. PBMCs, PFMCs, and ESCs were obtained from 10 endometriosis patients and 10 non‐endometriotic individuals. After treating cells with 0.1 μM of 1,25(OH)2D3 for 6, 24, and 48 h, the gene and protein expression of mentioned factors were evaluated by real‐time PCR and ELISA methods, respectively. 1,25(OH)2D3 treatment significantly reduced the protein expression of MCP‐1, HGF, and IGF‐1 in PBMCs and PFMCs of endometriotic patients at 48 h (p < 0.05–<0.01). Also, this treatment significantly reduced MCP‐1, HGF, and IGF‐1 gene and/or protein expression in EESCs and EuESCs at 24 and 48 h (p < 0.05–<0.01). 1,25(OH)2D3 treatment also reduced the proliferation of PBMCs and PFMCs of endometriotic patients compared with controls (p < 0.01). 1,25(OH)2D3 can be considered as a potentially effective agent in the prevention and treatment of endometriosis along with other therapies.

Association Between Vitamin D Receptor (VDR) and Vitamin D Binding Protein (VDBP) Genes Polymorphisms to Endometriosis Susceptibility in Iranian Women

Endometriosis is a chronic inflammatory disease that has been reported to be associated with immune system dysfunction. On the other hand, the effect of Vitamin D as an immune modulator and its relation with several autoimmune and inflammatory diseases has been previously investigated. Moreover, several studies have reported the polymorphisms of VDR and VDBP genes can change the functions of these molecules. Therefore, these polymorphisms may be influential on endometriosis pathogenesis. In this study, we aimed at evaluating the association between VDR gene (FokI (F/f), BsmI (B/b), ApaI (A/a), TaqI (T/t)), and VDBP gene (GC*1S, GC*1F, and GC*2) polymorphisms with endometriosis in Iranian women population. This case-control study was performed on 120 women with endometriosis and 110 healthy women. ARMS-PCR and PCR-RFLP methods were used to inspect polymorphisms in VDR and VDBP genes, respectively. Based on the results, there was no statistically significant difference between the cases with endometriosis and control subjects in terms of genotypes and allele frequencies of VDR and VDBP gene polymorphisms. These data suggest that VDR and VDBP gene polymorphisms may have no role in endometriosis susceptibility in Iranian women.