Vitamin D metabolites--relation to age, menopause and endometriosis

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.

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 deficiency as a risk factor for endometriosis in Iranian women

PURPOSE

Vitamin D (Vit D), as an immunomodulator, has been hypothesized to play a critical role in the pathogenesis of endometriosis. Thus, in this study, we evaluated whether there is an association between 25-hydroxyvitamin D [25(OH)D] and susceptibility to endometriosis in Iranian women.

METHODS

Women at reproductive age, including 56 healthy women and 54 patients with endometriosis, were enrolled in the study. Serum levels of 25(OH)D, calcium, parathyroid hormone (PTH), and peritoneal fluid (PF) levels of 25(OH)D were assessed.

RESULTS

The serum and PF levels of 25(OH)D in the patients with endometriosis were significantly lower than the control group (P = 0.001 and P = 0.03, respectively). Subjects with serum levels of 25(OH)D lower than 20 ng/mL had a 2.7 times higher risk of endometriosis than people with 25(OH)D serum levels higher than 20 ng/mL (non-deficient) (OR = 2.7, 95 % confidence interval: 1.24-5.80, P = 0.01). The serum levels of calcium and PTH were significantly lower and higher in patients with endometriosis compared with controls, respectively (P < 0.001, P = 0.02, respectively). Also, the serum levels of 25(OH)D were lower in stages I-II endometriosis than stage III-IV; however, no significant difference was observed.

CONCLUSION

Our findings showed that people with Vit D deficiency are at higher risk of endometriosis.

Influence of Stress on the Vitamin D-Vitamin D Receptor System, Macrophages, and the Local Inflammatory Milieu in Endometriosis

We previously demonstrated the negative impact of stress in an animal model of endometriosis. Although its role is unclear, altered levels of vitamin D (VitD) have been found in patients with this condition. VitD signaling through the VitD receptor (VDR) has anti-proliferative properties and induces an anti-inflammatory phenotype in macrophages. We hypothesized that stress impacts the vitamin D-VDR system, influencing macrophage behavior and the local inflammatory milieu in endometriosis. Endometriosis was surgically induced in female Sprague-Dawley rats, which were then exposed to uncontrollable, controllable, or no stress for 10 days. Sham controls received sutures only. VitD levels were measured by ELISA; cytokine levels by multiplex assay and PCR; and VDR expression and macrophage numbers assessed by immunohistochemistry and immunofluorescence. VDR expression in patient samples was assessed by immunohistochemical staining of a tissue microarray. Serum VitD levels were higher in endometriosis animals compared with sham (p < 0.01) with no significant effect of stress. Uncontrollable stress increased macrophage infiltration (p < 0.01) and VDR expression in vesicles, which were attenuated by controllable stress. Macrophage infiltration correlated with vesicle area (p < 0.05), and peritoneal vitamin D levels correlated with vesicle VDR expression (r = 0.81, p < 0.01). Decreased expression of chemokine ligand 2 (p < 0.05) and TGFβ was observed in endometriosis with uncontrollable stress, whereas IL12 increased with controllable stress. Differential expression of VDR was observed in patient tissues. Stress exacerbates development of cysts in endometriosis through mechanisms that include macrophage recruitment, cytokine changes, and a potentially perturbed VitD:VDR axis, suggesting an impact on the local inflammatory environment.

[Vitamin D and reproductive health]

Vitamin D insufficiency and deficiency in women with infertility is more common than in the population. However, we still do not know the exact mechanisms for the participation of vitamin D in the regulation of reproductive function. The purpose of this study is to analyze actual literature data on the role of vitamin D in the regulation of reproductive system and its influence on using of assisted reproductive technologies for the treatment of infertility. A search was carried out for literary sources published in the NSBI database PubMed, Medline, and others with a search depth of up to 20 years. 135 sources on this topic were studied, of which 54 were included in the analysis. The review presents data obtained in animal studies, in vitro and in clinical studies. Thus, the absence of vitamin D resulted in a dramatical decrease in fertility in both female and male rats and mice, due to the development of hypocalcemia. In vitro studies describe its involvement in the receptive transformation of the endometrium and in the regulation of the immune response during embryo implantation. However, clinical studies often show conflicting results. There is no unequivocal data on the effect of vitamin D levels on spermogram parameters, but a decrease in the pregnancy rate was shown when ovulation was induced in pairs, where a vitamin D deficiency was revealed in men. A meta-analysis published in 2017 showed a decrease in the pregnancy and live birth rate in women with low levels of vitamin D after the use of assisted reproductive technologies (ART). It was not possible to establish whether this decrease depends on oocyte quality or endometrium. There is an opportunity that the effect of vitamin D deficiency on fertility will not come with all forms of infertility. For example, in women with anovulation due to polycystic ovary syndrome, vitamin D deficiency is demonstrated to decrease pregnancy rate in ovulation induction cycles and in ART. Such relationship was not found in women with unexplained infertility.Thus, the role of vitamin D in the pathogenesis of infertility requires further study, as well as the possibilities of therapy in order to increase the effectiveness of infertility treatment methods and assisted reproductive technology programs.

Association between vitamin D and endometriosis: a systematic review

BACKGROUND

Endometriosis is one of the most common gynecological diseases of reproductive age, with a prevalence of 5-10% and grave consequences for quality of life and fertility. Vitamin D (vit D), a classic regulator of plasma calcium concentration and skeleton mineralization, is also an effective modulator of the immune system. Several studies suggest that immunologic properties attributed to vit D along with vit D receptor (VDR) expression in reproductive tissues may be involved in the pathogenesis of endometriosis.

OBJECTIVE

To systematically review the literature for the association between components of vit D metabolism and endometriosis.

MATERIALS AND METHODS

A systematic review of the literature published in the Medline and Cochrane Central databases was conducted for original research articles on humans, published in any language.

RESULTS

Twenty-one studies were included in the systematic review. Among them, 12 examined the relationship of endometriosis with vit D metabolites, eight with vit D-binding protein (VDBP), three with VDR polymorphisms, and two with vit D regulatory enzymes. There are discrepancies between the outcomes of the available literature publications.

CONCLUSIONS

This is a systematic attempt to collect, evaluate, and present the known data on the association between vit D and endometriosis. Given the heterogeneity and the diversity of the present studies, more research is required to elucidate the association between vit D and endometriosis.

Vitamin D status in endometriosis: a systematic review and meta-analysis

PURPOSE

No consensus exists on the relationship between vitamin D status and endometriosis. The chief aim of our study was to evaluate the association between serum vitamin D levels and endometriosis.

METHODS

We searched for MEDLINE, EMBASE, and China National Knowledge Infrastructure (CNKI) databases for studies elucidated the circulating vitamin D levels in endometriosis. The standardized mean differences (SMDs) or odds ratios (ORs) with their 95% confidence interval (CIs) were calculated to evaluate the association between vitamin D levels and endometriosis.

RESULTS

Nine studies were included in this meta-analysis. The pooled results indicated that women with endometriosis had lower vitamin D status than that in controls (SMD - 0.97 ng/mL, 95% CI - 1.80 to - 0.14; p = 0.02), and vitamin D status had a negative correlation with the severity of the disease (stage III-IV vs stage I-II: SMD - 1.33 ng/mL, 95% CI - 2.54 to - 0.12; p = 0.03). Although it was not statistically significantly different, hypovitaminosis D had a tendency to be associated with endometriosis (OR 2.77, 95% CI 0.85-6.08, p = 0.10). Heterogeneity was high among included studies. Subgroup analyses revealed that women with no hormone use had lower vitamin D status when compared with controls (SMD - 1.38 ng/mL, 95% CI - 2.59 to - 0.18; p = 0.02). For studies which sample size < 100, serum vitamin D levels were significantly lower in patients than that in controls (SMD - 0.65 ng/mL, 95% CI - 1.19 to - 0.11; p = 0.02).

CONCLUSIONS

Women with endometriosis had lower vitamin D status when compared with controls, and a negative relationship between vitamin D levels and severity of endometriosis was observed. In addition, hypovitaminosis D was a potential risk factor for endometriosis.

Is there a Relationship Between Vitamin D and Endometriosis? An Overview of the Literature

BACKGROUND

Vitamin D is involved in the physiological functions of several tissues, however, its deficiency may contribute to the development of various disorders. Recent research has been focusing on the role of vitamin D in the pathogenesis of endometriosis based on the evidence of the presence of vitamin D receptor and the enzymes required for vitamin D synthesis in the ectopic endometrium. Endometriosis, defined as the presence of endometrial glands and stroma in ectopic locations, is considered an estrogen-dependent disease and Vitamin D seems to have a role in modulation of the inflammatory state and proliferation of endometriotic cells.

OBJECTIVE

This study aimed to review the available literature regarding the relationship between vitamin D and endometriosis as well as the effects of vitamin D supplementation.

METHODS

A search on PubMed database has been performed.

RESULTS

The relationship between endometriosis and Vitamin D has been analyzed through the evaluation of vitamin D serum level, the polymorphism of vitamin D receptor and the role of vitamin D-binding protein in patient with endometriosis. The possible role of Vitamin D in the endometriosis therapy has also been investigated, in particular, the effect of vitamin D on pain relief, on endometriotic lesion in vitro and in rat models and in addition to a future target immunotherapy.

CONCLUSION

Although promising, the data analyzed are not sufficient to evidence a cause-effect relationship between VD status and endometriosis, therefore further studies are needed in order to better clarify the association between vitamin D and endometriosis, especially in the context of the possibility of new treatment options.

Differences in 25-hydroxy vitamin D and vitamin D-binding protein concentrations according to the severity of endometriosis

Objective

To investigate serum 25-hydroxyl vitamin D (25(OH)D) and vitamin D-binding protein (VDBP) concentrations in women with endometriosis according to the severity of disease.

Methods

Women with mild endometriosis (n = 9) and advanced endometriosis (n = 7), as well as healthy controls (n = 16), were enrolled in this observational study. Serum total 25(OH)D concentrations were analyzed using the Elecsys vitamin D total kit with the Cobas e602 module. Concentrations of bioavailable and free 25(OH)D were calculated. Concentrations of VDBP were measured using the Human Vitamin D BP Quantikine ELISA kit. Variables were tested for normality and homoscedasticity using the Shapiro-Wilk test and Leven F test, respectively. Correlation analysis was used to identify the variables related to total 25(OH)D and VDBP levels. To assess the effects of total 25(OH)D and VDBP levels in the three groups, multivariate generalized additive modeling (GAM) was performed.

Results

Gravidity and parity were significantly different across the three groups. Erythrocyte sedimentation rate (ESR) and CA-125 levels increased as a function of endometriosis severity, respectively (p= 0.051, p= 0.004). The correlation analysis showed that total 25(OH)D levels were positively correlated with gravidity (r = 0.59, p< 0.001) and parity (r = 0.51, p< 0.003). Multivariate GAM showed no significant relationship of total 25(OH)D levels with EMT severity after adjusting for gravidity and ESR. However, the coefficient of total 25(OH)D levels with gravidity was significant (1.87; 95% confidence interval, 0.12–3.63; p= 0.040).

Conclusion

These results indicate that vitamin D and VDBP levels were not associated with the severity of endometriosis.

Endometriosis and food habits: Can diet make the difference?

Endometriosis is a chronic, inflammatory, estrogenic-dependent disease characterized by the presence of endometrial glands outside the uterine cavity, affecting approximately 2%–10% of women in reproductive age and 30%–50% of women in general. Despite the high prevalence of the disease, not much is known about etiology, possible risk factors, and an adequate and satisfactory therapy. In the past years, many studies have focused on food intake (nutrients and food groups) and on its possible correlation with endometriosis, demonstrating how diet could be identified as a possible risk factor. Comprehensive searches in the largest medical information databases (Medline-PubMed, Embase, Lilacs, and Cochrane Library) were conducted using the Medical Subject Heading terms “diet,” “food,” “nutrition,” “fatty acids,” vitamins,” “fruit,” “vegetables,” “coffee,” “caffeine,” “fish,” “soy food,” “dairy products,” “tea,” “curcumin” combined with “endometriosis.” Purpose of this review is to revise the literature, in order to determine potential modifiable risk factors of the disease.

Differential gene expression by 1,25(OH)2D3 in an endometriosis stromal cell line

Endometriosis is a common female reproductive disease characterized by invasion of endometrial cells into other organs, frequently causing pelvic pain and infertility. Alterations of the vitamin D system have been linked to endometriosis incidence and severity. To shed light on the potential mechanism for these associations, we examined the effects of 1,25(OH)₂D₃ on gene expression in endometriosis cells. Stromal cell lines derived from endometriosis tissue were treated with 1,25(OH)₂D₃, and RNA-seq was used to identify genes differentially expressed between treated and untreated cells. Gene ontology and pathway analyses were carried out using Partek Flow and Ingenuity software suites, respectively. We identified 1627 genes that were differentially expressed (886 down-regulated and 741 up-regulated) by 1,25(OH)₂D₃. Only one gene, CYP24A1, was strongly up-regulated (369-fold). Many genes were strongly down-regulated. 1,25(OH)₂D₃ treatment down-regulated several genetic pathways related to neuroangiogenesis, cellular motility, and invasion, including pathways for axonal guidance, Rho GDP signaling, and matrix metalloprotease inhibition. These findings support a role for vitamin D in the pathophysiology of endometriosis, and provide new targets for investigation into possible causes and treatments.

Shedding new light on female fertility: The role of vitamin D

In the last decades several studies suggested that vitamin D is involved in the modulation of the reproductive process in women due to the expression of VDR and 1α-hydroxylase in reproductive tissues such as ovary, uterus, placenta, pituitary and hypothalamus. Vitamin D has also a role in the regulation of sex hormone steroidogenesis. Increasing evidence suggests that vitamin D might have a regulatory role in polycystic ovary syndrome (PCOS)-associated symptoms, including ovulatory dysfunction, insulin resistance and hyperandrogenism. Vitamin D deficiency also has been reported to contribute to the pathogenesis of endometriosis due to its immunomodulatory and anti-inflammatory properties. Although most of the studies supported a role of vitamin D in the onset of these diseases, randomized controlled trials to assess the efficacy of vitamin D supplementation have never been performed. In this review we critically discuss the role of vitamin D in female fertility, starting from in vitro and in vivo studies, focusing our attention on the two most frequent causes of female infertility: PCOS and endometriosis.

Self-management and psychological-sexological interventions in patients with endometriosis: strategies, outcomes, and integration into clinical care

Endometriosis has a multifactorial etiology. The onset and progression of the disease are believed to be related to different pathogenic mechanisms. Among them, the environment and lifestyle may play significant roles. Diet, dietary supplements, physical exercise, osteopathy, massage, acupuncture, transcutaneous electrical nerve stimulation, and Chinese herbal medicine may represent a complementary and feasible approach in the treatment of symptoms related to the disease. In this narrative review, we aimed to examine the most updated evidence on these alternative approaches implicated in the self-management of the disease. In addition, several studies have demonstrated that endometriosis may negatively impact mental health and quality of life, suggesting that affected women may have an increased risk of developing psychological suffering as well as sexual problems due to the presence of pain. In light of these findings, we discuss the importance of integrating psychological interventions (including psychotherapy) and sexual therapy in endometriosis treatment.

Effects of 1,25-Dihydroxy Vitamin D3 on Endometriosis

CONTEXT

Endometriosis is an estrogen-dependent, chronic inflammatory disease. Recent studies have shown that vitamin D (VD) is an effective modulator of the immune system and plays an important role in controlling many inflammatory diseases.

OBJECTIVE

The objective of the study was to clarify the in vitro effects of 1,25-dihydroxy vitamin D3 (1,25[OH]2D3) on human endometriotic stromal cells (ESCs) and to determine the serum levels of VD in endometriosis patients.

DESIGN, PATIENTS, AND MAIN OUTCOME MEASURES

ESCs were isolated from ovarian endometrioma and cultured with 1,25(OH)2D3. Gene expression of IL-8, cyclooxygenase-2, microsomal prostaglandin E synthase-1, microsomal prostaglandin E synthase-2, cytosolic prostaglandin E synthase, 15-hydroxyprostaglandin dehydrogenase, matrix metalloproteinase (MMP)-2, and MMP-9 was examined using quantitative RT-PCR. The production of IL-8 and prostaglandin E2 was measured using an ELISA and an enzyme immunoassay. Viable cell number was assessed using a cell-counting assay, and DNA synthesis was assessed using the bromodeoxyuridine incorporation assay. Apoptosis was assessed using flow cytometry. The expression of inhibitory-κBα protein was detected using Western blotting. The serum levels of 25-hydroxyvitamin D3 and 1,25(OH)2D3 were measured by a RIA.

RESULTS

In vitro studies showed that 1,25(OH)2D3 significantly reduced IL-1β- or TNF-α-induced inflammatory responses, such as IL-8 expression and prostaglandin activity. 1,25(OH)2D3 also reduced viable ESC numbers and DNA synthesis but did not affect apoptosis. MMP-2 and MMP-9 expressions were reduced by 1,25(OH)2D3. 1,25(OH)2D3 inhibited nuclear factor-κB activation. The serum 25-hydroxyvitamin D3 levels were significantly lower in women with severe endometriosis than in the controls and women with mild endometriosis. Serum 1,25(OH)2D3 levels were not different between groups.

CONCLUSIONS

VD modulates inflammation and proliferation in endometriotic cells, and a lower VD status is associated with endometriosis. Taken together, VD supplementation could be a novel therapeutic strategy for managing endometriosis.

Vitamin D and benign gynaecological diseases: a critical analysis of the current evidence

Vitamin D is a fat-soluble pro-hormone that plays an important role in bone homeostasis; beside this principal function, vitamin D promotes modulation of cell growth, neuromuscular and immune function, and reduction of inflammation. In addition, several in vitro and in vivo studies have demonstrated that vitamin D deficiency could increase the risk of cancer, autoimmune and cardiovascular diseases. Moreover, vitamin D plays also an important role in female reproduction, because vitamin D receptors are expressed in ovarian tissue, endometrium, fallopian epithelial cells as well as in decidua and placenta. We aimed to review the most updated evidence, which suggests a link between vitamin D metabolism and the development of some gynaecological diseases, such as endometriosis, uterine fibroids and polycystic ovary syndrome.

Role of vitamin D in female reproduction

Vitamin D is a fat-soluble vitamin that belongs to the family of steroid hormones. The biological actions of vitamin D are exerted through a soluble protein, the vitamin D receptor (VDR). VDR is a transcription factor located in the nuclei of target cells that mediates the genomic action of the active form of vitamin D (1,25(OH)2D3). This transcription factor is distributed in various tissues, including the reproductive system. The presence of VDR in female reproductive tissue suggests that vitamin D is involved in female reproduction. The present article reviews the impact of vitamin D on anti-Müllerian hormone (AMH), as an ovarian reserve marker, and ovarian steroidogenesis. This article also discusses the impact of vitamin D as a factor that influences infertility and the outcome of in vitro fertilization (IVF), insulin resistance (IR), hyperandrogenism, endometriosis and polycystic ovary syndrome (PCOS).

Vitamin D in human reproduction: a narrative review

BACKGROUND

Special attention has been given to the effect of vitamin D supplementation on fertility outcomes in both sexes.

AIMS

The purpose of this narrative review was to elucidate the role of vitamin D in male and female reproduction, providing current evidence from both animal and human studies.

MATERIALS AND METHODS

Using PubMed and Medline, we searched for publications during the last 30 years regarding the role of vitamin D in human reproduction.

RESULTS

Accumulating evidence from animal and human studies suggests that vitamin D is involved in many functions of the reproductive system in both genders. In women, vitamin D status has been associated with in vitro fertilization (IVF) outcome, features of polycystic ovarian syndrome (PCOS) and endometriosis. Although several data converge towards a beneficial effect of vitamin D supplementation in metabolic disturbances in women with PCOS, a significant knowledge gap precludes the establishment of a clear cause-effect relationship. In men, vitamin D status has been associated with semen quality and sperm count, motility and morphology. There is evidence for a favourable effect of vitamin D supplementation on semen quality, testosterone concentrations and fertility outcomes.

DISCUSSION

Studies with superior methodological characteristics are needed in order to establish a role for vitamin D on the treatment of female and male infertility.

CONCLUSIONS

Recent data on vitamin D provide new insights in the complex pathogenesis and treatment of infertility.

Dairy-food, calcium, magnesium, and vitamin D intake and endometriosis: a prospective cohort study

The etiology of endometriosis is poorly understood, and few modifiable risk factors have been identified. Dairy foods and some nutrients can modulate inflammatory and immune factors, which are altered in women with endometriosis. We investigated whether intake of dairy foods, nutrients concentrated in dairy foods, and predicted plasma 25-hydroxyvitamin D (25(OH)D) levels were associated with incident laparoscopically confirmed endometriosis among 70,556 US women in Nurses' Health Study II. Diet was assessed via food frequency questionnaire. A score for predicted 25(OH)D level was calculated for each participant. During 737,712 person-years of follow-up over a 14-year period (1991-2005), 1,385 cases of incident laparoscopically confirmed endometriosis were reported. Intakes of total and low-fat dairy foods were associated with a lower risk of endometriosis. Women consuming more than 3 servings of total dairy foods per day were 18% less likely to be diagnosed with endometriosis than those reporting 2 servings per day (rate ratio = 0.82, 95% confidence interval: 0.71, 0.95; P(trend) = 0.03). In addition, predicted plasma 25(OH)D level was inversely associated with endometriosis. Women in the highest quintile of predicted vitamin D level had a 24% lower risk of endometriosis than women in the lowest quintile (rate ratio = 0.76, 95% confidence interval: 0.60, 0.97; P(trend) = 0.004). Our findings suggest that greater predicted plasma 25(OH)D levels and higher intake of dairy foods are associated with a decreased risk of endometriosis.

Diet and endometriosis risk: a literature review

A connection between dietary factors and endometriosis onset has become a topic of interest mostly due to the observation that physiological and pathological processes of the disease can be influenced by diet. This paper systematically reviews prior publications dealing with this aspect in order to identify potentially modifiable risk factors. Comprehensive searches in the electronic databases MEDLINE, EMBASE and Science Citation Index Expanded were conducted to identify published studies evaluating the association between food intake (nutrients and food groups) and endometriosis. Eleven studies were identified: 10 case-control and one cohort study. Information on diet was collected using food frequency questionnaires in seven studies, while in one study the questionnaire focused on caffeine and alcohol intake. Women with endometriosis seem to consume fewer vegetables and omega-3 polyunsaturated fatty acids and more red meat, coffee and trans fats but these findings could not be consistently replicated. Most data have also been discussed herein in light of the available experimental and animal model results. At present, evidence supporting a significant association between diet and endometriosis is equivocal. Further studies are needed to clarify the role of diet on endometriosis risk and progression.

Vitamin D and fertility: a systematic review

BACKGROUND

Vitamin D has been well-known for its function in maintaining calcium and phosphorus homeostasis and promoting bone mineralization. There is some evidence that in addition to sex steroid hormones, the classic regulators of human reproduction, vitamin D also modulates reproductive processes in women and men.

AIM

The aim of this review was to assess the studies that evaluated the relationship between vitamin D and fertility in women and men as well as in animals.

METHODS

We performed a systematic literature search in Pubmed for relevant English language publications published until October 2011.

RESULTS AND DISCUSSION

The vitamin D receptor (VDR) and vitamin D metabolizing enzymes are found in reproductive tissues of women and men. Vdr knockout mice have significant gonadal insufficiency, decreased sperm count and motility, and histological abnormalities of testis, ovary and uterus. Moreover, we present evidence that vitamin D is involved in female reproduction including IVF outcome (clinical pregnancy rates) and polycystic ovary syndrome (PCOS). In PCOS women, low 25-hydroxyvitamin D (25(OH)D) levels are associated with obesity, metabolic, and endocrine disturbances and vitamin D supplementation might improve menstrual frequency and metabolic disturbances in those women. Moreover, vitamin D might influence steroidogenesis of sex hormones (estradiol and progesterone) in healthy women and high 25(OH)D levels might be associated with endometriosis. In men, vitamin D is positively associated with semen quality and androgen status. Moreover, vitamin D treatment might increase testosterone levels. Testiculopathic men show low CYP21R expression, low 25(OH)D levels, and osteoporosis despite normal testosterone levels.

Vitamin D - roles in women's reproductive health?

In the past few years a growing interest in vitamin D can be observed in the lay and biomedical literature due to findings demonstrating a low vitamin D status in the population. In addition to its importance for the regulation of calcium and phosphorus homeostasis recent epidemiologic studies have observed relationships between low vitamin D levels and multiple disease states. This secosteroid hormone also regulates the expression of a large number of genes in reproductive tissues implicating a role for vitamin D in female reproduction. In this report we summarize the recent evidence that vitamin D status influences female reproductive and pregnancy outcomes. Human and animal data suggest that low vitamin D status is associated with impaired fertility, endometriosis and polycystic ovary syndrome. Evidence from observational studies shows higher rates of preeclampsia, preterm birth, bacterial vaginosis and gestational diabetes in women with low vitamin D levels. However, confirmation of experimental observations establishing an association of vitamin D deficiency with adverse reproductive outcomes by high quality observational and large-scale randomized clinical trials is still lacking. The determination of optimal 25(OH)D3 levels in the reproductive period and the amount of vitamin D supplementation required to achieve those levels for the numerous actions of vitamin D throughout a woman's life would have important public health implications.

'Here comes the sun': pigmentary traits and sun habits in women with endometriosis

BACKGROUND

There is limited but interesting evidence suggesting that endometriosis may be associated with specific pigmentary traits and sun habits. In this case-control study, we aimed to further clarify this point.

MATERIALS AND METHODS

Consecutive patients with a first laparoscopic diagnosis of endometriosis according to Holt and Weiss criteria were selected as cases. Controls were women who underwent laparoscopy during the same study period, but who were found to be free of the disease. Selected women were interviewed and examined by two trained physicians. An unconditional logistic regression model that included age and baseline variables significantly differing between the two groups was used to estimate the adjusted odds ratios (OR).

RESULTS

There were 98 women with endometriosis and 94 controls selected. Overall, women with the disease had a more photo-sensitive phenotype and were exposed less to sun or ultraviolet radiation. A statistically significant difference was documented for eye color, skin reaction to first sun exposure, freckles score and the use of tanning creams. The adjusted OR (95% CI) for the disease was 1.95 (1.02-3.72) for women with green/blue eyes, 2.19 (1.12-4.28) for those who frequently/always had skin burn reaction to first sun exposure, 5.67 (1.98-16.24) for those with a higher number of freckles and 0.35 (0.15-0.85) for the use of tanning creams.

CONCLUSIONS

Women with endometriosis have a specific photo-sensitive phenotype and protect themselves more from the sun. This latter habit may be consequent to the former. We speculate that there is a shared genetic background between pigmentation and endometriosis.

Vitamin D reserve is higher in women with endometriosis

BACKGROUND

An immune-mediated defect in recognition and elimination of endometrial fragments refluxed in the peritoneal cavity has been hypothesized to play a crucial role in endometriosis development. Since vitamin D is an effective modulator of the immune system, we have hypothesized that the vitamin D status may have a role in the pathogenesis of endometriosis.

METHODS

Women of reproductive age selected for surgery for gynecological indications were enrolled in this prospective cohort study. Serum levels of 25-hydroxyvitamin-D(3), 1,25-dihydroxyvitamin-D(3) and Ca(2+) were assessed.

RESULTS

Eighty-seven women with endometriosis and 53 controls were recruited. Mean (+/- SD) levels of 25-hydroxyvitamin-D(3) in women with and without endometriosis were 24.9 +/- 14.8 ng/ml and 20.4 +/- 11.8, respectively (P = 0.05). The Odds Ratio (95% Confidence Interval) for endometriosis in patients with levels exceeding the 75th percentile of the serum distribution of the molecule (28.2 ng/ml) was 4.8 (1.7-13.5). A positive gradient according to the severity of the disease was also documented. A trend towards higher levels of 1,25-dihydroxyvitamin-D(3) and Ca(2+) was observed in women with endometriosis, but differences did not reach statistical significance. As expected, serum concentrations of 25-hydroxyvitamin-D(3) and 1,25-dihydroxyvitamin-D(3,) but not Ca(2+), are influenced by the season (P < 0.001, P = 0.004, P = 0.57, respectively), while levels of the three molecules did not vary according to the phase of the menstrual cycle.

CONCLUSIONS

Endometriosis is associated with higher serum levels of vitamin D.

Polymorphisms of the vitamin D receptor gene predict the onset of surgical menopause in Caucasian females

We tested association of four single nucleotide polymorphisms (SNPs) of the vitamin D receptor gene (VDR) with age at surgical and natural menopause in a sample of Caucasians composed of 153 women with surgical and 260 with natural menopause. A significant association was observed between age at surgical menopause and two SNPs, rs1544410 (BsmI) and rs731236 (TaqI) (p < 0.05). For rs1544410, homozygotes of the minor allele, AA, had about two-fold higher risk of surgical menopause than homozygotes of the major allele, GG (95% confidence ratio (CI) 1.09-3.82). For rs731236, the CC subjects had a greater chance of surgical menopause than the TT subjects (odds ratio = 2.01, 95% CI 1.07-3.78). Since rs1544410 and rs731236 are in strong linkage disequilibrium, the haplotypes based on these two loci were also tested. The haplotype AC was highly significantly associated with age at surgical menopause (p = 0.008). Women with this haplotype had surgical menopause on average 2.8 years earlier than non-carriers. These results reveal the potential effect of the VDR gene on ovaries and uterus, and suggest that its SNPs can be used as predictors of genetic susceptibility for early surgical menopause and respective causal health problems.

Measurement of vitamin D and its metabolites (calcidiol and calcitriol) and their clinical significance

The serum concentration of vitamin D will only give information about the recent exposure to either nutritional vitamin D or to recent vitamin D production in the skin. Within hours vitamin D is removed from the circulation and reappears again a few hours later as 25(OH)D. Measurements of vitamin D therefore are not useful to judge the vitamin D status of man. Plasma concentrations of 25-hydroxyvitamin D (25(OH)D) are the best markers of imminent or existing vitamin D deficiency. Suboptimal vitamin D supply (or 25(OH)D plasma concentrations) are observed in most European countries and North America from November to April. Vitamin D substitution is recommended to persons with a serum concentration of 25(OH)D below 50 nmol/L (20 micrograms/L). Plasma concentrations of 1,25(OH)2D3 (calcitriol) depend mainly on renal function, concentrations of intact PTH and the supply of the organism with calcium and phosphate. High PTH, low calcium and low phosphate supply are the main stimulators of the production of calcitriol. Vitamin D substitution, or if necessary, therapy with active vitamin D metabolites or analogs, e.g. calcitriol or alfacalcidol, are often necessary in hypercalcemic persons with low serum concentrations of calcitriol, e.g. in patients with renal failure. Disorders with low or high vitamin D metabolite concentrations in serum are described in this paper.

Relations between calcidiol serum levels and bone mineral density in postmenopausal women with low bone density

The relationship between vitamin D and bone density was studied in 150 selected, mature (45-74), postmenopausal women with a lumbar spine Z score below 0. Vitamin D status was evaluated using calcidiol serum levels. Serum calcitriol and parathyroid hormone (PTH) values were also evaluated in some subjects. Bone mass was evaluated by ascertaining bone density and Z and T scores in the lumbar spine and femur region. The reference group consisted of 25 premenopausal women. The postmenopausal group was divided into subgroups according to age, i.e., under or over 60 years old. Additionally, the whole group was also subdivided according to their lumbar spine Z scores into group I (Z > -1), group II (Z < -1; > -2), and group III (Z < -2). Group III of postmenopausal women had higher PTH and lower calcitriol levels than premenopausal women. Calcidiol serum levels were lower in postmenopausal women groups II or III than in the group I and premenopausal women. Calcidiol serum levels and the bone mass values for the lumbar spine were correlated positively in all the postmenopausal women; in the women over 60 years of age, calcidiol levels also correlated with the bone mass values expressed as the bone density in three femur regions: femoral neck, trocanter, and Ward's triangle. In conclusion, mature post-menopausal woman showed high PTH levels and low calcidiol and calcitriol values. Calcidiol status is significantly related to bone mineral density in the lumbar spine and in women over 60 years, calcidiol levels also correlated with bone density in the femur regions.

Extending the use of gonadotropin-releasing hormone agonists: the emerging role of steroidal and nonsteroidal agents

OBJECTIVE

To review and summarize the state of the art as it relates to the long-term application of GnRH agonists (GnRH-a).

DESIGN

A retrospective analysis of the available literature and results and an up-to-date review of a rapidly evolving field.

CONCLUSION

Although the precise use of long-term GnRH-a therapy (in conjunction with sex steroid add-back therapy) remains unknown, the information provided strongly supports additional studies in this area to achieve a body of promising preliminary data.

Uterine cells other than stromal decidual cells are required for 1,25-dihydroxyvitamin D3 production during early human pregnancy

Human decidual cells are known to produce 1,25-(OH)2D3 at the end of pregnancy, the present study evaluates this capacity, and the part played by stromal decidual cells, in early pregnancy. Cells were obtained from nine human decidua by aspiration or curettage during early pregnancy (7-10 weeks), separated on Ficoll-Paque and plastic adherence, and incubated for 1 h with 25-(OH)D3. Incubation medium and cells were extracted and chromatographed on two successive HPLC systems. The cells examined were of both physiological and pathological (ectopic pregnancy) origin. Endometrial cells obtained in four non-pregnant situations (myomas) were also studied to determine whether the 1,25-(OH)2D3 synthesis by the uterus is associated with the appearance of decidual cells. Results show that human decidual cells from early pregnancy convert 25(OH)D3 (2.5 nM or 2.5 microM) into a metabolite with the physicochemical characteristics of synthetic 1,25-(OH)2D3. This ability is shared by cells isolated during early pregnancy, whether physiological or ectopic (tubal pregnancy). Non-adherent cells, which include mainly stromal decidual cells, are less able to produce 1,25-(OH)2D3 than are the adherent cells, suggesting that macrophages, granulocytes or as yet unidentified cell types are required for the 1,25-(OH)2D3 production by decidual tissue during early human pregnancy. In addition, one out of four experiments with non-pregnant endometrial cells could produce 1,25-(OH)2D3 suggesting that, although not the rule in the non-pregnant state, in vitro production of 1,25-(OH)2D3 by uterine cells can be found in the absence of decidual cells.

Age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of bone metabolism in Chinese women

OBJECTIVE

To study the age-related changes in bone density, serum parathyroid hormone, calcium absorption and other indices of calcium metabolism in Chinese women who habitually have a low calcium intake.

DESIGN

Cross-sectional study.

SUBJECTS

One hundred and fifty-six healthy Chinese women aged 20-83 years. None were on any medication or vitamin supplements. Subjects over the age of 60 years were all living in a hostel; younger subjects were nurses or subjects attending a family clinic for minor illnesses.

MEASUREMENTS

Fasting blood and urine samples were collected for biochemical measurements and calcium absorption was measured using 45Ca by the method of Marshall and Nordin. Bone density was measured by dual energy X-ray densitometry (Norland X R20 X-ray bone densitometer) at the left hip and lumbar spine. Serum parathyroid hormone was measured by a chemiluminometric assay.

RESULTS

Plasma ionized calcium concentration, alkaline phosphatase, bicarbonate, plasma creatinine and serum B2 microglobulin were significantly higher in the elderly than in the young, whereas plasma phosphate and the anion gap were higher in the young. Urinary excretion of calcium, phosphate and hydroxyproline were all higher in older women. Plasma parathyroid hormone concentration was positively correlated with age even after taking into account the decline in renal function (as indicated by the rise in B2 microglobulin (r = 0.506, P less than 0.001). Serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were not lower in the older women. Fractional calcium absorption from an oral load of radiolabelled calcium was significantly lower in the older women and 37% of the older women were below the 2.5 percentile found in the younger women. Bone density measured by dual energy X-ray densitometry was also significantly lower in the elderly.

CONCLUSION

In Chinese women there is an increase in PTH and a decrease in calcium absorption with age in spite of the presence of normal vitamin D metabolites.

Comparison of vitamin D metabolism in early healthy and late osteoporotic postmenopausal women

We studied 20 healthy premenopausal women aged 36.5 +/- 4.0 years (mean +/- 1 SD), 123 healthy postmenopausal women aged 50.0 +/- 2.4 years, and 103 postmenopausal women aged 65.1 +/- 5.6 years with symptomatic osteoporosis (forearm and spinal fracture). Serum levels of vitamin D metabolites [25(OH)D, 24,25(OH)2D3, and 1,25-(OH)2D] were compared with (1) bone mass in the forearm (single photon absorptiometry) and in the spine (dual photon absorptiometry); (2) biochemical indices of bone formation (serum alkaline phosphatase, plasma bone Gla protein), and bone resorption (fasting urinary hydroxyproline); and (3) other biochemical estimates of calcium metabolism (serum calcium, serum phosphate, 24-hour urinary calcium, intestinal absorption of calcium). The present study revealed no difference in any of the vitamin D metabolites between the premenopausal women, the healthy postmenopausal women and the osteoporotic women as a group. The concentrations of 1,25(OH)2D and 25(OH)D were significantly lower in patients with spinal fracture than in those with forearm fracture. In the early postmenopausal women serum 1,25(OH)D was related to forearm bone mass (r = -0.20; P less than 0.05), intestinal calcium absorption (r = 0.18; P less than 0.05), and 24-hour urinary calcium (r = 0.21; P less than 0.05); serum 25(OH)D was related to spinal bone mass (r = 0.23; P less than 0.01). In the osteoporotic women, serum vitamin D metabolites were not related to bone mass, but 1,25(OH)2D was related to bone Gla protein (r = 0.33; P less than 0.001), serum phosphate (r = -0.27; P less than 0.01), and 24-hour urinary calcium (r = 0.43; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)