Vitamin D: emerging new roles in insulin sensitivity

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 Association Between Vitamin D Deficiency and the Level of Fasting C Peptide Among Patients With Uncontrolled Type 2 Diabetes Mellitus: A Retrospective Cohort Study

This study investigates the relationship between vitamin D deficiency and uncontrolled type 2 diabetes mellitus (T2DM) indicated by elevated glycosylated hemoglobin (HbA1c) levels, alongside assessing the association between fasting C peptide levels and uncontrolled T2DM, considering their roles in β-cell function and insulin secretion. The study employs a cohort design, selecting individuals diagnosed with T2DM aged 18 years or older with baseline data on vitamin D, fasting C peptide, and HbA1c. Data were collected through electronic medical records and follow-up assessments at regular intervals. Binary logistic regression analyses were conducted to explore associations between exposure variables and uncontrolled T2DM. Significant associations were observed between vitamin D and C peptide levels with uncontrolled diabetes, with coefficients of -0.097 and -0.222, respectively. Higher vitamin D and C peptide levels are linked to a decreased likelihood of uncontrolled diabetes. In conclusion, there is a potential connection between vitamin D levels, C peptide levels, and uncontrolled diabetes mellitus (HbA1C > 7%), while higher levels of both vitamin D and C peptide appeared to correlate with a decreased likelihood of uncontrolled diabetes.

Cholecalciferol ameliorates insulin signalling and insulin regulation of enzymes involved in glucose metabolism in the rat heart

CONTEXT

The evidence on potential cross-talk of vitamin D and insulin in the regulation of cardiac metabolism is very scanty.

OBJECTIVE

Cholecalciferol was administered to male Wistar rats for six weeks to study its effects on cardiac glucose metabolism regulation.

MATERIALS AND METHODS

An expression, phosphorylation and/or subcellular localisation of insulin signalling molecules, glucose transport and metabolism key proteins were studied.

RESULTS

Circulating non-esterified fatty acids (NEFA) level was lower after cholecalciferol administration. Cholecalciferol decreased cardiac insulin receptor substrate 1 Ser307 phosphorylation, while insulin-stimulated Akt Thr308 phosphorylation was increased. Cardiac 6-phosphofructo-2-kinase protein, hexokinase 2 mRNA level and insulin-stimulated glycogen synthase kinase 3β Ser9 phosphorylation were also increased. Finally, FOXO1 transcription factor cytosolic level was reduced.

CONCLUSION

Vitamin D-related improvement of insulin signalling and insulin regulation of glucose metabolism in the rat heart is accompanied by the decrease of blood NEFA level and dysregulation of cardiac FOXO1 signalling.

Do GLP-1 Analogs Have a Place in the Treatment of PCOS? New Insights and Promising Therapies

Polycystic ovary syndrome (PCOS) is the most prevalent endocrinopathy in women of reproductive age. This condition is characterized by hyperandrogenism and either oligo- or anovulation. PCOS patients often present comorbidities such as obesity, insulin resistance, impaired glucose metabolism, dyslipidemia, hypertension, metabolic syndrome, and an increased risk of diabetes. Given the profound implications of metabolic impairment in PCOS, the accurate diagnosis and management of these facets are imperative. The first-line approach to treatment involves lifestyle modifications, including dietary adjustments and exercise aimed at achieving weight loss, a strategy consistently emphasized across the literature. Supplementation with probiotics, vitamin D, and L-carnitine have also provided additional benefits to patients. In select cases, pharmacological interventions are needed for optimal therapeutic results. The most common medications used in PCOS include metformin, thiazolidinediones, inositols, and two classes of antidiabetic agents: dipeptidyl peptidase-IV (DPP-IV) inhibitors, and sodium-glucose cotransporter-2 (SGLT-2) inhibitors. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are a new addition to the therapeutic arsenal for the metabolic management of PCOS. GLP-1 receptor agonists cause insulin release in a glucose-dependent manner, yielding clinical benefits such as heightened satiety, reduced appetite, and appetite regulation. GLP-1RAs have demonstrated efficacy in reducing glycated hemoglobin levels and promoting weight loss while ameliorating hyperlipidemia. Prior to initiating GLP-1RA therapy, patients should undergo screening for contraindications, including history of pancreatitis, diabetic retinopathy, or thyroid cancer. The effects of treatment should be monitored using laboratory testing and body weight measurements. Effective communication between clinician and patient should be maintained with regular check-in for a period of 6 to 12 months.

Key Nutrients for Optimal Blood Glucose Control and Mental Health in Individuals with Diabetes: A Review of the Evidence

Diabetes is associated with an increased risk of mental disorders, including depression, anxiety, and cognitive decline. Mental disorders can also contribute to the development of diabetes through various mechanisms including increased stress, poor self-care behaviors, and adverse effects on glucose metabolism. Consequently, individuals suffering from either of these conditions frequently experience comorbidity with the other. Nutrition plays an important role in both diabetes and mental health disorders including depression and anxiety. Deficiencies in specific nutrients such as omega-3 fatty acids, vitamin D, B vitamins, zinc, chromium, magnesium, and selenium have been implicated in the pathogenesis of both diabetes and mental disorders. While the impact of nutrition on the progression and control of diabetes and mental disorders is broadly acknowledged, there is a notable knowledge gap concerning the implications of distinct nutrients in preventing and mitigating symptoms of both conditions when they coexist. The aim of this study was to examine the role of nutrition in improving glucose homeostasis and promoting mental well-being among individuals with diabetes. Further, we evaluated the preventive or delaying effects of key nutrients on the simultaneous manifestation of these conditions when one of them is present. Our findings indicated that the use of personalized dietary interventions and targeted nutrient supplementation can improve metabolic and mental health outcomes in patients with type 2 diabetes.

A comprehensive review on the impact of calcium and vitamin D insufficiency and allied metabolic disorders in females

Calcium is imperative in maintaining a quality life, particularly during later ages. Its deficiency results in a wide range of metabolic disorders such as dental changes, cataracts, alterations in brain function, and osteoporosis. These deficiencies are more pronounced in females due to increased calcium turnover throughout their life cycle, especially during pregnancy and lactation. Vitamin D perform a central role in the metabolism of calcium. Recent scientific interventions have linked calcium with an array of metabolic disorders in females including hypertension, obesity, premenstrual dysphoric disorder, polycystic ovary syndrome (PCOS), multiple sclerosis, and breast cancer. This review encompasses these female metabolic disorders with special reference to calcium and vitamin D deficiency. This review article aims to present and elaborate on available data regarding the worldwide occurrence of insufficient calcium consumption in females and allied health risks, to provide a basis for formulating strategies and population-level scientific studies to adequately boost calcium intake and position where required.

Genetic association of vitamin D receptor gene with female infertility

BACKGROUND

Infertility is defined as failure to achieve a clinical pregnancy after 12 months of unprotected intercourse. It affects 15% of couples globally and 22% of couples within Pakistan. Female infertility can be caused by numerous genetic or environmental factors including hormone imbalances and exposure to chemicals or radiation. The prevalence of vitamin D deficiency among the adult population was reported to be 14-59% with a higher prevalence in Asian countries. Furthermore, the expression of Vitamin D receptor (VDR) can play a vital role in the reproductive organs of females. Hence, the aim of our present study was to check the association of VDR polymorphisms with infertile females. For this purpose, blood samples were collected for genotyping of four known VDR mutations [FokI (rs2228570), TaqI (rs731236), ApaI (rs7975232), and BsmI (rs1544410)] via PCR-based RFLP assay.

RESULTS

Genotyping indicated that FokI, TaqI, and ApaI are associated with infertility (p = 0.004*, p = 0.013*, and p = 0.033*, respectively). However, BsmI did not show any significance. Multinomial regression analysis indicated that FokI heterozygous genotypes increase the risk of infertility by 2.5 times (hetero: OR = 2.5, 95%, p = 0.001*) as compared to wild type. Heterozygous genotypes of TaqI and ApaI were found to play a protective role and reduce the risk of infertility by 58 and 52%, respectively [TaqI: OR = 0.42, 95%, p = 0.004*, ApaI: OR = 0.48, 95%, p = 0.01*, respectively] as compared to wild type. Multinomial logistic regression analysis was also performed for allelic data as well.

CONCLUSION

Thus, it could be summarized that among the studied polymorphisms of VDR, FokI SNP greatly increased the risk of infertility, while TaqI and ApaI genotypes protect from infertility. However, BsmI does not influence the risk of infertility in Pakistani females.

Intake of Low Glycaemic Index Foods but Not Probiotics Is Associated with Atherosclerosis Risk in Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) are at high cardiometabolic risk. The atherogenic index of plasma (AIP) strongly predicts atherosclerosis. Some studies suggest that probiotic intake may lower AIP. This study analysed the relationship between the frequency of dietary intake of low glycaemic index (prebiotic) and probiotic foods and atherosclerosis risk in women with PCOS. Methods: A total of 127 women were divided into two groups: AIP over 0.11 (highAIP) and AIP ≤ 0.11 (lowAIP). The KomPAN® questionnaire was used to measure food frequency intake; pro-healthy, non-healthy, low glycaemic and probiotic dietary indexes were calculated based on daily food consumption. Body composition was measured by air displacement plethysmography (BodPod). AIP was calculated as a logarithm of triglycerides and high-density lipoproteins from plasma. Results: The highAIP group was 63% less likely to consume low glycaemic index foods three or more times a day than the lowAIP group. The HighAIP group was also 62% less likely to consume buckwheat, oats, whole-grain pasta or coarse-ground grains at least a few times a week. Pro-healthy foods tended to be less frequently consumed by the highAIP group, when adjusted for BMI and age. Conclusion: Women with PCOS at high risk of atherosclerosis consumed less low glycaemic index foods than women with a low risk of atherosclerosis. Intake of high-fibre, low glycaemic index foods could prevent atherosclerosis in women with PCOS; however, the effect of probiotic food intake remains unclear.

Circulating 25-hydroxyvitamin D is associated with metabolic phenotypes of obesity: National Food and Nutrition Surveillance

Different phenotypes of obesity are each related with different complications and comorbidities. We hypothesized that suboptimal vitamin D status is directly associated with an unhealthy metabolic status, especially if allied with obesity. This cross-sectional study was performed in the framework of the National Food and Nutrition Surveillance. Overall, 1098 men and women participated in this study. In addition to height and weight, serum concentrations of 25-hydroxyvitamin D (25(OH)D) and glycemic and lipidemic status were evaluated. Then participants were classified into 4 groups based on body mass index and lipidemic and glycemic profile status, as follows: hyperglycemic-dyslipidemic obese (HDO), hyperglycemic-dyslipidemic nonobese (HDNO), normoglycemic-normolipidemic obese (NNO), and normoglycemic-normolipidemic nonobese (NNNO). In this study, 31.6% of participants were classified as HDO, 7.5% as HDNO, 34.5% as NNO, and 26.4% as NNNO. The frequency of suboptimal vitamin D status was more prevalent in HDO (81.8%) than in other phenotypes (HDNO, 80%; NNO, 77.6%; NNNO, 73.8%; P = .015). In the multivariate model, suboptimal vitamin D status significantly increased the odds of being NNO (odds ratio [OR], 1.28; 95% CI, 0.84-1.95), HDNO (OR, 1.48; 95% CI, 0.77-2.83), and HDO (OR, 1.73; 95% CI, 1.11-2.7) compared with the NNNO group. Likewise, in multivariate model, per each unit (ng/mL) increment in 25(OH)D concentration, the odds of HDNO and HDO decreased significantly by 4% (OR, 0.96; 95% CI, 0.94-0.98) and 7% (OR, 0.93; 95% CI, 0.92-0.95), respectively. The results of the study showed a significant relationship between serum 25(OH)D concentrations and metabolic obesity phenotypes; these data confirm the association between suboptimal vitamin D status and metabolic complications, especially in obese individuals.

Sex-Specific Cut-Offs of Single Point Insulin Sensitivity Estimator (SPISE) in Predicting Metabolic Syndrome in the Arab Adolescents

The Single Point Insulin Sensitivity Estimator (SPISE) is a novel surrogate marker for insulin sensitivity and was found comparable to the gold standard clamp test as well as for predicting the Metabolic Syndrome (MetS) in several populations. The present study aimed to assess for the first time, the validity of SPISE in predicting MetS among Arab adolescents. In this cross-sectional study, 951 Saudi adolescents aged 10−17 years were randomly recruited from different schools across Riyadh, Saudi Arabia. Anthropometrics were measured and fasting blood samples were collected for the assessment of glucose, lipid profile, adipokines, C-reactive protein and 25 hydroxyvitamin (OH) D. MetS was defined using the National Cholesterol Education Program’s (NCEP) criteria with age-specific thresholds for adolescents. The SPISE as well as insulin resistance (HOMA-IR) indices were calculated. The over-all prevalence of MetS was 8.6% (82 out of 951). SPISE index was significantly lower in MetS than non-MetS participants in both sexes (5.5 ± 2.5 vs. 9.4 ± 3.2, p < 0.001 in boys and 4.4 ± 1.4 vs. 8.6 ± 3.2, p < 0.001 in girls). The SPISE index showed a significant inverse correlation with resistin, leptin, and C-reactive protein, and a significant positive correlation with adiponectin and 25(OH) D. Areas under the curve (AUC) revealed fair and good accuracy for predicting MetS 84.1% and 90.3% in boys and girls, respectively. The sex-specific cut-off proposed was SPISE index ≤6.1 (sensitivity 72.2% and specificity 83.9%) for boys and ≤6.46 (sensitivity 96.3% and specificity 73.4%), for girls. This study suggests that the SPISE index is a simple and promising diagnostic marker of insulin sensitivity and MetS in Arab adolescents.

Vitamin D, Gut Microbiota, and Cardiometabolic Diseases-A Possible Three-Way Axis

Metabolic syndrome (MetSyn) is a precursor for several cardiometabolic diseases such as obesity, type-2 diabetes mellitus (T2DM), and cardiovascular diseases. Emerging evidence suggests that vitamin D deficiency links to cardiometabolic diseases through microbiota. A combination of poor vitamin D status and dysbiosis may contribute to the progression of cardiometabolic diseases. Therefore, in this review, we present the relationship among vitamin D, microbiota, and cardiometabolic diseases with a focus on MetSyn. We searched major databases for reports on vitamin D, microbiota, and MetSyn until June 2022. We reviewed 13 reports on the relation between vitamin D and MetSyn (6 randomized controlled and 7 cross-sectional studies) and 6 reports on the effect of vitamin D on the gut microbiome. Adequate vitamin D status has a beneficial effect on gut microbiota, therefore preventing the progression of MetSyn. Further, well-controlled studies are needed for a better understanding of the mechanisms of action involving vitamin D and microbiota in the pathogenesis of cardiometabolic diseases.

Global research trends on the links between insulin resistance and obesity: a visualization analysis

Background

Obesity increases the chance of developing insulin resistance. Numerous inflammatory markers have been linked to an increased risk of insulin resistance in obese individuals. Therefore, we performed a bibliometric analysis to determine global research activity and current trends in the field of obesity and insulin resistance.

Methods

Scopus was used between 2002 and 2021 to retrieve publications related to terms related to obesity and insulin resistance. Data were exported to Microsoft Excel. Additionally, we use VOSviewer software to create visualization maps that describe international collaborations and research hotspots.

Results

We identified 6626 publications, including 5754 journal articles, 498 review articles, and 109 letters to the editor. The most productive countries were the United States (n = 995, 30.11%), followed by China (n = 650, 9.81%), Italy (n = 412, 6.22%) and Spain (n = 386, 5.83%). Previously to 2012, this field was mainly focused on ‘adipocyte dysfunctions that link obesity with insulin resistance”; and ‘relationship between obesity, insulin resistance, and risk of cardiovascular disease’. ‘Supplements improve insulin sensitivity‘, and ‘obesity-induced inflammation and insulin resistance’ were found more recently (after 2014), indicating that research in this field has acquired significant interest and emphasis in recent years.

Conclusions

This is the first bibliometric study to focus on publications related to insulin resistance and obesity at the global level. Our reporting of quantifiable knowledge in this field may be useful in providing evidence and direction for future research, clinical practice, and educational initiatives.

Association between vitamin D serum levels and insulin resistance assessed by HOMA-IR among non-diabetic adults in the United States: Results from NHANES 2007-2014

Insulin resistance, a pathological response to insulin hormone in insulin-dependent cells, is characterized by the presence of high glucose and insulin concentrations. The homeostasis model of insulin resistance (HOMA-IR) is one of the most used indexes to estimate insulin resistance by assessing the fasting glucose and insulin levels. An association was observed between vitamin D levels and insulin resistance, which varied in different ethnic groups, and there is some evidence that vitamin D supplementation could contribute to the improvement of insulin resistance. This study assessed the association between 25-hydroxyvitamin D (25[OH]D) concentration and HOMA-IR in American adults aged 20 years and older, without diabetes and other chronic diseases that can influence insulin resistance. The data from the National Health and Nutrition Examination Survey (NHANES) 2007–2014 were used by exploiting the free and publicly-accessible web datasets. Linear regression models were performed to evaluate the association between serum 25(OH)D concentration and HOMA-IR, and a negative association was observed, which remained significant following the adjustment for age, gender, race/ethnicity, education, body mass index (BMI), physical activity, the season of examination, current smoking, hypertension, the use of drugs which can influence insulin resistance, serum bicarbonates, triglycerides, and calcium and phosphorus levels. Only in non-Hispanic Blacks was this inverse association between vitamin D and HOMA-IR not observed in the fully adjusted model. Further studies are needed to explain the mechanisms of the observed ethnic/racial differences in the association of vitamin D levels with HOMA-IR.

Associations of Serum Total 25OHD, 25OHD3, and epi-25OHD3 with Insulin Resistance: Cross-Sectional Analysis of the National Health and Nutrition Examination Survey, 2011–2016

Background: Vitamin D may have a role in insulin sensitivity. However, the data on the association between various metabolites of Vitamin D and insulin-related parameters have been limited. Methods: We identified 6026 adults aged 20–80 years who participated in the 2011–2016 National Health and Nutrition Examination Survey (NHANES). Serum total 25OHD, 25OHD3, and epi-25OHD3, fasting glucose, insulin, and HOMA2-IR were obtained from the NHANES data. The association between serum Vitamin D-related values and insulin resistance was analyzed using a generalized linear model. For risk analysis, multifactorial logistic regression was used. Results: The median total 25-hydroxyvitamin D level, 25-hydroxyvitamin D3 level, and 3-epi-25-hydroxyvitamin D3 level were 62.5 nmol/L, 58.8 nmol/L, and 3.3 nmol/L, respectively. After adjustment for sex, age, race, ethnicity, and education status, the ORs for the insulin resistance of participants of total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.32 (95% CI 0.24, 0.43), 0.34 (95% CI 0.26, 0.44), and 0.64 (95% CI 0.53, 0.77), respectively. After an adjustment for body mass index, diabetes, and drinking and smoking, the ORs for the insulin resistance of the participants for total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.56 (95% CI 0.40, 0.78), 0.63 (95% CI 0.46, 0.85), and 0.99 (95% CI 0.80, 1.24), respectively. Conclusions: Our study provides suggestive evidence for the association between Vitamin D concentrations and a lower risk of insulin resistance. Evidence from larger and more adequately powered cohort studies is needed to confirm our results.

Glutamic acid decarboxylase immunotherapy for type 1 diabetes

PURPOSE OF REVIEW

To describe recent development of an autoantigen (GAD) treatment towards well tolerated and efficacious precision medicine in type 1 diabetes.

RECENT FINDINGS

Although subcutaneous GAD-alum treatment failed to reach primary endpoint in a phase III trial, metanalyses showed a 97% probability of efficacy, and clear efficacy in patients carrying Hyman Leucoycte Antigen (HLA) DR3DQ2. Efforts have been made to improve efficacy by trying combination therapies with vitamin D + Ibuprofen resp vitamin D + Etanercept (TNF-α inhibition), without any breakthrough until the administration of GAD-alum was changed from subcutaneous to intralymphatic. With a very small dose of GAD-alum (4 μg) given into an inguinal lymph three times with 1 month interval, the efficacy in patients with HLADR3DQ2 has been impressive, with significantly better beta cell preservation than patients who got placebo in a double-blind randomized trial, and clinical efficacy with more patients in partial remission (IDAA1c < 9) and larger proportion of patients with CGM-measured blood glucose Time In Range (TIR), significantly correlated to the C-peptide values. The treatment has been easy for patients and healthcare without treatment-related risk or adverse events.

SUMMARY

Intralymphatic GAD-alum treatment in type 1 diabetes patients carrying HLA DR3DQ2 seems to be an attractive immune intervention.

Combined resveratrol and vitamin D treatment ameliorate inflammation-related liver fibrosis, ER stress, and apoptosis in a high-fructose diet/streptozotocin-induced T2DM model

A high fructose diet is a major cause of diabetes and various metabolic disorders, including fatty liver. In this study, we investigated the effects of resveratrol and vitamin D (VitD) treatments on endoplasmic reticulum (ER) stress, oxidative stress, inflammation, apoptosis, and liver regeneration in a rat model of type 2 diabetes mellitus, namely, T2DM Sprague-Dawley rats. This T2DM rat model was created through a combination treatment of a 10% fructose diet and 40 mg/kg streptozotocin (STZ). Resveratrol (1 mg/kg/day) and VitD (170/IU/week) were administered alone and in combination to both the diabetic and control groups. Immunohistochemical staining was performed to evaluate PCNA, NF-κB, TNF-α, IL-6, IL-1β, GRP78, and active caspase-3 in liver tissue. The TUNEL method and Sirius red staining were used to determine apoptosis and fibrosis, respectively. G6PD, 6-PGD, GR, and GST activities were measured to determine oxidative stress status. We found that the expressions of cytokines (TNF-α, IL-6, and IL-1β) correlated with NF-κB activation and were significantly increased in the T2DM rats. Increased GRP78 expression, indicating ER stress, increased in apoptotic cells, enhanced caspase-3 activation, and collagen accumulation surrounding the central vein were observed in the T2DM group compared with the other groups. The combination VitD + resveratrol treatment improved antioxidant defense via increasing G6PD, 6-PGD, GR, and GST activities compared to the diabetic groups. We concluded that the combined administration of resveratrol with VitD ameliorates the adverse effects of T2DM by regulating blood glucose levels, increasing antioxidant defense mechanisms, controlling ER stress, enhancing tissue regeneration, improving inflammation, and reducing apoptosis in liver cells. In conclusion, this study indicates that the combination treatment of resveratrol + VitD can be a beneficial option for preventing liver damage in fructose-induced T2DM.

The consumption of micronutrients in relation to calorie intake and risk of insulin resistance

BACKGROUND AND AIMS

Adequate dietary intakes of essential micronutrients are critical to prevent insulin resistance (IR)-related diseases. Even though the excess calorie intake linked with obesity is also associated with such diseases, no previous studies evaluated the importance of meeting the Dietary Reference Intake (DRI) of micronutrients in relation to calorie intake in those at risk for developing IR.

METHODS AND RESULTS

We evaluated the relationship between the ability or failure to meet the DRI of micronutrients in relation to daily calorie intake in 463 childbearing-age women with a higher prevalence of IR. 56-65% women met the DRIs for vitamin B12, vitamin C, thiamine, and riboflavin while only 0%-49% met the DRIs for folate, pyridoxine, niacin, pantothenic acid, total carotene, vitamins A, D and E by consuming an acceptable number of calories. Women who met the DRIs of folate and vitamin C within acceptable daily calorie intakes were 59% and 66% less likely to have higher Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) compared to women who did not.

CONCLUSIONS

Understanding the mechanisms that explain our findings will be of value to address IR-associated with exposure to high calorie/low-micronutrient dense diets consumed by childbearing-age women. Since there is a global recognition that IR has been increasing in adults and children, similar studies of this nature in pregnant women at risk for IR will provide much needed data to assess the burden of such adverse dietary habits in the offspring. Our study approach may form the foundation for such studies.

Association of Fasting Glucose and Glycated Hemoglobin with Vitamin D Level According to Diabetes Mellitus Status in Korean Adults

Objectives

Previous studies have suggested that vitamin D deficiency might increase the risk of type 2 diabetes mellitus(DM). However, few studies have examined whether vitamin D continues to affect glucose control after DM diagnosis. Therefore, we examined the association between vitamin D and glucose in nondiabetics and DM patients.

Methods

We analyzed data for 32,943 adults aged 19 years and older from the 2008 to 2014 Korea National Health and Nutrition Examination Survey. Vitamin D levels were determined using the 25-hydroxyvitamin D concentration, and patients were grouped into one of three categories according to those results DM was defined as a fasting glucose level ≥ 126 mg/dL, current use of DM medications or insulin injections, or a self-reported diagnosis of DM by a doctor.

Results

In male DM patients, hemoglobin A1c(HbA1c) level increased significantly as vitamin D levels became severely deficient. Among the abnormal HbA1c subgroups of males and postmenopausal females, HbA1c levels were significantly higher in the severe vitamin D deficiency subgroup (p for trend = 0.0044 and 0.0219 for males and postmenopausal females, respectively). There were significant differences between abnormal HbA1c subgroups and normal HbA1c subgroups in both males and females. Regardless of sex or menopause status, however, there was no significant association between vitamin D and fasting glucose in fasting glucose subgroups.

Conclusion

Males and females in the abnormal HbA1c subgroups showed markedly elevated blood glucose when they also had vitamin D deficiency. Furthermore, there was a more distinct difference in the HbA1c subgroups than in the fasting glucose subgroups.

Vitamin D Deficiency Is Associated with Glycometabolic Changes in Nondiabetic Patients with Arterial Hypertension

Recent evidence indicates that mildly increased fasting and post-oral load blood glucose concentrations contribute to development of organ damage in nondiabetic patients with hypertension. In previous studies, vitamin D deficiency was associated with decreased glucose tolerance. The aim of this study was to examine the relationships between serum 25(OH)D levels and glucose tolerance and insulin sensitivity in hypertension. In 187 nondiabetic essential hypertensive patients free of cardiovascular or renal complications, we measured serum 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) and performed a standard oral glucose tolerance test (OGTT). Patients with 25(OH)D deficiency/insufficiency were older and had significantly higher blood pressure, fasting and post-OGTT (G-AUC) glucose levels, post-OGTT insulin (I-AUC), PTH levels, and prevalence of metabolic syndrome than patients with normal serum 25(OH)D. 25(OH)D levels were inversely correlated with age, blood pressure, fasting glucose, G-AUC, triglycerides, and serum calcium and PTH, while no significant relationships were found with body mass index (BMI), fasting insulin, I-AUC, HOMA index, and renal function. In a multivariate regression model, greater G-AUC was associated with lower 25(OH)D levels independently of BMI and seasonal vitamin D variations. Thus, in nondiabetic hypertensive patients, 25(OH)D deficiency/insufficiency could contribute to impaired glucose tolerance without directly affecting insulin sensitivity.

Mechanisms Linking Vitamin D Deficiency to Impaired Metabolism: An Overview

Vitamin D deficiency is a common health problem worldwide. Despite its known skeletal effects, studies have begun to explore its extra-skeletal effects, that is, in preventing metabolic diseases such as obesity, hyperlipidemia, and diabetes mellitus. The mechanisms by which vitamin D deficiency led to these unfavorable metabolic consequences have been explored. Current evidence indicates that the deficiency of vitamin D could impair the pancreatic β-cell functions, thus compromising its insulin secretion. Besides, vitamin D deficiency could also exacerbate inflammation, oxidative stress, and apoptosis in the pancreas and many organs, which leads to insulin resistance. Together, these will contribute to impairment in glucose homeostasis. This review summarizes the reported metabolic effects of vitamin D, in order to identify its potential use to prevent and overcome metabolic diseases.

Female Fertility and the Nutritional Approach: The Most Essential Aspects

Infertility is an increasing problem that affects couples attempting pregnancy. A growing body of evidence points to a link between diet and female fertility. In fact, data show that a diet high in trans fats, refined carbohydrates, and added sugars can negatively affect fertility. Conversely, a diet based on the Mediterranean dietary patterns, i.e., rich in dietary fiber, omega-3 (ɷ-3) fatty acids, plant-based protein, and vitamins and minerals, has a positive impact on female fertility. An unhealthy diet can disrupt microbiota composition, and it is worth investigating whether the composition of the gut microbiota correlates with the frequency of infertility. There is a lack of evidence to exclude gluten from the diet of every woman trying to become pregnant in the absence of celiac disease. Furthermore, there are no data concerning adverse effects of alcohol on female fertility, and caffeine consumption in the recommended amounts also does not seem to affect fertility. On the other hand, phytoestrogens presumably have a positive influence on female fertility. Nevertheless, there are many unanswered questions with regard to supplementation in order to enhance fertility. It has been established that women of childbearing age should supplement folic acid. Moreover, most people experience vitamin D and iodine deficiency; thus, it is vital to control their blood concentrations and consider supplementation if necessary. Therefore, since diet and lifestyle seem to be significant factors influencing fertility, it is valid to expand knowledge in this area.

A Clinician’s guide to vitamin D supplementation for patients with cystic fibrosis

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Vitamin D deficiency is multifactorial in the cystic fibrosis population.

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Vitamin D deficiency can adversely affect multiple organ systems in the cystic fibrosis population.

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In the cystic fibrosis population in the United States, we aim to treat to serum 25-hydroxyvitamin D levels over 30 ng/ml.

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Cholecalciferol is used in preference to ergocalciferol.

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Daily or once weekly dosing regimens are chosen according to patient preference and compliance.

Vitamin D deficiency is common in the general population, and even more so in patients with cystic fibrosis. Deficiency is exacerbated in cystic fibrosis patients because of a myriad of causes including malabsorption, decreased fat mass, reduced 25-hydroxylation of vitamin D, reduced exposure to sunlight, decreased vitamin D binding protein, and exposure to drugs that increase catabolism. In turn, vitamin D deficiency can contribute to poor bone health. Additionally, it may contribute to pulmonary decline in the form of worsening pulmonary function, increased colonization with pathogens, and increased pulmonary exacerbation. Because vitamin D deficiency is correlated with negative clinical effects in multiple organ systems of patients with cystic fibrosis, it is important to screen for and treat deficiency in these patients. The Cystic Fibrosis Foundation has issued guidelines for the treatment of vitamin D deficiency, targeting serum levels of 25-hydroxyvitamin D of at least 30 ng/ml. The guidelines offer age-specific escalating dose regimens depending on serum vitamin D levels, with monitoring at 12- week intervals after changing therapy. They address the literature on alternative vitamin D sources, such as UV lamps, ideal formulations (cholecalciferol in preference to ergocalciferol), and optimal vehicles of administration. Despite these detailed recommendations, most centers are still unable to achieve in-target serum vitamin D levels for many of their patients. Future research examining ideal treatment regimens to achieve serum targets and maximize clinical effects are needed. Moreover, it is unknown whether vitamin D sufficiency will be easier to achieve on new triple therapy cystic fibrosis drug combinations, and how these drugs will contribute to vitamin D-related clinical outcomes.

Effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in Japanese

An intervention study was conducted to investigate the effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in 26 healthy people and 8 older adults living in a nursing home. The serum 25-hydroxyvitamin D [25(OH)D] level was 13.4 ± 0.8 ng / mL and it markedly increased to 29.6 ± 0.9 ng / mL after daily 1000-IU vitamin D-fortified milk intake for 6 months. Handgrip strength (kg) also significantly increased in the 21-50 years and total groups, and male subjects, and the timed up and go test significantly improved in the 21-50 years and total groups, and female subjects after 6-month vitamin D intake. However, there were no significant differences between baseline and post-treatment in the Barthel Index (BI), walking speed (m / sec) or skeletal muscle mass (kg, % of BW, kg / m2). Therefore, the present study suggested that vitamin D-fortified milk intake is effective at improving muscle strength and physical function in Japanese, although further studies are needed, particularly for older adults. J. Med. Invest. 68 : 249-255, August, 2021.

Sex-Dependent Association of Vitamin D With Insulin Resistance in Humans

BACKGROUND

Animal studies suggested that vitamin D might decrease insulin resistance. Estrogen increased insulin sensitivity and glucose tolerance in rodents. However, sex-specific association of vitamin D with insulin resistance in humans remains unclear.

OBJECTIVES

To investigate the sex-dependency of the association of insulin resistance and 25-hydroxyvitamin D [25(OH)D] in a large Caucasian population.

METHODS

Cross-sectional study from out-patients' blood samples with measurements of 25(OH)D and homeostatic model assessment of insulin resistance (HOMA-IR) drawn at exactly the same day (n = 1887). This cohort was divided into 3 groups: (1) group with vitamin D deficiency (n = 1190), (2) group with vitamin D sufficiency (n = 686), and (3) vitamin D excess groups (n = 11); the vitamin D excess group was excluded from further analysis due to the small size.

RESULTS

Analysis of the entire study population showed that serum 25(OH)D was inversely associated with HOMA-IR [Spearman correlation coefficient (rs) = -0.19, P < 0.0001]. When considering the vitamin D status, this association was only seen in the vitamin D deficiency group but not in the vitamin D sufficient group. The correlation was sex-dependent: HOMA-IR was inversely correlated with vitamin D in women with vitamin D deficiency (rs = -0.26, P < 0.0001) but not in men with vitamin D deficiency (rs = 0.01, P = 0.714). After multivariate linear regression analysis considering confounding factors, this relationship was again only seen in women.

CONCLUSION

Vitamin D was inversely and independently associated with insulin resistance only in women with vitamin D deficiency. Based on our data, we suggest that in particular vitamin D deficient women might benefit from vitamin D substitution by improving insulin resistance. This, however, needs to be proven in adequately designed double-blind placebo-controlled clinical studies.

Effect of vitamin D supplementation on microvascular reactivity in obese adolescents: A randomized controlled trial

BACKGROUND AND AIM

Childhood obesity is associated with vitamin D (VD) deficiency and vascular dysfunction. Considering evidence indicates that VD may improve vascular function, this study, for the first time, assessed the effect of VD supplementation on microvascular reactivity in obese adolescents (OA).

METHODS AND RESULTS

This randomized controlled trial included 26 OA, receiving fruit juice with (n = 13) or without VD (4000 IU/d; n = 13) over a 3-month lifestyle program, as well as 23 normal-weight adolescents (controls). The primary outcome was the pre-to-post-program change in microvascular reactivity determined by laser speckle contrast imaging with acetylcholine and sodium nitroprusside iontophoresis. Changes in 25 hydroxyvitamin D (25(OH)D), flow-mediated dilation (FMD), nitrate-mediated dilation (NMD), insulin resistance (HOMA-IR) and inflammatory markers (C-reactive protein [CRP]) were monitored. At inclusion, in comparison to controls, OA exhibited lower total and free 25(OH)D, impaired microvascular responses, and impaired FMD, but similar NMD. After the lifestyle program, total and free 25(OH)D increased in all OA, with a greater increase in those receiving VD supplements. HOMA-IR and CRP decreased in all OA. Neither FMD nor NMD were altered in either group. Endothelium-dependent microvascular reactivity only increased in the VD-supplemented group, reaching values comparable to that of controls. Similar results were found when analyzing only OA with a VD deficiency at baseline.

CONCLUSION

VD supplementation during a lifestyle program attenuated microvascular dysfunction in OA without altering macrovascular function.

REGISTRATION NUMBER FOR CLINICAL TRIAL

NCT02400151.

Nutrition Strategy and Life Style in Polycystic Ovary Syndrome-Narrative Review

Here we present an extensive narrative review of the broadly understood modifications to the lifestyles of women with polycystic ovary syndrome (PCOS). The PubMed database was analyzed, combining PCOS entries with causes, diseases, diet supplementation, lifestyle, physical activity, and use of herbs. The metabolic pathways leading to disturbances in lipid, carbohydrate, and hormonal metabolism in targeted patients are described. The article refers to sleep disorders, changes in mental health parameters, and causes of oxidative stress and inflammation. These conditions consistently lead to the occurrence of severe diseases in patients suffering from diabetes, the fatty degeneration of internal organs, infertility, atherosclerosis, cardiovascular diseases, dysbiosis, and cancer. The modification of lifestyles, diet patterns and proper selection of nutrients, pharmacological and natural supplementation in the form of herbs, and physical activity have been proposed. The progress and consequences of PCOS are largely modifiable and depend on the patient’s approach, although we have to take into account also the genetic determinants.

A Narrative Review of Current Understanding of the Pathophysiology of Polycystic Ovary Syndrome: Focus on Plausible Relevance of Vitamin D

Polycystic ovarian syndrome (PCOS) is the most prevalent endocrinopathy of reproductive years. Salient features in presentation of patients PCOS include menstrual dysfunction, hyperandrogenism and/or polycystic appearance of ovaries on ultrasound. While the diagnosis of PCOS depends on presence of specified criteria, misdiagnoses are common. Despite years of extensive research, the exact aetiology of PCOS remains largely unknown. In the past decade, apart from insulin resistance and hyperandrogenemia, anti-mullerian hormone (AMH), an important marker of ovarian reserve, and vascular endothelial growth factor (VEGF), a crucial factor in angiogenesis, have been examined as plausible players of causative relevance for PCOS. Vitamin D, a sex-steroid hormone that is universally known for its relevance for skeletal health, has received increasing attention due to growing evidence supporting its pivotal in reproductive physiology and in PCOS. In this review we summarize our current understanding of the mechanisms relevant to the pathophysiology of PCOS and examine the role of vitamin D signalling in this context.

Nutrition in Gynecological Diseases: Current Perspectives

Diet and nutrition are fundamental in maintaining the general health of populations, including women’s health. Health status can be affected by nutrient deficiency and vice versa. Gene–nutrient interactions are important contributors to health management and disease prevention. Nutrition can alter gene expression, as well as the susceptibility to diseases, including cancer, through several mechanisms. Gynecological diseases in general are diseases involving the female reproductive system and include benign and malignant tumors, infections, and endocrine diseases. Benign diseases such as uterine fibroids and endometriosis are common, with a negative impact on women’s quality of life, while malignant tumors are among the most common cause of death in the recent years. In this comprehensive review article, a bibliographic search was performed for retrieving information about nutrients and how their deficiencies can be associated with gynecological diseases, namely polycystic ovary syndrome, infertility, uterine fibroids, endometriosis, dysmenorrhea, and infections, as well as cervical, endometrial, and ovarian cancers. Moreover, we discussed the potential beneficial impact of promising natural compounds and dietary supplements on alleviating these significant diseases.

The association of vitamin D levels and insulin resistance

OBJECTIVE

Vitamin D deficiency and insulin resistance have great prevalence in society. The latest studies indicate an inverse association between Vitamin D levels, insulin resistance, and Type 2 diabetes. The objective of this study was to investigate the effect of vitamin D status on insulin resistance.

METHODS

In a cross-sectional study, 2160 participants were randomly recruited from a nutrition clinic in Tehran, Iran, 1057 (48.9%) were female and 1103 (51.1%) male. Information was gathered by a questionnaire. Following 12-h fasting, fasting plasma glucose (FPG) and insulin levels, as well as 25-hydroxy vitamin D levels were measured. 2-H glucose and insulin levels measured after consumption of 75 g glucose, HOMA2-IR, and HOMA-β indices were then calculated.

RESULTS

The average serum Vitamin D was 22.3 + 8.9 nmol/L and the prevalence of Vitamin D deficiency was 100%. There was an inverse relationship between Vitamin D levels and age, BMI, waist circumference, and all metabolic parameters (p < 0.001 in all) and a direct association with levels of exercise. Two logistic regression models were used to adjust for confounding variables; firstly, for age, gender, and smoking and secondly, additionally for BMI and energy intake. Both models showed a significant inverse relationship between Vitamin D levels and FPG and insulin levels, 2-h glucose and insulin levels, and HOMA2-IR. The optimum cut point for vitamin D was calculated at about 25 nmol/L for preventing insulin resistance.

CONCLUSION

This study illustrated that there is a statistically significant inverse relationship between Vitamin D levels and insulin resistance.

The effect of PCOS status on atherosclerosis markers and cardiovascular disease risk factors in young women with vitamin D deficiency

OBJECTIVE

To investigate whether polycystic ovary syndrome (PCOS) had further deteriorating influence on endothelial function or cardiometabolic parameters in women with vitamin D deficiency during reproductive age.

STUDY DESIGN

The study group was composed of women with PCOS and vitamin D deficiency and insufficiency between the ages of 18 and 35 years. Age and body mass index (BMI)-matched women were chosen as controls. Serum 25(OH) Vit D levels below 20 ng/mL were considered as vitamin D deficiency. The cutoff level of vitamin D insufficiency was suggested at 30 ng/mL. Serum FSH, LH, estradiol, testosterone, DHEA-S, fasting glucose, total cholesterol, HDL, LDL, triglyceride levels were analyzed. Carotid artery intima-media thickness (CIMT) was measured, and the flow-mediated vasodilation (FMD) was calculated.

RESULTS

CIMT and FMD values in both vitamin D deficiency and insufficiency subgroups showed no significant difference between PCOS and non-PCOS groups. There was a weak negative correlation between BMI, waist/hip ratio, CRP, and 25(OH) Vitamin D.

CONCLUSION

PCOS is a heterogeneous disease with different combinations of the diagnostic components. Vitamin D is an important variable for a healthy cardiovascular system. We did not find any difference in early atherosclerotic markers and cardiometabolic features between PCOS and non-PCOS group with Vitamin D deficiency.

Vitamin D, Bone Metabolism, and Fracture Risk in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder among premenopausal women. PCOS may have reproductive, metabolic, cardiovascular, and psychological implications. Vitamin D deficit is often encountered in PCOS women and may contribute to the pathophysiology of this disorder. As of the key role of vitamin D in bone and mineral metabolism, and because the vitamin D status appears to be closely linked with the PCOS manifestations including insulin resistance, obesity, ovulatory and menstrual irregularities, oxidative stress and PTH elevation, hypovitaminosis D may directly and indirectly via the different facets of PCOS impair bone health in these women. Although limited data are available on life-long fracture risk in women with PCOS, the importance of preserving bone health in youth and adults to prevent osteoporosis and related fractures is also recognized in PCOS women. Evidence of the association between vitamin D and the clinical hallmarks of PCOS are summarized and discussed. Vitamin D arises as a cornerstone in women with PCOS and contributes to the pathophysiological link between PCOS and bone metabolism.

The Associations Between Vitamin D Receptor BsmI and ApaI Polymorphisms and Obesity in Korean Patients with Type 2 Diabetes Mellitus

BACKGROUND

Vitamin D receptor (VDR) polymorphisms are associated with osteoporosis, diabetes, immunological diseases, and cancers. However, the association of obesity with VDR polymorphisms has shown inconsistent results, and perhaps it depends upon the characteristics of a population. Therefore, we evaluated the association between BsmI (rs1544410) and ApaI (rs7975232) polymorphisms of VDR and obesity in Korean patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 506 patients with T2DM participated in the study. Polymerase chain reaction-restriction fragment length polymorphism was used to analyze BsmI and ApaI polymorphisms; the genotypes were presented as BB, Bb, or bb for BsmI and AA, Aa, or aa for ApaI. Obesity was defined using the body mass index (BMI) with a cutoff level of 25 kg/m².

RESULTS

The prevalence of obesity was higher in patients with the bb genotype than in those with BB or Bb genotypes (48.4% vs 33.9%, P = 0.031). The mean BMI was 25.2 ± 3.5 kg/m² in patients with bb genotype and 24.1 ± 3.1 kg/m² in patients with BB or Bb genotypes. Patients with Aa or aa genotypes showed a higher prevalence of obesity than patients with AA genotype (47.6% vs 26.1%, P = 0.043). Glycemic control parameters and lipid profiles did not show significant differences with either polymorphism.

CONCLUSION

To our knowledge, this is the first study to assess the association between VDR polymorphisms and obesity in Korean patients with T2DM. Further studies in larger populations and multiethnic cohorts are needed to validate our findings.

The Relationship between Low 25-Hydroxyvitamin D and Cardio-Metabolic Risk Factors among Ellisras Young Adults

Introduction: 25-hydroxyvitamin D (25(OH)D) is found in circulating blood and is regarded as an estimate of vitamin D status. Low circulating 25(OH)D levels are associated with a high body mass index (BMI), increased weight and the increased development of adipose tissue. This study aimed to determine the relationship between low 25(OH)D and cardio-metabolic risk factors among Ellisras young adults. Materials and methods: This is a cross-sectional study that took place in a rural area at Ellisras in Limpopo Province South Africa. The study included 631 young adults (327 females and 304 males) aged between 20 and 29 years. Anthropometric measurements including height, weight and waist circumference were measured following standard procedures. Blood pressure, pulse pressure and blood parameters including fasting plasma glucose, total cholesterol and triglycerides were also measured. Correlations and linear regression were performed to determine the relationship between low 25(OH)D and cardio-metabolic risk factors. Results: Descriptive statistics showed significant (p < 0.05) mean difference of LDL, HDL and blood pressure between males and females. There was a significant association between low 25(OH)D and WC (p = 0.010) based on Spearman correlation. There was no association found between low 25(OH)D and HDL in all models (B ranges from 0.072 to 0.075). There was also no association found between low 25(OH)D and systolic blood pressure (SBP) in all models (B ranges from −0.009 to −0.024). Conclusion: Low 25(OH)D was correlated with WC, and therefore with adiposity. Knowledge of the associations between 25(OH)D deficiency and cardio-metabolic risk before the development of the disease is therefore important to establish whether 25(OH)D supplementation can be used for the prevention of these conditions. Educational programmes should be implemented to educate the communities and the nation at large on how to prevent 25(OH)D deficiency.

The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders

Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca²⁺ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.

Relation of serum vitamin D level in polycystic ovarian syndrome (PCOS) patients to ICSI outcome

Background

Recently, vitamin D was discovered to have an important role in female reproduction and IVF. However, there were no studies specifically addressed its role in polycystic ovarian syndrome (PCOS) patients undergoing ICSI cycles. Therefore, this cross-sectional study in a university hospital was conducted to evaluate the effect of serum level of vitamin D (VD) on the number of retrieved and fertilized oocytes, and chemical and clinical pregnancy rate in PCOS females undergoing ICSI cycles. The study included 80 PCOS cases undergoing ICSI cycles in the age from 20 to 39 years using antagonist protocol. Cases with severe male or tubal factors were excluded. Serum 25 (OH) D vitamin level was assessed by the ELIZA method on the day of oocyte retrieval. Correlation and regression analyses were used in the analysis.

Results

VD was positively correlated to both numbers of retrieved and fertilized oocytes (r = 0.35, 95% CI 0.15, 0.53, P = 0.001; r = 0.33; 95% CI 0.03, 0.57, P = 0.03, respectively). It was still significantly correlated to the number of oocytes (coefficient 0.47; 95% CI 0.1, 0.9; P = 0.018) and to the number of fertilized eggs (coefficient 0.3; 95% CI 0.02, 0.58; P = 0.03) after adjusting for age, BMI, and type of ovulation-triggering agent. This means with each 2 ng/mL increase in serum VD level, around one more egg will be retrieved. In addition, there will be one more fertilized oocyte with each 3 ng/mL increase in the vitamin level. However, no significant correlation was found between the vitamin level and the occurrence of chemical or clinical pregnancy.

Conclusions

Serum vitamin D level is positively correlated with the number of retrieved and fertilized oocytes in PCOS patients undergoing ICSI cycles.

Autoantigen Treatment in Type 1 Diabetes: Unsolved Questions on How to Select Autoantigen and Administration Route

Autoantigen treatment has been tried for the prevention of type 1 diabetes (T1D) and to preserve residual beta-cell function in patients with a recent onset of the disease. In experimental animal models, efficacy was good, but was insufficient in human subjects. Besides the possible minor efficacy of peroral insulin in high-risk individuals to prevent T1D, autoantigen prevention trials have failed. Other studies on autoantigen prevention and intervention at diagnosis are ongoing. One problem is to select autoantigen/s; others are dose and route. Oral administration may be improved by using different vehicles. Proinsulin peptide therapy in patients with T1D has shown possible minor efficacy. In patients with newly diagnosed T1D, subcutaneous injection of glutamic acid decarboxylase (GAD) bound to alum hydroxide (GAD-alum) can likely preserve beta-cell function, but the therapeutic effect needs to be improved. Intra-lymphatic administration may be a better alternative than subcutaneous administration, and combination therapy might improve efficacy. This review elucidates some actual problems of autoantigen therapy in the prevention and/or early intervention of type 1 diabetes.

Vitamin D binding protein is related to cardiac autonomic function and metabolic status in prediabetes

A putative causal relationship between vitamin D status and glucose metabolism and a direct effect of vitamin D on cardiac autonomic function (CAF) have been suggested. We hypothesized that vitamin D binding protein (DBP), as a transporter of vitamin D, might also influence CAF and the overall metabolic risk. The present study aims to assess the relationship between DBP and CAF and metabolic status in a high-risk population with prediabetes. A total of 174 subjects (mean age 49.1±12.9 years, mean body mass index 30.2±6.2 kg/m²) were divided into 2 groups according to glucose tolerance: 48 with normal glucose tolerance and 126 with prediabetes. Glucose tolerance was assessed during oral glucose tolerance test, applying 2006 World Health Organization criteria. Fasting and postload glucose and immunoreactive insulin were measured (homeostatic model assessment of insulin resistance and homeostatic model assessment of β-cell function were calculated). Anthropometric indexes, blood pressure, hemoglobin A1c, creatinine, lipids, high-sensitivity C-reactive protein, total 25-hydroxyvitamin D, DBP (free 25-hydroxyvitamin D was calculated), and intact parathormone were measured. Body composition was estimated by impedance analysis (InBody 720), whereas tissue advanced glycation end products were assessed by skin autofluorescence (AGE Reader, DiagnOptics, the Netherlands). CAF was evaluated by АNX-3.0 system, applying standard autonomic tests. DBP was found to be elevated in women, as well as in the presence of cardiac autonomic dysfunction and metabolic syndrome. DBP was related to parasympathetic activity in both sexes and in prediabetes; to body fat in women and in prediabetes; and to age and high-density lipoprotein cholesterol in men. Vitamin D deficiency was established in 40.8% of the studied cohort. These results support the hypothesis that DBP is associated with CAF and some metabolic parameters in prediabetes.

Vitamin D Deficiency Is Associated With Metabolic Risk Factors in Women With Polycystic Ovary Syndrome: A Cross-Sectional Study in Shaanxi China

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women at reproductive age, which is characterized by obesity, hyperandrogenemia, and insulin resistance (IR). This study aimed to investigate the vitamin D status, and analyze the relationship between vitamin D deficiency and metabolic risk factors in PCOS women in Shaanxi China. Methods: A cross-sectional study included 169 women diagnosed with PCOS and 114 control women without PCOS. The serum 25(OH)D and metabolic markers were measured. Vitamin D deficiency was defined as serum 25(OH)D concentration less than 20 ng/mL. The primary outcome was the difference in vitamin D status between the PCOS and control groups, the secondary outcomes were correlations between serum 25(OH)D concentration and metabolic risk factors in women with PCOS. Results: The serum 25(OH)D concentration was significantly lower in women with PCOS than in controls (P < 0.05), and the prevalence rates of 25(OH)D deficiency and insufficiency were significantly higher in women with PCOS than in controls (P < 0.05). The serum 25(OH)D concentration was significantly lower in PCOS women with obesity or IR than in women without obesity or IR (P < 0.05), and the prevalence of 25(OH)D deficiency in PCOS women with obesity or IR was significantly higher than in women without obesity or IR (P < 0.05). Serum 25(OH)D concentration was significantly negatively correlated with body mass index (BMI), waist-to-hip ratio (WHR), fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-sensitivity C-reactive protein (hs-CRP) (P < 0.05). In comparison, serum 25(OH)D concentration was significantly positively correlated with high-density lipoprotein cholesterol (HDL-C) (P < 0.05). Increased BMI and WHR, high levels of fasting insulin, HOMA-IR, total cholesterol, LDL-C and hs-CRP were regarded as risk factors, but high level of HDL-C was considered to be protective factor of vitamin D deficiency in PCOS women. Conclusions: Vitamin D deficiency is prevalent in PCOS women in Shaanxi China, especially in those with obesity and IR. The serum 25(OH)D level was correlated with metabolic risk factors in PCOS women. Multi-center randomized controlled trials with large sample sizes are needed to probe the metabolic effect of vitamin D supplementation in PCOS women.

A single injection of vitamin D3 improves insulin sensitivity and β-cell function but not muscle damage or the inflammatory and cardiovascular responses to an acute bout of resistance exercise in vitamin D-deficient resistance-trained males

Vitamin D deficiency is now a recognised problem affecting multiple physiological functions. The aim of the present study was to evaluate the effect of a single dose of vitamin D3 injection on the inflammatory, muscular damage, metabolic and cardiovascular responses to an acute bout of resistance exercise (RE) in vitamin D-deficient resistance-trained males. Blood samples from fourteen vitamin D-deficient resistance-trained males were obtained during two separate trials: lower vitamin D (LVD) and higher vitamin D (HVD, after vitamin D3 injection). Metabolic, inflammatory, muscle damage and cardiovascular markers were evaluated at baseline, immediately and 1 h after RE. There were significant trial-by-time interactions for insulin and homeostatic model assessment of insulin resistance (HOMA-IR) which significantly (P < 0·05) declined for 1 h after RE in the HVD trial compared with the LVD trial. Homeostasis model assessment of β-cell function (HOMA-β) declines at 1 h post-RE in the HVD trial. There was also a time effect for blood sugar which significantly (P < 0·05) decreased and for creatine kinase, lactate dehydrogenase and IL-6 which increased significantly 1 h post-RE in both trials. There were no significant changes in other inflammatory and cardiovascular markers following both trials. A single injection of vitamin D3 improved insulin resistance and β-cell function following RE in previously vitamin D-deficient resistance-trained males. Conversely, the injection did not change muscle damage and the inflammatory response to acute RE. Intramuscular vitamin D replacement may have key implications for the promotion of glucose metabolism and lowering the risk of diabetes in vitamin D-deficient individuals.

Does vitamin D status correlate with insulin resistance in obese prediabetic patients? An Egyptian multicenter study

BACKGROUND

The link between Vitamin-D deficiency and type 2 diabetes (T2D) is well-established. Since prediabetic obese populations have the greatest risk to develop to T2D, it was important in our study to examine serum 25(OH) D3 concentration among prediabetic obese patients and to evaluate the correlation between serum level of vitamin D and BMI, FBS, HOMA IR and HbA1c among prediabetes patients.

METHODS

A multicenter case control study was carried out among 101 prediabetic persons & 50 controls, after obtaining consent from subjects and clearance from institutional ethics committee. Serum vitamin D level, Plasma levels of glycosylated hemoglobin (HbA1c) and fasting insulin levels were measured by ELISA in both groups enrolled in the study.

RESULTS

The prevalence of vitamin-D deficiency/insufficiency was (73.3%) (n = 74) among 101 prediabetic obese individuals. Also, A significant inverse correlation was observed between vitamin D levels & body mass index(r = - 0.28, P = 0.004); fasting blood sugar (r = - 0.22, P = 0.002); HOMA insulin resistance (r = - 0.25 P = 0.01); HbA1C (r = - 0.2, P= 0.004).

CONCLUSIONS

High prevalence of vitamin D deficiency exists among obese prediabetic individuals and there is significant inverse correlation between BMI, FBS, HOMA IR, HbA1c and vitamin D level.

Microalgal Derivatives as Potential Nutraceutical and Food Supplements for Human Health: A Focus on Cancer Prevention and Interception

Epidemiological studies are providing strong evidence on beneficial health effects from dietary measures, leading scientists to actively investigate which foods and which specific agents in the diet can prevent diseases. Public health officers and medical experts should collaborate toward the design of disease prevention diets for nutritional intervention. Functional foods are emerging as an instrument for dietary intervention in disease prevention. Functional food products are technologically developed ingredients with specific health benefits. Among promising sources of functional foods and chemopreventive diets of interest, microalgae are gaining worldwide attention, based on their richness in high-value products, including carotenoids, proteins, vitamins, essential amino acids, omega-rich oils and, in general, anti-inflammatory and antioxidant compounds. Beneficial effects of microalgae on human health and/or wellness could in the future be useful in preventing or delaying the onset of cancer and cardiovascular diseases. During the past decades, microalgal biomass was predominately used in the health food market, with more than 75% of the annual microalgal biomass production being employed for the manufacture of powders, tablets, capsules or pastilles. In this review, we report and discuss the present and future role of microalgae as marine sources of functional foods/beverages for human wellbeing, focusing on perspectives in chemoprevention. We dissected this topic by analyzing the different classes of microalgal compounds with health outputs (based on their potential chemoprevention activities), the biodiversity of microalgal species and how to improve their cultivation, exploring the perspective of sustainable food from the sea.

Effects of vitamin D supplementation on insulin resistance and dyslipidemia in overweight and obese premenopausal women

INTRODUCTION

Vitamin D deficiency is a common problem, and it is related to increased risk of obesity, metabolic syndrome, atherosclerosis, and cardiovascular disease. Vitamin D has a beneficial effect on dyslipidemia and insulin secretion. We aimed to investigate the impact of vitamin D3 supplementation on anthropometric and laboratory parameters in overweight and obese premenopausal women.

MATERIAL AND METHODS

Seventy-two overweight and 50 obese vitamin-D-deficient premenopausal women (mean age: 43.1 ±10.4 years) were included in the study. Baseline mean 25-hydroxyvitamin D [25(OH)D] level was 6.1 (min.-max. = 2.9-15.8) ng/ml in overweight and was 5.6 (min.-max. = 3.0-22.0) ng/ml in obese subjects. At baseline and at the sixth month of supplementation, serum 25(OH)D, intact parathormone (iPTH), calcium, phosphorus, homeostasis model assessment of insulin resistance (HOMA-IR), and lipid profiles were assessed.

RESULTS

Following vitamin D3 supplementation in overweight and obese subjects, serum 25(OH)D increased from 6.1 to 34.7 ng/ml and 5.6 to 34.7 ng/ml, respectively (p < 0.001). At the sixth month of supplementation in both overweight and obese subjects, a significant reduction was detected in HOMA-IR (p < 0.001), low-density lipoprotein cholesterol (LDL-C) (p = 0.046, p = 0.044; respectively) and iPTH levels (p ≤ 0.001, p < 0.001; respectively). A negative adjusted correlation was found between changes in 25(OH)D and HOMA-IR (r = -0.581, p < 0.001; r = -0.389, p = 0.005; respectively). A 1 ng/ml increase in serum 25(OH)D level led to a 0.30-fold reduction in HOMA-IR level (p = 0.002).

CONCLUSIONS

Our results support the effect of vitamin D3 supplementation in HOMA-IR and LDL-C improvement in both obese and overweight subjects. Further studies focused on low serum 25(OH)D levels with insulin resistance and dyslipidemia are needed.

Analysis of Association between Vitamin D Deficiency and Insulin Resistance

Recent evidence revealed extra skeleton activity of vitamin D, including prevention from cardiometabolic diseases and cancer development as well as anti-inflammatory properties. It is worth noting that vitamin D deficiency is very common and may be associated with the pathogenesis of insulin-resistance-related diseases, including obesity and diabetes. This review aims to provide molecular mechanisms showing how vitamin D deficiency may be involved in the insulin resistance formation. The PUBMED database and published reference lists were searched to find studies published between 1980 and 2019. It was identified that molecular action of vitamin D is involved in maintaining the normal resting levels of ROS and Ca2+, not only in pancreatic β-cells, but also in insulin responsive tissues. Both genomic and non-genomic action of vitamin D is directed towards insulin signaling. Thereby, vitamin D reduces the extent of pathologies associated with insulin resistance such as oxidative stress and inflammation. More recently, it was also shown that vitamin D prevents epigenetic alterations associated with insulin resistance and diabetes. In conclusion, vitamin D deficiency is one of the factors accelerating insulin resistance formation. The results of basic and clinical research support beneficial action of vitamin D in the reduction of insulin resistance and related pathologies.

Serum Vitamin D Levels in Fertile and Infertile Women with Polycystic Ovary Syndrome

Introduction In polycystic ovary syndrome, serum vitamin D levels are known to correlate with metabolic conditions such as diabetes mellitus, metabolic syndrome and cardiovascular disease. However, there are not enough studies showing such a relationship with female fertility. We aimed to compare serum vitamin D levels in fertile and infertile women with polycystic ovary syndrome to evaluate whether vitamin D may play a role in the pathogenesis of fertility problems in women with polycystic ovary syndrome.

Materials and Methods 274 infertile and 111 fertile women with polycystic ovary syndrome were included in this retrospective study. Infertile and fertile groups were matched by age, body mass index and homeostasis model assessment of insulin resistance. Anthropometric, clinical and laboratory characteristics of the women were recorded. Serum 25(OH)D ₃ levels were used to assess serum vitamin D levels.

Results No significant differences were detected between groups in terms of anthropometric, clinical and laboratory features except for serum 25(OH)D ₃ levels and the incidence of vitamin D deficiency. Vitamin D levels were significantly lower and vitamin D deficiency was more common in the infertile group compared to the fertile group. When the groups were stratified into obese/non-obese or insulin resistance positive/negative, infertile obese and infertile insulin resistance-positive women had the lowest serum 25(OH)D ₃ levels.

Conclusion Serum vitamin D levels are lower in infertile women with polycystic ovary syndrome compared to fertile women. When insulin resistance or obesity was present, vitamin D levels were reduced further. Thus, in polycystic ovary syndrome, lower vitamin D levels may play a role in the pathogenesis of fertility problems.

Association of vitamin D deficiency with insulin resistance in middle-aged type 2 diabetics

BACKGROUND

Vitamin D deficiency contributes to the pathophysiology of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). We investigated the association of 25-hydroxyvitamin D [25(OH)D] with IR and β-cell function in middle-aged participants.

METHODS

We enrolled 90 controls and 90 T2DM patients of both genders aged 30-50 years. Serum 25(OH)D, fasting plasma insulin (FPI), fasting plasma glucose (FPG), HbA1c, and lipid profile were measured by standard methods. Insulin resistance and sensitivity were assessed by triglyceride glucose (TyG) index, homeostatic model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), and β-cell function by HOMA-B.

RESULTS

25(OH)D deficiency was reported as 40% in control and 70% in T2DM patients. 25(OH)D concentration was positively associated with age, blood pressure, T2DM duration, FPG, HbA1c, TyG index, and HOMA-IR and negatively associated with HOMA-B and QUICKI among all the participants (p ≤.001). Participants with severe 25(OH)D deficiency (<10 ng/ml) were 39 times higher odds of being T2DM, while, those with moderate deficiency (10-19ng/ml) and insufficiency (20-29 ng/ml) were 16 times and 13 times higher odds of being T2DM, respectively.

CONCLUSION

Sufficient 25(OH)D concentration may lower the risk of development of IR and T2DM in middle-aged control and diabetic participants.

Does high-dose vitamin D supplementation impact insulin resistance and risk of development of diabetes in patients with pre-diabetes? A double-blind randomized clinical trial

AIMS

The aim of this study is to evaluate the effect of high-dose vitamin D on insulin sensitivity and the risk of progression to diabetes.

METHODS

In this double-blind, placebo-controlled randomized clinical trial adults with pre-diabetes and vitamin D deficiency were randomly assigned to either vitamin D₃ or placebo. Fasting plasma glucose (FPG), 2-h oral glucose tolerance test plasma glucose (OGTT PG), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), and the rate of progression of glucose tolerance was compared.

RESULTS

A total of 162 patients were randomized, from which 83 finished the 6-month follow-up (44 in intervention group and 39 in control group). In 6 months, serum 25-hydroxyvitamin D levels were significantly higher in the intervention group (36 ng/ml vs 16 ng/ml, P value < 0.001). There was no significant difference between FPG or 2H-OGTT PG in two groups. HOMA-IR score was significantly lower in the vitamin D group (2.6 vs. 3.1; P value = 0.04). The rate of progression toward diabetes was significantly lower in the intervention group (28% vs. 3%; P value = 0.002).

CONCLUSIONS

In patients with pre-diabetes and hypovitaminosis D, high dose vitamin D improves insulin sensitivity and decreases risk of progression toward diabetes.

The influences of vitamin D and omega-3 co-supplementation on clinical, metabolic and genetic parameters in women with polycystic ovary syndrome

OBJECTIVE

The aim of this study was to evaluate the effect of the co-administration of vitamin D and omega-3 fatty acid on clinical, metabolic and genetic parameters in women with polycystic ovary syndrome (PCOS).

METHODS

This randomized, double-blinded, placebo-controlled clinical trial was conducted on 60 subjects, aged 18-40 years old with PCOS. Subjects were randomly allocated to take either 50,000 IU vitamin D every 2 weeks plus 2000 mg/day omega-3 fatty acid from fish oil (n = 30) or placebo (n = 30) for 12 weeks. Gene expression analysis of inflammatory cytokines was conducted on peripheral blood mononuclear cells (PBMCs) of PCOS women using RT-PCR method.

RESULTS

Vitamin D and omega -3 fatty acid co-supplementation significantly decreased serum total testosterone levels (-0.2 ± 0.5 vs. + 0.1 ± 0.4 ng/mL, P = 0.02) compared with the placebo. In addition, vitamin D and omega-3 fatty acid co-supplementation resulted in a significant improvement in beck depression inventory (-1.4 ± 1.6 vs. -0.5 ± 0.6, P = 0.01), general health questionnaire scores (-4.5 ± 4.3 vs. -1.9 ± 2.3, P = 0.005) and depression anxiety and stress scale scores (-5.0 ± 5.1 vs. -2.3 ± 3.5, P = 0.01) compared with the placebo. Additionally, vitamin D and omega-3 fatty acid co-administration significantly decreased serum high-sensitivity C-reactive protein (hs-CRP) (-1.2 ± 1.9 vs. + 0.1 ± 0.7 mg/L, P = 0.001) and malondialdehyde (MDA) levels (-0.4 ± 0.4 vs. + 0.2 ± 0.6 µmol/L, P < 0.001), and significantly increased plasma total antioxidant capacity (TAC) levels (+ 114.6 ± 122.2 vs. -2.4 ± 168.2 mmol/L, P = 0.003) compared with the placebo. Results of RT-PCR demonstrated that vitamin D and omega-3 fatty acid co-supplementation significantly downregulated gene expression of interleukin-1 (IL-1) (P = 0.03), and upregulated vascular endothelial growth factor (VEGF) (P = 0.004) in PBMCs of subjects with PCOS, when compared with placebo.

CONCLUSIONS

Overall, the co-administration of vitamin D and omega-3 fatty acid for 12 weeks had beneficial effects on mental health parameters, serum total testosterone, hs-CRP, plasma TAC and MDA levels, and gene expression of IL-1 and VEGF among women with PCOS.