The effects of vitamin D supplementation on proatherogenic inflammatory markers and carotid intima media thickness in subjects with metabolic syndrome: a randomized double-blind placebo-controlled clinical trial

Relationship of serum and dietary vitamin D with high cardiometabolic risk in Mexican systemic lupus erythematosus patients: A cross-sectional study

Objetive: Serum and dietary vitamin D could influence clinical disease activity and cardiometabolic outcomes in systemic lupus erythematosus (SLE). This study aimed to assess the relationship of serum and dietary vitamin D with cardiometabolic risk in Mexican SLE patients and healthy subjects (HS).Methods: 224 SLE patients and 201 HS were included in this cross-sectional study. Serum calcidiol was measured using a competitive enzyme-linked immunosorbent assay (ELISA). Vitamin D dietary intake was assessed by collecting three 24h food records. Dietary patterns (DPs) were identified using principal component analysis (PCA). Cardiometabolic status was analyzed through biochemical measurements and cardiometabolic indexes.Results: Calcidiol deficiency (<20 ng/mL) was associated with 1.66-fold higher risk of excess weight by body mass index (BMI) (≥25 kg/m2) (p = .02), 2.25-fold higher risk to low high-density lipoprotein-cholesterol (HDL-C) (<40 mg/dL) (p < .001), and 1.74-fold higher risk to high triglycerides (TG) ≥150 mg/dL (p = .02). Inadequate vitamin D dietary intake was associated with 1.92-fold higher risk of presenting non-healthy waist circumference (WC) (>80 cm) (p < .01), 2.05-fold higher risk of android waist to hip ratio (WHR ≥85) (p < .01), and 1.72-fold higher risk to excess weight (p = .02). Non-adherence to a DP rich in vitamin D food sources was associated with higher WC, WHR, triglycerides, and lower high-density lipoprotein-cholesterol (HDL-C); furthermore, in HS, non-adherence to the DP rich in vitamin D food sources provided 2.11-fold higher risk to calcidiol deficiency.In Cconclusion: A pattern of Calcidiol deficiency, inadequate vitamin D dietary intake, and non-adherence to a DP rich in vitamin D food sources was related to high cardiometabolic risk in SLE patients and HS.

Natural products for managing metabolic syndrome: a scoping review

Introduction

Metabolic syndrome comprises a collection of metabolic disorders stemming from factors like genetic predisposition, inadequate nutrition, stress, decreased physical activity, aging, and ethnicity. Although traditional pharmaceutical treatments exist for metabolic syndrome, their limited popularity is attributed to high costs and adverse effects. Consequently, natural products with fewer side effects have been explored for managing this condition. This literature review aims to explore the role of natural products including herbs, botanicals, vitamins, minerals, probiotics, and dietary supplements in managing metabolic syndrome.

Methods

This scoping review was conducted in five steps, involving the formulation of a research question, the retrieval and extraction of relevant studies, the selection of pertinent studies, the organization of information into tables, and the reporting of results. Data was collected from various databases including Embase, Science Direct, PubMed, Google Scholar, Scopus, and Web of Science, with a focus on studies published from 2010 to the present, available in English and with full-text accessibility.

Results

We identified 1,259 articles, screened their titles, abstracts, and full texts, ultimately incorporating 169 pertinent articles into this review (comprising 90 review articles, 32 trial articles, 6 in vitro articles, 38 in vivo articles, 1 experimental article and 2 observational articles). The study's outcomes revealed that natural products, encompassing plants and their derivatives, vitamins and supplements, as well as probiotics, can exert a beneficial influence on metabolic syndrome by regulating blood sugar, blood pressure, lipid profiles, obesity, and abnormal cholesterol and triglyceride levels.

Conclusion

The current study underscores the significance of natural products in addressing metabolic syndrome. Consequently, it is advisable to conduct further extensive research to assess the efficacy of these products, potentially integrating them into treatment regimens for individuals with metabolic syndrome.

Natural products for managing metabolic syndrome: a scoping review

Introduction

Metabolic syndrome comprises a collection of metabolic disorders stemming from factors like genetic predisposition, inadequate nutrition, stress, decreased physical activity, aging, and ethnicity. Although traditional pharmaceutical treatments exist for metabolic syndrome, their limited popularity is attributed to high costs and adverse effects. Consequently, natural products with fewer side effects have been explored for managing this condition. This literature review aims to explore the role of natural products including herbs, botanicals, vitamins, minerals, probiotics, and dietary supplements in managing metabolic syndrome.

Methods

This scoping review was conducted in five steps, involving the formulation of a research question, the retrieval and extraction of relevant studies, the selection of pertinent studies, the organization of information into tables, and the reporting of results. Data was collected from various databases including Embase, Science Direct, PubMed, Google Scholar, Scopus, and Web of Science, with a focus on studies published from 2010 to the present, available in English and with full-text accessibility.

Results

We identified 1,259 articles, screened their titles, abstracts, and full texts, ultimately incorporating 169 pertinent articles into this review (comprising 90 review articles, 32 trial articles, 6 in vitro articles, 38 in vivo articles, 1 experimental article and 2 observational articles). The study’s outcomes revealed that natural products, encompassing plants and their derivatives, vitamins and supplements, as well as probiotics, can exert a beneficial influence on metabolic syndrome by regulating blood sugar, blood pressure, lipid profiles, obesity, and abnormal cholesterol and triglyceride levels.

Conclusion

The current study underscores the significance of natural products in addressing metabolic syndrome. Consequently, it is advisable to conduct further extensive research to assess the efficacy of these products, potentially integrating them into treatment regimens for individuals with metabolic syndrome.

Effects of vitamin D supplementation on cardiometabolic parameters among patients with metabolic syndrome: A systematic review and GRADE evidence synthesis of randomized controlled trials

Various pathophysiologic mechanisms were proposed to underlie the effect of vitamin D on MetS components. In this systematic review, we reviewed randomized control clinical trials to verify whether vitamin D supplementation (VDS) at different doses is effective concomitantly in controlling high-density lipoprotein cholesterol (HDL-c), triglycerides (TG), fasting glucose level, blood pressure, and central obesity in adults diagnosed with MetS. The following scientific databases were searched from 1998 until April 2023: EMBASE, MEDLINE (PubMed), Web of Science, Latin American and Caribbean Health Sciences Literature (Lilacs), the Cochrane Central Register of Controlled Trials, clinicaltrial.gov, and Google Scholar. No language restrictions were applied. Seven studies were included, and they showed a high level of heterogeneity. All studies reported a significant increase in serum 25(OH)D levels in the intervention groups. Of these, only two noted a significant decrease in triglyceride (TG) level and waist circumference. However, the certainty levels of the evidence rating were very low and low for triglyceride (TG) level and waist circumference, respectively, and moderate for fasting glucose level, blood pressure, and HDL-c. In conclusion, despite these benefits, considering the low certainty, the evidence does not support that VDS decreases triglyceride (TG) level and waist circumference in adults with MetS.

Sun Exposure and Intima-Media Thickness in the Mexican Teachers' Cohort Study

Objective: To determine whether long-term sun exposure has a protective role in subclinical cardiovascular disease in adult Mexican women. Materials and Methods: We conducted a cross-sectional analysis of a sample of women from the Mexican Teachers' Cohort (MTC) study. Sun exposure was assessed in the MTC 2008 baseline questionnaire, in which women were asked about their sun-related behavior. Vascular neurologists measured carotid intima-media thickness (IMT) using standard techniques. Multivariate linear regression models were used to estimate the difference in mean IMT and 95% confidence intervals (95% CIs), according to categories of sun exposure and multivariate logistic regression models were used to estimate the odds ratio (OR) and 95% CIs for carotid atherosclerosis. Results: The mean age of participants was 49.6 ± 5.5 years, the mean IMT was 0.678 ± 0.097 mm, and the mean accumulated hours of weekly sun exposure were 2.9 ± 1.9. Prevalence of carotid atherosclerosis was 20.9%. Compared with women in the lowest quartile of sun exposure, women in the highest quartile had lower mean IMT, but this was not significant in the multivariable adjusted analysis. (Adjusted mean % difference: -0.8; 95% CI: -2.3 to 0.8). The multivariate adjusted ORs of carotid atherosclerosis were 0.54 (95% CI: 0.24-1.18) for women who were exposed 9 hours. For women who denied regular sunscreen use, those in the higher exposure category (9 hours) had lower mean IMT compared with those in the lower category (multivariable-adjusted mean % difference = -2.67; 95% CI: -6.9 to -1.5). Conclusions: We observed that cumulative sun exposure was inversely associated with IMT and subclinical carotid atherosclerosis. If these findings are further replicated and seen for other cardiovascular outcomes, sun exposure could be an easy, affordable strategy to lower overall cardiovascular risk.

Vitamin D and neurodegenerative diseases

Neurodegenerative diseases, featured by progressive loss of structure or function of neurons, are considered incurable at present. Movement disorders like tremor and postural instability, cognitive or behavioral disorders such as memory impairment are the most common symptoms of them and the growing patient population of neurodegenerative diseases poses a serious threat to public health and a burden on economic development. Hence, it is vital to prevent the occurrence of the diseases and delay their progress. Vitamin D can be transformed into a hormone in vivo with both genomic and non-genomic actions, exerting diverse physiological effects. Cumulative evidence indicates that vitamin D can ameliorate neurodegeneration by regulating pertinent molecules and signaling pathways including maintaining Ca²⁺ homeostasis, reducing oxidative stress, inhibiting inflammation, suppressing the formation and aggregation of the pathogenic protein, etc. This review updates discoveries of molecular mechanisms underlying biological functions of vitamin D in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, multiple sclerosis, and vascular dementia. Clinical trials investigating the influence of vitamin D supplementation in patients with neurodegenerative diseases are also summarized. The synthesized information will probably provoke an enhanced understanding of the neuroprotective roles of vitamin D in the nervous system and provide therapeutic options for patients with neurodegenerative diseases in the future.

Effect of vitamin D supplementation on cardiac-metabolic risk factors in elderly: a systematic review and meta-analysis of clinical trials

BACKGROUND

There has been a longstanding interest in the potential effect of vitamin D in preventing cardiac-metabolic diseases. However, there are divergent results regarding the impact of vitamin D supplementation (VDS) on managing cardiac-metabolic outcomes in the elderly population.

MATERIAL AND METHOD

We systematically searched electronic databases; Web of Science, PubMed, Scopus, EMBASE, Cochrane, and ProQuest. We included all trials that evaluated the effect of VDS on cardiac-metabolic risk factors in the elderly population, which were published until 30 September 2021. The effects of VDS on cardiac-metabolic outcomes were assessed using standardized mean difference (SMD). A random-effect model was used to pool the SMD and 95% confidence interval (CI).

RESULT

The literature search identified 4409 studies, of which 12 trials met inclusion criteria. Results of random effect meta-analysis indicated a significant reduction in total cholesterol (TC) (SMD: - 0.14 mg/dl; 95% CI: - 0.25, - 0.02) and triglyceride (TG) (SMD: - 0.45 mg/dl; 95% CI: - 0.86, - 0.04) with VDS compared to the placebo. The subgroup analyses revealed that the reduction of TG in patients with diabetes and vitamin D deficiency was significant. Furthermore, short-term intervention (≤ 6 months) induced a significantly lower level of TG and insulin in comparison to longer duration (> 6 months).

CONCLUSION

The study suggests that VDS could improve insulin concentration and dyslipidemia in the elderly population. The systematic review was registered in Alborz university of medical sciences with 2060-01-03-1397 number and the Ethics council IR.ABZUMS.REC.1397.207 number.

Correlation of Carotid Artery Intima-Media Thickness with Calcium and Phosphorus Metabolism, Parathyroid Hormone, Microinflammatory State, and Cardiovascular Disease

The internal thickness of the carotid artery is the vertical distance between the intima of the carotid artery and the middle mold. Its normal thickness is less than 1 mm. It can be used to judge the degree of arteriosclerosis. Under normal circumstances, the change of the internal thickness of the carotid artery is caused by cardiovascular disease. The purpose of this article is to study the relationship between the thickness of the carotid artery and the metabolism of calcium and phosphorus, parathyroid hormone, microinflammatory state, and cardiovascular disease. This article uses ultrasound measurement to measure the IMT of ESRD patients and carotid arteries with normal renal function. The analysis includes blood pressure, blood phosphorus, blood calcium, blood creatinine, blood urea nitrogen, blood sugar, glycosylated hemoglobin, blood lipids, parathyroid hormone, and C reaction. The correlation between clinical indicators includes protein and carotid IMT in ESRD patients which can be used in designing a diagnostic plan for patients through correlation research. The results showed that the carotid artery IMT of ESRD nondialysis patients was 13% thicker than that of those with normal renal function, and it was significantly positively correlated with age, blood pressure, blood phosphorus, glycosylated hemoglobin, and C-reactive protein. The correlation ratio with calcium and phosphorus was about 0.1.

Protective actions of vitamin D, anandamide and melatonin during vascular inflammation: Epigenetic mechanisms involved

Vascular inflammation is one of the main activating stimuli of cardiovascular disease and its uncontrolled development may worsen the progression and prognosis of these pathologies. Therefore, the search for new therapeutic options to treat this condition is undoubtedly needed. In this regard, it may be better to repurpose endogenous anti-inflammatory compounds already known, in addition to synthesizing new compounds for therapeutic purposes. It is well known that vitamin D, anandamide, and melatonin are promising endogenous substances with powerful and wide-spread anti-inflammatory properties. Currently, the epigenetic mechanisms underlying these effects are often unknown. This review summarizes the potential epigenetic mechanisms by which vitamin D, anandamide, and melatonin attenuate vascular inflammation. This information could contribute to the improvement in the therapeutic management of multiple pathologies associated with blood vessel inflammation, through the pharmacological manipulation of new target sites that until now have not been addressed.

The effects of vitamin D supplementation on inflammatory biomarkers in patients with abnormal glucose homeostasis: A systematic review and meta-analysis of randomized controlled trials

FINDINGS

on the level of inflammatory cytokines following vitamin D supplementation among individuals with abnormal glucose homeostasis (AGH) are controversial. Therefore, the present study was conducted on AGH patients to assess the impact of vitamin D on inflammatory cytokines such as CRP, TNF-α and IL-6. A systematic search up to September 2020 was performed through PubMed and Scopus databases. All clinical studies which evaluated the effect of oral vitamin D supplementation on inflammation in patients with AGH were included. The random-effects model was applied to obtain pooled results. For dose-response analysis, we used a fractional polynomial model. Overall, 38 studies, with 46 effect sizes, were included in this study. Combining effect sizes, we found that vitamin D considerably decrease serum concentrations of CRP (weight mean difference (WMD): - 0.67 mg/l; 95%CI: - 0.92, - 0.43; P < 0.001), IL-6 (WMD: -1.93 pg/mL; 95%CI: -2.80, -1.07; P < 0.001) and TNF-α (WMD: -0.81 pg/mL; 95%CI: -1.59, -0.03; P = 0.04). In the dose-response analysis, we failed to find any correlation between dosage of supplements and inflammatory biomarkers concentrations. Summarizing earlier studies, we demonstrated that circulating concentrations of inflammatory cytokines such as CRP, TNF-α, and IL-6 might be decreased following vitamin D supplementation among individuals with AGH.

Effects of vitamin supplements on clinical cardiovascular outcomes: Time to move on! - A comprehensive review

BACKGROUND & AIMS

Vitamin supplementations have increasingly been advertised on media and reported to be widely used by the general public to improve cardiovascular health. Due to the COVID-19 pandemic, people have become more interested in ways to improve and maintain their health. Increased awareness of people on healthy lifestyle is translating into inquisition regarding dietary supplements.

AIM

First, focus on the most commonly used vitamin supplements and comprehensively review the evidence for and against recommending them to patients to improve and/or maintain cardiovascular health. Second, illustrate how the interest in studies shifted over time from Vitamin A, E, C, and B to Vitamin D and observational studies led to randomized controlled trials.

METHODS

A thorough PubMed search with the phrase: "Vitamin supplements and cardiovascular health" was performed. In the present review, focus was maintained on the evidence for the use of vitamin supplements in the prevention of major cardiovascular events and/or the maintenance of cardiovascular health by comprehensively reviewing all previous studies indexed in PubMed. Studies with clinical 'hard' end-points were included only.

RESULTS

A total of 87 studies met the inclusion criteria and were reviewed in the present article. High-quality evidence suggesting benefits for the use of vitamin supplements to maintain or improve cardiovascular health in people is minimal to non-existent.

CONCLUSIONS

Vitamin supplementation does not improve clinical cardiovascular outcomes in general population. Counseling on the importance of maintaining a healthy lifestyle with adequate and nutritious food intake seems more appropriate to improve and maintain cardiovascular health.

Vitamin D and Its Role in the Lipid Metabolism and the Development of Atherosclerosis

Vitamin D, a crucial hormone in the homeostasis and metabolism of calcium bone, has lately been found to produce effects on other physiological and pathological processes genomically and non-genomically, including the cardiovascular system. While lower baseline vitamin D levels have been correlated with atherogenic blood lipid profiles, 25(OH)D supplementation influences the levels of serum lipids in that it lowers the levels of total cholesterol, triglycerides, and LDL-cholesterol and increases the levels of HDL-cholesterol, all of which are known risk factors for cardiovascular disease. Vitamin D is also involved in the development of atherosclerosis at the site of the blood vessels. Deficiency of this vitamin has been found to increase adhesion molecules or endothelial activation and, at the same time, supplementation is linked to the lowering presence of adhesion surrogates. Vitamin D can also influence the vascular tone by increasing endothelial nitric oxide production, as seen in supplementation studies. Deficiency can lead, at the same time, to oxidative stress and an increase in inflammation as well as the expression of particular immune cells that play a pivotal role in the development of atherosclerosis in the intima of the blood vessels, i.e., monocytes and macrophages. Vitamin D is also involved in atherogenesis through inhibition of vascular smooth muscle cell proliferation. Furthermore, vitamin D deficiency is consistently associated with cardiovascular events, such as myocardial infarction, STEMI, NSTEMI, unstable angina, ischemic stroke, cardiovascular death, and increased mortality after acute stroke. Conversely, vitamin D supplementation does not seem to produce beneficial effects in cohorts with intermediate baseline vitamin D levels.

Associations Between Different Dietary Vitamins and the Risk of Obesity in Children and Adolescents: A Machine Learning Approach

BACKGROUNDS

Simultaneous dietary intake of vitamins is considered as a common and real scenario in daily life. However, limited prospective studies have evaluated the association between multivitamins intake and obesity in children and adolescents.

OBJECTIVES

This study aimed to evaluate the relationship between the intake of different dietary vitamins and the risk of obesity in children (6-11 years) and adolescents (12-19 years).

METHODS

We conducted a cross-sectional study based on data from U.S. National Health and Nutrition Examination Survey, 2013-2016. A total of 3634 children and adolescents were included who had available data on dietary vitamins, obesity and covariates. We analyzed the dietary intake levels of nine vitamins, including vitamin A, vitamin B₁, vitamin B₂, vitamin B₆, vitamin B₁₂, vitamin C, vitamin D, vitamin E, vitamin K. Multivariate logistic regression was used to model the associations between vitamins and obesity. Bayesian kernel machine regression (BKMR) was employed to explore the joint and independent effects of vitamins on obesity among children and adolescents.

RESULTS

In the multivariate logistic regression model, five vitamins (vitamin A, vitamin B₁, vitamin B₂, vitamin B₁₂, and vitamin D) were negatively associated with obesity in children and adolescents. BKMR analysis showed that when the concentration of the nine vitamins was at or above the 55th percentile compared with the median value, the combined intake of these vitamins could significantly reduce the risk of obesity in children and adolescents. Potential interactions between vitamin B₂ and vitamin B₁₂ in increasing the risk of obesity in children and adolescents were observed.

CONCLUSIONS

We determine the combined effects of multivitamins on obesity in children and adolescents, and observe a significant interaction between vitamin B₂ and vitamin B₁₂. Further cohort studies are needed to clarify the health effects of multivitamins intake in a larger population.

Mechanistic Effects of Vitamin D Supplementation on Metabolic Syndrome Components in Patients with or without Vitamin D Deficiency

The prevalences of metabolic syndrome (MetS) and vitamin D deficiency are increasing dramatically worldwide. MetS is a major challenge because it can increase the risk of most non-communicable diseases. The beneficial effect of vitamin D on MetS components remains controversial, so the present review focused on the clinical effects of vitamin D supplementation on MetS components. Vitamin D can inhibit the protein expression of nuclear factor beta; improve arterial stiffness; decrease renin-angiotensin-aldosterone system activity, parathyroid hormone levels, inflammatory cytokines, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, and lanosterol 14 α-demethylase enzyme activity; increase the activity of lipoprotein lipase; alter gene expression in C2C12 cells; and improve phospholipid metabolism and mitochondrial oxidation. We tried to elucidate and analyze almost all evidence from randomized controlled trial studies of the efficacy of vitamin D supplementation in patients with MetS. The findings of the present study reported beneficial effects of vitamin D supplementation on mentioned factors. Vitamin D supplementation is recommended in people with vitamin D deficiency even if it has no considerable effect on most MetS factors. However, existing data from interventional studies are insufficient to reach a definitive conclusion about the effect of vitamin D supplementation on MetS components in patients without vitamin D deficiency. Thus, new clinical studies are needed to test the hypothesis that vitamin D supplementation could alleviate MetS components in patients with sufficient intake of vitamin D.

Effects of Vitamin D Supplementation on Lipid Profile in Adults with the Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Metabolic syndrome (MetS) increases the risk of cardiovascular disease, with atherogenic dyslipidemia being a major contributing factor.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to assess whether vitamin D supplementation (VDS) alleviates dyslipidemia in adults with MetS. Scientific databases (PUBMED, MEDLINE, CINAHL, EMBASE, Cochrane Library, ClinicalTrials.gov, International Clinical Trials Registry Platform) and the gray literature were searched for randomized controlled trials of VDS, reporting on blood lipids. A narrative review, meta-analyses, sensitivity analyses, and appraisal of the risk of bias and overall quality of evidence produced were conducted.

RESULTS

Seven studies were included, and four were meta-analyzed. The risk of bias was generally low, and the final quality of evidence was low or very low. VDS, whether in high or low dose, significantly increased endline vitamin D blood levels; did not affect total, low-density, high-density cholesterol levels, and novel lipid-related biomarkers; yet, significantly increased triglycerides (TG) levels compared with placebo (MD: 30.67 (95%CI: 4.89-56.45) mg/dL; p = 0.02 for low-dose VDS; and MD: 27.33 (95%CI: 2.06-52.59) mg/dL; p = 0.03 for high-dose VDS). Pertaining heterogeneity was high (I² = 86%; and I² = 51%, respectively), and some included studies had significantly higher baseline TG in the intervention arm. The sensitivity analyses revealed robust results.

CONCLUSION

VDS seems not to affect blood lipids in adults with MetS.

Delta-like 1 (DLK1) is a possible mediator of vitamin D effects on bone and energy metabolism

Vitamin D effects on bone and mineral metabolism are well recognized, and its anti-inflammatory actions are gaining particular interest. Delta-like 1 (DLK1) is a protein, expressed by progenitor cells of different tissues, and increases the size of progenitor cell population during the inflammatory phase of tissue regeneration. DLK1 also plays a role in energy metabolism as it antagonizes insulin signaling in bone. In this one-year randomized clinical trial of overweight elderly individuals that received either 600 or 3750 IU daily cholecalciferol we assessed the effect of vitamin D supplementation on pre-specified secondary outcomes: DLK1, leptin, adiponectin, C-Reactive Protein (CRP) and Vascular Cell Adhesion Molecule (VCAM). We also examined correlations between DLK1 and bone (BMD, bone markers), fat (adipokines, body composition), insulin sensitivity and inflammatory markers. Multivariate analyses were conducted to further explore these associations. Overall, there was a significant increase in serum DLK1 and leptin and a decrease in VCAM, but no change in CRP, after 12 months of vitamin D supplementation. DLK1 was negatively correlated with BMD and positively correlated with bone markers, associations that persisted after adjusting for age, gender and BMI. DLK1 was also positively associated with indices of insulin resistance and negatively with indices of insulin sensitivity. Correlations between DLK1 and fat parameters, such as adipokines, and DXA derived fat mass were less consistent. There were no correlations between DLK1 and inflammatory markers. In conclusion, twelve months supplementation of vitamin D3 increased serum DLK1. DLK1 was negatively associated with indices of bone health and fuel metabolism, and with 1,25(OH)2D levels. Similar to the role of DLK1 in animal models, our findings support the hypothesis that DLK1 can be targeted to regulate bone and energy metabolism and develop drugs to improve BMD and insulin sensitivity. However, further studies are needed to explore the role of DLK1 and its relationship to vitamin D metabolites in vivo.

High-Dose Vitamin D Supplementation Improves Microcirculation and Reduces Inflammation in Diabetic Neuropathy Patients

We assessed the effect of different doses of vitamin D supplementation on microcirculation, signs and symptoms of peripheral neuropathy and inflammatory markers in patients with type 2 diabetes (T2DM). Sixty-seven patients with T2DM and peripheral neuropathy (34 females) were randomized into two treatment groups: Cholecalciferol 5000 IU and 40,000 IU once/week orally for 24 weeks. Severity of neuropathy (NSS, NDS scores, visual analogue scale), cutaneous microcirculation (MC) parameters and inflammatory markers (ILs, CRP, TNFα) were assessed before and after treatment. Vitamin D deficiency/insufficiency was detected in 78% of the 62 completed subjects. Following treatment with cholecalciferol 40,000 IU/week, a significant decrease in neuropathy severity (NSS, p = 0.001; NDS, p = 0.001; VAS, p = 0.001) and improvement of cutaneous MC were observed (p < 0.05). Also, we found a decrease in IL-6 level (2.5 pg/mL vs. 0.6 pg/mL, p < 0.001) and an increase in IL-10 level (2.5 pg/mL vs. 4.5 pg/mL, p < 0.001) after 24 weeks of vitamin D supplementation in this group. No changes were detected in the cholecalciferol 5000 IU/week group. High-dose cholecalciferol supplementation of 40,000 IU/week for 24 weeks was associated with improvement in clinical manifestation, cutaneous microcirculation and inflammatory markers in patients with T2DM and peripheral neuropathy.

Effects of vitamin D supplementation on fasting glucose, dyslipidemia, blood pressure, and abdominal obesity among patients with metabolic syndrome: a protocol for systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Vitamin D deficiency can play a role in extraskeletal functions that are involved with a set of risk factors associated with metabolic syndrome (MetS). The purpose of this review is to investigate the impact of vitamin D supplementation on fasting glucose, dyslipidemia, blood pressure, and abdominal obesity among patients with MetS.

METHODS

EMBASE, Medline, Web of Science, Lilacs, the Cochrane Central Register of Controlled Trials, clinicaltrials.gov databases, and grey literature will be systematically searched for randomized controlled trials (RCTs) of vitamin D supplementation compared with placebo, through December 2020. We will include in the study patients with MetS diagnosed by the criteria set forth by the National Cholesterol Education Program Adult Treatment Panel III or the International Diabetes Federation. The effect of oral vitamin D supplementation on lipid profile improvement (triglycerides, high-density lipoprotein cholesterol-HDL-C) is this review's primary outcome. The systematic review will be performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The study screening, data extraction, and quality assessment will be fulfilled by two independent reviewers according to the Cochrane Risk of Bias tool (RoB 2.0). The results of the systematic review will be provided according to the type of intervention, characteristics of the target population, the methods of measurement of vitamin D, the calculated vitamin D concentrations, types of biological samples, and types of outcomes. Meta-analyses will be conducted where appropriate. The Cochran's Q test and the I2-heterogeneity test will be used to assess the presence of heterogeneity and whether the fixed or the random-effects model would be appropriate for combining study results using the inverse variance method or the DerSimonian-Lair method, respectively. Publication bias will be evaluated using funnel plots and Egger's and Begg's tests. The strength of the evidence will be assessed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

DISCUSSION

This systematic review will assess the effects of vitamin D supplementation on fasting glucose and triglyceride levels, waist circumference and mean blood pressure, and HDL-C among individuals with MetS. These findings may assist with decision-making within a clinical setting.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42019123212.

The effect of intramuscular megadose of vitamin D injections on E-selectin, CRP and biochemical parameters in vitamin D-deficient patients with type-2 diabetes mellitus: A randomized controlled trial

BACKGROUND AND AIMS

Inflammatory processes has been shown to be associated with the development of type 2 diabetes mellitus (T2DM) in which vitamin D supplementation might exert beneficial outcomes. We examined the effects of vitamin D supplement on inflammatory and cell adhesion molecule in patients with T2DM.

METHODS

This study consisted of 50 patients with T2DM who had vitamin D deficiency. Participants were randomized into two groups of 25 in which the intervention group received two intramuscular injections of a 200000-IU vitamin D supplement, one at week 0 and another at week 4. The concentrations of fasting blood glucose (FBG), lipid profiles, liver enzymes, E-selectin, C-reactive protein (CRP), calcium, phosphorus, serum 25-hydroxyvitamin D [25(OH)D] and anthropometric indices were obtained before and after 8 weeks.

RESULTS

Vitamin D resulted in significant reductions in CRP(P = 0.01) and gamma glutamyl transferase (GGT) levels(P = 0.03) and significant increases in 25(OH)D concentrations(P = 0.01) in the intervention group compared with the control. Within-group comparisons showed that FBG decreased significantly in the intervention group(P = 0.04). No significant changes were observed regarding within- and between-group comparisons of the other markers.

CONCLUSION

Vitamin D had beneficial effects on the levels of CRP, serum 25(OH)D and GGT among vitamin D deficient patients with T2DM. (http://www.irct.ir: IRCT2017100336539N1).

Assessment of Subclinical Atherosclerosis in Vitamin D Deficiency

PURPOSE

Patients with vitamin D deficiency (VDD) have potential to have increased cardiovascular morbidity and mortality. In this study, we aimed to discover the findings of early atherosclerosis in patients with VDD by measuring carotid intima-media thickness (CIMT) and epicardial fat thickness (EFT).

MATERIALS AND METHODS

The study population includes 52 patients with VDD (n = 30 [57% female], mean ± SD age 54.28 ± 8.77 years, mean ± SD serum 25-hydroxyvitamin D (25 [OH] D) 11 ± 2.4 ng/mL) and 82 participants for control group (n = 52 [63.4% female], mean ± SD age 56.40 ± 7.90 years, mean ± SD serum (25 [OH] D) 53 ± 4.2 ng/mL) who have no cardiovascular disease. Carotid intima-media thickness was assessed by using ultrasonography, and EFT was measured on the free wall of the right ventricle at end diastole from the parasternal long-axis views by standard transthoracic 2-dimensional echocardiography.

RESULTS

Both CIMT and EFT were significantly higher in patients with VDD compared with controls (0.75 ± 0.16 mm vs 0.68 ± 0.21 mm, P < 0.05, and 0.66 ± 0.15 cm vs 0.56 ± 0.15 cm, P < 0.001).

CONCLUSIONS

Patients with VDD seem to have increased CIMT and EFT, which are predictors of atherosclerotic process. Further studies are needed to confirm these results.

Association of 25-hydroxyvitamin D with cardiometabolic risk factors and metabolic syndrome: a mendelian randomization study

Background

Low circulating vitamin D levels have been associated with increased risk of metabolic syndrome (MS) and cardiometabolic risk factors in multiple epidemiology studies. However, whether this association is causal is still unclear. We aimed to test whether genetically lowered vitamin D levels were associated with MS and its metabolic traits, using mendelian randomization (MR) methodology.

Methods

Ten thousand six hundred fifty-five participants were enrolled from the SPECT-China study, which was performed in 23 sites in East China during 2014 to 2016. Using four single-nucleotide polymorphisms (SNPs) in the DHCR7, CYP2R1, GC and CYP24A1 genes with known effects on 25(OH) D concentrations, we created a genetic risk score (GRS) as instrumental variable (IV) to estimate the effect of genetically lowered 25(OH) D on MS and cardiometabolic risk factors. MS was defined according to the International Diabetes Federation criteria.

Results

Lower measured 25(OH)D levels were associated with MS (OR 0.921, 95% CI 0.888, 0.954) after multivariable adjustment. However, the MR-derived odds ratio of genetically determined 25(OH) D for risk of MS was 0.977 (95% CI 0.966, 1.030). The MR-derived estimates for raised fasting plasma glucose was 0.578 (95% CI 0.321, 0.980) per 10 nmol/L GRS_synthesis determined increase of 25(OH) D levels.

Conclusions

We found no evidence that genetically determined reduction in 25(OH)D conferred an increased risk of MS and its metabolic traits. However, we created our GRS only on the basis of common variants, which represent limited amount of variance in 25(OH)D. MR studies using rare variants, and large-scale well-designed RCTs about the effect of vitamin D supplementation on MS are warranted to further validate the findings.

Vitamin D Status in Women with Pelvic Floor Disorders: A Meta-Analysis of Observational Studies

The current evidence regarding the association between vitamin D status and pelvic floor disorder (PFD) are inconclusive. This meta-analysis was aimed to summarize existing data demonstrating the association between Vitamin D status and PFD using published observational studies. All national and international databases including Web of Science, PubMed, Google Scholar, and Scopus were searched up until January 30, 2018, and related published studies retrieved for meta-analysis. The effect sizes of Vitamin D status were presented as standardized mean difference (SMD) with 95% confidence interval (CI), using random-effect models and inverse variance method. The Cochran Q statistic and I² tests were used to evaluate the heterogeneity across included studies. Seven studies with 3219 women were included our meta-analysis. There was heterogeneity existing among included studies (I² = 96.4%, P < 0.001), so a random-effect model was used. The findings of this meta-analysis revealed that the mean serum Vitamin D levels in women with PFD were significantly lower than healthy women (SMD −0.60; 95% CI, −1.06, −0.13; P = 0.01). This meta-analysis demonstrates lower levels of serum Vitamin D in women with PFD rather than healthy women. Additional prospective studies regarding the association between Vitamin D status and PFD are required to confirm our findings.

Long-term vitamin D and high-dose n-3 fatty acids' supplementation improve markers of cardiometabolic risk in type 2 diabetic patients with CHD

This study was performed to evaluate the effects of vitamin D and n-3 fatty acids' co-supplementation on markers of cardiometabolic risk in diabetic patients with CHD. This randomised, double-blinded, placebo-controlled trial was conducted among sixty-one vitamin D-deficient diabetic patients with CHD. At baseline, the range of serum 25-hydroxyvitamin D levels in study participants was 6·3-19·9 ng/ml. Subjects were randomly assigned into two groups either taking 50 000 IU vitamin D supplements every 2 weeks plus 2× 1000 mg/d n-3 fatty acids from flaxseed oil (n 30) or placebo (n 31) for 6 months. Vitamin D and n-3 fatty acids' co-supplementation significantly reduced mean (P = 0·01) and maximum levels of left carotid intima-media thickness (CIMT) (P = 0·004), and mean (P = 0·02) and maximum levels of right CIMT (P = 0·003) compared with the placebo. In addition, co-supplementation led to a significant reduction in fasting plasma glucose (β -0·40 mmol/l; 95 % CI -0·77, -0·03; P = 0·03), insulin (β -1·66 μIU/ml; 95 % CI -2·43, -0·89; P < 0·001), insulin resistance (β -0·49; 95 % CI -0·72, -0·25; P < 0·001) and LDL-cholesterol (β -0·21 mmol/l; 95 % CI -0·41, -0·01; P = 0·04), and a significant increase in insulin sensitivity (β +0·008; 95 % CI 0·004, 0·01; P = 0·001) and HDL-cholesterol (β +0·09 mmol/l; 95 % CI 0·01, 0·17; P = 0·02) compared with the placebo. Additionally, high-sensitivity C-reactive protein (β -1·56 mg/l; 95 % CI -2·65, -0·48; P = 0·005) was reduced in the supplemented group compared with the placebo group. Overall, vitamin D and n-3 fatty acids' co-supplementation had beneficial effects on markers of cardiometabolic risk.

Serum 25-hydroxyvitamin D is associated with obesity and metabolic parameters in US children

OBJECTIVE

To explore the relationships of serum 25-hydroxyvitamin D (25(OH)D) with obesity and metabolic parameters in US children.

DESIGN

Cross-sectional analysis. We evaluated the associations between serum 25(OH)D and multiple measurements of adiposity, serum lipid concentrations, fasting glucose and insulin resistance in children aged 6-18 years with adjustments for multiple covariates.

SETTING

The National Health and Nutrition Examination Survey, 2001-2006.

PARTICIPANTS

A nationally representative sample of 6311 children and adolescents aged 6-18 years.

RESULTS

Among US children and adolescents, the prevalence of vitamin D deficiency has been especially high in older children, girls and the non-Hispanic Black population. Higher odds of obesity were found at a 25(OH)D concentration of <30 nmol/l (deficiency) than at >50 nmol/l under both criteria for obesity in children (OR = 3·27, Ptrend ≤ 0.001). Moreover, increased odds of having abnormal HDL-cholesterol (OR = 1·71, Ptrend ≤ 0.001) and impaired insulin resistance (OR = 4·15, Ptrend ≤ 0·001) were found for children deficient in 25(OH)D compared with those with normal 25(OH)D concentrations. When the children and adolescents were stratified by gender, we found stronger associations between serum 25(OH)D concentration and both HDL-cholesterol and insulin resistance in girls. No association of 25(OH)D with any other metabolic parameter was found.

CONCLUSIONS

Our results suggest a potential harmful association between low serum 25(OH)D concentration and the risk of obesity among children. However, the underlying mechanisms require further investigation.

The effects of vitamin D supplementation on endothelial activation among patients with metabolic syndrome and related disorders: a systematic review and meta-analysis of randomized controlled trials

Background and objective

The current systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effect of vitamin D supplementation on endothelial activation among patients with metabolic syndrome and related disorders.

Methods

Cochrane library, Embase, PubMed, and Web of Science database were searched to identify related RCTs published before 30th April 2018. The heterogeneity among the included studies was assessed using Cochran’s Q test and I-square (I²) statistic. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as summary effect size.

Results

Fourteen clinical trials that contained a total of 1253 participants were included in the current meta-analysis. Vitamin D supplementation significantly decreased von willebrand factor (vWF) (SMD -0.27; 95% CI, − 0.46, − 0.08; P = 0.006; I²:40.5%). However, we found no significant impact of vitamin D supplementation on intercellular adhesion molecule 1(ICAM-1) (SMD -1.96; 95% CI, − 4.02, 0.09; P = 0.06; I²:97.4%), vascular celladhesion molecule 1 (VCAM-1) (SMD -0.50; 95% CI, − 1.19, 0.19; P = 0.15; I²:91.2%), on E-selectin (SMD -0.04; 95% CI, − 0.36, 0.28; P = 0.81; I²:78.8%) and endothelin (SMD -0.49; 95% CI, − 1.18, 0.19; P = 0.15; I²:90.5%). The pooled data from trials of vitamin D supplementation with dosage of ≤4000 IU/day (− 0.37, 95% CI: -0.65, − 0.10, I²: 73.5%) significantly reduced vWF concentrations, while there was no effect of vitamin D supplementation on vWF concentrations among trials with the dosage of intervention > 4000 IU/day (− 0.17, 95% CI: -0.43, 0.10, I²: 0.0%). VWF concentrations significantly reduced in pooled data from trials with duration study ≤8 weeks (− 0.37, 95% CI: -0.67, − 0.07, I²: 60.6%), but there was no effect of vitamin D supplementation on vWF concentrations among trials with > 8 weeks (− 0.20, 95% CI: -0.45, 0.05, I²: 0.0%). While there was no effect of vitamin D supplementation on vWF concentrations among trials with total sample size of ≤60 patients (− 0.03, 95% CI: -0.42, 0.36, I²: 0.0%), vWF concentrations in trials with more than 60 patients decreased significantly (− 0.34, 95% CI: -0.56, − 0.12, I²: 60.9%).

Conclusions

Overall, the current meta-analysis demonstrated that vitamin D supplementation to patients with metabolic syndrome and related disorders resulted in an improvement in vWF, but did not affect ICAM-1, VCAM-1, E-selectin and endothelin levels.

Electronic supplementary material

The online version of this article (10.1186/s12986-018-0320-9) contains supplementary material, which is available to authorized users.

Vitamin D supplementation and serum heat shock protein 60 levels in patients with coronary heart disease: a randomized clinical trial

BACKGROUND

The aim in this study was to investigate the effect of vitamin D (25(OH)D3) supplementation on heat shock protein 60 (HSP 60) and other inflammatory markers (IL-17, TNF-α, PAB) in patients with coronary heart disease (CHD).

METHODS

In this double-blind, randomized clinical trial, we recruited 80 male and female patients aged 30-60 with CHD and 25(OH)D3 serum levels < 30 ng/ml from Rasool-e-Akram Hospital in Tehran, Iran. Serum levels of HSP 60 as primary outcome, and 25(OH)D3, IL-17, TNF-α, PAB, lipid profiles and parathyroid hormone (PTH) as secondary outcomes were measured at baseline and post-intervention. We randomly assigned eligible participants to a placebo group (N = 40) or an intervention group (N = 40) (50,000 IU/wk. vitamin D supplement) for eight weeks.

RESULTS

The results demonstrated that vitamin D supplementation resulted in a significant increase in 25(OH) D3 serum levels in the intervention group compared to the placebo group (46.86 vs. 7.28 ng/ml). PTH levels decreased in the intervention group compared to the placebo group (- 19.81 vs. 2.92 pg/ml) after eight weeks of supplementation. Furthermore, we observed a significant change in waist circumference (- 0.97 vs. -0.26 cm), fat percentage (-.13 vs. 0.1%), systolic blood pressure (- 3.85 vs. -2.11 mmHg) and diastolic blood presure (- 4 vs. -1.86 mmHg) in the vitamin D group compared to the placebo group (all P values < 0.05). Other variables did not significantly change after the intervention.

CONCLUSION

Based on our findings, weekly vitamin D supplementation of 50,000 IU for eight weeks in patients with CHD resulted in decreased systolic and diastolic blood pressure, waist circumference and fat percentage. No significant effect on HSP 60, inflammatory markers or lipid profiles was observed.

TRIAL REGISTRATION

IRCT, IRCT201612122365N14. Registered 12 December 2016.

Soluble Tumor Necrosis Factor Like Weak Inducer of Apoptosis and Vitamin D in Hemodialysis Patients: Relation to Carotid Intima-Media Thickness

Cardiovascular disease, as the leading cause of patient death with chronic kidney disease, could be predicted by carotid atherosclerosis. The aim of the present study was to evaluate a possible relationship between serum soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK) and Vitamin D levels with mean right/left carotid intima-media thickness (cIMT), in the hemodialysis (HD) patients. In this cross-sectional study, serums were obtained from 50 stable chronic HD patients and 39 healthy controls. The serum levels of sTWEAK, Vitamin D, intact parathyroid hormone (iPTH) in both groups, and cIMT were determined in HD patients by standard methods. Serum levels of sTWEAK were higher [808.8 (521.6-5032.4) pg/ml vs. 664.4 (487.4-2955.8) pg/ml (p = 0.006)] and Vitamin D levels were lower [13.4 (2.5-153) ng/ml vs. 27.8 (18.4-59.0) ng/ml (p = 0.001)] in the hemodialysis patients than in the healthy control. No important correlation was found between sTWEAK Vitamin D levels (r = 0.010/p = 0.946), and mean right(r = -0.194/p = 0.178) and left (r = 0.061/p = 0.673) cIMT in the HD patients. Our study shows that sTWEAK levels are elevated in HD patients. This elevation has no association with the cIMT.

Vitamin D and cardiovascular disease

Vitamin D, a soluble steroid hormone synthesized in the skin after sun exposure, plays a crucial role in calcium metabolism and is also involved in cardiovascular pathophysiology. The aim of this review is to summarize the available evidence (a) on the association between endogenous vitamin D status and cardiovascular disease, and (b) on the effect of vitamin D supplementation on cardiovascular outcomes. Most studies have shown an inverse association between vitamin D levels and cardiovascular outcomes. Randomized controlled trials, however, do not consistently support a beneficial effect of vitamin D administration on cardiovascular health. Population characteristics, comorbid conditions such as diabetes, the overall population prevalence of cardiovascular disease, vitamin D status and the regimen of vitamin D supplementation may account for the conflicting results.

Association of vitamin D status with metabolic syndrome and its components: A cross-sectional study in a population of high educated Iranian adults

AIM

We aimed to assess the association of vitamin D status with metabolic syndrome and its components among high educated Iranian adults.

METHOD

In this cross-sectional study, 352 faculty members with age of 35 years or more, belong to Tarbiat Modares University, Tehran, Islamic Republic of Iran, were recruited during 2016 and 2017. Fasting blood samples were obtained to quantify serum 25(OH)D concentrations, glycemic indicators and lipid profile. Metabolic syndrome was defined based on the guidelines of the National Cholesterol Education Program Adult Treatment Panel III (ATP III). Multivariate logistic regression adjusted for potential confounders was used to evaluate the association between vitamin D status and metabolic syndrome.

RESULT

Metabolic syndrome and vitamin D insufficiency were prevalent among 26% and 60.2% of subjects, respectively. There was no statistically significant difference in the prevalence of metabolic syndrome across quartiles of 25(OH)D levels either before or after adjusting for potential confounders (OR: 0.94, 95% CI: 0.43-1.95). In terms of metabolic syndrome components, subjects in the highest quartile of vitamin D levels had 59% decreased risk of abdominal obesity compared with those in the lowest quartile (OR: 0.41, 95% CI: 0.17-0.99), after adjusting for potential confounders. Such inverse relationship was also seen for elevated blood pressure (OR: 0.37, 95% CI: 0.14-0.99), and abnormal glucose homeostasis (OR: 0.40, 95% CI: 0.19-0.85).

CONCLUSION

Serum levels of 25(OH)D was inversely associated with the risk of abdominal obesity, hypertension, and abnormal glucose homeostasis. However, no significant relationship was seen for metabolic syndrome.

Nutraceutical approaches to metabolic syndrome

Metabolic Syndrome (MetS), affecting at least 30% of adults in the Western World, is characterized by three out of five variables, from high triglycerides, to elevated waist circumference and blood pressure. MetS is not characterized by elevated cholesterolemia, but is rather the consequence of a complex interaction of factors generally leading to increased insulin resistance. Drug treatments are of difficult handling, whereas well-characterized nutraceuticals may offer an effective alternative. Among these, functional foods, e.g. plant proteins, have been shown to improve insulin resistance and reduce triglyceride secretion. Pro- and pre-biotics, that are able to modify intestinal microbiome, reduce absorption of specific nutrients and improve the metabolic handling of energy-rich foods. Finally, specific nutraceuticals have proven to be of benefit, in particular, red-yeast rice, berberine, curcumin as well as vitamin D. All these can improve lipid handling by the liver as well as ameliorate insulin resistance. While lifestyle approaches, such as with the Mediterranean diet, may prove to be too complex for the single patient, better knowledge of selected nutraceuticals and more appropriate formulations leading to improved bioavailability will certainly widen the use of these agents, already in large use for the management of these very frequent patient groups. Key messages Functional foods, e.g. plant proteins, improve insulin resistance. Pro- and pre-biotics improve the metabolic handling of energy-rich foods. Nutraceutical can offer a significant help in handling MetS patients being part of lifestyle recommendations.