Systematic review: Vitamin D and cardiometabolic outcomes

The effect of vitamin D2 on lipid profile, anthropometric indices, blood pressure, and inflammatory and glycemic biomarkers in humans: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Even though the role of D2 (ergocalciferol) on cardiovascular disease risk components has been studied, conflicting results have been reported. Moreover, no single study has studied all these parameters and the role of vitamin D2 individually has not been assessed; hence, this systematic review and meta-analysis of randomized controlled trials was conducted to assess the effect of vitamin D2 supplementation on lipid profile, anthropometric indices, blood pressure, and inflammatory and glycemic biomarkers in humans.

METHODS

Web of Science, Scopus, PubMed/Medline, and Embase were searched from database inception to July 2024, and the random effects model, according to the DerSimonian and Laird method, was used to generate combined estimates of the intervention's effect on the outcomes.

RESULTS

After full-text analysis, 11 eligible articles were included in our meta-analyses. No statistically significant association was observed between vitamin D2 administration and BMI, WC, TC, HDL-C, LDL-C, TG, DBP or SBP; however, a statistically significant decrease in CRP (WMD: - 1.92 mg/dL, 95 % CI: - 3.30 to - 0.54, P = 0.006) and HbA1c levels (WMD: - 0.37 %, 95 % CI: - 0.66 to - 0.09, P = 0.009), and a non-statistically significant decrease in FBG (WMD: - 4.61 mg/dL, 95 % CI: - 14.71 to 5.47, P = 0.370, I2 = 90 %, P ˂ 0.001) and HOMA-IR (WMD: - 0.10, 95 % CI: - 0.17-0.03, P = 0.002) were detected.

CONCLUSION

In summary, our systematic review and meta-analysis discovered that vitamin D2 administration was associated with a statistically significant decrease in CRP and HbA1c levels, without a significant correlation with other outcomes.

Effects of vitamin D supplementation on metabolic syndrome parameters in patients with obesity or diabetes in Brazil, Europe, and the United States: A systematic review and meta-analysis

Plasma 25-dihydroxyvitamin D levels appear reduced in patients with obesity or type 2 diabetes, as reported in several observational studies. However, the association between these reduced hormone levels and metabolic parameters is unclear. In any case, vitamin D supplementation in patients with Metabolic Syndrome is standard. Still, the impacts of this supplementation on conditions such as glycemia, blood pressure, and lipidemia are debatable. Based on this question, we carried out a systematic review and meta-analysis of randomized clinical trials in Brazil, Europe, and the United States that analyzed the effects of vitamin D supplementation on Metabolic Syndrome parameters in patients with obesity or type 2 diabetes. Our search yielded 519 articles and included 12 randomized controlled trials in the meta-analysis. Vitamin D supplementation had no effect on any of the outcomes analyzed (fasting blood glucose and insulinemia, glycated hemoglobin, HOMA index, systolic and diastolic blood pressure, weight, waist circumference, total cholesterol, LDL and HDL, and triglycerides). However, subgroup analyses indicated that using vitamin D up to 2000 IU daily reduced participants' fasting blood glucose and glycated hemoglobin. Furthermore, the intervention reduced diastolic blood pressure only in participants with vitamin D deficiency. At least two studies showed a high risk of bias using the Rob2 protocol. According to the GRADE protocol, the evidence quality varied from moderate to very low. These results indicate that vitamin D supplementation does not improve patients' metabolic parameters and that the association between plasma 25-dihydroxyvitamin D levels and Metabolic Syndrome may not be causal but caused by other confounding characteristics. However, in any case, the quality of evidence is still low, and more randomized clinical trials are essential to clarify these relationships.

Vitamin D and the Risk of Developing Hypertension in the SUN Project: A Prospective Cohort Study

Vitamin D deficiency has been associated with a higher risk of multiple diseases, including cardiovascular disorders. The purpose of this study was to examine the potential association between predicted levels of serum 25(OH)D and the risk of new-onset hypertension in a large Mediterranean cohort. A validated 136-item food frequency questionnaire was used as the dietary assessment tool. 25(OH)D serum levels were predicted using a previously validated equation. We performed Cox regression models to analyze the association between predicted serum 25(OH)D and the risk of hypertension, according to quartiles of forecasted vitamin D at baseline, after adjusting for multiple potential confounders. Over a median follow-up of 12.3 years, 2338 new cases of hypertension were identified. The analyses revealed a significant inverse association between predicted serum levels of 25(OH)D at baseline and the risk of hypertension. Individuals in the highest quartile showed a 30% relatively lower risk of hypertension compared to the lowest quartile (hazard ratio (HR): 0.70; 95% confidence interval (CI): 0.60-0.80, p-trend < 0.001). The outcomes remained significant after performing sensitivity analyses. The findings suggested that higher levels of forecasted vitamin D are inversely and independently associated with the risk of incident hypertension, implying that vitamin D may offer protective benefits against the disease.

Vitamin D Status and Cardiovascular Disease in College Athletes After SARS-CoV-2 Infection

OBJECTIVE

To evaluate the association between vitamin D status and CV disease after COVID-19 in college athletes.

DESIGN

Retrospective cohort study.

SETTING

National College Athletic Association Division-I college athletes from a single academic institution.

PATIENTS

A total of 157 athletes (60 female; median age: 20 years) from 9 sports with a positive SARS-CoV-2 test, cardiac magnetic resonance imaging (CMR), and vitamin D level.

INDEPENDENT VARIABLES

Serum 25-hydroxyvitamin D level (primary); age, sex (regression models).

MAIN OUTCOMES MEASURES

Differences in age, sex, race, ethnicity, myocarditis, pericarditis, and CMR metrics by vitamin D status were analyzed. Regression models were used to assess the relationship between vitamin D status and CMR metrics accounting for age and sex.

RESULTS

Low vitamin D (LVD) was found in 33 (21.0%) of athletes, particularly Black males (P < 0.001). Athletes with LVD had higher biventricular and lower mid-ventricular extracellular volumes, but these differences were not significant when corrected for age and sex. Athletes with LVD had higher left ventricle (LV) mass (P < 0.001) and LV mass index (P = 0.001) independent of age and sex. Differences in global circumferential strain were noted but are likely clinically insignificant. Vitamin D status did not associate with myocarditis and pericarditis (P = 0.544).

CONCLUSIONS

LVD is common in athletes, particularly in Black males. Although athletes with LVD had higher LV mass, cardiac function and tissue characterization did not differ by vitamin D status. Future studies are needed to determine if the differences in LV mass and LV mass index by vitamin D status are clinically significant. This study suggests that vitamin D status does not impact the development of myocarditis or pericarditis after COVID-19 infection.

Vitamin D and Risk of Incident Type 2 Diabetes in Older Adults: An Updated Systematic Review and Meta-Analysis

Vitamin D deficiency is very common worldwide, particularly in old age, when people are at the highest risk of the negative adverse consequences of hypovitaminosis D. Additionally to the recognized functions in the regulation of calcium absorption, bone remodeling, and bone growth, vitamin D plays a key role as a hormone, which is supported by various enzymatic, physiological, metabolic, and pathophysiological processes related to various human organs and systems. Accruing evidence supports that vitamin D plays a key role in pancreatic islet dysfunction and insulin resistance in type 2 diabetes. From an epidemiological viewpoint, numerous studies suggest that the growing incidence of type 2 diabetes in humans may be linked to the global trend of prevalent vitamin D insufficiency. In the past, this association has raised discussions due to the equivocal results, which lately have been more convincing of the true role of vitamin D supplementation in the prevention of incident type 2 diabetes. Most meta-analyses evaluating this role have been conducted in adults or young older persons (50-60 years old), with only one focusing on older populations, even if this is the population at greater risk of both hypovitaminosis D and type 2 diabetes. Therefore, we conducted an update of the previous systematic review and meta-analysis examining whether hypovitaminosis D (low serum 25OHD levels) can predict incident diabetes in prospective longitudinal studies among older adults. We found that low 25OHD was associated with incident diabetes in older adults even after adjusting for several relevant potential confounders, confirming and updating the results of the only previous meta-analysis conducted in 2017.

A Prospective Open-Label Dose-Response Study to Correct Vitamin D Deficiency in Cirrhosis

BACKGROUND

Patients with advanced liver disease often have vitamin D deficiency, but the daily dosages of vitamin D3 needed to raise their serum 25-hydrodroxyvitamin D [25(OH)D] concentrations are unknown.

OBJECTIVE

We aimed to establish the dose-response relationship between vitamin D3 and 25(OH)D in patients with liver cirrhosis.

DESIGN

An open-label study of orally-administered vitamin D3 (gelcaps) was conducted in patients with liver cirrhosis using a tiered-dosing regimen: 4,000 IU/d for baseline 25(OH)D ≤ 15 ng/mL and 2,000 IU/d for baseline 25(OH)D > 15 to ≤ 25 ng/mL (NCT01575717). Supplementation continued for 6 months, or until liver transplantation. Changes in 25(OH)D were measured after ≥ 3 months. Dose-response data on 48 patients (21 receiving 4000 IU/d and 27 receiving 2,000 IU/d) reporting ≥ 80% adherence were analyzed using generalized estimating equations (GEE).

RESULTS

Among the 48 patients, 39 (81%) had 25(OH)D > 20 ng/mL while on supplements, and none experienced hypercalcemia. The magnitude of the increase in 25(OH)D was approximately twofold greater in patients receiving the higher dose. The mean incremental increase was 5.1 ng/ml ± 3.9 of 25(OH)D per 1000 IU/d of vitamin D3. Multivariable models demonstrated a significant positive relationship between baseline 25(OH)D and serum albumin (p < 0.01) and hemoglobin (p = 0.01), and a negative relationship with the MELD score (p < 0.01) and total bilirubin (p < 0.01).

CONCLUSIONS

A two-tiered dosing regimen of daily oral vitamin D3 supplementation safely raised 25(OH)D concentrations in the majority of adults with liver cirrhosis who were adherent to supplement use.

Vitamin D levels and the risk of overactive bladder: a systematic review and meta-analysis

CONTEXT

Overactive bladder is treated mainly with behavioral and drug therapy, and symptoms of urinary frequency and incontinence are challenging to eliminate. There is thus a continuous unmet need for new drugs with a substitution effect mechanism.

OBJECTIVE

It not known whether vitamin D deficiency can lead to overactive bladder or urinary incontinence or whether vitamin D supplementation alleviates bladder symptoms. This comprehensive systematic review with meta-analysis was conducted to determine whether overactive bladder is associated with vitamin D deficiency.

DATA SOURCES

The PubMed and Cochrane Library databases were searched systematically up to July 3, 2022.

DATA EXTRACTION

Initially, 706 articles were identified in the literature search, of which 13 were included in the systematic review: 4 randomized controlled trials, 3 cohort studies, 3 cross-sectional studies, and 3 case-control studies.

DATA ANALYSIS

An increased risk of overactive bladder and urinary incontinence was observed with vitamin D deficiency (odds ratio [OR] = 4.46; 95%CI, 1.03-19.33; P = 0.046 and OR = 1.30; 95%CI, 1.01-1.66; P = 0.036, respectively). Vitamin D levels were relatively low in patients with overactive bladder or urinary incontinence (SMD = -0.33; 95%CI, -0.61 to -0.06, P = 0.019). On the basis of existing data, the risk of urinary incontinence was reduced by 66% after vitamin D supplementation (OR = 0.34; 95%CI, 0.18-0.66; P = 0.001). Egger test was conducted to assess publication bias, and the results were tested for robustness using a sensitivity analysis.

CONCLUSIONS

Vitamin D deficiency increases the risk of overactive bladder and urinary incontinence, and vitamin D supplementation reduces the risk of urinary incontinence. The development of new strategies to prevent or alleviate bladder symptoms is crucial. Vitamin D supplementation may be gaining recognition as an effective strategy for prevention or alleviation of bladder symptoms such as overactive bladder and incontinence.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022351443.

Impact of ultraviolet radiation on cardiovascular and metabolic disorders: The role of nitric oxide and vitamin D

BACKGROUND/PURPOSE

Ultraviolet (UV) radiation has both harmful and beneficial effects on human skin and health. It causes skin damage, aging, and cancer; however, it is also a primary source of vitamin D. Additionally, UV radiation can impact energy metabolism and has protective effects on several cardiovascular and metabolic disorders in mice and humans. However, the mechanisms of UV protection against these diseases have not been clearly identified.

METHODS

This review summarizes the systemic effects of UV radiation on hypertension and several metabolic diseases such as obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) in mice, and we also consider the mechanisms of action of the related regulators nitric oxide (NO) and vitamin D.

RESULTS

UV exposure can lower blood pressure and prevent the development of cardiovascular diseases and metabolic disorders, such as metabolic syndrome, obesity, and type 2 diabetes, primarily through mechanisms that depend on UV-induced NO. UV radiation may also effectively delay the onset of type 1 diabetes through mechanisms that rely on UV-induced vitamin D. UV-induced NO and vitamin D play roles in preventing and slowing the progression of NAFLD.

CONCLUSION

UV exposure is a promising nonpharmacological intervention for cardiovascular and metabolic disorders. NO and vitamin D may play a crucial role in mediating these effects. However, further investigations are required to elucidate the exact mechanisms and determine the optimal dosage and exposure duration of UV radiation.

Effects of Vitamin D Supplementation on Testosterone, Prostate, and Lower Urinary Tract Symptoms: A Prospective, Comparative Study

PURPOSE

Several studies have associated the serum vitamin D level with total testosterone levels and the prostate volume. Herein, we investigated the effect of vitamin D supplementation on testosterone, prostate, and lower urinary tract symptoms (LUTS) in men.

MATERIALS AND METHODS

Men over 40 years of age diagnosed with a vitamin D deficiency (25[OH]D <20 ng/mL) who received vitamin D supplementation for one year were included in the study and administered 25,000 IU of cholecalciferol every 2 weeks. Prostate ultrasound, uroflowmetry, postvoid residual urine volume measurement, and serological tests (serum testosterone levels, etc.) were performed upon diagnosis and one year later. Participants also answered the International Prostate Symptom Score (IPSS) and Aging Males' Symptoms Scale (AMS) questionnaires.

RESULTS

A significant increase was observed in the vitamin D level following one year of vitamin D supplementation, with a significant decrease in the postvoid residual urine volume, total IPSS score and without a significant change in the prostate volume. Improved psychological subscale score of AMS questionnaire was observed with a statistical significance.

CONCLUSIONS

Vitamin D supplementation suppressed the increase in the prostate volume and improved the LUTS. Although there is no direct effect on serum testosterone levels, vitamin D supplementation helped improve hypogonadal symptoms.

The Role of Vitamin D in Cardiovascular Diseases

Cardiovascular diseases (CVD) are the leading cause of death in the United States. The previous literature demonstrates the importance of vitamin D for overall health, and a significant body of literature has examined the benefits of optimal serum 25-hydroxyvitamin D [25(OH)D] on cardiovascular health, but the results remain inconclusive. The objective of this study was to determine the association between reported CVD and [25(OH)D]. We utilized the 2015-2018 National Health and Nutrition Examination Survey and included adults aged 20 years and older (n = 9825). CVD was defined as having a stroke, heart attack, heart failure, or coronary heart disease. Vitamin D status was categorized as a serum 25(OH)D deficiency at <30 nmol/L; insufficiency at 30 to 49.9 nmol/L; normal/optimal at 50 to 125 nmol/L; and adequacy at >125 nmol/L. Statistical analysis was performed using Chi-square tests, t-tests were conducted to investigate the differences in participant characteristics among those with CVD and without CVD, and regression models were used to explore the association between vitamin D levels and CVD status. We found 25(OH)D deficiency associated with CVD (Adjusted Odds Ratio (AOR) = 1.48; 95% CI = 1.11-1.98; p < 0.05). [25(OH)D] insufficiency was also associated with CVD (AOR = 1.28; 95% CI = 1.06-1.54; p < 0.05). The 25(OH)D adequacy was not associated with reported CVD. For the prevention of CVD, healthcare professionals may recommend the use of vitamin D supplementation to improve cardiovascular health in adults while considering individual needs.

Knowledge, attitudes, and practices associated with vitamin D supplementation: A cross-sectional online community survey of adults in the UK

OBJECTIVE

Assess knowledge, attitudes, and practices (KAPs) of a diverse population. Identify barriers and facilitators that inform routine vitamin D supplementation and self-care in the community setting.

DESIGN

Cross-sectional online voluntary survey. Electronic survey link published on college Qualtrics platform and advertised widely. Study information provided with Participant Information Sheet.

SETTING AND PARTICIPANTS

556 community dwelling adults across the UK.

METHODS

The overarching study included two phases, incorporating quantitative and qualitative methodologies. This paper reports findings from the first phase of the FABCOM-D (Facilitators and Barriers to Community (Healthy) Vitamin D status) study. Online survey questions were iteratively developed after background literature searches and piloted to ensure clarity and ease of understanding. Survey responses summarised using frequencies and percentages, and univariable and multivariable logistic regression models explored for any association. A p-value less than 0.05 was considered statistically significant. The Checklist for Reporting Results of Internet E-Surveys guided reporting. Statistical analysis performed using IBM SPSS software.

MAIN OUTCOME MEASURES

Awareness of vitamin D information sources, health benefits and testing. Attitudes to supplementation, sun exposure and fortification.

RESULTS

Three quarters of the community had some awareness of vitamin D and around half were taking supplements. The two most trusted sources of information included health professionals and the NHS website. Participants were willing to pay for supplements, supporting a self-care agenda. With increasing age, there was significant reduced intake of vitamin D supplements. This aspect needs to be explored further as this could be a concern in deficiency status in the elderly. There was acceptance of food fortification but uncertainty on how to balance food intake with supplementation.

CONCLUSION

We were successful in eliciting views on KAPs around vitamin D from a community population including a large proportion of Black and Minority Ethnic individuals. The community wanted information and guidance to help manage individual vitamin D status, especially for high-risk groups, and on balancing supplementation, food fortification and sun exposure.

25(OH)D Concentration in Neonates, Infants, Toddlers, Older Children and Teenagers from Poland-Evaluation of Trends during Years 2014-2019

INTRODUCTION

Local and international guidelines have provided schedules for the vitamin D supplementation of general populations of different ages, including children. Our study aimed to assess 25(OH)D concentration and its potential change during a growth and maturation period, adding parameters that reflect the risk of hypercalcemia.

MATERIALS AND METHODS

The available 25(OH)D concentration values (n = 17,636; 7.8 ± 6.0 years), calcium (n = 2673; 16.3 ± 6.1 years) and phosphate (n = 2830; 3.8 ± 5.2 years) metabolism markers were analyzed in a studied group of patients (0-18 years).

RESULTS

In the studied group the mean 25(OH)D concentration was 29.4 ± 11.7 ng/mL. Concentrations of 25(OH)D < 10 ng/mL were observed in 1.7% of patients (n = 292), 10-20 ng/mL in 17.2% (n = 3039), 20-30 ng/mL in 39.5% (n = 6960) and 30-50 ng/mL in 37.2% (n = 6567). In patients with a 25(OH)D concentration <10 ng/mL, normal calcemia (2.25-2.65 mmol/L) was observed in 29.5% of cases (n = 86). Three patients had 25(OH)D concentrations above 100 ng/mL with co-existing hypercalcemia; the mean was Ca = 3.40 mmol/L. Hypocalcemia (Ca < 2.25 mmol/L) was observed in 10,4% of patients (n = 2797). Furthermore, 5.0% of patients showed an increased calcium concentration >2.65 mmol/L (n = 1327). The highest mean 25(OH)D concentration of 32.1 ng/mL ± 12.9 was noted in the years 2018-2019 (n = 3931) and the lowest in the year 2015 (27.2 ng/mL ± 11.0; n = 2822).

CONCLUSIONS

Vitamin D deficiency (<20 ng/mL) was noted in 18,9% of subjects in the years 2014-2019. An effective prevention of vitamin D deficiency was observed in children aged 3 years and younger. A relationship between the concentrations of calcium and 25(OH)D was not observed.

Mechanisms Suggesting a Relationship between Vitamin D and Erectile Dysfunction: An Overview

Vitamin D deficiency (VDD) and erectile dysfunction (ED) heavily burden the male population. The higher prevalence of both conditions in the elderly suggests a possible relationship between the two conditions. In addition, in vitro, animal, and human studies have revealed several mechanisms that may relate VDD to ED. The main mechanism by which vitamin D might exert its action on sexual function appears to be through the regulation of endothelial function. Indeed, VDD correlates with several markers of endothelial function. The action of vitamin D on the endothelium would be exercised both indirectly through its intervention in inflammatory processes and through the production of oxygen free radicals, and directly through the regulation of vascular stiffness, the production of nitric oxide, and the regulation of vessel permeability. Furthermore, the ubiquitous distribution of the vitamin D receptor in the human body means that this hormone can also exert a beneficial effect on erectile function by interfering with those comorbidities significantly associated with ED, such as hypertension, diabetes mellitus, hypercholesterolemia, chronic kidney disease, and hypogonadism. In this review, we thoroughly and carefully presented the evidence and mechanisms that would appear to relate vitamin D levels to erectile function. Furthermore, we have summarized the meta-analytic evidence for and against this association to provide a true representation of this topic. Data published to date suggest that low levels of vitamin D could contribute to worsening erectile function through several mechanisms. Therefore, vitamin D levels should be measured in patients with ED and maintained at adequate levels by specific supplementation in case of deficiency. However, the low quality and heterogeneity of clinical trials evaluating the effects of vitamin D administration on erectile function and ED-associated comorbidities do not allow for a univocal conclusion, and indicate the need for further studies to analyze these aspects.

A Scoping Review of Vitamin D for Nonskeletal Health: A Framework for Evidence-Based Clinical Practice

BACKGROUND

Low serum 25-hydroxy-vitamin D [25(OH)D] levels are prevalent worldwide. Although the benefits of vitamin D supplementation have focused on skeletal disorders (eg, rickets, osteomalacia, osteoporosis), emerging evidence for nonskeletal health merits further discussion.

PURPOSE

The purpose of this review was to critically examine the vitamin D supplementation literature pertaining to nonskeletal health to help guide clinicians.

METHODS

A scoping review that included observational studies and randomized clinical trials (RCTs) was performed. Evidence from meta-analyses and individual RCTs are discussed, and controversies and future directions are considered.

FINDINGS

25(OH)D deficiency is a ubiquitous condition associated with multiple nonskeletal diseases, including cardiometabolic (heart disease, diabetes, and kidney disease), immune (HIV/AIDS and cancer), lung (from traditional chronic disorders to coronavirus disease 2019), and gut diseases. Vitamin D deficiency also affects health across the life span (children, pregnant, and elderly), mental illness, and reproduction in both men and women. In contrast, vitamin D supplementation does not necessarily improve major medical outcomes, even when low 25(OH)D levels are treated. Screening for 25(OH)D status remains an important practice, primarily for high-risk patients (eg, elderly, women with osteoporosis, people with low exposure to sunlight). It is reasonable to supplement with vitamin D to treat 25(OH)D deficiency, such that if beneficial nonskeletal health occurs, this may be considered as a coadjutant instead of the central tenet of the disease. Furthermore, optimizing dosing regimens is an important clinical consideration.

IMPLICATIONS

Although 25(OH)D deficiency is prevalent in nonskeletal diseases, there is no uniform evidence that vitamin D supplementation improves major medical outcomes, even when low 25(OH)D levels are corrected. Findings from RCTs warrant caution due to possible selection bias. Overall, vitamin D supplementation must be guided by circulating levels as a reasonable medical practice to correct 25(OH)D deficiency.

A beneficial cardiometabolic health profile associated with dietary supplement use: A cross-sectional study

As a follow-up to an earlier study demonstrating healthier cardiometabolic profiles among long-term multiple dietary supplement (LTMDS) users, we examined if cardiometabolic health benefits associated with LTMDS use persisted with aging. The study is based on LTMDS users from North America and 2007-2010 NHANES participants who were used for comparison to the LTMDS users. NHANES subjects were classified as non-dietary supplement (NS) users, single supplement/single purpose supplement (SS) users, multivitamin/mineral supplement (MVMS) users, and multiple dietary supplement (MDS) users. Supplement groups were compared for total, HDL and LDL cholesterol; triglycerides; glucose; insulin; CRP and HbA1c ≥ 6.5%, adjusting for age, sex, income, education, BMI, history of CVD, and medications for hypercholesterolemia and diabetes. Geometric mean (95% confidence interval) LDL cholesterol was significantly lower (P < 0.05) for all supplement groups (SS: 110 (104-117) mg/dL; MVMS: 113 (107-119) mg/dL; MDS: 115 (111-118) mg/dL; LTMDS: 112 (105, 119) mg/dL) compared with the NS users (122 (118-126) mg/dL). Compared with the NS group, MDS users had significantly (P < 0.05) lower mean total cholesterol (198 (194-201) vs 201 (197, 206) mg/dL), MDS and LTMDS users higher mean HDL cholesterol (54.2 (53.3-55.1) and 60.0 (57.4, 62.7) mg/dL vs 52.0 (50.8-53.3) mg/dL), LTMDS users lower fasting glucose (100 (98-103) vs 105 (103-106) mg/dL), SS and MDS users lower insulin (8.4 (7.4-9.6) and 9.1 (8.3-9.9) vs 10.2 (9.4-11.1) μIU/mL), and MDS users lower CRP (% ≥ 1.5 mg/L, 50.8 (47.9-53.6) vs 57.0 (52.4-61.6) %). These findings add to the evidence that use of dietary supplements may provide cardiometabolic health benefits.

Vitamin D and risk of hypertension among Black women

Evidence of an association between plasma 25-hydroxyvitamin D [25(OH)D] levels and risk of hypertension, predominantly from studies of White individuals, suggests an inverse relationship. Limited data are available on Black individuals, who are more likely to have vitamin D deficiency. In the Black Women's Health Study (BWHS), a prospective study of 59 000 self-identified Black women from across the US, we assessed levels of a validated predicted vitamin D score in relation to incident hypertension. We followed 42 239 participants who were free of cardiovascular disease and cancer from 1995 to 2019, during which time 19 505 incident cases of hypertension were identified. Cox proportional hazards model were used to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of predicted vitamin D with the risk of incident hypertension. In age-adjusted analyses, there was a strong inverse dose-response association between predicted vitamin D score and hypertension risk, with an HR of .66 (95% CI: .63-.68, p trend < .0001) for the highest quartile of predicted vitamin D relative to the lowest. After control for potential confounders including body mass index, physical activity, and cigarette smoking, the HR was attenuated to .91 (95% CI: .87-.95, p trend = .002). In this prospective cohort study of Black women, predicted vitamin D score was weakly inversely associated with the incidence of hypertension. This observed association may reflect an inability to fully control for confounding factors.

Co-occurrence of chronic kidney disease and glaucoma: Epidemiology and etiological mechanisms

As the histology, physiology, and pathophysiology of eyes and kidneys show substantial overlap, it has been suggested that eye and kidney diseases, such as glaucoma and chronic kidney disease (CKD), may be closely interlinked. We review the relationship between CKD and various subtypes of glaucoma, including primary open-angle glaucoma, primary angle- closure glaucoma, normal tension glaucoma, pseudoexfoliation syndrome, and several glaucoma endophenotypes. We also discuss the underlying pathogenic mechanisms and common risk factors for CKD and glaucoma, including atherosclerosis, the renin-angiotensin system, genes and genetic polymorphisms, vitamin D deficiency, and erythropoietin. The prevalence of glaucoma appears elevated in CKD patients, and vice versa, and the literature points to many intriguing associations; however, the associations are not always confirmed, and sometimes apparently opposite observations are reported. Glaucoma and CKD are complex diseases, and their mutual influence is only partially understood.

Obesity-Associated Vitamin D Deficiency Correlates with Adipose Tissue DNA Hypomethylation, Inflammation, and Vascular Dysfunction

Vitamin D (VD) deficiency is a hallmark of obesity and vascular dysfunction. We sought to test the hypothesis that VD deficiency may contribute to obesity-related vascular dysfunction by inducing adipokine hypomethylation and augmented expression. To this end, we collected blood and adipose tissues (ATs) from a cohort of 77 obese participants who were classified as having mild, moderate, or severe VD deficiency. The body composition, vascular reactivity, cardiometabolic profiles, and DNA methylation of 94 inflammation-related adipokines were measured. Our results show that higher degrees of VD deficiency were associated with lower DNA methylation and induced the expression of inflammatory adipokines such as B-cell lymphoma 6 (BCL6), C-X-C Motif Chemokine Ligand 8 (CXCL8), histone deacetylase 5 (HDAC5), interleukin 12A (IL12A), and nuclear factor κB (NFκB) in the ATs. They were also associated with higher BMI and total and visceral fat mass, impaired insulin sensitivity and lipid profiles, AT hypoxia, and higher concentrations of circulating inflammatory markers. Moderate and severe VD deficiency correlated with impaired vasoreactivity of the brachial artery and AT-isolated arterioles, reduced nitric oxide generation, and increased arterial stiffness. In a multivariate regression analysis, the VD deficiency level strongly predicted the adipokine methylation score, systemic inflammation, and microvascular dysfunction. In conclusion, our findings suggest that VD deficiency is a possible contributor to obesity-related adipokine hypomethylation, inflammation, and vascular dysfunction.

Association of 25-Hydroxy Vitamin D with IL-17 Inflammatory Cytokines, and Osteoporosis in patients with Rheumatoid Arthritis in Kurdish nation / Iraq

Introduction:

Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. Lower Vitamin D (Vit. D) levels correlate with more severe clinical manifestations in RA and other rheumatic diseases. IL-17A promotes inflammation by inducing various proinflammatory cytokines and chemokines. In this study, we evaluated the association between Vitamin. D and IL-17 in osteoporosis in Rheumatoid Arthritis in Kurdish nation / Iraq.

Objective:

Blood samples from rheumatoid arthritis (RA) patients were used to measure the levels of the inflammatory cytokine IL-17 and the Vit. D precursor 25(OH)D and bone loss in patients with RA in this study.

Methods:

In this study, 40 healthy controls were included in the research, which comprised 100 new cases of RA. ELISA was used to measure the level of serum 25(OH)D and IL-17. Moreover, DXA was used to assess average bone mineral density (BMD).

Results:

We discovered no difference between the two groups in terms of age or gender. This means that compared to the control group, the 25(OH)D serum levels in the RA group were lower (P 0.01; 16.85+8.7 nmol/l vs. 39.95 (-+9.8)). IL-17 serum levels were highly and negatively associated with 25(OH)D levels in arthritic patients. A comparison of 25(OH)D levels in patients with osteoporosis and osteopenia and those with BMD was also performed.

Conclusion:

Bone loss and IL-17 have been associated with reduced Vit. D levels in patients with rheumatoid arthritis; a lack of Vit. D may have a role in developing the disease, according to the data presented in this study.

Vitamin D status and prevalence of metabolic syndrome by race and Hispanic origin in US adults: findings from the 2007-2014 NHANES

BACKGROUND

Vitamin D status has been found to be inversely associated with metabolic syndrome (MetS) in some studies. Vitamin D status varies by race and ethnicity, and the association of MetS with vitamin D status in US adults and by race and Hispanic origin has not been evaluated extensively.

OBJECTIVES

We aimed to examine the associations between vitamin D status and MetS overall, and across race and Hispanic origin groups, in a nationally representative sample of US adults who participated in the NHANES from 2007 to 2014.

METHODS

The total sample included 8639 adults, ≥20 y of age. Serum vitamin D was measured using a standardized LC-tandem MS method and was categorized using data-driven tertiles. MetS was defined using measured waist circumference, triglycerides, HDL cholesterol, blood pressure, and fasting glucose. Multivariable logistic regression models were fitted [accounting for sociodemographic and lifestyle factors, dietary supplement use, and BMI (in kg/m2)] to examine the associations of serum vitamin D with MetS among adults overall, and by race and Hispanic origin.

RESULTS

Serum vitamin D in the lowest tertile (≤56 nmol/L) was significantly associated with increased odds of MetS compared with the highest tertile (>77.9 nmol/L) (fully adjusted model OR: 1.85; 95% CI: 1.51, 2.27). Inverse associations were noted for all race-Hispanic origin groups: non-Hispanic white (NHW) (OR: 2.24; 95% CI: 1.67, 3.01), non-Hispanic black (OR: 1.56; 95% CI: 1.06, 2.29), and Hispanic (OR: 1.48; 95% CI: 1.03, 2.14) adults.

CONCLUSIONS

Lower vitamin D status was significantly associated with MetS among US adults after adjusting for sociodemographic and lifestyle factors, dietary supplement use, and BMI. This finding was noted across all race and Hispanic origin groups, although the strength of the association varied, being strongest for NHW adults.

An empirical evaluation of the impact scenario of pooling bodies of evidence from randomized controlled trials and cohort studies in medical research

BACKGROUND

Randomized controlled trials (RCTs) and cohort studies are the most common study design types used to assess treatment effects of medical interventions. We aimed to hypothetically pool bodies of evidence (BoE) from RCTs with matched BoE from cohort studies included in the same systematic review.

METHODS

BoE derived from systematic reviews of RCTs and cohort studies published in the 13 medical journals with the highest impact factor were considered. We re-analyzed effect estimates of the included systematic reviews by pooling BoE from RCTs with BoE from cohort studies using random and common effects models. We evaluated statistical heterogeneity, 95% prediction intervals, weight of BoE from RCTs to the pooled estimate, and whether integration of BoE from cohort studies modified the conclusion from BoE of RCTs.

RESULTS

Overall, 118 BoE-pairs based on 653 RCTs and 804 cohort studies were pooled. By pooling BoE from RCTs and cohort studies with a random effects model, for 61 (51.7%) out of 118 BoE-pairs, the 95% confidence interval (CI) excludes no effect. By pooling BoE from RCTs and cohort studies, the median I² was 48%, and the median contributed percentage weight of RCTs to the pooled estimates was 40%. The direction of effect between BoE from RCTs and pooled effect estimates was mainly concordant (79.7%). The integration of BoE from cohort studies modified the conclusion (by examining the 95% CI) from BoE of RCTs in 32 (27%) of the 118 BoE-pairs, but the direction of effect was mainly concordant (88%).

CONCLUSIONS

Our findings provide insights for the potential impact of pooling both BoE in systematic reviews. In medical research, it is often important to rely on both evidence of RCTs and cohort studies to get a whole picture of an investigated intervention-disease association. A decision for or against pooling different study designs should also always take into account, for example, PI/ECO similarity, risk of bias, coherence of effect estimates, and also the trustworthiness of the evidence. Overall, there is a need for more research on the influence of those issues on potential pooling.

Vitamin D Status and Steatohepatitis in Obese Diabetic and Non-Diabetic Patients

BACKGROUND AND AIMS

The presence of steatohepatitis in obese patients can be multifactorial. The current study tries to determine the differences between diabetic and non-diabetic patients regarding the presence of steatohepatitis. We evaluated sequential liver samples and collected the times of bariatric surgery to assess the presence of NASH in patients with obesity, in the circuit of bariatric surgery.

METHODS

We performed a retrospective study of 49 patients presenting high-grade obesity in the circuit of bariatric surgery, with liver biopsy. The patients underwent bariatric surgery at a single center in France and were followed for 2 years. The liver biopsies were performed intraoperatively on all 49 patients before the bariatric surgery. The primary endpoint of the study was to evaluate the relationships between steatohepatitis/liver fibrosis and the presence of diabetes and to evaluate the current relationships between the biochemical work-ups. Special importance was accorded to the correlations between vitamin D levels and the presence of hepatic steatosis, due to the antifibrogenic pattern in the liver, as shown in many important papers in the field.

RESULTS

Significant correlations were found between the presence of liver fibrosis and the presence of diabetes (p = 0.022), but not regarding the antidiabetic treatment. An important correlation was found between the vitamin D levels and the presence of liver fibrosis, as well as with the levels of A1C hemoglobin and LDL cholesterol levels.

CONCLUSIONS

Vitamin D deficiency presents a strong correlation with hepatic steatosis in individuals with morbid obesity. Correcting vitamin D deficiency may present a beneficial role in treating hepatic steatosis, diabetes, and cardiovascular risk in patients with morbid obesity.

Vitamin D Supplementation in the Assessment of Cardiovascular Risk Factors in Overweight and Obese Children

Background: Childhood obesity is associated with cardiovascular-disease (CVD) risk factors, an unfavorable lipid profile and reduced levels of 25(OH)D. The aim of our study is to evaluate whether vitamin D supplementation may play a role in the assessment of the CVD risk factors in overweight/obese children and adolescents. Methods: We performed a retrospective observational study involving children (9−15 years of age) with a known diagnosis of overweight or obesity (BMI > 25) and decreased levels of 25(OH)D (<25 ng/mL), who underwent oral vitamin D supplementation (100,000 UI, one vial/month) for six months. The anthropometric parameters, 25(OH)D, serum lipids and ALT levels were measured at the beginning (T0) and after 6 months (T1). Results: Of the 58 patients recruited, 45 had an increase in the serum 25(OH)D levels after supplementation. Vitamin D supplementation was associated with a decrease in the serum levels of the total cholesterol (p = 0.009), LDL-C (p = 0.005) and ALT (p = 0.005), and an increase in HDL-C (p = 0.03). These results were confirmed when the correction for the body mass index (BMI) was applied. Conclusions: The favorable effect of vitamin D supplementation on the total cholesterol, LDL-C, HDL-C and ALT could transform these values into modifiable risk factors starting in early childhood, with beneficial effects on long-term health.

Factors associated with vitamin D deficiency among patients with musculoskeletal disorders seeking physiotherapy intervention: a hospital-based observational study

Background

A considerable number of studies have suggested that there is a strong correlation between 25-hydroxyvitamin D or vitamin D levels and overall health, with reported impacts ranging from mental health and vital organ health to musculoskeletal health. This study aimed to determine the prevalence of 25-hydroxyvitamin D deficiency and identify its associated factors among patients with musculoskeletal disorders (MSDs) currently seeking medical attention.

Methods

A total of 143 patients with MSDs were randomly selected for blood sample collection to measure serum 25-hydroxyvitamin D levels. Descriptive statistics were used to describe the demographic and clinical characteristics of the study participants. Multiple logistic regression analyses were performed to compute the adjusted odds ratio.

Results

Overall, 53.1% of patients had vitamin D deficiency. Vitamin D deficiency was more prevalent among patients with higher body mass index, a bachelor’s degree, lower sun exposure time, and lower serum calcium levels and those living in an urban setting. The multiple logistic regression model suggested that the duration of weekly sun exposure and living location were the independent predictors of vitamin D deficiency.

Conclusion

It is recommended for patients with MSDs to participate in routine physical exercise, consume calcium- and vitamin D-enriched foods, and have regular sun exposure for minimizing the risk of vitamin D deficiency.

Vitamin D status and its correlation to depression

BACKGROUND

Vitamin D can influence more than 200 genes in various tissues showing its credibility among the fat-soluble vitamins. Vitamin D deficiency is directly proportional to major clinical conditions such as cardiovascular diseases, diabetes, malignancy, and multiple sclerosis. This study was conducted to determine the vitamin D level of individuals and its association with depression.

METHODS

Vitamin D levels of 100 healthy and 100 depressed subjects were determined. The isolated subjects were screened on the Beck Depression Inventory (BDI) scale and divided into three groups according to their age. Group-I comprised subjects of age 20 years and below, Group-II included subjects of age 21 to 60, and Group-III comprised subjects of ≥ 61 years of age. A sufficient level of vitamin D in normal subjects was noted, while mild deficiency of vitamin D status was observed in depressed subjects.

RESULTS

Our study has reported a higher percentage of vitamin D deficiency in the Peshawar region. The results of our study indicated that depression was common in individuals having vitamin D deficiency.

CONCLUSIONS

The study showed a very high frequency of vitamin D deficiency in subjects with depression in Peshawar, Pakistan. The deficiency of vitamin D was observed more in females as compared to males. Further studies should explicate whether the highly widespread vitamin D deficiency could be cost-effectively treated as part of preventive or treatment interventions for depression.

The effect of daily UVA phototherapy for 2 weeks on clinic and 24-h blood pressure in individuals with mild hypertension

Latitude and season determine exposure to ultraviolet radiation and correlate with population blood pressure. Evidence for Vitamin D causing this relationship is inconsistent, and temperature changes are only partly responsible for BP variation. In healthy individuals, a single irradiation with 20 J/cm² UVA mobilises NO from cutaneous stores to the circulation, causes arterial vasodilatation, and elicits a transient fall in BP. We, therefore, tested whether low-dose daily UVA phototherapy might be an effective treatment for mild hypertension. 13 patients with untreated high-normal or stage 1 hypertension (BP 130-159/85-99 mm Hg), confirmed by 24-h ambulatory blood pressure (ABP), were recruited. Using home phototherapy lamps they were either exposed to 5 J/cm² full body UVA (320-410 nm) radiation each day for 14 days, or sham-irradiated with lamps filtered to exclude wavelengths <500 nm. After a washout period of 3 ± 1 week, the alternate irradiation was delivered. 24-h ABP was measured on day 0 before either irradiation sequence and on day 14. Clinic BP was recorded on day 0, and within 90 min of irradiation on day 14. There was no effect on 24-h ABP following UVA irradiation. Clinic BP shortly after irradiation fell with UVA (-8.0 ± 2.9/-3.8 ± 1.1 mm Hg p = 0.034/0.029) but not sham irradiation (1.1 ± 3.0/0.9 ± 1.5 mm Hg). Once daily low-dose UVA does not control mildly elevated BP although it produces a transient fall shortly after irradiation. More frequent exposure to UVA might be effective. Alternatively, UVB, which photo-releases more NO from skin, could be tried.

Vitamin D, Vitamin D-Binding Proteins, and VDR Polymorphisms in Individuals with Hyperglycaemia

Vitamin D reportedly plays an important role in the pathogenesis of diabetes mellitus; however, this role is unclear and debated. This study investigated the association between 25(OH) vitamin D, vitamin D-binding proteins, and vitamin D receptor (VDR) polymorphisms in healthy individuals and those with prediabetes and type 2 diabetes mellitus (T2D) from South Africa. A cross-sectional study was conducted involving subjects of mixed ancestry aged ≥20 years. Males presented with higher mean 25(OH) vitamin D levels than females, while females exhibited significantly higher serum vitamin D-binding protein levels. Significant differences in mean 25(OH) vitamin D levels were observed in normo-glycaemic, prediabetes, screen-detected DM, and known DM individuals. Vitamin D receptor SNPs Fok1 and Taq1 were not associated with glycaemic status. Fok1 was not associated with 25(OH) vitamin D deficiency, while Taq1 was associated with vitamin D insufficiency. This study showed a high prevalence of vitamin D deficiency/insufficiency in this South African population, with decreased vitamin D levels observed in hyperglycaemic individuals, which was not linked to either vitamin D-binding protein or polymorphisms in Fok1 of the VDR gene. These results may be used as a platform for further research into diagnosis and treatment of hyperglycaemia.

Reduced nitric oxide synthesis in winter: A potential contributing factor to increased cardiovascular risk

BACKGROUND

Nitric oxide is a key signalling molecule that elicits a range of biological functions to maintain vascular homeostasis. A reduced availability of nitric oxide is implicated in the progression of cardiovascular diseases and increases the risk of pathogenic events.

AIMS

To compare the concentration of nitric oxide metabolites in healthy adults between winter and summer months.

DESIGN

An observational study of healthy adults (age 32 ± 9 years) living in central Scotland.

METHODS

Thirty-four healthy adults (13 females) were monitored for 7 days in summer and winter to record sunlight exposure (ultraviolet-A (UV-A) radiation), diet, and physical activity. At the end of each phase, blood pressure was measured, and samples of blood and saliva collected. The samples were analysed to determine the concentrations of plasma and salivary nitrate and nitrite and serum 25-hydroxyvitamin D (25(OH)D).

RESULTS

The participants maintained similar diets in each measurement phase but were exposed to more UV-A radiation (550%) and undertook more moderate-vigorous physical activity (23%) in the summer than in winter. Plasma nitrite (46%) and serum 25(OH)D (59%) were higher and blood pressure was lower in the summer compared to winter months. Plasma nitrite concentration was negatively associated with systolic, diastolic, and mean arterial blood pressure.

CONCLUSIONS

Plasma nitrite, an established marker of nitric oxide synthesis, is higher in healthy adults during the summer than in winter. This may be mediated by a greater exposure to UV-A which stimulates the release of nitric oxide metabolites from skin stores. While it is possible that seasonal variation in nitric oxide availability may contribute to an increased blood pressure in the winter months, the overall impact on cardiovascular health remains to be determined.

Overview of Nutraceuticals and Cardiometabolic Diseases following Socio-Economic Analysis

The importance of functional food and nutraceutical products to deal with cardiometabolic diseases (CMDs) and metabolic syndrome (MetS) has gained attention in the past few years. The aim of this narrative review is to highlight the potential and effectiveness of nutraceutical in the improvement of CMDs and MetS biomarkers, alongside their burden of disease and economic health expenditure. A science database search was conducted between May and June 2021. A total of 35 studies were included in this paper. We included male and female subjects, children, and adults, in good health or with cardiovascular or metabolic disease. CMDs and MetS have gradually become worldwide health problems, becoming two of the major causes of morbidity and mortality in western countries. The results indicate a positive link between daily consumption of nutraceutical products and an improvement in cardiometabolic and anthropometric biomarkers. In this paper we included a wide range of nutraceutical products. Most of them showed promising data, indicating that nutraceuticals could provide a new therapeutic treatment to reduce prevalence and pharmaceutical expenditures attributed to CMDs and MetS. Unfortunately, there is a huge vacuum of data on nutraceutical usage, savings, and burden reduction. Therefore, further clinical and pharmaco-economic research in the field is highly required.

Circulating 25-hydroxyvitamin D levels and hypertension risk after adjusting for publication bias

BACKGROUND

Previous systematic reviews reported that serum vitamin D deficiency was associated with risk of hypertension. The aim was to conduct a meta-epidemiological analysis for evaluating the potential effects of publication bias.

METHODS

The selection criterion was defined as a follow-up study for evaluating the association between circulating 25-hydroxyvitam D level and hypertension risk in adults. A funnel plot and Egger's test were used to detect a publication bias. If a publication bias was identified, trim-and-fill analysis (TFA) with linear estimator was performed to estimate a summary relative risk (sRR).

RESULTS

The meta-analysis of 13 cohorts resulted in the lower the vitamin D, the higher the risk of hypertension statistically significant (sRR, 1.22; 95% confidence interval [CI], 1.05 to 1.41). But The P-value of Egger's test (=0.015) and asymmetry of the funnel plot showed that there was a publication bias. TFA resulted in that statistical significance disappeared in the association between vitamin D level and hypertension risk in total cohorts (filled sRR, 1.03; 95% CI, 0.89 to 1.18) as well as men and women cohorts.

CONCLUSIONS

The publication bias-adjusted results by TFA had no statistically significant association between vitamin D levels and the risk of hypertension. The significant results in previous systematic reviews might be interpreted as due to publication bias.

Evaluating agreement between bodies of evidence from randomized controlled trials and cohort studies in medical research: a meta-epidemiological study

BACKGROUND

Randomized controlled trials (RCTs) and cohort studies are the most common study design types used to assess the treatment effects of medical interventions. To evaluate the agreement of effect estimates between bodies of evidence (BoE) from randomized controlled trials (RCTs) and cohort studies and to identify factors associated with disagreement.

METHODS

Systematic reviews were published in the 13 medical journals with the highest impact factor identified through a MEDLINE search. BoE-pairs from RCTs and cohort studies with the same medical research question were included. We rated the similarity of PI/ECO (Population, Intervention/Exposure, Comparison, Outcome) between BoE from RCTs and cohort studies. The agreement of effect estimates across BoE was analyzed by pooling ratio of ratios (RoR) for binary outcomes and difference of mean differences for continuous outcomes. We performed subgroup analyses to explore factors associated with disagreements.

RESULTS

One hundred twenty-nine BoE pairs from 64 systematic reviews were included. PI/ECO-similarity degree was moderate: two BoE pairs were rated as "more or less identical"; 90 were rated as "similar but not identical" and 37 as only "broadly similar". For binary outcomes, the pooled RoR was 1.04 (95% CI 0.97-1.11) with considerable statistical heterogeneity. For continuous outcomes, differences were small. In subgroup analyses, degree of PI/ECO-similarity, type of intervention, and type of outcome, the pooled RoR indicated that on average, differences between both BoE were small. Subgroup analysis by degree of PI/ECO-similarity revealed high statistical heterogeneity and wide prediction intervals across PI/ECO-dissimilar BoE pairs.

CONCLUSIONS

On average, the pooled effect estimates between RCTs and cohort studies did not differ. Statistical heterogeneity and wide prediction intervals were mainly driven by PI/ECO-dissimilarities (i.e., clinical heterogeneity) and cohort studies. The potential influence of risk of bias and certainty of the evidence on differences of effect estimates between RCTs and cohort studies needs to be explored in upcoming meta-epidemiological studies.

Vitamin D, infections and immunity

Vitamin D, best known for its role in skeletal health, has emerged as a key regulator of innate immune responses to microbial threat. In immune cells such as macrophages, expression of CYP27B1, the 25-hydroxyvitamin D 1α-hydroxylase, is induced by immune-specific inputs, leading to local production of hormonal 1,25-dihydroxyvitamin D (1,25D) at sites of infection, which in turn directly induces the expression of genes encoding antimicrobial peptides. Vitamin D signaling is active upstream and downstream of pattern recognition receptors, which promote front-line innate immune responses. Moreover, 1,25D stimulates autophagy, which has emerged as a mechanism critical for control of intracellular pathogens such as M. tuberculosis. Strong laboratory and epidemiological evidence links vitamin D deficiency to increased rates of conditions such as dental caries, as well as inflammatory bowel diseases arising from dysregulation of innate immune handling intestinal flora. 1,25D is also active in signaling cascades that promote antiviral innate immunity; 1,25D-induced expression of the antimicrobial peptide CAMP/LL37, originally characterized for its antibacterial properties, is a key component of antiviral responses. Poor vitamin D status is associated with greater susceptibility to viral infections, including those of the respiratory tract. Although the severity of the COVID-19 pandemic has been alleviated in some areas by the arrival of vaccines, it remains important to identify therapeutic interventions that reduce disease severity and mortality, and accelerate recovery. This review outlines of our current knowledge of the mechanisms of action of vitamin D signaling in the innate immune system. It also provides an assessment of the therapeutic potential of vitamin D supplementation in infectious diseases, including an up-to-date analysis of the putative benefits of vitamin D supplementation in the ongoing COVID-19 crisis.

Simultaneous determination of vitamin D metabolites 25(OH)D3 and 1α,25(OH)2D3 in human plasma using liquid chromatography tandem mass spectrometry

•

LC-MS/MS method development and optimization for simultaneous determination of 25(OH)D₃ and 1α,25(OH)₂D₃ in human plasma.

•

Lowest concentration of 25(OH)D₃ and 1α,25(OH)₂D₃ was 1000 and 20 pg/mL, respectively.

•

The validated method was applied to a pharmacokinetic study in humans.

Background

Although measurement of 25(OH)D₃ is a routine analytical method to determine plasma vitamin D status, 1α,25(OH)₂D₃ is the biologically active form. Hence, simultaneous measurement of 25(OH)D₃ and 1α,25(OH)₂D₃ could provide better insight into vitamin D status and pharmacokinetics. However, 1α,25(OH)₂D₃ has a low plasma concentration, making its quantification challenging for most analytical techniques. Here, we demonstrate use of liquid chromatography tandem mass spectrometry (LC-MSMS) for the development of a simple and rapid method for the simultaneous quantification of 25(OH)D₃ and 1α,25(OH)₂D₃.

Methods

Samples were purified from 250 µL human plasma. Chromatography was performed on an analytical column, under gradient conditions using a mobile phase consisting of methanol-lithium acetate. The mass detector was operated in positive multiple reaction monitoring mode. The established method was validated according to the guidance issued by ICH and FDA. Furthermore, a clinical study was performed using this method to detect the plasma concentrations of 1α,25(OH)₂D₃ after oral administration of calcitriol.

Results and conclusion

The method was acceptably linear over the concentration ranges of 20–1200 pg/mL for 1α,25(OH)₂D₃ and 1–60 ng/mL for 25(OH)D₃, respectively, with correlation coefficients of r² > 0.993. Both the inter-assay and intra-assay precision was < 15%, and the analytical recoveries were within 100% ± 10%, with no significant matrix effect or carryover. Thereby, we, provide a facile method for the simultaneous detection of vitamin D metabolites in plasma.

Insulin Resistance and Vitamin D Deficiency: A Link Beyond the Appearances

Vitamin D is a steroid hormone that plays a key role in the regulation of body homeostasis, including cardiovascular function. Although the chronic deficiency of vitamin D is associated with cardiovascular risk factors, as well as with an adverse prognosis, randomized controlled trials have failed in demonstrating that dietary vitamin D supplementation could ameliorate the prognosis of patients with cardiovascular diseases, and suggested that vitamin D deficiency is the expression of the effects of other determinants of cardiovascular risk. Thus, the supplementation of vitamin D is not sufficient to improve the cardiovascular risk profile and prognosis. Insulin resistance is a complex phenomenon that plays a key role in the pathogenesis of conventional cardiovascular risk factors. Interestingly, defects of vitamin D and insulin resistance have a superimposable epidemiological distribution. According to the common view, Insulin resistance is considered the direct or indirect consequence of vitamin D deficiency. However, it is also reasonable to speculate that the deficit or the impaired action of vitamin D, in some circumstances, could be the result of the same pathogenic mechanisms responsible of insulin resistance development. In this case, vitamin D deficiency could be considered an epiphenomenon of insulin resistance. Insulin resistance is a reversible condition, being possibly ameliorated by physical activity and hypocaloric diets. Notably, both physical exercise and energy-restricted dietary regimens are associated with an increase of vitamin D levels. These findings indicate that improving insulin resistance condition is a necessary step to ameliorate vitamin D supplementation-based strategies in cardiovascular prevention.

Vitamin D, respiratory infections, and chronic disease: Review of meta-analyses and randomized clinical trials

BACKGROUND

Observational studies have suggested associations of vitamin D deficiency (VDD) with respiratory tract infections, impaired bone health, and myriad chronic diseases.

OBJECTIVE

To assess potential causal relationships between vitamin D supplementation and a reduced risk of these conditions, a review of the evidence across available meta-analyses of randomized control trials (RCTs) and RCTs was performed.

METHOD

PubMed, Embase, Cochrane Library, and Web of Science were searched from their inception to March 2021. We included only RCTs and meta-analyses of RCTs focusing on the association between vitamin D and respiratory disease, bone health, cardiovascular disease (CVD), diabetes mellitus, and cancer.

RESULTS

A total of 107 RCTs and 62 meta-analysis of RCTs were included. Although most RCTs did not support benefits of vitamin D supplementation, suggestive evidence for benefit was found in populations at greater risk of VDD and for acute respiratory infections, fractures in institutionalized older adults, type 2 diabetes among patients with prediabetes, and cancer mortality. In contrast, no compelling evidence for benefit was found for other respiratory conditions, fractures in community-dwelling adults, falls, cancer incidence, or CVD.

CONCLUSIONS

Current evidence from RCTs and meta-analyses of RCTs is inconsistent regarding the effects of vitamin D supplementation on respiratory infections and chronic diseases. Individuals most likely to benefit are those with baseline VDD or with selected high-risk conditions. Public health initiatives are needed to eliminate VDD globally, and future research will be enhanced by a 'precision prevention' approach to identify those most likely to benefit from vitamin D supplementation.

A new perspective on cholesterol in pediatric health: association of vitamin D metabolism, respiratory diseases, and mental health problems

Cholesterol, the main structural molecule of cell membranes, is involved in essential functions of the human body. Dyslipidemia is an established risk factor for cardiovascular diseases (CVDs) that is observed even in childhood. To reduce the risk of CVDs in children, several clinical guidelines have been published for the management of pediatric dyslipidemia. However, pediatric dyslipidemia is also associated with several health problems other than CVDs. This article reviews the current data on dyslipidemia-related pediatric health issues. There is strong evidence that low serum vitamin D levels, asthma, and mental health problems may be associated with dyslipidemia in the pediatric population regardless of body mass index. This review also highlights the need for further large-scale population-based studies in the Korean pediatric population to establish effective strategies for promoting children's health.

Association Between Plasma Vitamin D2 and Type 2 Diabetes Mellitus

OBJECTIVE

To investigate the relationship between plasma vitamin D2(VD2) and type 2 diabetes(T2DM).

METHOD

Data from electronic medical records of 797 inpatients treated at Sun Yat Sen Memorial Hospital, Sun Yat-sen University between June 24, 2019 and December 24, 2020 were collected, and a total of 596 patients were enrolled after screening based on inclusion and exclusion criteria. Patients were divided into diabetic and non-diabetic groups according to whether they had T2DM. The Wilcoxon rank sum test was finally selected for the analysis of differences between groups according to the distribution of patients' plasma VD2, and logistic regression models were used to find the corresponding influencing factors.

RESULT

Of the 596 hospitalized patients, 138 (23.15%) were diagnosed with T2DM. The Wilcoxon test showed no statistically significant difference in plasma VD2 concentrations between the T2DM and non-T2DM groups (p=0.833). After adjustment for confounders by multivariate logistic regression, there was still no significant difference in plasma VD2 concentrations between the two groups (P=0.316, OR: 1.15 (0.88,1.49)). The uncorrelated relationship between VD2 and T2DM was not found to change after incorporating 12 indicators, including demographic characteristics, laboratory indicators and complications, into the logistic regression model by 3 steps, even the OR (1.08 (0.92,1.26)) did not change in the 3 models. Similarly, the adjusted ORs agreed that there was no statistical association between VD2 and T2DM.

CONCLUSION

VD2 levels are similar in patients with T2DM compared to those without T2DM. Clinical caution should be exercised in giving VD2 supplementation to patients with T2DM unless other diseases requiring VD2 supplementation (e.g., rickets, osteoporosis) are present.

1,25-dihydroxyvitamin D and cardiometabolic risk in healthy sedentary adults: The FIT-AGEING study

BACKGROUND

A growing body of scientific works investigating the physio-pathological mechanisms behind cardiovascular disease has suggested that vitamin D deficiency could play a key role on its development. However, it remains unclear whether its active form (1,25-dihydroxyvitamin D [1,25(OH)₂D] is associated with cardiometabolic risk factors in healthy individuals. The aim of the present study was to investigate the relationships of 1,25(OH)₂D plasma levels with cardiometabolic risk factors in a sample of healthy sedentary adults.

METHODS

A total of 73 adults (~53% women; 54 ± 5 years old) were included in the current cross-sectional study. A sex-specific cardiometabolic risk score (MetScore) was calculated for each subject based on clinical parameters (i.e., waist circumference, systolic and diastolic blood pressure, plasma glucose, high-density lipoprotein cholesterol, and triglycerides) according to the International Diabetes Federation's clinical criteria. Plasma levels of 1,25(OH)₂D were measured using a DiaSorin Liaison® immunochemiluminometric analyzer.

RESULTS

No significant association was detected between 1,25(OH)₂D and MetScore (β = 0.037, R² = 0.001, p = 0.77), independently of age, sex and fat body mass index. A significant inverse association were observed between 1,25(OH)₂D and waist circumference (β = -0,303, R² = 0.092, p = 0.01). These results were consistent after controlling by potential confounders.

CONCLUSION

In summary, the present results suggest that 1,25(OH)₂D plasma levels are not associated with either cardiometabolic risk factors or insulin resistance in healthy sedentary adults. However, an inverse association of 1,25(OH)₂D plasma levels with central adiposity was observed in our study sample.

Vitamin D and Multiple Health Outcomes: An Umbrella Review of Observational Studies, Randomized Controlled Trials, and Mendelian Randomization Studies

Observational studies, randomized controlled trials (RCTs), and Mendelian randomization (MR) studies have yielded inconsistent results on the associations of vitamin D concentrations with multiple health outcomes. In the present umbrella review we aimed to evaluate the effects of low vitamin D concentrations and vitamin D supplementation on multiple health outcomes. We summarized current evidence obtained from meta-analyses of observational studies that examined associations between vitamin D concentrations and multiple health outcomes, meta-analyses of RCTs that investigated the effect of vitamin D supplementation on multiple health outcomes, and MR studies that explored the causal associations of vitamin D concentrations with various diseases (international prospective register of systematic reviews PROSPERO registration number CRD42018091434). A total of 296 meta-analyses of observational studies comprising 111 unique outcomes, 139 meta-analyses of RCTs comprising 46 unique outcomes, and 73 MR studies comprising 43 unique outcomes were included in the present umbrella review. Twenty-eight disease outcomes were identified by both meta-analyses of observational studies and MR studies. Seventeen of these reported disease outcomes had consistent results, demonstrating that lower concentrations of vitamin D were associated with a higher risk for all-cause mortality, Alzheimer's disease, hypertension, schizophrenia, and type 2 diabetes. The combinations of consistent evidence obtained by meta-analyses of observational studies and MR studies together with meta-analyses of RCTs showed that vitamin D supplementation was associated with a decreased risk for all-cause mortality but not associated with the risk for Alzheimer's disease, hypertension, schizophrenia, or type 2 diabetes. The results indicated that vitamin D supplementation is a promising strategy with long-term preventive effects on multiple chronic diseases and thus has the potential to decrease all-cause mortality. However, the current vitamin D supplementation strategy might not be an efficient intervention approach for these diseases, suggesting that new strategies are highly needed to improve the intervention outcomes.

Association of vitamin D status and cardio-metabolic risk factors in children and adolescents: the CASPIAN-V study

BACKGROUND

Metabolic syndrome (MetS) starts from early life and is one of the important underlying factors for non-communicable diseases (NCDs) in adulthood. Controversial evidence exists on the role of vitamin D deficiency in increasing the risk of pediatric MetS.

OBJECTIVE

This study aimed to assess the relationship between vitamin D level with MetS and its components in children and adolescents.

METHODS

This nationwide cross-sectional study was performed as part of a surveillance program in Iran. Participants were 2596 students, aged 7 to 18 years, living in 30 provinces. In addition to filling questionnaires, a physical examination was conducted, and blood samples were collected. The serum concentration of 25-hydroxy vitamin D (25(OH)D) was measured using the direct competitive immunoassay chemiluminescence method.

RESULTS

2596 students with a mean age of 12.2 y (55.1% boys) were recruited. Prevalence of vitamin D deficiency and insufficiency in participants was 10.6% (n = 276), and 60.5% (n = 1570), respectively. The prevalence of MetS was higher in the vitamin D deficient group. Students with deficient vitamin D levels had higher odds of MetS (OR: 4.25, 95%CI: 2.26-7.98), abdominal obesity (OR: 2.24, 95%CI: 1.61-3.12), low HDL-C (OR: 1.65, 95%CI: 1.18-2.30) and high fasting blood sugar (OR: 2.56, 95%CI: 1.43-4.57) in comparison to those with sufficient level of vitamin D.

CONCLUSION

Vitamin D deficiency was associated with increased odds of MetS and its components in the Iranian pediatric population. These findings underscore the importance of prevention and control of vitamin D deficiency in preventative programs against NCDs.

Vitamin D-independent benefits of safe sunlight exposure

This review examines the beneficial effects of ultraviolet radiation on systemic autoimmune diseases, including multiple sclerosis and type I diabetes, where the epidemiological evidence for the vitamin D-independent effects of sunlight is most apparent. Ultraviolet radiation, in addition to its role in the synthesis of vitamin D, stimulates anti-inflammatory pathways, alters the composition of dendritic cells, T cells, and T regulatory cells, and induces nitric oxide synthase and heme oxygenase metabolic pathways, which may directly or indirectly mitigate disease progression and susceptibility. Recent work has also explored how the immune-modulating functions of ultraviolet radiation affect type II diabetes, cancer, and the current global pandemic caused by SARS-CoV-2. These diseases are particularly important amidst global changes in lifestyle that result in unhealthy eating, increased sedentary habits, and alcohol and tobacco consumption. Compelling epidemiological data shows increased ultraviolet radiation associated with reduced rates of certain cancers, such as colorectal cancer, breast cancer, non-Hodgkins lymphoma, and ultraviolet radiation exposure correlated with susceptibility and mortality rates of COVID-19. Therefore, understanding the effects of ultraviolet radiation on both vitamin D-dependent and -independent pathways is necessary to understand how they influence the course of many human diseases.

Vitamin D Deficiency as a Risk Factor for Myocardial Ischemia

Background and Objectives: Vitamin D (Vit D) deficiency has been implicated in various conditions, including cardiovascular disease. The purpose of this retrospective study was to investigate the incidence of patients with myocardial ischemia in relation to their serum levels of vitamin D. Materials and Methods: A 64-month search (January 2016 to April 2021) in our database of the Nuclear Medicine Laboratory revealed 113 patients who had both myocardial perfusion imaging with single photon emission computed tomography (MPI SPECT) and Vit D measurements. MPI SPECT obtained myocardial images during both stress (summed stress score, SSS) and rest (summed rest score, SRS). Abnormal MPI SPECT was when the SSS was ≥4. Vit D was determined by radioimmunoassay (RIA). Patients with Vit D values <10 ng/mL, 10-29 ng/mL and ≥30 ng/mL were defined as having a deficiency, insufficiency and sufficiency, respectively. Results: Among patients, 46/113 (40.7%) were male and 67/113 (59.3%) were female. Abnormal MPI was found in 58/113 (51.3%) patients. Vit D deficiency was noted in 20/113 (17.7%) patients, insufficiency in 86/113 (76.1%) patients, and normal Vit D was noted in only 7/113 (6.2%) patients. Sixteen of the 20 patients (80%) with Vit D deficiency, and 38/86 (44.2%) with insufficiency had an abnormal MPI SPECT. In contrast, only 1/7 (14.3%) patients with sufficient Vit D levels had an abnormal MPI SPECT. The Mann-Whitney U-test showed that ischemia reduced the values of Vit D. Correlation analysis showed a negative association of Vit D levels with SSS (rho = -0.232, p = 0.014) and SRS (rho = -0.250, p = 0.008). Further evaluation with a Vit D cut off 20 ng/mL retrieved no statistical significance. Finally, Vit D and gender were independently associated with myocardial ischemia. Conclusions: Low Vit D levels may represent a risk factor for myocardial ischemia.

Changes in Bone Turnover, Inflammatory, Oxidative Stress, and Metabolic Markers in Women Consuming Iron plus Vitamin D Supplements: a Randomized Clinical Trial

We aimed to investigate whether combination of vitamin D and iron supplementation, comparing vitamin D alone, could modify bone turnover, inflammatory, oxidative stress, and metabolic markers. Eighty-seven women with hemoglobin (Hb) ≤ 12.7 g/dL and 25OHD ≤ 29 ng/mL vitamin D deficiency/insufficiency aged 18-45 years were randomly assigned into two groups: (1) receiving either 1000 IU/day vitamin D3 plus 27 mg/day iron (D-Fe); (2) vitamin D3 plus placebo supplements (D-P), for 12 weeks. In D-Fe group, significant decrease in red blood cells (RBC) (P = 0.001) and hematocrit (Hct) (P = 0.004) and increases in mean corpuscular hemoglobin concentration (MCHC) (P = 0.001), 25OHD (P < 0.001), osteocalcin (P < 0.001), high-density cholesterol (HDL) (P = 0.041), and fasting blood sugar (FBS) (P < 0.001) were observed. D-P group showed significant decrease in RBC (P < 0.001), Hb (P < 0.001), Hct (P < 0.001), mean corpuscular volume (MCV) (P = 0.004), mean corpuscular hemoglobin (MCH) (P < 0.001), MCHC (P = 0.005), serum ferritin (P < 0.001), and low-density cholesterol (LDL) (P = 0.016) and increases of 25OHD (P < 0.001), osteocalcin (P < 0.001), C-terminal telopeptide (CTX) (P = 0.025), triglyceride (TG) (P = 0.004), FBS (P < 0.001), and interleukin-6 (IL-6) (P = 0.001) at week 12. After the intervention, the D-P group had between-group increases in mean change in the osteocalcin (P = 0.007) and IL-6 (P = 0.033), and decreases in the RBC (P < 0.001), Hb (P < 0.001), Hct (P < 0.001), and MCV (P = 0.001), compared with the D-Fe group. There were significant between-group changes in MCH (P < 0.001), MCHC (P < 0.001), ferritin (P < 0.001), and serum iron (P = 0.018). Iron-vitamin D co-supplementation does not yield added benefits for improvement of bone turnover, inflammatory, oxidative stress, and metabolic markers, whereas, vitamin D alone may have some detrimental effects on inflammatory and metabolic markers. IRCT registration number: IRCT201409082365N9.

Vitamin D status and blood pressure in children and adolescents: a systematic review of observational studies

BACKGROUND

Childhood hypertension is a growing public health problem. Simultaneously, hypovitaminosis D is widespread in this population and could be associated with hypertension. This study systematically reviewed the literature on the relationship between vitamin D status and blood pressure (BP) in children and adolescents.

METHODS

Following the PRISMA guidelines, PUBMED, MEDLINE, CINAHL, EMBASE, Cochrane Library, and ClinicalTrials.gov and the gray literature without language or time restrictions were searched. We included observational studies, assessed their risk of bias, and extracted data on population characteristics, vitamin D status and BP measurements, and the association between the two variables. A narrative analysis of the studies was performed.

RESULTS

In total, 85 studies were included. Prospective cohort studies showed no association between vitamin D and BP, and generally, they were flawed. Also, the majority of non-prospective cohort studies (cross-sectional, retrospective, case-control) did not report an association between vitamin D and BP. They were mostly flawed regarding BP measurement and adjusting to potential confounders.

CONCLUSION

The results on the relationship between vitamin D status and BP in children and adolescents varied between the studies, and mainly pointed towards lack of association.

Vitamin D supplements: The pharmacists' perspective

OBJECTIVE

The purpose of this narrative review was to provide guidance for pharmacists concerning vitamin D supplementation.

METHODS

Relevant studies were identified in a search of MEDLINE/PubMed, EBSCOhost, and Google Scholar from January 1966 to September 2020 using the search terms vitamin D, vitamin D₂, vitamin D₃, calcitriol, and vitamin D deficiency. Abstracts were reviewed for relevance and, if relevant, full-text articles were retrieved and reviewed. References were checked, and citation searches using identified studies were conducted. The literature search included English-language studies involving administration of vitamin D monotherapy compared with placebo.

RESULTS

Serum 25-hydroxyvitamin D levels of less than 12 ng/mL indicate a vitamin D deficiency. The Institute of Medicine recommends a daily intake of 600 IU of vitamin D in individuals aged up to 70 years and 800 IU in those aged above 70 years. Vitamin D is labeled for rickets, osetomalacia, hypophosphatemia (familial or secondary), renal osteodystrophy, and corticosteroid-induced osteoporosis. When used for these indications, vitamin D should be prescribed with appropriate monitoring by a qualified health care practitioner. There is evidence for vitamin D supplementation in individuals aged 75 years or older and in those with problems associated with mobility, gait, or balance. There is insufficient evidence to support vitamin D supplementation in the prevention of cardiovascular disease, cancer, asthma, chronic obstructive pulmonary disease exacerbations, new-onset type 2 diabetes, infectious lung diseases, cognitive dysfunction, Alzheimer disease, and depression, or in prenatal use.

CONCLUSION

Pharmacists can provide evidence-based recommendations concerning the indications, dosing, monitoring, and adverse effects of vitamin D supplements.

Vitamin D status in infancy and cardiometabolic health in adolescence

BACKGROUND

Vitamin D deficiency is associated with obesity-related conditions, but the role of early life vitamin D status on the development of obesity is poorly understood.

OBJECTIVES

We assessed whether serum 25-hydroxyvitamin D [25(OH)D] at age 1 y was related to metabolic health through adolescence.

METHODS

We quantified serum 25(OH)D in samples obtained at age 1 y from 306 participants in a cohort study in Santiago, Chile. Anthropometry was performed at ages 5, 10, and 16/17 y. At 16/17 y, we determined body composition using DXA and quantified metabolic parameters in a blood sample. We examined the associations of infancy 25(OH)D with BMI-for-age z-score (BMIZ) at ages 5, 10, and 16/17 y; with percentage fat and percentage lean body mass at age 16/17 y; and with a metabolic syndrome (MetS) score and its components at age 16/17 y.

RESULTS

Infancy 25(OH)D was inversely associated with BMIZ in childhood. Every 25-nmol/L difference in 25(OH)D was related to an adjusted 0.11 units lower BMIZ at age 5 y (95% CI: -0.20, -0.03; P = 0.01) and a 0.09 unit lower BMIZ change from ages 1 to 5 y (95% CI: -0.17, -0.01; P = 0.02). Also, every 25-nmol/L 25(OH)D in infancy was associated with an adjusted 1.3 points lower percentage body fat mass (95% CI: -2.2, -0.4; P = 0.005) and an adjusted 0.03 units lower MetS score (95% CI: -0.05, -0.01; P = 0.01) at age 16/17 y, through inverse associations with waist circumference and the HOMA-IR.

CONCLUSIONS

Serum 25(OH)D at age 1 y is inversely associated with childhood BMIZ, percentage body fat at age 16/17 y, and a MetS score at age 16/17 y. Intervention studies are warranted to examine the effects of vitamin D supplementation in early life on long-term cardiometabolic outcomes.