Regulation of Immune Function by Vitamin D and Its Use in Diseases of Immunity

Vitamin D and Acute Kidney Injury: A Reciprocal Relationship

Vitamin D is a sterol prohormone with no intrinsic biological activity. Calcitriol, the active form of vitamin D, is synthesized in the kidneys. It has well-known pleiotropic and cytoprotective properties. In addition to regulating parathyroid hormone secretion and enhancing gut calcium absorption, it exhibits antioxidant, anti-inflammatory, antiproliferative, and antineoplastic effects. However, the role of vitamin D in AKI is unclear, unlike in CKD. Thus, this review aimed to understand how dysregulated vitamin D homeostasis occurs in AKI, as well as to explore how vitamin D deficiency and excess influence AKI. A comprehensive literature search was conducted between January 2000 and June 2024 to uncover relevant works detailing vitamin D homeostasis in health as well as investigating the impact of vitamin D deficiency and excess in humans, animals, and in vitro cell models of AKI. According to the findings of this review, vitamin D appears to have a reciprocal relationship with AKI. Acute renal injury, among other factors, can cause hypo- or hypervitaminosis D. Conversely, AKI can also be caused by vitamin D deficiency and toxicity. Even though hypovitaminosis D is associated with AKI, it is uncertain how it impacts AKI outcomes in distinct clinical scenarios. Newer therapeutic options might emerge as a result of understanding these challenges. Vitamin D supplementation may ameliorate renal injury but needs further validation. Furthermore, hypervitaminosis D has also been implicated in AKI by causing hypercalcemia and hyperphosphatemia. It is crucial to avoid prolonged, uncontrolled, and unsupervised supraphysiological vitamin D administration, especially intramuscular injection.

Vitamin D Status as a Risk Factor for Tuberculosis Infection

Vitamin D is a principal regulator of bone and mineral metabolism. Recent data have provided evidence that vitamin D is a polyfunctional hormone with actions that extend beyond its classical role as a nutrient for bone and mineral metabolism. These additional actions include its potential role to prevent infections and autoimmunity. This review will focus on the relationship between vitamin D and infections, specifically on tuberculosis (TB). The literature review was conducted on PubMed using the search terms "Vitamin D" and "Tuberculosis." As one of the most resilient infectious microorganisms on the planet, TB remains a public health concern because of the emergence of resistant strains, the burden, and side effects of treatment. Vitamin D plays an important role in the innate immune system that is the first line of defense against TB infection. Although there appears to be pathophysiological interplay between vitamin D and TB, more research is necessary to determine with certainty the extent of this relationship. Social determinants of health including population density, income, poverty, public assistance, unemployment, and education also play a role in estimating the prevalence of vitamin D deficiency and the burden of TB. This review explores the interplay between vitamin D and TB through factors including the immune system and social determinants of health.

Multivitamin supplementation and its impact in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an emerging global health concern with limited therapeutic options. Multivitamins, widely consumed dietary supplements, have been proposed to modulate oxidative stress and inflammation, potentially impacting MASLD progression. However, their efficacy in reducing mortality and other complications in MASLD remains unclear. Using data from the UK Biobank with 7 years of median follow-up period, this study assessed the association between multivitamin use and health outcomes, including all-cause mortality, liver-related mortality, cardio-cerebrovascular disease (CVD), and chronic kidney disease (CKD), in individuals with MASLD and those without steatotic liver disease. Inverse probability of treatment weighting (IPTW) was employed to adjust for confounders. Multivitamin users showed a significantly lower all-cause mortality risk in the MASLD cohort both before (HR: 0.88, 95% CI 0.81-0.95, P = 0.034) and after (HR: 0.94, 95% CI 0.88-1.00, P = 0.037) IPTW adjustment. Multivitamin use was also associated with the lower risk of CVD (HR: 0.72, 95% CI 0.68-0.76, P < 0.001) and CKD (HR: 0.73, 95% CI 0.67-0.81, P < 0.001) in the MASLD cohort. No significant reduction was found for liver-related mortality or liver cirrhosis incidence. These findings suggest that multivitamins might provide broader protective effects in populations with metabolic dysfunction. Further research is needed to clarify their role in liver-specific outcomes.

Genetic Evidence Indicates that Serum Micronutrient Levels Mediate the Causal Relationships Between Immune Cells and Neuropathic Pain: A Mediation Mendelian Randomization Study

A growing body of evidence suggests a correlation among immune cells, serum micronutrient levels, and neuropathic pain. However, previous studies have been limited in scope, hindering the establishment of conclusive findings. Therefore, this study employs mendelian randomization (MR) analysis to investigate the genetic perspectives on the causal relationships among these factors. Initially, the relationship between five serum micronutrient levels (specifically, four vitamin levels and zinc levels) and neuropathic pain was examined using a bidirectional MR design. Subsequently, positive results identified through the inverse variance weighted (IVW) method prompted further analysis, using immune cells as exposures to explore their causal links with neuropathic pain. As a result, a two-step MR analysis demonstrated that serum vitamin levels mediate the relationship between immune cells and neuropathic pain, quantifying both direct impacts and mediation effects. This study revealed that low serum levels of vitamin D and 25-hydroxyvitamin D increased the risk of postherpetic neuralgia and thoracic spine pain. Reverse MR analysis suggested that neuropathic pain does not contribute to a reduction in the serum levels of vitamin D and 25-hydroxyvitamin D. Furthermore, significant associations were observed between 27 immune cells and postherpetic neuralgia, as well as between 22 immune cells and thoracic spine pain. Additionally, the mediation analysis identified causal relationships between immune cells and serum micronutrient levels, confirming the "immune cells-serum micronutrient levels-neuropathic pain" pathway. This study provides valuable insights into the potential mechanisms by which vitamin D and 25-hydroxyvitamin D regulate the interaction between the immune system and neuropathic pain. These findings are crucial for the timely detection, treatment, and management of neuropathic pain, offering new perspectives on how vitamin levels influence immune cell behavior and neuropathic pain susceptibility.

Association Between Vitamin D and COVID-19-Related Outcomes: An Umbrella Review of Meta-Analyses

CONTEXT

COVID-19 remains globally pandemic, and although several meta-analyses have explored the association between vitamin D and COVID-19 relative to clinical outcomes, a unified view has not yet emerged.

OBJECTIVE

To summarize the evidence for associations between vitamin D levels and COVID-19-related clinical outcomes and to assess the strength and validity of these associations.

DATA SOURCES

PubMed, Embase, Web of Science, Scopus, and the Cochrane Database of Systematic Reviews databases were searched from January 1, 2020, to June 15, 2024.

DATA EXTRACTION

Two reviewers independently extracted data and assessed study quality.

DATA ANALYSIS

Low vitamin D levels increased the risk of infection by 1.26- to 2.18-fold, the risk of severe illness by 1.50- to 5.57-fold, the risk of intensive care unit (ICU) admission by more than 2-fold, and the risk of death by 1.22- to 4.15-fold. In addition, patients with vitamin D deficiency had an average increase in length of hospital stay of 0.54 days compared with patients with high vitamin D levels. Overall, vitamin D supplementation may reduce severity (eg, ICU admissions, need for mechanical ventilation) and shorter length of hospital stay but has a nonsignificant effect on infection and mortality rates. In addition, there were significant differences in vitamin D levels between individuals testing positive for COVID-19 and those testing negative (mean difference [MD] = -3.22 ng mL-1; 95% CI, -5.18 to -1.25), those with severe cases and those with mild cases (MD = -4.60 ng mL-1; 95% CI, -5.49 to -3.71), and nonsurvivors and survivors of COVID-19 infection (MD = -6.59 ng mL-1; 95% CI: -8.94 to -4.24).

CONCLUSIONS

Low vitamin D levels are associated with higher infection rates, more severe disease, and higher mortality rates among individuals with COVID-19, whereas vitamin D supplementation may reduce patients' disease severity. The beneficial effects on infection rates and mortality remain to be further explored, however, in higher-quality, randomized controlled studies. Nonetheless, caution is warranted because the methodological quality of most meta-analyses and the level of evidence for most outcomes are very low.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration No. CRD42022385036.

The Mechanisms of Sepsis Induced Coagulation Dysfunction and Its Treatment

Sepsis is a critical condition characterized by organ dysfunction due to a dysregulated response to infection that poses significant global health challenges. Coagulation dysfunction is nearly ubiquitous among sepsis patients. Its mechanisms involve platelet activation, coagulation cascade activation, inflammatory reaction imbalances, immune dysregulation, mitochondrial damage, neuroendocrine network disruptions, and endoplasmic reticulum (ER) stress. These factors not only interact but also exacerbate one another, leading to severe organ dysfunction. This review illustrates the mechanisms of sepsis-induced coagulopathy, with a focus on tissue factor activation, endothelial glycocalyx damage, and the release of neutrophil extracellular traps (NETs), all of which are potential targets for therapeutic interventions.

The Immunomodulatory Activity of High Doses of Vitamin D in Critical Care Patients with Severe SARS-CoV-2 Pneumonia-A Randomized Controlled Trial

Vitamin D receptor [VDR] expression promotes LL37 expression, possibly contributing to host defense. The hypothesis was that an increase in 25 hydroxyvitamin D [25vitD] could lead to enhanced VDR expression and increased LL-37 production, thereby contributing to improved prognosis in critically ill patients. Methods: A nonblinded, randomized controlled trial was conducted. A total of 207 patients admitted to ICU with severe SARS-CoV-2 pneumonia were included and received different doses of cholecalciferol (500 MU, 3 MU/day, no cholecalciferol) during their ICU and hospital stay. 25vitD levels as well as LL37 and monocytes' VDR gene expression were evaluated on admission and after. Clinical evolution, ICU mortality, hospital mortality, and 60-day mortality were evaluated. Results: The median age was 57.7 years and the majority of patients were Caucasian [87.4%] and male [70.5%]. There was a significant difference in 25vitD levels between groups on the third [p = 0.002] and seventh [p < 0.001] days. Patients supplemented with 500 MU of cholecalciferol had a very significant increase in monocytes' VDR gene expression and showed a better clinical evolution in the ICU, with a significant correlation to evolution factors. Higher LL37 on admission had a significant negative association with hospital and ICU mortality, lost after adjustment for comorbidities to a nearly significant association with ICU, hospital, and 60-day mortality. Conclusion: Supplementation with higher doses of cholecalciferol may contribute to a significant increase in 25vitD levels but not in LL37 levels. Higher LL37 levels on admission may be related to a decrease in ICU, hospital, and 60-day mortality. VDR gene expression in monocytes is much higher in patients supplemented with higher doses of cholecalciferol.

Relationship Between Vitamin D Levels with In-Hospital Complications and Morphofunctional Recovery in a Cohort of Patients After Severe COVID-19 Across Different Obesity Phenotypes

BACKGROUND AND OBJECTIVES

the COVID-19 pandemic underscored the necessity of understanding the factors influencing susceptibility and disease severity, as well as a better recovery of functional status, especially in postcritical patients. evidence regarding the efficacy of vitamin D supplementation in reducing the severity of COVID-19 is still insufficient due to the lack of primary robust trial-based data and heterogeneous study designs. the principal aims of our study were to determine the impact of vitamin D deficiency or insufficiency on complications during intensive care unit (icu) stay, as well as its role in muscle mass and strength improvement as well as morphofunctional recovery during a multispecialty 6-month follow-up program based on adapted nutritional support and specific physical rehabilitation. as a secondary objective, we compared the association mentioned above between patients with sarcopenic obesity and non- sarcopenic obesity.

METHODS

this prospective observational study included 94 outpatients postcritical COVID-19. two weeks after hospital discharge, patients were divided into sufficient (≥30 ng/mL), insufficient (20.01-29.99 ng/mL), or deficient (≤20 ng/mL) vitamin D levels. the differences in in-hospital complications and morphofunctional parameters including phase angle (PhA), body cell mass (BCM), handgrip strength (HGS), timed get-up-and-go (UAG), 6 min walk test (6MWT), and proinflammatory biochemical variables were analyzed. Incremental (Δ) changes in these parameters were also analyzed at the end of follow-up according to vitamin D levels and the presence vs. absence of sarcopenic obesity. A multivariate linear regression analysis was performed to detect possible confounding factors in the impact analysis of vitamin D changes on functional recovery in patients with obesity.

RESULTS

A total of 36.2% of patients exhibited vitamin D deficiency, 29.8% vitamin D insufficiency, and only 32.9% showed sufficient levels at hospital discharge. A total of 46.8% of patients had obesity, and 36.1% had sarcopenic obesity. Vitamin D deficiency was associated with longer hospital stays (p = 0.04), longer ICU stays (p = 0.04), more days of invasive mechanical ventilation (IMV) (p = 0.04), lower skeletal muscle mass/weight (SMM/w) (p = 0.04) and skeletal muscle index (SMI) (p = 0.047), higher fat mass percentage (FM%) (p = 0.04), C-reactive-protein (CRP) (p = 0.04), and glycated hemoglobin (HbA1c) (p = 0.03), and better performance in R-HGS (p = 0.04), UAG (p = 0.03), and 6MWT (p = 0.034) when compared with those with normal vitamin D levels. At six months, Δvitamin D significantly correlated with ΔHbA1c (p = 0.002) and CRP (p = 0.049). Patients with normal vitamin D values showed better recovery of ΔSMI (p = 0.046), ΔSMM/w (p = 0.04), ΔR-HGS (p = 0.04), and ΔUAG (p = 0.04) compared to those with abnormal vitamin D levels, and these improvements in ΔR-HGS and ΔUAG were greater in the subgroup of sarcopenic obesity compared than in nonsarcopenic obesity (p = 0.04 and p = 0.04, respectively). Multivariate regression analysis detected that these results were also attributable to a longer hospital stay and lower ΔCRP in the subgroup of patients with sarcopenic obesity.

CONCLUSIONS

Vitamin D deficiency was associated with longer hospital stays, longer VMI requirement, worse muscle health, and a higher degree of systemic inflammation. Furthermore, normal vitamin D levels at the end of the follow-up were associated with better morphofunctional recovery in postcritical COVID-19, particularly in patients with sarcopenic obesity partly due to a higher degree of inflammation as a result of a longer hospital stay.

The correlation between serum vitamin D status and the occurrence of diabetic foot ulcers: a comprehensive systematic review and meta-analysis

The association between vitamin D concentrations and the occurrence of diabetic foot ulcers (DFUs) remains a topic of ongoing debate. In order to provide a comprehensive and updated review, we conducted this meta-analysis to further investigate the relationship between vitamin D concentrations and DFUs occurrence. The following databases, including Cochrane Library, EMBASE, Web of Science, PubMed, CBM, CNKI, WANFANG DATA and VIP Database, were systematically searched for studies published up to Dec. 20th, 2023. The combined estimation was calculated using both fixed-effects and random-effects models. The overall effect size was reported as a weighted mean difference (WMD) with a corresponding 95% confidence interval (95%CI). Data analysis was performed utilizing Review Manager 5.4 and Stata 14. The Protocol has been registered in PROSPERO CRD42024503468. This updated meta-analysis, incorporating thirty-six studies encompassing 11,298 individuals with or without DFUs, demonstrated a significant association between vitamin D deficiency/insufficiency and an elevated risk of DFUs occurrence (< 25 nmol/L, OR 3.28, P < 0.00001; < 50 nmol/L, OR 2.25, P < 0.00001; < 75 nmol/L, OR 1.67, P = 0.0003). Vitamin D concentrations were significantly lower in individuals with DFUs compared to those without DFUs (P < 0.00001). Subgroup analyses consistently demonstrated this trend among the older population (> 50 years, P < 0.00001), individuals with long duration of diabetes (> 10 years, P < 0.00001), and those with poor glycemic control (mean HbA1c 8%-9% and > 9%, P < 0.00001).

4-Hydroxy-1α,25-Dihydroxyvitamin D3: Synthesis and Structure-Function Study

The active vitamin D metabolites, 25-hydroxyvitamin D3 (25D3) and 1,25-dihydroxyvitamin D3 (1,25D3), are produced by successive hydroxylation steps and play key roles in several cellular processes. However, alternative metabolic pathways exist, and among them, the 4-hydroxylation of 25D3 is a major one. This study aims to investigate the structure-activity relationships of 4-hydroxy derivatives of 1,25D3. Structural analysis indicates that 1,4α,25(OH)3D3 and 1,4β,25(OH)3D3 maintain the anchoring hydrogen bonds of 1,25D3 and form additional interactions, stabilizing the active conformation of VDR. In addition, 1,4α,25D3 and 1,4β,25D3 are as potent as 1,25D3 in regulating the expression of VDR target genes in rat intestinal epithelial cells and in the mouse kidney. Moreover, these two 4-hydroxy derivatives promote hypercalcemia in mice at a dose similar to that of the parent compound.

Vitamin D3 Regulates Energy Homeostasis under Short-Term Fasting Condition in Zebrafish (Danio Rerio)

Vitamin D3 (VD3) is a steroid hormone that plays pivotal roles in pathophysiology, and 1,25(OH)2D3 is the most active form of VD3. In the current study, the crucial role of VD3 in maintaining energy homeostasis under short-term fasting conditions was investigated. Our results confirmed that glucose-depriving pathways were inhibited while glucose-producing pathways were strengthened in zebrafish after fasting for 24 or 48 h. Moreover, VD3 anabolism in zebrafish was significantly suppressed in a time-dependent manner under short-fasting conditions. After fasting for 24 or 48 h, zebrafish fed with VD3 displayed a higher gluconeogenesis level and lower glycolysis level in the liver, and the serum glucose was maintained at higher levels, compared to those fed without VD3. Additionally, VD3 augmented the expression of fatty acids (FAs) transporter cd36 and lipogenesis in the liver, while enhancing lipolysis in the dorsal muscle. Similar results were obtained in cyp2r1-/- zebrafish, in which VD3 metabolism is obstructed. Importantly, it was observed that VD3 induced the production of gut GLP-1, which is considered to possess a potent gluconeogenic function in zebrafish. Meanwhile, the gene expression of proprotein convertase subtilisin/kexin type 1 (pcsk1), a GLP-1 processing enzyme, was also induced in the intestine of short-term fasted zebrafish. Notably, gut microbiota and its metabolite acetate were involved in VD3-regulated pcsk1 expression and GLP-1 production under short-term fasting conditions. In summary, our study demonstrated that VD3 regulated GLP-1 production in zebrafish by influencing gut microbiota and its metabolite, contributing to energy homeostasis and ameliorating hypoglycemia under short-term fasting conditions.

Clinical Evidence on the Potential Beneficial Effects of Diet and Dietary Supplements against COVID-19 Infection Risk and Symptoms' Severity

BACKGROUND

Diet and dietary supplements aim to add trace elements, vitamins, and minerals to the body to improve human health and boost the immune system. In the previous few years, the new SARS-CoV-2 coronavirus strain has been threatening the health of individuals and public health more broadly, with rates of intensive care unit cases on the rise, while long-term COVID-19 complications are persisting until today. In the peculiar circumstances of the COVID-19 pandemic, in combination with disease prevention techniques, the strengthening of the immune system is considered particularly important to enable it to effectively respond to and eliminate the SARS-CoV-2 viral pathogen in the event of infection. The purpose of the current literature review is to thoroughly summarize and critically analyze the current clinical data concerning the potential beneficial effects of diet and dietary supplements against COVID-19 infection risk and symptoms' severity. The micronutrients/supplements examined in this study in relation to COVID-19 infection are vitamins A, B, C, and D, zinc, selenium, magnesium, iron, omega-3 fatty acids, glutamine, resveratrol, beta-glucans, and probiotics. The potential effects of dietary patterns such as the Mediterranean diet against SARS-CoV-2 infection risk and symptoms' severity were also analyzed. Our literature review suggests that micro- and macronutrient supplementation and a healthy diet and lifestyle may provide support to immune system function, with beneficial effects both before and during SARS-CoV-2 infection. However, additional studies are recommended to draw safe conclusions and formulate dietary recommendations concerning dietary supplements and their possible effects on preventing and co-treating COVID-19 disease.

Immunomodulatory effect of vitamin D supplementation on Behçet's disease patients: effect on nitric oxide and Th17/Treg cytokines production

INTRODUCTION

In the last decade, an immuno-modulatory effect of vitamin D supplementation have emerged as a potential therapeutic approach for some inflammatory and autoimmune diseases. As previously reported, vitamin D deficiency was strongly linked to several diseases as Behçet's disease (BD). BD is a chronic systemic inflammatory disorder with autoimmunity, genetic and environmental factors involvement. The aim of our current study is to set up a new therapeutic strategy in BD, combining conventional therapy and vitamin D supplementation.

MATERIALS AND METHODS

Blood samples were collected from active and inactive BD patients and healthy controls (HC) to evaluate 25(OH) vitamin D levels using an electrochemiluminescence method. All deficient and insufficient vitamin D BD patients' were supplemented with vitamin D3 (CHOLECALCIFEROL, 200 000 UI/1 ml). In this context, NO, IL-17A and IL-10 levels were evaluated in patients and HC in vivo and ex vivo using Griess and ELISA methods respectively.

RESULTS

Before supplementation, we noted with interest that BD patients had vitamin D deficiency, associated with elevated in vivo and ex vivo NO and IL-17A levels compared to HC. Conversely, low IL-10 levels were observed in the same BD patients in comparison to HC. Interestingly, restored vitamin D status in supplemented BD patients was related to the decreased NO levels. In the same way, the IL-10/IL-17A ratio was improved.

CONCLUSIONS

Collectively, our data suggest that vitamin D supplementation in combination with conventional treatments has a beneficial effect and could constitute a good therapeutic candidate for alleviating inflammatory responses during Behçet disease.

Vitamin D status and the risk of neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

BACKGROUND

Previous studies have linked vitamin D deficiency with autoimmune diseases, and recent research has found low vitamin D levels in neuromyelitis optica spectrum disorder (NMOSD) patients. We aimed to determine the variances in serum 25(OH)D levels between NMOSD patients and healthy controls.

METHODS

We searched English and Chinese databases (PubMed, Embase, Cochrane Library, Web of Science, CBM, CNKI, WanFang Med, VIP) for observational studies related to serum 25(OH)D levels in NMOSD patients published up to August 24, 2023. We included studies with healthy controls and compared serum 25(OH)D levels between NMOSD patients and controls. We computed the mean difference (MD) and 95% confidence interval (CI) for continuous variables to evaluate serum 25(OH)D levels and combined odds ratios (ORs) and 95% CIs for dichotomized 25(OH)D data.

RESULTS

Six papers were selected for meta-analysis, including 794 participants (347 in the NMOSD group and 447 in the healthy control group). Meta-analysis showed significantly lower serum 25(OH)D levels in the NMOSD group (MD: -7.83, 95 % CI: -10.99 to -4.68). The risk of 25(OH)D deficiency was 23.36 times higher in the NMOSD group (OR: 23.36, 95 % CI: 0.85 to 640.76, p = 0.06>0.05), with a 94 % occurrence rate. There was no significant difference in the risk of having sufficient 25(OH)D between the groups (p = 0.12>0.05).

CONCLUSION

NMOSD patients have lower serum 25(OH)D levels than healthy controls. However, the current research results do not provide evidence for a causal relationship between serum 25(OH)D levels and the onset of NMOSD. Routine vitamin D supplementation may be advantageous for patients with NMOSD.

Effects of vitamin D supplementation on autoantibodies and thyroid function in patients with Hashimoto's thyroiditis: A systematic review and meta-analysis

BACKGROUND

Hashimoto's thyroiditis (HT) is the prevailing form of autoimmune thyroiditis and the leading cause of hypothyroidism in iodine-sufficient regions worldwide. This study aims to evaluate the efficacy of vitamin D supplementation on HT through a meta-analysis of randomized controlled trials (RCTs).

METHODS

The databases searched included PubMed, and others. We included RCTs that the treatment group received vitamin D, while the control group received either a placebo or no treatment. The studies measured the baseline and endpoint levels of 25-hydroxyvitamin D [25(OH)D], thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), anti-thyroid peroxidase antibody (TPO-Ab), and thyroglobulin antibody (TG-Ab). We performed a meta-analysis to calculate the standardized mean difference (SMD) and 95% confidence interval (CI).

RESULTS

A total of 12 studies involving 862 individuals were included. Vitamin D supplementation has a significant impact on reducing the titers of TPO-Ab (SMD = -1.084, 95% CI = -1.624 to -0.545) and TG-Ab (SMD = -0.996, 95% CI = -1.579 to -0.413) in patients with HT, and it also improves thyroid function by decreasing TSH level (SMD = -0.167, 95% CI = -0.302 to 0.031) and increasing FT3 (SMD = 0.549, 95% CI = 0.077-1.020) and FT4 (SMD = 0.734, 95% CI = 0.184-1.285) levels. Active vitamin D (calcitriol) significantly reduces the titer of TPO-Ab compared to naive forms of vitamin D (vitamin D2 or D3); treatment durations > 12 weeks result in a more effective reduction of TPO-Ab levels and a more significant increase in FT4 and FT3 levels in patients with HT (meta-regression P < .05).

CONCLUSION

Vitamin D supplementation may have beneficial effects on HT patients by modulating immune responses and improving thyroid function.

Benefits and Harms of Edible Vegetable Oils and Fats Fortified with Vitamins A and D as a Public Health Intervention in the General Population: A Systematic Review of Interventions

This systematic review aims to assess whether edible vegetable oils and fats fortified with vitamin A and/or D are effective and safe in improving vitamin intake and ameliorating deficiency states in the general population. In November 2022, we systematically searched MEDLINE, Cochrane CENTRAL, Scopus, Global Index Medicus, ClinicalTrials.gov, and WHO ICTRP (International Clinical Trials Registry Platform) for randomized controlled trials (RCT) and non-randomized studies of interventions (NRSI) investigating the fortification of edible vegetable oils and fats with either vitamin A or vitamin D or both as compared to the same vegetable oils and/or fats without vitamin A and D fortification or no interventions, in the general population, without age restriction. We assessed the methodological quality of included RCTs using Cochrane's risk of bias tool 2.0 and of NRSIs using ROBINS-I tool. We performed random-effects meta-analysis and assessed certainty of evidence using GRADE. We included eight studies. Available evidence showed no significant effect of fortification with vitamin A on serum retinol levels (RCTs: MD 0.35 µmol/L, 95% CI -0.43 to 1.12; two trials; 514 participants; low-certainty evidence; CCTs: MD 0.31 µmol/L, 95% CI -0.18 to 0.80; two trials; 205 participants; very low-certainty evidence) and on subclinical vitamin A deficiency. Low-certainty evidence showed no effect of vitamin D fortification on serum 25-hydroxy vitamin D concentration (MD 6.59 nmol/L, 95% CI -6.89 to 20.07; one trial; 62 participants). In conclusion, vitamin A-fortified vegetable oils and fats may result in little to no difference in serum retinol levels in general populations. The dose of vitamin A used in the trials may be safe but may not be sufficient to reduce subclinical vitamin A deficiency. Further, the evidence suggests that vitamin D fortification results in little to no difference in serum 25-hydroxy vitamin D concentration. Several aspects of providing fortified oils and fats to the general population as a public health intervention should be further investigated, including optimal fortification dose, effects on vitamin D deficiency and its clinical symptoms and potential adverse effects.

Hypovitaminosis D in persons with Down syndrome and autism spectrum disorder

BACKGROUND

Plasma levels of vitamin D have been reported to be low in persons with Down syndrome (DS) and existing data is limited to small and homogenous cohorts. This is of particular importance in persons with DS given the high rates of autoimmune disease in this population and the known relationship between vitamin D and immune function. This study sought to investigate vitamin D status in a multi-center cohort of individuals with DS and compare them to individuals with autism spectrum disorder (ASD) and neurotypical (NT) controls.

METHODS

A retrospective, multi-center review was performed. The three sites were located at latitudes of 42.361145, 37.44466, and 34.05349. Patients were identified by the International Classification of Diseases (ICD)-9 or ICD-10 codes for DS, ASD, or well-child check visits for NT individuals. The first vitamin D 25-OH level recorded in the electronic medical record (EMR) was used in this study as it was felt to be the most reflective of a natural and non-supplemented state. Vitamin D 25-OH levels below 30 ng/mL were considered deficient.

RESULTS

In total, 1624 individuals with DS, 5208 with ASD, and 30,775 NT controls were identified. Individuals with DS had the lowest mean level of vitamin D 25-OH at 20.67 ng/mL, compared to those with ASD (23.48 ng/mL) and NT controls (29.20 ng/mL) (p < 0.001, 95% CI: -8.97 to -6.44). A total of 399 (24.6%) individuals with DS were considered vitamin D deficient compared to 1472 (28.3%) with ASD and 12,397 (40.3%) NT controls (p < 0.001, 95% CI: -5.43 to -2.36). Individuals with DS with higher body mass index (BMI) were found to be more likely to have lower levels of vitamin D (p < 0.001, 95% CI: -0.3849 to -0.1509). Additionally, having both DS and a neurologic diagnosis increased the likelihood of having lower vitamin D levels (p < 0.001, 95% CI: -5.02 to -1.28). Individuals with DS and autoimmune disease were much more likely to have lower vitamin D levels (p < 0.001, 95% CI: -6.22 to -1.55). Similarly, a history of autoimmunity in a first-degree relative also increased the likelihood of having lower levels of vitamin D in persons with DS (p = 0.01, 95% CI: -2.45 to -0.63).

CONCLUSIONS

Individuals with DS were noted to have hypovitaminosis D in comparison to individuals with ASD and NT controls. Associations between vitamin D deficiency and high BMI, personal autoimmunity, and familial autoimmunity were present in individuals with DS.

Long COVID-19 Pathophysiology: What Do We Know So Far?

Long COVID-19 is a recognized entity that affects millions of people worldwide. Its broad clinical symptoms include thrombotic events, brain fog, myocarditis, shortness of breath, fatigue, muscle pains, and others. Due to the binding of the virus with ACE-2 receptors, expressed in many organs, it can potentially affect any system; however, it most often affects the cardiovascular, central nervous, respiratory, and immune systems. Age, high body mass index, female sex, previous hospitalization, and smoking are some of its risk factors. Despite great efforts to define its pathophysiology, gaps remain to be explained. The main mechanisms described in the literature involve viral persistence, hypercoagulopathy, immune dysregulation, autoimmunity, hyperinflammation, or a combination of these. The exact mechanisms may differ from system to system, but some share the same pathways. This review aims to describe the most prevalent pathophysiological pathways explaining this syndrome.

Infections and Autoimmunity-The Immune System and Vitamin D: A Systematic Review

Both 25-autoimmunity and(25(OH)D: calcifediol) and its active form, 1,25-dihydroxyvitamin D (1,25(OH)2D: calcitriol), play critical roles in protecting humans from invasive pathogens, reducing risks of autoimmunity, and maintaining health. Conversely, low 25(OH)D status increases susceptibility to infections and developing autoimmunity. This systematic review examines vitamin D's mechanisms and effects on enhancing innate and acquired immunity against microbes and preventing autoimmunity. The study evaluated the quality of evidence regarding biology, physiology, and aspects of human health on vitamin D related to infections and autoimmunity in peer-reviewed journal articles published in English. The search and analyses followed PRISMA guidelines. Data strongly suggested that maintaining serum 25(OH)D concentrations of more than 50 ng/mL is associated with significant risk reduction from viral and bacterial infections, sepsis, and autoimmunity. Most adequately powered, well-designed, randomized controlled trials with sufficient duration supported substantial benefits of vitamin D. Virtually all studies that failed to conclude benefits or were ambiguous had major study design errors. Treatment of vitamin D deficiency costs less than 0.01% of the cost of investigation of worsening comorbidities associated with hypovitaminosis D. Despite cost-benefits, the prevalence of vitamin D deficiency remains high worldwide. This was clear among those who died from COVID-19 in 2020/21-most had severe vitamin D deficiency. Yet, the lack of direction from health agencies and insurance companies on using vitamin D as an adjunct therapy is astonishing. Data confirmed that keeping an individual's serum 25(OH)D concentrations above 50 ng/mL (125 nmol/L) (and above 40 ng/mL in the population) reduces risks from community outbreaks, sepsis, and autoimmune disorders. Maintaining such concentrations in 97.5% of people is achievable through daily safe sun exposure (except in countries far from the equator during winter) or taking between 5000 and 8000 IU vitamin D supplements daily (average dose, for non-obese adults, ~70 to 90 IU/kg body weight). Those with gastrointestinal malabsorption, obesity, or on medications that increase the catabolism of vitamin D and a few other specific disorders require much higher intake. This systematic review evaluates non-classical actions of vitamin D, with particular emphasis on infection and autoimmunity related to the immune system.

Vitamin D Supplementation during Intensive Care Unit Stay Is Associated with Improved Outcomes in Critically Ill Patients with Sepsis: A Cohort Study

BACKGROUND

Vitamin D, as a common micronutrient, has been widely used in critically ill patients. However, whether supplementation of vitamin D in adult patients with sepsis can improve their prognosis remains controversial.

METHODS

Data from the Mart for Intensive Care IV database was used in this retrospective cohort study, and adult patients with sepsis were enrolled. Critically ill patients, admitted to intensive care units (ICUs) between 2008 and 2019 at the Beth Israel Deaconess Medical Center (BIDMC), were divided into the vitamin D supplementation group and non-vitamin D supplementation group. The primary outcomes were defined as all-cause in-hospital, 28-day, and 90-day mortality rates after admission to the ICU. A 1:1 propensity score matching (PSM), inverse probability of treatment weighting (IPTW), and overlap weighting (OW) analyses were used to minimize selection bias and balance the baseline demographic characteristics. Regression and survival analyses were performed to assess the association between vitamin D supplementation and clinical outcomes in patients with sepsis.

RESULTS

In total, 3539 patients with sepsis were enrolled as study participants; of these, 315 were supplemented with vitamin D during their ICU stay. In-hospital, 28-day, and 90-day mortality rates were significantly lower in patients with sepsis supplemented with vitamin D. Multivariate regression analysis showed vitamin D supplementation as a potential protective factor for in-hospital mortality with an odds ratio (OR) = 0.70 (0.51-0.96) after adjusting for all confounders. The hazard ratios (HRs) for 28-day and 90-day mortality were 0.65 (0.50-0.85) and 0.70 (0.55-0.90), respectively. The survival analysis showed that the vitamin D supplementation group had a higher survival probability within 28 and 90 days (p-value < 0.05). These results remained relatively stable post PSM, IPTW, and OW. However, we found no evidence that vitamin D supplementation could shorten the length of stay in the ICU or hospital.

CONCLUSIONS

Vitamin D supplementation during an ICU stay was associated with improved prognosis in patients with sepsis, as evidenced by lower in-hospital, 28-day, and 90-day mortality rates and lower disease severity-related scores, but showed no influence on the length of stay in the hospital or ICU.

Role of Coactivator Associated Arginine Methyltransferase 1 (CARM1) in the Regulation of the Biological Function of 1,25-Dihydroxyvitamin D3

1,25-Dihydroxyvitamin D3 (1,25(OH)₂D₃), the hormonally active form of vitamin D, activates the nuclear vitamin D receptor (VDR) to mediate the transcription of target genes involved in calcium homeostasis as well as in non-classical 1,25(OH)₂D₃ actions. In this study, CARM1, an arginine methyltransferase, was found to mediate coactivator synergy in the presence of GRIP1 (a primary coactivator) and to cooperate with G9a, a lysine methyltransferase, in 1,25(OH)₂D₃ induced transcription of Cyp24a1 (the gene involved in the metabolic inactivation of 1,25(OH)₂D₃). In mouse proximal renal tubule (MPCT) cells and in mouse kidney, chromatin immunoprecipitation analysis demonstrated that dimethylation of histone H3 at arginine 17, which is mediated by CARM1, occurs at Cyp24a1 vitamin D response elements in a 1,25(OH)₂D₃ dependent manner. Treatment with TBBD, an inhibitor of CARM1, repressed 1,25(OH)₂D₃ induced Cyp24a1 expression in MPCT cells, further suggesting that CARM1 is a significant coactivator of 1,25(OH)₂D₃ induction of renal Cyp24a1 expression. CARM1 was found to act as a repressor of second messenger-mediated induction of the transcription of CYP27B1 (involved in the synthesis of 1,25(OH)₂D₃), supporting the role of CARM1 as a dual function coregulator. Our findings indicate a key role for CARM1 in the regulation of the biological function of 1,25(OH)₂D₃.

Vitamin D deficiency on admission to the emergency department is a mortality predictor for patients with septic shock treated with early protocol-driven resuscitation bundle therapy

BACKGROUND

Vitamin D is an important immune modulator and is associated with susceptibility to infection. However, past studies have reported inconsistent results regarding the association between vitamin D deficiency and mortality in patients with sepsis, and early-stage data regarding septic shock are limited. This study aimed to determine the relationship between vitamin D deficiency on admission to the emergency department (ED) and mortality in patients with septic shock.

METHODS

We analyzed prospectively collected data on adult patients with septic shock who were treated with protocol-driven resuscitation bundle therapy in the ED between September 2019 and February 2021. Septic shock was defined by the sepsis-3 definition and vitamin D deficiency was defined as a 25-hydroxyvitamin D <20 ng/ml. The primary outcome was 30-day mortality.

RESULTS

A total of 302 patients were included, 236 (78.1%) patients had vitamin D deficiency; it was significantly higher in non-survivors than in survivors (89.3% vs. 73.9%, P = 0.004). Mortality was higher in vitamin D deficient patients than in non-deficient patients (31.8% vs. 13.6%, P = 0.004). In multivariate analysis, vitamin D deficiency (odds ratio [OR], 2.43; 95 % confidence interval [CI], 1.03-5.74), hyperlactatemia (OR, 3.65; 95 % CI, 1.95-6.83), Sequential Organ Failure Assessment scores (OR, 1.22; 95% CI, 1.09-1.36), and albumin levels (OR, 0.39; 95% CI, 0.21-0.73) were significantly associated with 30-day mortality.

CONCLUSIONS

Vitamin D deficiency was prevalent in patients with septic shock visiting the ED and was associated with mortality.

The relationship between serum cytokine profile and vitamin D in calves with neonatal diarrhea

It is important to know the characteristics of the immunological response in newborn calf diarrhea, which is often caused by bacterial, viral and protozoal pathogens. Cytokinesare proteins that serve as chemical messengers to regulate theinnate and adaptive arms of theimmune response. Changes in circulatory cytokine levels provide valuable information for understanding the pathophysiological process and monitoring disease progression and inflammation. Vitamin D has important immunomodulatory effects, which include enhancing the innate immune system and inhibiting adaptative immune responses. The objective of this study was to evaluate the relationship between serum cytokine profile and vitamin D level in neonatal calves with diarrhea. The study population was comprised of 40 neonatal calves, 32 of which had diarrhea and 8 of which were healthy calves. The calves with diarrhea were allocated to four groups according to bacterial (Escherichia coli), viral (Rotavirus, Coronavirus) and protozoal (Cryptosporidium parvum) etiologies. Circulatory vitamin D metabolites (25-hydroxyvitamin D, 1,25-dihydroxyvitamin D) and cytokines (TNF-α, IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13 and IL-17) in the calves were determined. There was no statistically significant difference among the groups in 25-hydroxyvitamin D levels. 1,25-dihydroxyvitamin D levels were higher in Coronavirus and E. coli groups compared to the controls. Serum levels of all cytokines except for IL-13, were higher in E. coli group than those of the control group. As a result, differences in serum cytokines and vitamin D levels according to etiological factors in calf diarrhea indicate that vitamin D may play a role in the immune response in the disease.

How Does Vitamin D Affect Immune Cells Crosstalk in Autoimmune Diseases?

Vitamin D is a secosteroid hormone that is highly involved in bone health. Mounting evidence revealed that, in addition to the regulation of mineral metabolism, vitamin D is implicated in cell proliferation and differentiation, vascular and muscular functions, and metabolic health. Since the discovery of vitamin D receptors in T cells, local production of active vitamin D was demonstrated in most immune cells, addressing the interest in the clinical implications of vitamin D status in immune surveillance against infections and autoimmune/inflammatory diseases. T cells, together with B cells, are seen as the main immune cells involved in autoimmune diseases; however, growing interest is currently focused on immune cells of the innate compartment, such as monocytes, macrophages, dendritic cells, and natural killer cells in the initiation phases of autoimmunity. Here we reviewed recent advances in the onset and regulation of Graves' and Hashimoto's thyroiditis, vitiligo, and multiple sclerosis in relation to the role of innate immune cells and their crosstalk with vitamin D and acquired immune cells.

Protective role of vitamin D status against COVID-19: a mini-review

An outbreak of pneumonia caused by a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is called COVID-19 and has led to a pandemic worldwide. It is reasonable to investigate and control factors affecting disease severity and mortality. The relation between vitamin D and viral pneumonia has been previously reported. Vitamin D deficiency is common and may increase hospital admission and mortality rate in patients with COVID-19. This mini-review examines the pathways that show the association between vitamin D and COVID-19. On the other hand, it deals with the available evidence related to the relationship between vitamin D deficiency and the effect of vitamin D supplementation on the prevalence, severity, and mortality of COVID-19. Also, we described the pathophysiology of the organs' involvement in COVID-19 and the effect of vitamin D on these outcomes. Vitamin D strengthens the innate and adaptive immune system, modulates immune responses, prevents lung and cardiovascular system damage, and reduces thrombotic events. Vitamin D exerts these effects in several pathways. Vitamin D prevents virus entry and replication by maintaining the integrity of the body's physical barrier. Vitamin D reduces the damage to vital organs and thrombotic events by increasing the level of Angiotensin-converting enzyme 2 (ACE2), nitric oxide, and antioxidants or by reducing inflammatory cytokines and free radicals. Sufficient vitamin D may be reduced morbidity and mortality due to COVID-19. However, this issue should be investigated and confirmed by further research in the future.

Effects of vitamin D insufficiency on sepsis severity and risk of hospitalisation in emergency department patients: a cross-sectional study

OBJECTIVE

To evaluate the association of 25-hydroxyvitamin D (25(OH)D) level on sepsis severity and risk of hospitalisation in emergency department (ED) septic patients when categorised as vitamin D insufficiency according to the level of 25(OH)D<30 ng/mL.

DESIGN

Cross-sectional observational study.

SETTING

A 900-bed academic tertiary hospital with an ED residency training programme in Bangkok, Thailand.

PARTICIPANTS

An observational study of 101 ED septic patients aged ≥18 years was conducted between March 2015 and September 2015.

OUTCOME MEASURES

The level of 25(OH)D was analysed and correlated with sepsis severity assessed by Acute Physiology Age Chronic Health Evaluation-II (APACHE-II) and Mortality in ED Sepsis (MEDS) scores, and the risk of hospitalisation.

RESULTS

One hundred and one patients were enrolled, with an average age of 68±18 years, 56% female, APACHE-II score of 14±6, MEDS score of 8±5 and 25(OH)D level was 19±11 ng/mL. The prevalence of vitamin D insufficiency in our ED septic patients was 87% and the admission rate was 88%. A significant association between 25(OH)D level and sepsis severity scores was found, which was measured by APACHE-II and MEDS scores (-0.29; 95% CI -0.41 to -0.17, p<0.001 and -0.15; 95% CI -0.25 to -0.06, p=0.002, respectively). However, vitamin D insufficiency could not determine hospitalisation (OR=1.42; 95% CI 0.27 to 7.34; p=0.68 and OR=1.65; 95% CI 0.07 to 41.7; p=0.76 when adjusted by baseline covariates).

CONCLUSIONS

The vitamin D insufficiency of septic patients in our ED was high and had a significant negative association with sepsis severity. However, vitamin D insufficiency status cannot predict the hospitalisation of septic patients who were admitted to the ED. Further research is needed to investigate the role of vitamin D supplementation in the ED in affecting sepsis severity.

TRIAL REGISTRATION NUMBER

TCTR20151127001.

Nutrients and rheumatoid arthritis: From the perspective of neutrophils

Neutrophils are considered as core immune cells involve in the early stage of rheumatoid arthritis (RA) and participate in the disease progression. The underlining mechanisms include the elevated chemotaxis and infiltration of neutrophils, the increase in the reactive oxygen species and the promotion of neutrophil extracellular traps formation. Accumulating studies demonstrated the important role of nutrients intake played in the initiation and progression of RA. This study summarized the effects of several macronutrients and micronutrients on regulating RA through the modulation of activated neutrophils and appealed for a healthy diet in RA-risk individuals as well as RA patients.

The Impact of Serum Levels of Vitamin D3 and Its Metabolites on the Prognosis and Disease Severity of COVID-19

Vitamin D is among the increasingly consumed dietary supplements during the COVID-19 pandemic. It plays a regulatory role in the immune system and moderates the renin-angiotensin system, which is implicated in infection pathogenesis. However, the investigation of serum levels of vitamin D3 forms and their relative ratios in COVID-19 patients is worth investigation to understand the impacts of disease severity. Hence, we investigated the serum levels of vitamin D3 (cholecalciferol) and its metabolites (calcifediol and calcitriol), in addition to their relative ratios and correlations with angiotensin-converting enzyme 2 (ACE2), interleukin-6 (Il-6), and neutrophil-lymphocyte ratio (NLR) in COVID-19 patients compared with healthy controls. Oropharyngeal specimens were collected from the study subjects for polymerase chain reaction testing for COVID-19. Whole blood samples were obtained for blood count and NLR testing, and sera were used for the analysis of the levels of the vitamin and its metabolites, ACE2, and IL-6. We enrolled 103 patients and 50 controls. ACE2, Il-6, and NLR were significantly higher in the patients group (72.37 ± 18.67 vs. 32.36 ± 11.27 U/L, 95.84 ± 25.23 vs. 2.76 ± 0.62 pg/mL, and 1.61 ± 0.30 vs. 1.07 ± 0.16, respectively). Cholecalciferol, calcifediol, and calcitriol were significantly lower in patients (18.50 ± 5.36 vs. 29.13 ± 4.94 ng/mL, 14.60 ± 3.30 vs. 23.10 ± 3.02 ng/mL, and 42.90 ± 8.44 vs. 65.15 ± 7.11 pg/mL, respectively). However, their relative ratios were normal in both groups. Levels of the vitamin and metabolites were strongly positively, strongly negatively, and moderately negatively correlated with ACE2, Il-6, and NLR, respectively. COVID-19 infection severity is associated with a significant decrease in vitamin D3 and its metabolites in a parallel pattern, and with a significant increase in ACE2, Il-6, and NLR. Higher levels of vitamin D and its metabolites are potentially protective against severe infection.

Knowledge and behaviors of using vitamin D to boost immunity against COVID-19 pandemic: A cross-sectional study in Saudi Arabia

The coronavirus 2019 (COVID-19) pandemic has globally impacted all aspects of life since its emergence and spread. There is a strong biological assumption and progressing epidemiological data supporting the role of vitamin D (VD) in COVID-19 infection. This study aims to determine the knowledge about VD supplements to boost immunity against COVID-19 and if participation in specific behaviors has increased the consumption of VD supplements during social distance restriction in Saudi Arabia (SA) in May 2021. This cross-sectional study used a structured online questionnaire for 2369 SA people, including demographic characteristics and knowledge about VD supplements to boost immunity against COVID-19 showed that there was a significant association between sex and vitamin D deficiency (VDD) (P = .000), and having VDD was strongly associated with having another vitamin deficiency (P = .008). Additionally, there was a statistically significant difference between VDD and cardiovascular (P = .027) and respiratory diseases (P = .019). Almost half of the participants used VD supplements to reduce or heal their COVID-19 symptoms. The adverse association between having VDD and understanding of COVID-19 symptoms was statistically significant (P = .01). Ginger is commonly used as an alternative medicine for the treatment of VD. The administration of VD is now known to be of physiological significance for general health, and evidence suggesting the beneficial role of VD in the prevention and/or treatment of diseases, particularly infectious diseases, such as COVID-19, is increasing.

Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites

Vitamin D has a well-known role in the calcium homeostasis associated with the maintenance of healthy bones. It increases the efficiency of the intestinal absorption of dietary calcium, reduces calcium losses in urine, and mobilizes calcium stored in the skeleton. However, vitamin D receptors are present ubiquitously in the human body and indeed, vitamin D has a plethora of non-calcemic functions. In contrast to most vitamins, sufficient vitamin D can be synthesized in human skin. However, its production can be markedly decreased due to factors such as clothing, sunscreens, intentional avoidance of the direct sunlight, or the high latitude of the residence. Indeed, more than one billion people worldwide are vitamin D deficient, and the deficiency is frequently undiagnosed. The chronic deficiency is not only associated with rickets/osteomalacia/osteoporosis but it is also linked to a higher risk of hypertension, type 1 diabetes, multiple sclerosis, or cancer. Supplementation of vitamin D may be hence beneficial, but the intake of vitamin D should be under the supervision of health professionals because overdosing leads to intoxication with severe health consequences. For monitoring vitamin D, several analytical methods are employed, and their advantages and disadvantages are discussed in detail in this review.

Vitamin D3 is well Correlated with Anti-Helicobacter pylori Immunoglobulins and could be a well Biomarker for Immunity Competence against the Disease

BACKGROUND

Helicobacter pylori (HPY) provokes gastrointestinal disorders and gastric cancer. We supposed that HPY disrupts the 25-OH-Vitamin-D3 (Vit.D3) absorption. We evaluated the association between Vit.D3 and anti-HPY immunoglobulins (Igs) and the Vit.D3 potency as a predictive biomarker for HPY infection.

MATERIALS AND METHODS

603 patients' raw data were gathered from a private clinical laboratory. Anti-HPY Igs including serum IgG, IgA, and IgM, in addition to HPY-stool antigen, were assessed by the immunoassay methods. Vit.D3 was determined by high-pressure liquid chromatography. Correlations, ordinal comparisons, cutoff points (COP), and odds ratio (OR) were estimated.

RESULTS

The age mean ± standard deviation was 39.83 ± 18.426 for female and 38.82 ± 16.937 for male participants (P = 0.521). Significant correlations existed after age and gender adjustment between Vit.D3 serum levels and the HPY IgG (R = 0.298) and IgA (R = 0.271) but not for IgM (R = -0.103). Approximately, 48% of males and 36% of females had insufficient/deficient Vit.D3 serum levels (male/female OR: 1.65; 1.16-2.33; P = 0.0051). After age and gender adjustment, the best COP of Vit.D3 to predict an HPY IgG-positive patient was Vit.D3 >32.80 ng/mL with 66.23% diagnostic accuracy (DAAC), 30.43% specificity (SPC), and 90.41% sensitivity (SEN). For the HPY IgA, the values were Vit.D3 >37.83 ng/mL, DAAC = 60.45%, SPC = 58.82%, SEN = 64.20%. For HPY IgM, the values were Vit.D3 >37.32 ng/mL, DAAC = 58.97%, SPC = 57.33%, and SEN = 100%.

CONCLUSIONS

Vit.D3 had a good association with anti-HPY Igs and may be a good biomarker for immunity competence against HPY infection if the patient's age and gender are considered when interpreting the laboratory results.

COVID-19 Vaccination in Kidney Transplant Candidates and Recipients

Kidney transplant candidates and kidney transplant recipients (KTRs) are at particular risk of severe complications of COVID-19 disease. In Western countries, mortality in affected hospitalized KTRs ranges between 19% and 50%. COVID-19 vaccination remains the most important measure to prevent the severity of infection in candidates and recipients of kidney transplant. However, the uraemic condition may affect the vaccine-induced immunity in patients with advanced chronic kidney disease (CKD) and in KTRs. Retention of uraemic toxins, dysbiosis, dysmetabolism, and dialysis can diminish the normal response to vaccination, leading to dysfunction of inflammatory and immune cells. In KTRs the efficacy of vaccines may be reduced by the immunosuppressive medications, and more than half of kidney transplant recipients are unable to build an immune response even after four administrations of anti-COVID-19 vaccines. The lack of antibody response leaves these patients at high risk for SARS-CoV-2 infection and severe COVID-19 disease. The aim of the present review is to focus on the main reasons for the impaired immunological response among candidates and kidney transplant recipients and to highlight some of the present options available to solve the problem.

Metabolism of 25-Hydroxy-Vitamin D in Human Macrophages Is Highly Dependent on Macrophage Polarization

Macrophages synthesize active vitamin D (1,25-dihydroxy-vitamin D) and express the vitamin D receptor in the nucleus; however, vitamin D metabolism in relation to macrophage polarization and function is not well understood. We studied monocyte-derived macrophages (MDMs) from human buffy coats polarized into M0, M1 (LPS + IFNγ), M2a (IL4 + IL13) and M2c (IL10) macrophage subtypes stimulated with 25-hydroxy-vitamin D (1000 and 10,000 nanomolar). We measured vitamin D metabolites (25-hydroxy-vitamin D, 1,25-dihydroxy-vitamin D, 24,25-dihydroxy-vitamin D and 3-epi-25-hydroxy-vitamin D) in cell media with liquid chromatography-mass spectrometry-mass spectrometry. The mRNA expression (CYP27B1, CYP24A1 and CYP24A1-SV) was measured with qPCR. We found that reparative MDMs (M2a) had significantly more 1,25-dihydroxy-vitamin D compared to the other MDMs (M0, M1 and M2c). All MDMs were able to produce 3-epi-25-hydroxy-vitamin D, but this pathway was almost completely attenuated in inflammatory M1 MDMs. All MDM subtypes degraded vitamin D through the 24-hydroxylase pathway, although M1 MDMs mainly expressed an inactive splice variant of CYP24A1, coding the degrading enzyme. In conclusion, this study shows that vitamin D metabolism is highly dependent on macrophage polarization and that the C3-epimerase pathway for vitamin D is active in macrophages.

Current evidence on the impact of the COVID-19 pandemic on paediatric endocrine conditions

Severe acute respiratory coronavirus 2 (SARS-CoV-2) interacts with the host cells through its spike protein by binding to the membrane enzyme angiotensin-converting enzyme 2 (ACE2) and it can have a direct effect on endocrine function as ACE2 is expressed in many glands and organs with endocrine function. Furthermore, several endocrine conditions have features that might increase the risk of SARS-CoV-2 infection and the severity and course of the infection, as obesity for the underlying chronic increased inflammatory status and metabolic derangement, and for the possible changes in thyroid function. Vitamin D has immunomodulatory effects, and its deficiency has negative effects. Adrenal insufficiency and excess glucocorticoids affect immune conditions also besides metabolism. This review aims to analyze the rationale for the fear of direct effects of SARS-Cov-2 on endocrinological disorders, to study the influence of pre-existing endocrine disorders on the course of the infection, and the actual data in childhood. Currently, data concerning endocrine function during the pandemic are scarce in childhood and for many aspects definite conclusions cannot be drawn, however, data on properly managed patients with adrenal insufficiency at present are re-assuring. Too little attention has been paid to thyroid function and further studies may be helpful. The available data support a need for adequate vitamin D supplementation, caution in obese patients, monitoring of thyroid function in hospitalized patients, and confirm the need for an awareness campaign for the increased frequency of precocious puberty, rapidly progressive puberty and precocious menarche. The changes in lifestyle, the increased incidence of overweight and the change in the timing of puberty lead also to hypothesize that there might be an increase in ovarian dysfunction, as for example polycystic ovarian disease, and metabolic derangements in the next years, and in the future we might be facing fertility problems. This prompts to be cautious and maintain further surveillance.

Vitamin D boosts immune response of macrophages through a regulatory network of microRNAs and mRNAs

Vitamin D is associated with the stimulation of innate immunity, inflammation, and host defense against pathogens. Macrophages express receptors of Vitamin D, regulating transcription of genes related to immune processes. However, the transcriptional and post-transcriptional strategies controlling gene expression in differentiated macrophages, and how they are influenced by Vitamin D are not well understood. We studied whether Vitamin D enhances immune response by regulating the expression of microRNAs and mRNAs. Analysis of the transcriptome showed differences in expression of 199 genes, of which 68% were up-regulated, revealing the cell state of monocyte-derived macrophages differentiated with Vitamin D (D3-MDMs) as compared to monocyte-derived macrophages (MDMs). The differentially expressed genes appear to be associated with pathophysiological processes, including inflammatory responses, and cellular stress. Transcriptional motifs in promoter regions of up- or down-regulated genes showed enrichment of VDR motifs, suggesting possible roles of transcriptional activator or repressor in gene expression. Further, microRNA-Seq analysis indicated that there were 17 differentially expressed miRNAs, of which, 7 were up-regulated and 10 down-regulated, suggesting that Vitamin D plays a critical role in the regulation of miRNA expression during macrophages differentiation. The miR-6501-3p, miR-1273h-5p, miR-665, miR-1972, miR-1183, miR-619-5p were down-regulated in D3-MDMs compared to MDMs. The integrative analysis of miRNA and mRNA expression profiles predict that miR-1972, miR-1273h-5p, and miR-665 regulate genes PDCD1LG2, IL-1B, and CD274, which are related to the inflammatory response. Results suggest an essential role of Vitamin D in macrophage differentiation that modulates host response against pathogens, inflammation, and cellular stress.

Analyzing the relationship between the vitamin D deficiency and COVID-19 mortality rate and modeling the time-delay interactions between body's immune healthy cells, infected cells, and virus particles with the effect of vitamin D levels

This paper presents some recent views on the aspects of vitamin D levels in relation to the COVID-19 infections and analyzes the relationship between the prevalence rates of vitamin D deficiency and COVID-19 death rates per million of various countries in Europe and Asia using the data from the PubMed database. The paper also discusses a new mathematical model of time-delay interactions between the body's immune healthy cells, infected cells, and virus particles with the effect of vitamin D levels. The model can be used to monitor the timely progression of healthy immune cells with the effects of the levels of vitamin D and probiotics supplement. It also can help to predict when the infected cells and virus particles free state can ever be reached as time progresses. The consideration of the time delay in the modeling due to effects of the infected cells or virus particles and the growth of healthy cells is also an important factor that can significantly change the outcomes of the body's immune cells as well as the infections.

High Serum Vitamin D Concentrations, Induced via Diet, Trigger Immune and Intestinal Microbiota Alterations Leading to Type 1 Diabetes Protection in NOD Mice

The hormonally-active form of vitamin D, 1,25-dihydroxyvitamin D3, can modulate both innate and adaptive immunity, through binding to the nuclear vitamin D receptor expressed in most immune cells. A high dose of regular vitamin D protected non-obese diabetic (NOD) mice against type 1 diabetes (T1D), when initiated at birth and given lifelong. However, considerable controversy exists on the level of circulating vitamin D (25-hydroxyvitamin D3, 25(OH)D3) needed to modulate the immune system in autoimmune-prone subjects and protect against T1D onset. Here, we evaluated the impact of two doses of dietary vitamin D supplementation (400 and 800 IU/day), given to female NOD mice from 3 until 25 weeks of age, on disease development, peripheral and gut immune system, gut epithelial barrier function, and gut bacterial taxonomy. Whereas serum 25(OH)D3 concentrations were 2.6- (400 IU/day) and 3.9-fold (800 IU/day) higher with dietary vitamin D supplementation compared to normal chow (NC), only the 800 IU/day vitamin D-supplemented diet delayed and reduced T1D incidence compared to NC. Flow cytometry analyses revealed an increased frequency of FoxP3+ Treg cells in the spleen of mice receiving the 800 IU/day vitamin D-supplemented diet. This vitamin D-induced increase in FoxP3+ Treg cells, also expressing the ecto-5’-nucleotidase CD73, only persisted in the spleen of mice at 25 weeks of age. At this time point, the frequency of IL-10-secreting CD4+ T cells was also increased in all studied immune organs. High-dose vitamin D supplementation was unable to correct gut leakiness nor did it significantly modify the increased gut microbial diversity and richness over time observed in NOD mice receiving NC. Intriguingly, the rise in alpha-diversity during maturation occurred especially in mice not progressing to hyperglycaemia. Principal coordinates analysis identified that both diet and disease status significantly influenced the inter-individual microbiota variation at the genus level. The abundance of the genera Ruminoclostridium_9 and Marvinbryantia gradually increased or decreased, respectively in faecal samples of mice on the 800 IU/day vitamin D-supplemented diet compared to mice on the 400 IU/day vitamin D-supplemented diet or NC, irrespective of disease outcome. In summary, dietary vitamin D reduced T1D incidence in female NOD mice at a dose of 800, but not of 400, IU/day, and was accompanied by an expansion of Treg cells in various lymphoid organs and an altered intestinal microbiota signature.

Vitamin D: A Potential Star for Treating Chronic Pancreatitis

Chronic pancreatitis (CP) is a chronic inflammatory and fibrotic disease of the pancreas. The incidence of CP is increasing worldwide but the effective therapies are lacking. Hence, it is necessary to identify economical and effective agents for the treatment of CP patients. Vitamin D (VD) and its analogues have been confirmed as pleiotropic regulators of cell proliferation, apoptosis, differentiation and autophagy. Clinical studies show that VD deficiency is prevalent in CP patients. However, the correlation between VD level and the risk of CP remains controversial. VD and its analogues have been demonstrated to inhibit pancreatic fibrosis by suppressing the activation of pancreatic stellate cells and the production of extracellular matrix. Limited clinical trials have shown that the supplement of VD can improve VD deficiency in patients with CP, suggesting a potential therapeutic value of VD in CP. However, the mechanisms by which VD and its analogues inhibit pancreatic fibrosis have not been fully elucidated. We are reviewing the current literature concerning the risk factors for developing CP, prevalence of VD deficiency in CP, mechanisms of VD action in PSC-mediated fibrogenesis during the development of CP and potential therapeutic applications of VD and its analogues in the treatment of CP.

Association of vitamin D status with COVID-19 and its severity : Vitamin D and COVID-19: a narrative review

Vitamin D is associated with biological activities of the innate and adaptive immune systems, as well as inflammation. In observational studies, an inverse relationship has been found between serum 25-hydroxyvitamin D (25(OH)D) concentrations and the risk or severity of coronavirus disease 2019 (COVID-19). Several mechanisms have been proposed for the role of vitamin D in COVID-19, including modulation of immune and inflammatory responses, regulation of the renin-angiotensin-aldosterone system, and involvement in glucose metabolism and cardiovascular system. Low 25(OH)D concentrations might predispose patients with COVID-19 to severe outcomes not only via the associated hyperinflammatory syndrome but also by worsening preexisting impaired glucose metabolism and cardiovascular diseases. Some randomized controlled trials have shown that vitamin D supplementation is beneficial for reducing severe acute respiratory syndrome coronavirus 2 RNA positivity but not for reducing intensive care unit admission or all-cause mortality in patients with moderate-to-severe COVID-19. Current evidence suggests that taking a vitamin D supplement to maintain a serum concentration of 25(OH)D of at least 30 ng/mL (preferred range 40-60 ng/mL), can help reduce the risk of COVID-19 and its severe outcomes, including mortality. Although further well designed studies are warranted, it is prudent to recommend vitamin D supplements to people with vitamin D deficiency/insufficiency during the COVID-19 pandemic according to international guidelines.

Long COVID-19 in Children: From the Pathogenesis to the Biologically Plausible Roots of the Syndrome

Long Coronavirus disease-19 (COVID-19) refers to the persistence of symptoms related to the infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). This condition is described as persistent and can manifest in various combinations of signs and symptoms, such as fatigue, headache, dyspnea, depression, cognitive impairment, and altered perception of smells and tastes. Long COVID-19 may be due to long-term damage to different organs-such as lung, brain, kidney, and heart-caused by persisting viral-induced inflammation, immune dysregulation, autoimmunity, diffuse endothelial damage, and micro thrombosis. In this review, we discuss the potential and biologically plausible role of some vitamins, essential elements, and functional foods based on the hypothesis that an individual's dietary status may play an important adjunctive role in protective immunity against COVID-19 and possibly against its long-term consequences.

Management of COVID-19 - A Review

Abstract::

Coronavirus disease-2019(COVID-19) has gained much popularity not only in the Wuhan city of China but internationally also; in January 2020, the corona rapidly spread to many countries like the USA, Italy, Russia, India, Singapore, Pakistan, Thailand, Canada, Australia, England, and so on through passengers traveling to other countries. Corona patients can be cured with synthetic drugs, traditional herbal medicines (THM), use of Vitamin D and the quarantine approach. Different allopathic medicines, herbal extracts, and vitamin D have been observed to be useful in the treatment of novel coronavirus, like Remdesivir, hydroxychloroquine, Teicoplanin, Lopinavir+ Ritonavir, Ribavirin + corticosteroids, Glycyrrhizin, Sanguisorbae radix, Acanthopanacis cortex, Sophorae radix, etc. Various antiviral drugs are used to treat COVID-19, alone or in combination with other medications like Interferon-α, Lopinavir + Ritonavir, Arbidol, corticosteroids, etc., and some herbal extracts; also quarantine approach and Vitamin D are used that not only cure the infection but also boost up our immunity. For this review article, different papers were searched on Google Scholar, Scopus, WHO’s website, PubMed, clinicaltrials.gov and other relevant scientific research websites. In this review article, we have discussed the current strategies that are being used to treat COVID-19. Along with allopathic drugs, some herbal extracts can also be used to treat this novel coronavirus, like Glycyrrhizin, Sanguisorbae radix, Acanthopanacis cortex, Sophorae radix, etc. and even vitamin D.

Vitamin D Attenuates Airway Inflammation in Asthmatic Guinea Pigs Using Mammalian Target of Rapamycin-Mediated Autophagy

The purpose of this experiment is to find out the function of Vitamin D (VD) in airway inflammation in asthmatic guinea pigs by regulating mammalian target of rapamycin (mTOR)-mediated autophagy. A total of 40 male guinea pigs were randomly assigned into the Con group, the ovalbumin (OVA)-sensitized group, the VD group, the VD + dimethyl sulfoxide group, and the VD + rapamycin (mTOR inhibitor) group. Then, serum from all groups was harvested for the measurement of immunoglobulin E (IgE), interleukin (IL)-4, and IL-5 levels. Next, bronchoalveolar lavage fluid was collected for cell counting. Moreover, lung tissues were extracted to assess levels of p-mTOR and autophagy factors (LC3B, Beclin1, Atg5, and P62). Compared with the Con group, the OVA group showed elevated levels of IgE, IL-4, and IL-5, increased contents of eosinophils, neutrophil, and lymphocytes, and declined monocytes. And the VD group improved inflammatory reactions in the guinea pigs. Besides, the OVA group showed lower levels of p-mTOR and P62 and higher autophagy levels than the Con group, while the VD group had opposite results. Rapamycin annulled the suppressive role of VD to airway inflammation in asthmatic guinea pigs. VD might inhibit OVA-induced airway inflammation by inducing mTOR activation and downregulating autophagy in asthmatic guinea pigs.

Efficacy and Safety of Vitamin D Supplementation to Prevent COVID-19 in Frontline Healthcare Workers. A Randomized Clinical Trial

Background

Associations between vitamin D (VD) deficiency and the risk of SARS-CoV-2 infection have been documented in cross-sectional population studies. Intervention studies in patients with moderate to severe COVID-19 have failed to consistently document a beneficial effect.

Objective

To determine the efficacy and safety of VD-supplementation in the prevention of SARS-CoV-2 infection in highly exposed individuals.

Methods

A double-blind, parallel, randomized trial was conducted. Frontline healthcare workers from four hospitals in Mexico City, who tested negative for SARS-CoV-2 infection, were enrolled between July 15 and December 30, 2020. Participants were randomly assigned to receive 4,000 IU VD (VDG) or placebo (PG) daily for 30 d. RT-PCR tests were taken at baseline and repeated if COVID-19 manifestations appeared during follow-up. Serum 25-hydroxyvitamin D3 and antibody tests were measured at baseline and at day 45. Per-protocol and intention-to-treat analysis were conducted.

Results

Of 321 recruited subjects, 94 VDG and 98 PG completed follow-up. SARS-CoV-2 infection rate was lower in VDG than in PG (6.4 vs. 24.5%, p <0.001). The risk of acquiring SARS-CoV-2 infection was lower in the VDG than in the PG (RR: 0.23; 95% CI: 0.09–0.55) and was associated with an increment in serum levels of 25-hydroxyvitamin D3 (RR: 0.87; 95% CI: 0.82–0.93), independently of VD deficiency. No significant adverse events were identified.

Conclusions

Our results suggest that VD-supplementation in highly exposed individuals prevents SARS-CoV-2 infection without serious AEs and regardless of VD status.

Remote management of osteoporosis in the first wave of the COVID-19 pandemic

We conducted a survey during the first pandemic wave of coronavirus disease 2019 (COVID-19) on a large group of osteoporotic patients to evaluate the general conditions of osteoporotic patients and the impact of the pandemic on the management of osteoporosis, finding high compliance to treatments and low COVID-19 lethality.

INTRODUCTION

During the first pandemic wave of coronavirus disease 2019 (COVID-19), 209,254 cases were diagnosed in Italy; fatalities were 26,892 and were overwhelmingly older patients. The high prevalence of osteoporosis in this age group suggests a potential relationship between SARS-CoV-2 infection and bone metabolism.

METHODS

In a telephone survey conducted from April to May 2020, patients from the Osteoporosis Center, Clinic of Endocrinology and Metabolic Diseases of Umberto I Hospital (Ancona, Italy), were interviewed to evaluate the general clinical conditions of osteoporotic patients, compliance with osteoporosis medications, COVID-19 prevalence, hospitalization rate, COVID-19 mortality, and lethality.

RESULTS

Among the 892 patients interviewed, 77.9% were taking osteoporosis treatment and 94.6% vitamin D supplementation as prescribed at the last visit. COVID-19-like symptoms were reported by 5.1%, whereas confirmed cases were 1.2%. A total number of 33 patients had been in hospital and the hospitalization rate of those who had not discontinued vitamin D supplementation was less than 4%. There were eight deaths, two with a concomitant COVID-19 diagnosis. The prevalence of severe osteoporosis was 50% in total COVID-19 patients and 87.5% in deceased COVID-19 patients. The overall COVID-19 mortality was 0.2%; lethality was 20%, lower than the national rate of the same age group.

CONCLUSIONS

This large group of osteoporotic patients showed high compliance and lower COVID-19 lethality compared to patients of the same age. Novel approaches such as telemedicine can provide critical support for the remote follow-up of patients with chronic diseases also in the setting of routine care.

Correlation between vitamin D levels and bone metabolism in children with cow's milk allergy

Objective

Research is limited regarding biochemical markers of bone metabolism among children with cow’s milk protein allergy (CMPA). We aimed to determine differences in vitamin D and bone metabolism markers between infants with CMPA and healthy infants and explore relationships between these in a cross-sectional study.

Methods

In total, we included 41 children diagnosed with CMPA and under systematic medical and nutritional care at our center, and 50 healthy children as a control group. We reviewed demographic and clinical characteristics and measured serum biomarkers.

Results

We found that serum 25-hydroxyvitamin D (25(OH)D) levels among infants in the CMPA group were significantly lower than those in the control group, and levels of bone-specific alkaline phosphatase (BALP), serum phosphorus, and serum calcitonin were reduced. Pearson correlation analysis showed that serum 25(OH)D concentrations in the CMPA group were negatively correlated with parathyroid hormone but not significantly correlated with calcitonin and BALP. Logistic regression showed that CMPA was a risk factor for vitamin D deficiency.

Conclusions

Our study indicated that CMPA was associated with disturbances in bone metabolism. Levels of vitamin D in children with CMPA were lower than those in healthy children. CMPA was a risk factor for vitamin D deficiency.

The Exposome and Immune Health in Times of the COVID-19 Pandemic

Growing evidence supports the importance of lifestyle and environmental exposures-collectively referred to as the 'exposome'-for ensuring immune health. In this narrative review, we summarize and discuss the effects of the different exposome components (physical activity, body weight management, diet, sun exposure, stress, sleep and circadian rhythms, pollution, smoking, and gut microbiome) on immune function and inflammation, particularly in the context of the current coronavirus disease 2019 (COVID-19) pandemic. We highlight the potential role of 'exposome improvements' in the prevention-or amelioration, once established-of this disease as well as their effect on the response to vaccination. In light of the existing evidence, the promotion of a healthy exposome should be a cornerstone in the prevention and management of the COVID-19 pandemic and other eventual pandemics.

25-Hydroxyvitamin D level is associated with mortality in patients with critical COVID-19: a prospective observational study in Mexico City

BACKGROUND/OBJECTIVES

Considering the high number of deaths from coronavirus disease 2019 (COVID-19) in Latin American countries, together with multiple factors that increase the prevalence of vitamin D deficiency, we aimed to determine 25-hydroxyvitamin D (25[OH]D) levels and its association with mortality in patients with critical COVID-19.

SUBJECTS/METHODS

This was a prospective observational study including adult patients with critical COVID-19. Data, including clinical characteristics and 25(OH)D levels measured at the time of intensive care unit admission, were collected. All patients were followed until hospital discharge or in-hospital death. The patients were divided into those surviving and deceased patient groups, and univariate and multivariate logistic regression analyses were performed to determine independent predictors of in hospital mortality.

RESULTS

The entire cohort comprised 94 patients with critical COVID-19 (males, 59.6%; median age, 61.5 years). The median 25(OH)D level was 12.7 ng/mL, and 15 (16%) and 79 (84%) patients had vitamin D insufficiency and vitamin D deficiency, respectively. The median serum 25(OH)D level was significantly lower in deceased patients compared with surviving (12.1 vs. 18.7 ng/mL, P < 0.001). Vitamin D deficiency was present in 100% of the deceased patients. Multivariate logistic regression analysis revealed that age, body mass index, other risk factors, and 25(OH)D level were independent predictors of mortality.

CONCLUSIONS

Vitamin D deficiency was present in 84% of critical COVID-19 patients. Serum 25(OH)D was independently associated with mortality in critical patients with COVID-19.