Beneficial Effect of Short-Term Supplementation of High Dose of Vitamin D3 in Hospitalized Patients With COVID-19: A Multicenter, Single-Blinded, Prospective Randomized Pilot Clinical Trial

Vitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVES

Vitamin D deficiency is prevalent among the population. Previous studies have shown that vitamin D supplementation might be useful for treating COVID-19 infection. Therefore, we performed a meta-analysis to explore vitamin D supplementation efficacy in treating COVID-19 patients with vitamin D deficiency.

DESIGN

Systematic review and meta-analysis DATA SOURCES: PubMed, Cochrane Library, Embase and Web of Science.

ELIGIBILITY CRITERIA

Randomised controlled trials exploring vitamin D supplementation for patients with COVID-19 and vitamin D deficiency.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers employed standardised methods to search, screen and code the included studies. The primary outcomes included mortality during follow-up, 28-day mortality, need for mechanical ventilation and intensive care unit (ICU). The secondary outcome included length of stay in hospital and ICU. The risk of bias was assessed using the Risk of Bias 2 tool. Depending on the level of heterogeneity, either a random-effects model or a fixed-effects model was applied. The findings were summarised using Grading of Recommendations Assessment, Development and Evaluation (GRADE) evidence profiles and synthesised qualitatively.

RESULTS

A total of nine studies, comprising 870 participants, were included in the analysis. The pooled results indicated that vitamin D supplementation was associated with a lower risk of mortality (risk ratio 0.76; 95% CI 0.60 to 0.97). However, this apparent benefit was not robust when examined through the leave-one-out method and trial sequential analysis. Regarding other outcomes, there was no statistically significant difference between vitamin D supplementation and no supplementation in terms of 28-day mortality, the need for mechanical ventilation and ICU admission. Vitamin D supplementation was associated with a 0.41 day shorter length of stay in the ICU (mean difference -0.41; 95% CI -1.09 to 0.28) and a 0.07 day shorter length of stay in the hospital (mean difference -0.07; 95% CI -0.61 to 0.46) compared with no supplementation; however, neither difference was statistically significant.

CONCLUSION

Based on evidence of low to moderate quality, vitamin D supplementation reduced the mortality rate during follow-up in COVID-19 patients with vitamin D deficiency. However, it did not improve 28-day mortality, nor did it reduce the need for mechanical ventilation and ICU admission, or the length of stay in the ICU and hospital.

PROSPERO REGISTRATION NUMBER

CRD42024573791.

Vitamin D: A Nutraceutical Supplement at the Crossroad Between Respiratory Infections and COVID-19

Even though in mid-2023 the World Health Organization declared the end of the public health emergency of international concern status for COVID-19, many areas of uncertainty about SARS-CoV-2 infection pathophysiology remain. Although in the last 4 years pharmaceutical industries widely invested in the development of effective antiviral treatments and vaccines, large disparities in their availability worldwide still exist, thus fostering the investigation of nutritional supplements as adjuvant therapeutic approaches for disease management, especially in resource-limited settings. During the COVID-19 pandemic, vitamin D has been widely used as an over-the-counter solution to improve disease evolution, thanks to its known immunomodulatory and anti-inflammatory actions. Ecological and observational studies support a relationship between hypovitaminosis D and COVID-19 negative outcomes and, according to this evidence, several research groups investigated the role of vitamin D supplementation in protecting from SARS-CoV-2 infection and/or improving disease evolution. This narrative review is intended to offer insights into the existing data on vitamin D's biological effects in respiratory infections, especially in COVID-19. Furthermore, it will also offer a brief overview of the complex interplay between vitamin D and vaccine-elicited immune response, with special attention to anti-COVID-19 vaccines.

Vitamin D Deficiency Meets Hill's Criteria for Causation in SARS-CoV-2 Susceptibility, Complications, and Mortality: A Systematic Review

Clinical trials consistently demonstrate an inverse correlation between serum 25-hydroxyvitamin D [25(OH)D; calcifediol] levels and the risk of symptomatic SARS-CoV-2 disease, complications, and mortality. This systematic review (SR), guided by Bradford Hill's causality criteria, analyzed 294 peer-reviewed manuscripts published between December 2019 and November 2024, focusing on plausibility, consistency, and biological gradient. Evidence confirms that cholecalciferol (D3) and calcifediol significantly reduce symptomatic disease, complications, hospitalizations, and mortality, with optimal effects above 50 ng/mL. While vitamin D requires 3-4 days to act, calcifediol shows effects within 24 h. Among 329 trials, only 11 (3%) showed no benefit due to flawed designs. At USD 2/patient, D3 supplementation is far cheaper than hospitalization costs and more effective than standard interventions. This SR establishes a strong inverse relationship between 25(OH)D levels and SARS-CoV-2 vulnerability, meeting Hill's criteria. Vitamin D3 and calcifediol reduce infections, complications, hospitalizations, and deaths by ~50%, outperforming all patented, FDA-approved COVID-19 therapies. With over 300 trials confirming these findings, waiting for further studies is unnecessary before incorporating them into clinical protocols. Health agencies and scientific societies must recognize the significance of these results and incorporate D3 and calcifediol for prophylaxis and early treatment protocols of SARS-CoV-2 and similar viral infections. Promoting safe sun exposure and adequate vitamin D3 supplementation within communities to maintain 25(OH)D levels above 40 ng/mL (therapeutic range: 40-80 ng/mL) strengthens immune systems, reduces hospitalizations and deaths, and significantly lowers healthcare costs. When serum 25(OH)D levels exceed 70 ng/mL, taking vitamin K2 (100 µg/day or 800 µg/week) alongside vitamin D helps direct any excess calcium to bones. The recommended vitamin D dosage (approximately 70 IU/kg of body weight for a non-obese adult) to maintain 25(OH)D levels between 50-100 ng/mL is safe and cost-effective for disease prevention, ensuring optimal health outcomes.

A narrative review focusing on randomized clinical trials of vitamin D supplementation for COVID-19 disease

Current evidence is inconsistent on whether vitamin D supplementation can prevent COVID-19 infection or improve its clinical outcomes. To better understand and look into the issue, we went through the background knowledge of COVID-19 and vitamin D, searched in Pubmed [by using key words in the title containing "randomized clinical trial", "COVID-19", and "vitamin D (25-hydroxyvitamin D, or cholecalciferol, or calcidiol, or calcifediol) supplementation"] for publications of studies on vitamin D/supplementation in COVID-19 patients, especially those about the randomized clinical trials (RCTs). After reviewing these papers, we did a short background review of vitamin D and the pathophysiology of COVID-19, summarized the key features of the 25 RCTs in text and tabulated in a table of some of the features, commented, compared and discussed the differences between RCTs (for example, change the serum 25-hydroxyvitamin D concentration from nmol/L to ng/mL, making the comparison easier). The take-home question of the review is that serum 25-hydroxyvitamin D concentration is an important indicator of the supplementation effect of vitamin D correction but may not be reliable in predicting the supplementation effect on the clinical outcomes of COVID-19.

The Roles of Vitamin D Levels, Gla-Rich Protein (GRP) and Matrix Gla Protein (MGP), and Inflammatory Markers in Predicting Mortality in Intensive Care Patients: A New Biomarker Link?

OBJECTIVES

Identifying reliable biomarkers to predict mortality in critically ill patients is crucial for optimizing management in intensive care units (ICUs). Inflammatory and metabolic markers are increasingly recognized for their prognostic value. This study aims to evaluate the association of various inflammatory and metabolic markers with ICU mortality.

METHODS

This prospective observational study was conducted from January 2023 to January 2024 in the City Hospital's ICU. A total of 160 critically ill patients were enrolled. Laboratory parameters, including white blood cell (WBC) count, red cell distribution width (RDW), platelet count, neutrophil count, mean platelet volume (MPV), monocyte count, lymphocyte count, procalcitonin (PCT), C-reactive protein (CRP), calcium (Ca++), and vitamin D levels, were analyzed. Additionally, ratios such as the platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), systemic inflammatory index (SII), and pan-immune-inflammation value (PIV) were calculated. Plasma levels of Gla-rich protein (GRP) and dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP) were measured using ELISA.

RESULTS

The mean age of the patients included in the study was 60.5 ± 15.8 years. Cardiovascular disease was present in 72 patients (45%), respiratory system disease in 58 (36%), and chronic kidney disease (CKD) in 38 (24%). Additionally, 61 patients (38%) had diabetes, and 68 (42%) had hypertension. Inflammatory markers, including PLR, NLR, and PIV, were all significantly higher in non-survivors, while calcium and vitamin D levels were lower (p < 0.05). Higher WBC, RDW, neutrophil count, PLR, NLR, PIV, CRP, procalcitonin, GRP, and dp-ucMGP levels were positively correlated with longer hospital stays and increased mortality. In contrast, platelet and lymphocyte counts were negatively correlated with both outcomes (p < 0.05). Vitamin D levels showed an inverse relationship with both hospital stay and mortality, indicating that lower levels were associated with worse outcomes (p < 0.05). In multiple logistic regression analysis, elevated WBC count (OR = 1.20, p = 0.02), RDW (OR = 1.35, p = 0.01), neutrophil count (OR = 1.25, p = 0.01), MPV (OR = 1.20, p = 0.02), PLR (OR = 1.30, p = 0.01), NLR (OR = 1.40, p = 0.001), PIV (OR = 1.50, p = 0.001), CRP (OR = 1.32, p = 0.01), procalcitonin (OR = 1.45, p = 0.001), GRP (OR = 1.40, p = 0.001), and dp-ucMGP (OR = 1.30, p = 0.001) levels were significantly associated with increased mortality.

CONCLUSIONS

Inflammatory and metabolic markers, particularly NLR, PLR, PIV, GRP, and dp-ucMGP, are strong predictors of mortality in ICU patients. These markers provide valuable insights for risk stratification and early identification of high-risk patients, potentially guiding more targeted interventions to improve outcomes.

The Effect of Vitamin D Supplementation Post COVID-19 Infection and Related Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Vitamin D's role in COVID-19 management remains controversial. This meta-analysis aimed to evaluate the efficacy of vitamin D supplementation in patients with SARS-CoV-2 infection, focusing on mortality, intensive care unit (ICU) admissions, intubation rates, and hospital length of stay (LOS).

METHODS

A systematic review of PubMed/MEDLINE, Scopus, Cochrane, and Google Scholar databases was conducted. Randomized controlled trials (RCTs) and analytical studies investigating vitamin D supplementation in COVID-19 patients were included. The meta-analysis was performed using STATA MP 18.5, employing random-effect or fixed-effect models based on heterogeneity.

RESULTS

Twenty-nine studies (twenty-one RCTs, eight analytical) were analyzed. Vitamin D supplementation significantly reduced ICU admissions (OR = 0.55, 95% CI: 0.37 to 0.79) in RCTs and analytical studies (OR = 0.35, 95% CI: 0.18 to 0.66). Intubation rates were significantly reduced in RCTs (OR = 0.50, 95% CI: 0.27 to 0.92). Mortality reduction was significant in analytical studies (OR = 0.45, 95% CI: 0.24 to 0.86) but not in RCTs (OR = 0.80, 95% CI: 0.61 to 1.04). Subgroup analyses revealed more pronounced effects in older patients and severe COVID-19 cases. LOS showed a non-significant reduction (mean difference = -0.62 days, 95% CI: -1.41 to 0.18).

CONCLUSIONS

This meta-analysis suggests potential benefits of vitamin D supplementation in COVID-19 patients, particularly in reducing ICU admissions. However, the evidence varies across outcomes and patient subgroups. Discrepancies between RCTs and analytical studies highlight the need for further large-scale, well-designed trials accounting for baseline vitamin D status, standardized supplementation protocols, and patient characteristics to inform clinical guidelines for vitamin D use in COVID-19 management.

Unveiling the Interplay-Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2

The interaction of the SARS-CoV-2 spike protein with membrane-bound angiotensin-converting enzyme-2 (ACE-2) receptors in epithelial cells facilitates viral entry into human cells. Despite this, ACE-2 exerts significant protective effects against coronaviruses by neutralizing viruses in circulation and mitigating inflammation. While SARS-CoV-2 reduces ACE-2 expression, vitamin D increases it, counteracting the virus's harmful effects. Vitamin D's beneficial actions are mediated through complex molecular mechanisms involving innate and adaptive immune systems. Meanwhile, vitamin D status [25(OH)D concentration] is inversely correlated with severity, complications, and mortality rates from COVID-19. This study explores mechanisms through which vitamin D inhibits SARS-CoV-2 replication, including the suppression of transcription enzymes, reduced inflammation and oxidative stress, and increased expression of neutralizing antibodies and antimicrobial peptides. Both hypovitaminosis D and SARS-CoV-2 elevate renin levels, the rate-limiting step in the renin-angiotensin-aldosterone system (RAS); it increases ACE-1 but reduces ACE-2 expression. This imbalance leads to elevated levels of the pro-inflammatory, pro-coagulatory, and vasoconstricting peptide angiotensin-II (Ang-II), leading to widespread inflammation. It also causes increased membrane permeability, allowing fluid and viruses to infiltrate soft tissues, lungs, and the vascular system. In contrast, sufficient vitamin D levels suppress renin expression, reducing RAS activity, lowering ACE-1, and increasing ACE-2 levels. ACE-2 cleaves Ang-II to generate Ang(1-7), a vasodilatory, anti-inflammatory, and anti-thrombotic peptide that mitigates oxidative stress and counteracts the harmful effects of SARS-CoV-2. Excess ACE-2 molecules spill into the bloodstream as soluble receptors, neutralizing and facilitating the destruction of the virus. These combined mechanisms reduce viral replication, load, and spread. Hence, vitamin D facilitates rapid recovery and minimizes transmission to others. Overall, vitamin D enhances the immune response and counteracts the pathological effects of SARS-CoV-2. Additionally, data suggests that widely used anti-hypertensive agents-angiotensin receptor blockers and ACE inhibitors-may lessen the adverse impacts of SARS-CoV-2, although they are less potent than vitamin D.

Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID-19: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials

The COVID-19 pandemic has emerged as a major global health crisis. Vitamin D, a crucial fat-soluble vitamin, has been recommended for COVID-19 patients, though evidence of its effectiveness is inconsistent. This systematic literature review and meta-analysis aimed to evaluate the impact of vitamin D supplementation on COVID-19-related outcomes. A comprehensive search was conducted across PubMed, Scopus, Web of Science, Embase, and Cochrane databases. Primary outcomes included mortality and hospital length of stay, while secondary outcomes encompassed C-reactive protein (CRP), ferritin, D-dimer, hemoglobin (Hb) concentrations, and lymphocyte, neutrophil, and platelet counts. Data analysis was performed using Stata™ Version 14. A total of 16 trials were analyzed. The meta-analysis revealed that vitamin D supplementation significantly reduced hospital length of stay (mean difference = -1.16; 95% confidence interval [CI]: -2.23, -0.09; p = .033) with significant heterogeneity (I2 = 69.2%, p = .002). Subgroup analysis showed a more pronounced reduction in studies with vitamin D dosages ≤10 000 international units (IU) (mean difference = -1.27; 95% CI: -1.96, -0.57; p < .001) and in patients over 60 years old (mean difference = -1.84; 95% CI: -2.53, -1.14; p < .001). Additionally, vitamin D significantly reduced CRP concentrations in older adults (>60 years) (mean difference = -1.13; 95% CI: -2.07, -0.18; p = .019). No significant changes were found in ferritin, D-dimer, Hb concentrations, or in lymphocyte, neutrophil, and platelet counts (p > .05). In conclusion, while vitamin D supplementation did not significantly affect most COVID-19-related biomarkers, however, it reduces the length of hospital stay.

The impact of supplementing vitamin D through different methods on the prognosis of COVID-19 patients: a systematic review and meta-analysis

Objective

To analyze the impact of different methods of Vitamin D administration on the prognosis of COVID-19 patients.

Methods

A comprehensive literature search was conducted across four databases: PubMed, Embase, Web of Science, and Cochrane, up to January 5, 2024. Eligible studies included randomized controlled trials and cohort studies that compared Vitamin D supplementation with control groups in COVID-19 patients. Outcomes of interest were mortality rate, ICU (Intensive Care Unit) admission rate, length of hospital stay, and endotracheal intubation rate. Subgroup analyses were performed based on the dosing regimen (single-dose vs. continuous-dose), total Vitamin D intake within 14 days (≥100,000 IU vs. <100,000 IU), and baseline serum Vitamin D levels (deficient group: 25OHD < 30 ng/mL vs. non-restricted group). A random-effects model was employed for meta-analysis to account for heterogeneity among studies.

Results

A total of 21 studies involving 4,553 participants were included. In terms of mortality, Vitamin D supplementation significantly reduced the mortality rate (RR = 0.72, 95% CI: 0.54-0.94, I 2 = 54%, p = 0.02), with continuous dosing being more effective (RR = 0.53, 95% CI: 0.34-0.83, I 2 = 55%, p = 0.006) compared to single-dose (RR = 0.88, 95% CI: 0.69-1.12, I 2 = 21%, p = 0.3), and lower total doses (<100,000 IU) showing greater benefit (RR = 0.30, 95% CI: 0.21-0.44, I 2 = 0%, p < 0.0001). Mortality was significantly reduced in the Vitamin D-deficient group (25OHD < 30 ng/mL) (RR = 0.73, 95% CI: 0.59-0.89, I 2 = 0%, p = 0.002) but not in the non-restricted group. Regarding ICU admission, supplementation reduced ICU admission rates (RR = 0.58, 95% CI: 0.38-0.88, I 2 = 74%, p = 0.01), with continuous dosing (RR = 0.44, 95% CI: 0.22-0.90, I 2 = 74%, p = 0.02) being more effective than single-dose (RR = 0.79, 95% CI: 0.61-1.03, I 2 = 22%, p = 0.08), and lower doses (<100,000 IU) providing more significant reduction (RR = 0.31, 95% CI: 0.21-0.47, I 2 = 0%, p = 0.001). ICU admission rates were significantly reduced in the Vitamin D-deficient group (RR = 0.63, 95% CI: 0.42-0.93, I 2 = 0%, p = 0.02) but not in the non-restricted group (RR = 0.59, 95% CI: 0.32-1.11, I 2 = 86%, p = 0.1). For length of hospital stay, no significant differences were observed between Vitamin D and control groups (MD = -1, 95% CI: -2.16 to 0.16, p = 0.13), and subgroup analyses by dosing regimen, total dose, and baseline Vitamin D levels also showed no significant differences. Similarly, for endotracheal intubation, there was no significant difference in intubation rates between groups (RR = 0.78, 95% CI: 0.56-1.08, p = 0.13), and subgroup analyses confirmed no significant effect of different dosing strategies or baseline Vitamin D status on intubation rates.

Conclusion

Vitamin D supplementation improves clinical outcomes in COVID-19 patients by reducing mortality and ICU admission rates, particularly when administered continuously with a total dose of less than 100,000 IU over 14 days, and among those with baseline Vitamin D deficiency (25OHD < 30 ng/mL). However, there were no significant effects on the length of hospital stay or endotracheal intubation rates, regardless of the dosing regimen or baseline Vitamin D levels. These findings emphasize the importance of considering both the total dose over 14 days and baseline Vitamin D status to optimize therapeutic benefits.

Effect of vitamin D3 on antiphospholipid antibodies in hospitalized patients with moderate to severe COVID-19

OBJECTIVE

To investigate the effect of a single oral dose of 200,000 IU of vitamin D3 on antiphospholipid antibodies in hospitalized patients with moderate to severe COVID-19.

METHODS

This is a post-hoc, exploratory analysis from a double-blind, placebo-controlled, randomized clinical trial performed in two centers in Sao Paulo, Brazil. Hospitalized patients with COVID-19 were randomly assigned to receive either vitamin D3 (n = 97) or placebo (n = 97). In this post-hoc analysis, the endpoints were titers and frequency of anti-β2-Glycoprotein-I (aβ2-GP) and Anticardiolipin (aCL) antibodies [Immunoglobulin G, M and A (IgG, IgM and IgA)].

RESULTS

Overall mean (SD) age was 55.3 (13.9) years, Body Mass Index (BMI) was 32.2 (7.1 kg/m2), and 106 participants (54.6 %) were male. There was a significant group by time interaction (p = 0.046) for frequency of aCL IgG, with increased values from baseline to discharge in the placebo group [n (%), from 13 (13.4) to 25 (25.8)] compared to the vitamin D3 [from 25 (25.8) to 29 (29.9)]. However, the frequency of aCL IgG did not change between the groups on discharge. No significant differences between vitamin D3 and placebo groups were found for any other autoantibodies.

CONCLUSION

These findings do not support the use of a single oral dose of 200,000 IU of vitamin D3 to modulate autoantibodies in hospitalized patients with moderate to severe COVID-19.

Vitamin D3 supplementation in COVID-19 patients with cardiovascular disease and gut dysbiosis

BACKGROUND

The COVID-19 pandemic has highlighted the vulnerability of particular patient groups to SARS-CoV-2 infection, including those with cardiovascular diseases, hypertension, and intestinal dysbiosis. COVID-19 affects the gut, suggesting diet and vitamin D3 supplementation may affect disease progression.

AIMS

To evaluate levels of Ang II and Ang-(1-7), cytokine profile, and gut microbiota status in patients hospitalized for mild COVID-19 with a history of cardiovascular disease and treated with daily doses of vitamin D3.

METHODS

We recruited 50 adult patients. We screened 50 adult patients and accessed pathophysiology study 22, randomized to daily oral doses of 10,000IU vitamin D3 (n=11) or placebo (n=11). Plasma levels of Ang II and Ang-(1-7) were determined by radioimmunoassay, TMA and TMAO were measured by liquid chromatography and interleukins (ILs) 6, 8, 10 and TNF-α by ELISA.

RESULTS

The Ang-(1-7)/Ang II ratio, as an indirect measure of ACE2 enzymatic activity, increased in the vitamin D3 group (24±5pg/mL vs. 4.66±2pg/mL, p<0.01). Also, in the vitamin D3-treated, there was a significant decline in inflammatory ILs and an increase in protective markers, such as a substantial reduction in TMAO (5±2μmoles/dL vs. 60±10μmoles/dL, p<0.01). In addition, treated patients experienced less severity of infection, required less intensive care, had fewer days of hospitalization, and a reduced mortality rate. Additionally, improvements in markers of cardiovascular function were seen in the vitamin D3 group, including a tendency for reductions in blood pressure in hypertensive patients.

CONCLUSIONS

Vitamin D3 supplementation in patients with COVID-19 and specific conditions is associated with a more favourable prognosis, suggesting therapeutic potential in patients with comorbidities such as cardiovascular disease and gut dysbiosis.

Therapeutic effects of vitamin D supplementation on COVID-19 aggravation: a systematic review and meta-analysis of randomized controlled trials

Background

The therapeutic effects of vitamin D supplementation on Coronavirus disease 2019 (COVID-19) aggravation remain controversial and inconclusive. To probe into this contentious issue, we performed the present meta-analysis of randomized controlled trials (RCTs).

Methods

Literature published up to June 2023 was retrieved from Cochrane Library, PubMed, Web of Science and Embase. RCTs assessing mortality, intensive care unit (ICU) admission, mechanical ventilation (MV), length of hospitalization (LOH), and inflammatory markers containing C-reactive protein (CRP), D-dimer, interleukin-6 (IL-6), lactate dehydrogenase (LDH) were included. 19 RCTs were involved in the analysis and were conducted subgroup analyses on the baseline COVID-19 severity and vitamin D administration.

Results

In the severity subgroup, statistically significant effects in moderate to severe group were observed in ICU admission (OR 0.43, 95% CI 0.23, 0.80; p = 0.008), MV (OR 0.44, 95% CI 0.27, 0.72; p = 0.001) and LOH (SMD -0.49, 95% CI -0.92, -0.06; p = 0.027). In the administration subgroup, effects of ICU admission (OR 0.39, 95% CI 0.16, 0.97; p = 0.044), MV (OR 0.18, 95% CI 0.07, 0.46; p = 0.000) and LOH (SMD -0.50, 95% CI -0.96, -0.04; p = 0.034) were more pronounced in patients supplied with multiple-dose vitamin D than single-dose. Although the result of mortality showed no statistically significant effect, it indicated a reduced trend (OR 0.87, 95% CI 0.63, 1.12; p > 0.05). The results of inflammatory markers reached no statistical differences.

Conclusion

This meta-analysis revealed that moderate to severe COVID-19 patients supplied with multiple doses of vitamin D were less apt to need ICU admission, mechanical ventilation and have shorter hospital stays.

Effect of Vitamin D3 Supplementation on Severe COVID-19: A Meta-Analysis of Randomized Clinical Trials

Since the beginning of the COVID-19 pandemic, vitamin D has attracted interest due to its immunomodulatory properties. Numerous studies show a correlation between vitamin D levels and COVID-19 cases and mortality. Therefore, we conducted a meta-analysis in order to assess the relationship between vitamin D3 supplementation and COVID-19 severity. We included 13 randomized clinical trials that contained the analyzed endpoints: length of COVID-19 hospitalization, number of intensive care unit (ICU) admissions, length of stay in the ICU, number of cases requiring any supplemental oxygenation, duration of any supplemental oxygenation, number of overall mortality and number of deaths associated with COVID-19. The relative risk with 95% confidence interval (CI) and the mean difference with 95% CI were calculated to compare the effect. A random effects model was used to calculate effect sizes. Our meta-analysis showed a positive effect of vitamin D3 supplementation on ICU admission (RR = 0.73; 95% CI [0.57; 0.95], p = 0.02, I2 = 19.6%) and mortality associated with COVID-19 among patients (RR = 0.56; 95% CI [0.34; 0.91]; p = 0.02; I2 = 0%). Vitamin D3 supplementation may potentially reduce the risk of ICU admission and death associated with COVID-19.

High-dose vitamin D supplementation in patients with COVID-19: A meta-analysis of randomized controlled trials

The efficacy of administering high doses of vitamin D to patients diagnosed with COVID-19 remains uncertain. We conducted a comprehensive search across multiple databases (PubMed, EMBASE, Cochrane Library, and ISI Web of Science) from inception until August 2022, with no limitations on language, to locate randomized controlled trials (RCTs) that investigated the impact of high-dose vitamin D supplementation (defined as a single dose of ≥100,000 IU or daily dose of ≥10,000 IU reaching a total dose of ≥100,000 IU) on COVID-19 patients. Risk ratios (RR) with 95% confidence intervals (CI) and weighted mean differences (WMD) with 95% CI were calculated. Our meta-analysis included 5 RCTs with a total of 834 patients. High-dose vitamin D supplementation did not show any significant benefits for mortality (I 2 = 0.0%, p = .670; RR 1.092, 95% CI 0.685-1.742, p = .711) or intensive care unit (ICU) admission (I 2 = 0.0%, p = .519; RR 0.707, 95% CI 0.454-1.102, p = .126) in COVID-19 patients compared to the control group. However, it was found to be safe and well-tolerated (I 2 = 0.0%, p = .887; RR 1.218, 95% CI 0.930-1.594, p = .151). Subgroup analysis also showed no benefits in overall mortality, including for patients with vitamin D deficiency (I 2 = 0.0%, p = .452; RR 2.441, 95% CI 0.448-13.312, p = .303) or compared to the placebo (I 2 = 0.0%, p = .673; RR 1.666, 95% CI 0.711-3.902, p = .240). Our research indicates that there is no evidence to support the efficacy of high-dose vitamin D supplementation in improving clinical outcomes among individuals with COVID-19, in line with previous studies focused on contexts including rickets. Considering the limitations of the study, additional research may be required.

Pharmacological evaluation of vitamin D in COVID-19 and long COVID-19: recent studies confirm clinical validation and highlight metformin to improve VDR sensitivity and efficacy

Nearly four years after its first appearance, and having gone from pandemic to endemic, the SARS-CoV-2 remains out of control globally. The purpose of this study was to evaluate the clinical efficacy of vitamin D (VD) in COVID-19 and long COVID-19, explain the discrepancy in clinical outcomes and highlight the potential impact of metformin on VD efficacy in recent articles. Articles from January 2022 to August 2023 were selected for this review. The objective of this study was achieved by reviewing, analyzing, and discussing articles demonstrating (1) the mechanism of action of VD (2) observational or randomized clinical trials (RCTs) that support or not the beneficial clinical effects of VD in COVID-19 or long COVID. (3) genetic and non-genetic reasons for the variation in the effects of VD. Articles were collected from electronic databases such as PubMed, Scopus, MEDLINE, Google Scholar, Egyptian Knowledge Bank, Science Direct, and Cochrane Database of Systematic Reviews. Twenty three studies conducted in vitro or in animal models indicated that VD may act in COVID-19 through protecting the respiratory system by antimicrobial peptide cathelicidins, reducing lung inflammation, regulating innate and adaptive immune functions and up regulation of autophagy gene activity. Our review identified 58 clinical studies that met the criteria. The number of publications supporting a beneficial clinical activity of VD in treating COVID-19 was 49 (86%), including 12 meta-analyses. Although the total patients included in all articles was 14,071,273, patients included in publications supporting a beneficial role of VD in COVID-19 were 14,029,411 (99.7%). Collectively, extensive observational studies indicated a decisive relationship between low VD levels and the severity of COVID-19 and mortality outcomes. Importantly, evidence from intervention studies has demonstrated the effectiveness of VD supplements in treating COVID-19. Furthermore, the results of 4 observational studies supported the beneficial role of VD in alleviating symptoms of long COVID-19 disease. However, eight RCTs and one meta-analysis of RCTs may contain low-grade evidence against a beneficial role of VD in COVID-19. Twenty-five articles have addressed the association between VDR and DBP genetic polymorphisms and treatment failure of VD in COVID-19. Impaired VDR signaling may underlie the variability of VD effects as non-genetic mechanisms. Interestingly, in recent studies, metformin has a beneficial therapeutic role in COVID-19 and long COVID-19, possibly by improving AMPK signaling of the VDR and enhancing the efficacy of the VD. In conclusion, evidence has been significantly strengthened over the past 18 months, with several meta-analyses and RCTs reporting conclusive beneficial effects of VD supplementation against COVID-19 and highlighting metformin to improve VDR sensitivity and efficacy in treating COVID-19 and long COVID-19.

The role of vitamin D in the prevention and treatment of SARS-CoV-2 infection: A meta-analysis of randomized controlled trials

BACKGROUND

Vitamin D (VitD) has been shown to be important for the immune response of the respiratory system, but the preventive and therapeutic effects of vitamin D supplementation on SARS-CoV-2 infection are controversial. This study aimed to determine the role of vitamin D supplementation in the prevention and treatment of SARS-CoV-2 infection through a meta-analysis of randomized controlled trials.

METHODS

The databases of PubMed, Cochrane Library, Embase, Web of Science and Google Scholar were searched systematically from inception to April 17,2023 to identify trials involving a randomized comparison of vitamin D supplementation versus non-vitamin D supplementation for SARS-CoV-2 infection prevention or treatment.

RESULTS

We retrieved 25 eligible trials, including 8128 participants. Four trials compared the preventive effects of vitamin D supplementation on SARS-CoV-2 infection, and the results (RR 0.31; 95%CI 0.07 to 1.32) were inconclusive. Regarding the treatment of SARS-CoV-2 infection with vitamin D supplementation, it was found that vitamin D supplementation could significantly reduce the rates of ICU admission (RR 0.63; 95%CI 0.44 to 0.89) and mechanical ventilation (RR 0.58; 95%CI 0.39 to 0.84), but had no statistically significant effect on mortality. However, in subgroup analyses based on the patients' specific conditions, vitamin D supplementation significantly reduced the mortality in patients with vitamin D deficiency (RR 0.76; 95%CI 0.58 to 0.98).

CONCLUSION

Vitamin D supplementation may have some beneficial impact on the severity of illness caused by SARS-CoV-2, particularly in VitD deficient patients, but further studies are still needed.

Effect of Single High Dose Vitamin D Substitution in Hospitalized COVID-19 Patients with Vitamin D Deficiency on Length of Hospital Stay

Vitamin D and its role in the coronavirus-19 disease (COVID-19) pandemic has been controversially discussed, with inconclusive evidence about vitamin D3 (cholecalciferol) supplementation in COVID-19 patients. Vitamin D metabolites play an important role in the initiation of the immune response and can be an easily modifiable risk factor in 25-hydroxyvitamin D₃ (25(OH)D₃)-deficient patients. This is a multicenter, randomized, placebo-controlled double-blind trial to compare the effect of a single high dose of vitamin D₃ followed by treatment as usual (TAU) of daily vitamin D₃ daily until discharge versus placebo plus TAU in hospitalized patients with COVID-19 and 25(OH)D₃-deficiency on length hospital stay. We included 40 patients per group and did not observe a significant difference in the median length of hospital stay (6 days in both groups, p = 0.920). We adjusted the length of stay for COVID-19 risk factors (β = 0.44; 95% CI: -2.17-2.22), and center (β = 0.74; 95% CI: -1.25-2.73). The subgroup analysis in patients with severe 25(OH)D₃-deficiency (<25 nmol/L) showed a non-significant reduction in the median length of hospital stay in the intervention group (5.5 vs. 9 days, p = 0.299). The competing risk model with death did not reveal significant differences between the group in the length of stay (HR = 0.96, 95% CI 0.62-1.48, p = 0.850). Serum 25(OH)D₃ level increased significantly in the intervention group (mean change in nmol/L; intervention: +26.35 vs. control: -2.73, p < 0.001). The intervention with 140,000 IU vitamin D₃ + TAU did not significantly shorten the length of hospital stay but was effective and safe for the elevation of serum 25(OH)D₃ levels.

Vitamin D and COVID-19: Narrative Review after 3 Years of Pandemic

Active vitamin D [1,25(OH)₂D₃-calcitriol] is a secosteroid hormone whose receptor is expressed on all cells of the immune system. Vitamin D has a global anti-inflammatory effect and its role in the management of a SARS-CoV-2 infection has been investigated since the beginning of the COVID-19 pandemic. In this narrative review, the laboratory and clinical results of a vitamin D supplementation have been collected from both open-label and blinded randomized clinical trials. The results are generally in favor of the utility of maintaining the serum concentrations of calcifediol [25(OH)D₃] at around 40 ng/mL and of the absolute usefulness of its supplementation in subjects with deficient serum levels. However, two very recent large-scale studies (one open-label, one placebo-controlled) have called into question the contribution of vitamin D to clinical practice in the era of COVID-19 vaccinations. The precise role of a vitamin D supplementation in the anti-COVID-19 armamentarium requires further investigations in light of the breakthrough which has been achieved with mass vaccinations.

Vitamin D Supplementation and COVID-19 Outcomes: Mounting Evidence and Fewer Doubts

The coronavirus disease 2019 (COVID-19) has already killed more than 6 million people around the world. A growing body of epidemiological evidence suggests that low 25-hydroxy vitamin D (25-OH-vitamin D) plasma levels are associated with an increased risk of developing COVID-19 and —most importantly—with a higher risk of developing more severe COVID-19 and dying. On the other hand, vitamin D supplementation during the early phases of COVID-19 has been related to a decreased length of hospital stay, less frequent need for oxygen, and a reduced mortality rate in inpatients. This seems to be particularly true when high dosages are used. In light of this evidence, further studies are needed to define the best timing for vitamin D supplementation and the most effective dosage schedule.