Title: Understanding a Low Vitamin D State in the Context of COVID-19

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.

Impact of the COVID-19 lockdown on the vitamin D status of people in the West of Ireland

OBJECTIVE

Identify the impact of COVID-19 lockdown restrictions on the vitamin D status of individuals in the west of Ireland.

DESIGN

Cross-sectional study.

SETTING

Adults who had wintertime serum 25(OH)D analysis completed in Galway University Hospital.

PARTICIPANTS

A total of 16,725 participants (2015-2020 (n = 13,449) and 2020-2021 (n = 3276)). Baseline demographics; sex, age, origin of the sample and the date of sample collection.

RESULTS

Median serum vitamin D and serum vitamin D3 concentrations were higher in the 5-month period from October-February 2020-2021 (61 nmol/L (± 36-85 nmol/L) and 60 nmol/L (± 34-85 nmol/L)) respectively, than for the corresponding 5-month period (October-February) in 2015-2020 (53 nmol/L (± 32-78 nmol/L) and 51 nmol/L (± 30-77 nmol/L)) respectively. These changes coincided with a decline in the prevalence of deficiency. In the 5-month period October-February 2020-2021, 19.2% of the population were vitamin D deficient (< 30 nmol/L) compared to 22.5% in the corresponding 5-month period in 2015-2020, and 38.1% were vitamin D deficient (< 50 nmol/L) in the 5-month period October-February 2020-2021 compared to 46.6% in the corresponding 5-month period in 2015-2020. Males were more likely to be deficient at both thresholds (p < 0.001). For the total cohort, at the < 30 nmol/L threshold, inpatients (25.5%) and nursing home residents (34.1%) had higher prevalence of deficiency.

CONCLUSIONS

Vitamin D levels were higher in the 5-month period of October-February 2020-2021, and this precipitated a decline in deficiency at both thresholds, indicating that lockdown coincided with enhanced vitamin D status. We postulate that it may be attributable to changes in diet and/or supplementation, or increased sun exposure, but further confirmatory studies are required.

Vitamin D status and clinical implications in the adult population of Malaysia: a position paper by the Malaysian Vitamin D Special Interest Group

PURPOSE

Vitamin D deficiency and insufficiency is common among populations globally, and in Asia and Malaysia. The purpose of this Position Paper is to propose recommendations for both clinicians and non-clinicians to promote vitamin D sufficiency in Malaysian adults. Formation of a national multisector, multidisciplinary alliance is also proposed to progress initiatives relating to safe sun exposure, adequate vitamin D intake through food fortification, and vitamin D supplementation for high-risk groups.

METHODS

Literature reviews were undertaken to inform summaries of the following: vitamin D status globally and in Asian and Malaysian populations, vitamin D status among individuals with common medical conditions, and current recommendations to achieve vitamin D sufficiency through sun exposure, food intake and supplementation. Recommendations were based on the findings of the literature reviews, recent European guidance on vitamin D supplementation, the 2018 road map for action on vitamin D in low- and middle-income countries, and research recommendations proposed by the Malaysian Ministry of Health in 2017.

RESULTS

Recommendations on assessment of vitamin D in the adult Malaysian population include using serum or plasma 25-hydroxyvitamin D concentration as a biomarker, widespread participation by Malaysian laboratories in the Vitamin D Standardization Program, adoption of the US Endocrine Society definitions of vitamin D deficiency and insufficiency, and development of a comprehensive nationwide vitamin D status study. Specific high-risk groups are identified for vitamin D assessment and recommendations relating to loading doses and ongoing management are also made.

CONCLUSION

This Position Paper provides individual clinicians and national stakeholder organisations with clear recommendations to achieve vitamin D sufficiency in the adult population of Malaysia.

Hospital Outcomes in Patients Hospitalized for COVID-19 Pneumonia: The Effect of SARS-CoV-2 Vaccination and Vitamin D Status

SARS-CoV-2 vaccination promises to improve outcomes for patients with COVID-19 pneumonia (most notably those with advanced age and at high risk for severe disease). Here, we examine serum 25-Hydroxyvitamin D (25(OH)D) status and outcomes in both old (>70 years) and young vaccinated (n = 80) and unvaccinated (n = 91) subjects, who were hospitalized due to COVID-19 pneumonia in a single center (Connolly Hospital Dublin). Outcomes included ICU admission and mortality. Serum 25(OH)D levels were categorized as D30 (<30 nmol/L), D40 (30-49.99 nmol/L) and D50 (≥50 nmol/L). In multivariate analyses, D30 was independently associated with ICU admission (OR: 6.87 (95% CI: 1.13-41.85) (p = 0.036)) and mortality (OR: 24.81 (95% CI: 1.57-392.1) (p = 0.023)) in unvaccinated patients, even after adjustment for major confounders including age, sex, obesity and pre-existing diabetes mellitus. While mortality was consistently higher in all categories of patients over 70 years of age, the highest observed mortality rate of 50%, seen in patients over 70 years with a low vitamin D state (D30), appeared to be almost completely corrected by either vaccination, or having a higher vitamin D state, i.e., mortality was 14% for vaccinated patients over 70 years with D30 and 16% for unvaccinated patients over 70 years with a 25(OH)D level greater than 30 nmol/L. We observe that high mortality from COVID-19 pneumonia occurs in older patients, especially those who are unvaccinated or have a low vitamin D state. Recent vaccination or having a high vitamin D status are both associated with reduced mortality, although these effects do not fully mitigate the mortality risk associated with advanced age.

The Effects of Vitamin D Supplementation in COVID-19 Patients: A Systematic Review

Vitamin D has an immune-modulating effect on respiratory tract infections. For this reason, it has been proposed as part of the treatment in COVID-19. Furthermore, vitamin D deficiency has been associated with worse clinical outcomes of this disease. The aim of this systematic review was to determine whether vitamin D supplementation modifies the disease course. Therefore, eleven studies involving randomised clinical trials are analysed, in which groups of COVID-19 patients with or without vitamin D supplementation as part of the treatment are compared. A control group was treated with best available therapy, and in some of the clinical trials, also with a placebo. According to the outcomes, it seems that patients benefit from receiving a daily or maintained in time vitamin D dose regardless of vitamin D serum levels at the beginning of the trial. The administration of a single vitamin D dose does not seem to have any effect on the health status of these patients. However, the outcomes are heterogeneous and larger clinical trials are necessary.

Comparing the Evidence from Observational Studies and Randomized Controlled Trials for Nonskeletal Health Effects of Vitamin D

Although observational studies of health outcomes generally suggest beneficial effects with, or following, higher serum 25-hydroxyvitamin D [25(OH)D] concentrations, randomized controlled trials (RCTs) have generally not supported those findings. Here we review results from observational studies and RCTs regarding how vitamin D status affects several nonskeletal health outcomes, including Alzheimer's disease and dementia, autoimmune diseases, cancers, cardiovascular disease, COVID-19, major depressive disorder, type 2 diabetes, arterial hypertension, all-cause mortality, respiratory tract infections, and pregnancy outcomes. We also consider relevant findings from ecological, Mendelian randomization, and mechanistic studies. Although clear discrepancies exist between findings of observational studies and RCTs on vitamin D and human health benefits these findings should be interpreted cautiously. Bias and confounding are seen in observational studies and vitamin D RCTs have several limitations, largely due to being designed like RCTs of therapeutic drugs, thereby neglecting vitamin D's being a nutrient with a unique metabolism that requires specific consideration in trial design. Thus, RCTs of vitamin D can fail for several reasons: few participants' having low baseline 25(OH)D concentrations, relatively small vitamin D doses, participants' having other sources of vitamin D, and results being analyzed without consideration of achieved 25(OH)D concentrations. Vitamin D status and its relevance for health outcomes can usefully be examined using Hill's criteria for causality in a biological system from results of observational and other types of studies before further RCTs are considered and those findings would be useful in developing medical and public health policy, as they were for nonsmoking policies. A promising approach for future RCT design is adjustable vitamin D supplementation based on interval serum 25(OH)D concentrations to achieve target 25(OH)D levels suggested by findings from observational studies.

Vitamin D Status and Mortality from SARS CoV-2: A Prospective Study of Unvaccinated Caucasian Adults

COVID-19 and a low vitamin D state share common risk factors, which might explain why vitamin D deficiency has been linked with higher COVID-19 mortality. Moreover, measures of serum vitamin D may become lower during systemic inflammatory responses, further confounding the association via reverse causality. In this prospective study (recruited over 12 months), we examined whether the association between a low vitamin D state and in-hospital mortality due to SARS-CoV-2 pneumonia in unvaccinated subjects is explained by (i) the presence of shared risk factors (e.g., obesity, advanced age) or (ii) a reduction in serum 25(OH)D due to COVID-19 (i.e., reverse causality). In this cohort of 232 (mean age = 56 years) patients (all had SARS-CoV-2 diagnosed via PCR AND required supplemental oxygen therapy), we failed to find an association between serum vitamin D and levels of CRP, or other inflammatory markers. However, the hazard ratio for mortality for subjects over 70 years of age (13.2) and for subjects with a serum 25(OH)D level less than 30 nmol·L−1 (4.6) remained significantly elevated even after adjustment for gender, obesity and the presence of diabetes mellitus. Subjects <70 years and >70 years had significantly higher mortality with a serum 25(OH)D less than 30 nmol·L−1 (11.8% and 55%), than with a serum 25(OH)D greater than 30 nmol·L−1 (2.2% and 25%). Unvaccinated Caucasian adults with a low vitamin D state have higher mortality due to SARS CoV-2 pneumonia, which is not explained by confounders and is not closely linked with elevated serum CRP.