Research2023-05-22T13:28:46-05:00

Review the Research

Get summaries of key research on vitamin D and COVID-19

Study Summaries

Vitamin D and SARS-CoV2 Infection, Severity and Mortality: A Systematic Review and Meta-Analysis

Vitamin D and SARS-CoV2 Infection, Severity and Mortality: A Systematic Review and Meta-analysis Take Home Message Vitamin D supplementation was associated with a significantly lower risk

Effects of Vitamin D Serum Level on Morbidity and Mortality in Patients with COVID-19: A Systematic Review and Meta-Analysis

Effects of Vitamin D Serum Level on Morbidity and Mortality in Patients with COVID-19: A Systematic Review and Meta-Analysis Take Home Message his analysis reported no

Vitamin D Deficiency and Comorbidities as Risk Factors of COVID-19 Infection: A Systematic Review and Meta-Analysis

Vitamin D Deficiency and Comorbidities as Risk Factors of COVID-19 Infection: A Systematic Review and Meta-Analysis Take Home Message Low serum vitamin -D levels were significantly

Prognostic and Therapeutic Role of Vitamin D in COVID-19: Systematic Review and Meta-Analysis

Prognostic and Therapeutic Role of Vitamin D in COVID-19: Systematic Review and Meta-Analysis Take Home Message This meta-analysis found vitamin D deficiency/insufficiency increased susceptibility to COVID-19

Effects of Vitamin D Supplementation on COVID-19 Related Outcomes: A Systematic Review and Meta-Analysis

Effects of Vitamin D Supplementation on COVID-19 Related Outcomes: A Systematic Review and Meta-Analysis Take Home Message Vitamin D supplementation had no significant impact on the

Association of vitamin D deficiency with COVID‐19 infection severity: Systematic review and meta‐analysis

Association of vitamin D deficiency with COVID‐19 infection severity: Systematic review and meta‐analysis Take Home Message Vitamin D deficiency leads to poorer outcomes in individuals diagnosed

COVID-19 and vitamin D (Co-VIVID study): a systematic review and meta-analysis of randomized controlled trials.

COVID-19 and vitamin D (Co-VIVID study): a systematic review and meta-analysis of randomized controlled trials. Take Home Message Vitamin D use was associated with significant decrease

Changes in 25‐hydroxyvitamin D levels post‐vitamin D supplementation in people of Black and Asian ethnicities and its implications during COVID‐19 pandemic: A systematic review

This study recommends that people with darker skin supplement their diet with vitamin D3 through oral modes aiming to reduce the risk of adverse outcomes of...

Association of vitamin D deficiency with COVID-19 infection severity: Systematic review and meta-analysis

Association of vitamin D deficiency with COVID-19 infection severity: Systematic review and meta-analysis Take Home Message In this meta-analysis it is suggested that Vitamin D deficiency

Association of Vitamin D Status with SARS-CoV-2 Infection or COVID-19 Severity: A Systematic Review and Meta-analysis

Association of Vitamin D Status with SARS-CoV-2 Infection or COVID-19 Severity: A Systematic Review and Meta-analysis Take Home Message This meta-analysis suggested that there is a

Low vitamin D status is associated with coronavirus disease 2019 outcomes: a systematic review and meta-analysis

Low vitamin D status is associated with coronavirus disease 2019 outcomes: a systematic review and meta-analysis. Take Home Message Vitamin D deficiency and obesity increases risk

Vitamin D supplementation and clinical outcomes in COVID-19: a systematic review and meta-analysis

Vitamin D supplementation and clinical outcomes in COVID-19: a systematic review and meta-analysis Take Home Message Vitamin D supplementation might be associated with improved clinical outcomes

Therapeutic and prognostic role of vitamin D for COVID-19 infection: A systematic review and meta-analysis of 43 observational studies

Therapeutic and prognostic role of vitamin D for COVID-19 infection: A systematic review and meta-analysis of 43 observational studies Take Home Message Vitamin D deficiency and

Vitamin D supplementation and COVID-19 treatment: A systematic review and meta-analysis.

Vitamin D supplementation and COVID-19 treatment: A systematic review and meta-analysis. Take Home Message This systematic review and meta-analysis of 5 studies found no significant difference

Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomised, placebo-controlled, study (SHADE study).

In this 40 person randomized, placebo-controlled  study in India a greater proportion of vitamin D-deficient individuals with mildly symptomatic COVID-19 infections tested COVID-19 negative...

Hospital and Laboratory Outcomes of Patients with COVID-19 who Received Vitamin D Supplementation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Hospital and Laboratory Outcomes of Patients with COVID-19 who Received Vitamin D Supplementation: A Systematic Review and Meta-Analysis...

Protective Effect of Vitamin D Supplementation on COVID-19-Related Intensive Care Hospitalization and Mortality: Definitive Evidence from Meta-Analysis and Trial Sequential Analysis

Protective Effect of Vitamin D Supplementation on COVID-19-Related Intensive Care Hospitalization and Mortality: Definitive Evidence from Meta-Analysis and Trial....

Correlation between 25-hydroxyvitamin D/D3 Deficiency and COVID-19 Disease Severity in Adults from Northern Colorado

Correlation between 25-hydroxyvitamin D/D3 Deficiency and COVID-19 Disease Severity in Adults from Northern Colorado Take Home Message In this observational study, lower levels of vitamin D

Vitamin D Deficiency is Associated with Higher Risks for SARS-CoV2 Infection and COVID-19 Severity: A Retrospective Case-Control Study

Vitamin D Deficiency is Associated with Higher Risks for SARS-CoV2 Infection and COVID-19 Severity: A Retrospective Case-Control Study Take Home Message

Association of vitamin D deficiency with COVID‐19 infection severity: Systematic review and meta‐analysis

Association of vitamin D deficiency with COVID‐19 infection severity: Systematic review and meta‐analysis Take Home Message Vitamin D deficiency leads to poorer outcomes in individuals diagnosed

COVID-19 and vitamin D (Co-VIVID study): a systematic review and meta-analysis of randomized controlled trials.

COVID-19 and vitamin D (Co-VIVID study): a systematic review and meta-analysis of randomized controlled trials. Take Home Message Vitamin D use was associated with significant decrease

Association of vitamin D deficiency with COVID-19 infection severity: Systematic review and meta-analysis

Association of vitamin D deficiency with COVID-19 infection severity: Systematic review and meta-analysis Take Home Message In this meta-analysis it is suggested that Vitamin D deficiency

Vitamin D supplementation and outcomes in coronavirus disease 2019 (COVID-19) patients from the outbreak area of Lombardy, Italy

This study did not find a benefit associated with vitamin D supplementation in COVID-19 patients but did identify that vitamin D deficiency may be a risk factor for higher in-patient mortality.

Habitual use of vitamin D supplements and risk of coronavirus disease 2019 (COVID-19) infection: a prospective study in UK Biobank

In this prospective study, the self-reported use of vitamin D supplements was associated with a lower risk of COVID-19 infection, independent of lifestyle, socio-economic status, prevalent chronic diseases and circulating...

Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomised, placebo-controlled, study (SHADE study).

In this 40 person randomized, placebo-controlled  study in India a greater proportion of vitamin D-deficient individuals with mildly symptomatic COVID-19 infections tested COVID-19 negative...

Vitamin D Deficiency is Associated with Higher Risks for SARS-CoV2 Infection and COVID-19 Severity: A Retrospective Case-Control Study

Vitamin D Deficiency is Associated with Higher Risks for SARS-CoV2 Infection and COVID-19 Severity: A Retrospective Case-Control Study Take Home Message

Pre-infection 25-hydroxyvitamin D3 levels and association with severity of COVID-19 illness.

Pre-infection 25-hydroxyvitamin D3 levels and  association with severity of COVID-19 illness. Take Home Message Vitamin D deficiency is a predictive risk factor associated with poorer COVID-19

Vitamin D and morbidity in children with multisystem inflammatory syndrome related to Covid-19.

Vitamin D and morbidity in children with multisystem inflammatory syndrome related to Covid-19. Take Home Message This study showed a potential association between severe vitamin D

A combined  role for low vitamin D and low albumin circulating levels as strong predictors  of worse outcome in COVID-19 patients.

A combined  role for low vitamin D and low albumin circulating levels as strong predictors  of worse outcome in COVID-19 patients. Take Home Message The measurement of

Associations between predicted vitamin D status, vitamin D intake, and risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) severity.

Associations between predicted vitamin D status, vitamin D intake, and risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) severity. Take

25 (OH) Vitamin D Levels of Patients with COVID-19 are not Associated with the Length of Hospital Stay.

25 (OH) Vitamin D Levels  of Patients with COVID-19 are not Associated with the Length of Hospital Stay. Take Home Message No statistically significant relationship was

Patients with COVID-19 pneumonia with 25(OH)D levels lower than 12 ng/ml are at increased risk of death

Patients with COVID-19 pneumonia with 25(OH)D levels lower than 12 ng/ml are at  increased risk of death. Take Home Message Serum level of 25(OH) D is an

Ongoing Studies

Explore current trials being conducted around the world focused on vitamin D and COVID-19.

Title Status Conditions Interventions Location
Severity of COVID-19 and Vitamin D Supplementation Active, not recruiting
  • COVID-19 Respiratory Infection
  • Drug: vitamin D
  • Almazov National Medical Research Centre, of the Ministry of Health of the Russian Federation
    Saint Petersburg, Russian Federation
Vitamin D Supplementation and Clinical Outcomes in Severe COVID-19 Patients Active, not recruiting
  • COVID-19
  • Respiratory Distress Syndrome
  • Vitamin D Deficiency
  • Dietary Supplement: cholecalciferol
  • University Hospital Split
    Split, Croatia
Vit D3 for Early Symptoms of COVID-19 Not yet recruiting
  • COVID-19
  • Drug: Standard of care
  • Dietary Supplement: Vitamin D3
  • Ayub Teaching Hospital
    Abbottabad, Khyber Pakhtunkhwa, Pakistan
The Efficacy of Nigella Sativa Versus VitaminD3 as Supplement Therapy in Coronavirus Disease 2019 (COVID-19) Recruiting
  • COVID-19
  • Dietary Supplement: Nigella Sativa capsule twice daily
  • Respiratory System specialized hospital at Kobry Elobba Military Medical hospitals.
    Cairo, Egypt
Low vs. Moderate to High Dose Vitamin D for Prevention of COVID-19 Recruiting
  • SARS-CoV-2 Infection
  • Dietary Supplement: Vitamin D3
  • Rush University Medical Center
    Chicago, Illinois, United States
  • University of Chicago
    Chicago, Illinois, United States
Vitamin D Supplementation in Pregnant Women at Risk and COVID-19 Not yet recruiting
  • Pregnancy Complications
  • COVID-19
  • Dietary Supplement: Vitamin D supplementation in pregnant women
  • Maria Jose Aguilar Cordero
    Granada, Spain
Baseline Vitamin D Deficiency and COVID-19 Disease Severity Recruiting
  • Vitamin D Deficiency
  • COVID-19
  • Other: Vitamin D
  • Parkview Medical Center
    Pueblo, Colorado, United States
Vitamin D3 Supplementation to Prevent Respiratory Tract Infections Active, not recruiting
  • Respiratory Tract Infections
  • COVID-19
  • Flu Like Illness
  • Dietary Supplement: Vitamin D supplementation
  • Cooper University Hospital
    Camden, New Jersey, United States
Vitamin D for COVID-19 Trial Active, not recruiting
  • COVID-19
  • Dietary Supplement: vitamin D
  • Dietary Supplement: Placebo
  • Brigham and Women’s Hospital
    Boston, Massachusetts, United States
High Dose Vitamin-D Substitution in Patients With COVID-19: a Randomized Controlled, Multi Center Study Active, not recruiting
  • COVID-19
  • Vitamin D Deficiency
  • Corona Virus Infection
  • (and 3 more…)
  • Drug: Single high dose vitamin D
  • Drug: Placebo
  • Drug: Treatment as usual vitamin D
  • Cantonal Hospital Baselland Liestal
    Liestal, BL, Switzerland
  • Cantonal Hospital St. Gallen
    Saint Gallen, SG, Switzerland
Vitamin D Supplementation in the Prevention and Mitigation of COVID-19 Infection Recruiting
  • COVID-19
  • Vitamin D Deficiency
  • Respiratory Viral Infection
  • Drug: Daily Vitamin D3
  • Drug: Daily placebo
  • Drug: Bolus vitamin D3
  • Drug: Bolus placebo
  • Medical University of South Carolina
    Charleston, South Carolina, United States
Vitamin D and COVID-19 Management Recruiting
  • COVID-19
  • Dietary Supplement: Ddrops® products, 50,000 IU, Oral
  • Dietary Supplement: Vitamin D3
  • University of Alberta
    Edmonton, Alberta, Canada
The VITDALIZE Study: Effect of High-dose Vitamin D3 on 28-day Mortality in Adult Critically Ill Patients Recruiting
  • Critical Illness
  • Vitamin D Deficiency
  • COVID-19
  • Drug: Cholecalciferol
  • Drug: Placebo
  • LKH Hochsteiermark Standort Bruck
    Bruck An Der Mur, Austria
  • LKH Enzenbach
    Enzenbach, Austria
  • LKH Feldbach
    Feldbach, Austria
  • (and 17 more…)

Impact of COVID-19 Vaccination on Serum 25-hydroxyvitamin D Level

 Recruiting
  • Acne Vulgaris
  • Vitamin D Deficiency
  • COVID-19
  • Diagnostic Test: Blood test and skin evaluation
  • Department of Dermatology, National Taiwan University Hospital, Taipei, Taiwan
Vitamin D Supplementation and Clinical Outcomes in Severe COVID-19 Patients Active, not recruiting •COVID-19
•Respiratory Distress Syndrome
•Vitamin D Deficiency		 •Dietary Supplement: cholecalciferol •University Hospital Split, Split, Croatia
Pilot Study of Vitamin K2 (MK-7) and Vitamin D3 Supplementation and the Effects on PASC Symptomatology and Inflammatory Biomarkers Recruiting •Post-acute COVID-19 Syndrome •Dietary Supplement: Vitamin K2 (MK-7)
•Dietary Supplement: Vitamin D3
  • University Hospitals Cleveland Medical Center, Cleveland, Ohio, United States
Long COVID Comorbidities: Endocrine, Metabolic, Neuropsychiatric, Muscle, Cardiovascular, Pulmonary, Dermatologic Dysfunctions Recruiting •Long COVID-19 •Diagnostic Test: Assessments of endocrinological phenotypes of LO-COCO patients

•Diagnostic Test: Assessment of muscular phenotypes of LO-COCO patients

•Diagnostic Test: Assessment of
neuropsychiatric phenotypes of LO-COCO patients

•Procedure: Muscle biopsy

•Diagnostic Test: Assessment of pulmonary phenotypes of LO-COCO patients

•Diagnostic Test: Assessment of
cardiological phenotypes of LO-COCO patients

•Diagnostic Test: Assessment of vascular phenotypes of LO-COCO patients

•Diagnostic Test: Assessment of
dermatological phenotypes of LO-COCO patients

•Procedure: Tissue biopsy

 •Federico II University of Naples, Naples, Italy
Severity of COVID-19 and Vitamin D Supplementation Active, not recruiting •COVID-19 Respiratory Infection •Drug: vitamin D •Almazov National Medical Research Centre, of the Ministry of
Health of the Russian Federation, Saint Petersburg, Russian
Federation
Vit D3 for Early Symptoms of COVID-19 Not yet recruiting •COVID-19 •Drug: Standard of care
•Dietary Supplement: Vitamin D3		 •Ayub Teaching Hospital, Abbottabad, Khyber Pakhtunkhwa,
Pakistan
The Efficacy of Nigella Sativa Versus Vitamin D3 as Supplement Therapy in Coronavirus Disease 2019 (COVID-19) Recruiting •COVID-19 •Dietary Supplement: Nigella Sativa capsule twice daily •Respiratory System specialized hospital at Kobry Elobba Military
Medical hospitals., Cairo, Egypt
Low vs. Moderate to High Dose Vitamin D for Prevention of COVID-19 Recruiting •SARS-CoV-2 Infection •Dietary Supplement: Vitamin D3 •Rush University Medical Center, Chicago, Illinois, United States
•University of Chicago, Chicago, Illinois, United States
The Effects of a Multi-factorial Rehabilitation Program for Healthcare Workers Suffering From Post-COVID-19 Fatigue Syndrome Completed •COVID-19 •Other: Exercise •Medical University of Vienna, Vienna, Austria
Vitamin D Supplementation in Pregnant Women at Risk and COVID-19 Not yet recruiting •Pregnancy Complications
•COVID-19		 •Dietary Supplement: Vitamin D
supplementation in pregnant women		 •Maria Jose Aguilar Cordero, Granada, Spain
Magnesium and Vitamin D Combination for Post-COVID Syndrome Not yet recruiting
  • Post-COVID-19 Syndrome
  • Long COVID
  • Vitamin D Deficiency
  • Magnesium Deficiency
  • Dietary Supplement: Magnesium chloride
  • Dietary Supplement: Vitamin D
  • Dietary Supplement: Inert placebo
 •Biomedical Research Unit, Durango, Dgo, Mexico
Baseline Vitamin D Deficiency and COVID-19 Disease Severity Recruiting •Vitamin D Deficiency
•COVID-19		 •Other: Vitamin D •Parkview Medical Center, Pueblo, Colorado, United States
Vitamin D3 Supplementation to Prevent Respiratory Tract Infections Active, not recruiting  •Respiratory Tract Infections
•COVID-19
•Flu Like Illness		 •Dietary Supplement: Vitamin D
supplementation		 •Cooper University Hospital, Camden, New Jersey, United States
Vitamin D for COVID-19 Trial Active, not recruiting •COVID-19 •Dietary Supplement: vitamin D
•Dietary Supplement: Placebo		 •Brigham and Women’s Hospital, Boston, Massachusetts, United
States
High Dose Vitamin D Substitution in Patients With COVID-19: a Randomized, Controlled, Multi Center Study Active, not recruiting •COVID-19
•Vitamin D Deficiency
•Corona Virus Infection
•ARDS
•Coronavirus
•SARS-CoV Infection		 •Drug: Single high dose vitamin D
•Drug: Placebo
•Drug: Treatment as usual vitamin D		 •Cantonal Hospital Baselland Liestal, Liestal, BL, Switzerland
•Cantonal Hospital St. Gallen, Saint Gallen, SG, Switzerland
Vitamin D Supplementation in the Prevention and Mitigation of COVID-19 Infection Recruiting •COVID-19
•Vitamin D Deficiency
•Respiratory Viral Infection		 •Drug: Daily Vitamin D3
•Drug: Daily placebo
•Drug: Bolus vitamin D3
•Drug: Bolus placebo		 •Medical Univjuersity of South Carolina, Charleston, South Carolina, United States
Vitamin D and COVID-19 Management Recruiting •COVID-19 •Dietary Supplement: Ddrops® products,
50,000 IU, Oral
•Dietary Supplement: Vitamin D3		 •University of Alberta, Edmonton, Alberta, Canada
The VITDALIZE Study: Effect of High-dose Vitamin D3 on 28-day Mortality in Adult Critically Ill Patients Recruiting  •Critical Illness
•Vitamin D Deficiency
•COVID-19		 •Drug: Cholecalciferol
•Drug: Placebo		 •LKH Hochsteiermark Standort Bruck, Bruck An Der Mur, Austria
•LKH Enzenbach, Enzenbach, Austria
•LKH Feldbach, Feldbach, Austria
•LKH Fürstenfeld, Fürstenfeld, Austria
•Medical University of Graz, Graz, Austria
•Medical University Innsbruck, Innsbruck, Austria
•Klinikum am Wörthersee, Klagenfurt, Austria
•LKH Hochsteiermark Standort Leoben, Leoben, Austria
•Barmherzige Brüder Konventhospital Linz, Linz, Austria
•Barmherzige Schwestern, Linz, Austria
•and 10 more

The Importance of Vitamin D

What percentage of Americans are vitamin D deficient or insufficient?

The prevalence of vitamin D deficiency was found to be 28.9% and vitamin D insufficiency 41% in a subset of 26,010 US adults surveyed as part of the ongoing National Health and Nutrition Examination Survey (NHANES) 2001-2010.1 Vitamin D deficiency is a major health concern because it has been linked to depression, fatigue, muscle aches, increased risk of respiratory infections, autoimmune disorders, osteoporosis, osteomalacia, osteoarthritis, increased risk of infection and some cancers. Vitamin D insufficiency has been associated with reduced calcium absorption, decreased bone density, potential mild decrease of the blood calcium level, accelerated bone resorption, an increased risk of falls, and potentially fractures. Vitamin D deficiency and insufficiency can seriously affect a person’s quality of life.2,3,4

How is vitamin D different than other vitamins?

Unlike other vitamins, vitamin D is a prohormone. Dietary vitamin D first goes to the liver then the kidney converts it to its active form and distributes the active form throughout the body, which by definition makes vitamin D a “hormone-like” vitamin. Meaning it is synthesized and released from an endocrine organ, the kidneys. Vitamin D receptors are located throughout the body and explain why vitamin D is important for so many aspects of health.8

Who is more at risk of vitamin D deficiency or insufficiency?

In the U.S. seniors, South Asians, Hispanics and non-Hispanic Blacks are groups that have a higher prevalence of low vitamin D levels. Other situations that may lead to vitamin D deficiency or insufficiency include limited sun exposure, fat malabsorption conditions (such as celiac disease), and obesity. 5,6,7

What is the importance of vitamin D in the body?

Vitamin D was first known for its role in bone health and plays a key role in the metabolism, or cellular processes, of calcium and phosphorus, which are needed for bone integrity. Vitamin D has many other important functions too. It plays a key role in the immune system, oral health, muscle health and strength. It plays an important role in regulating gene transcription and promoting protein synthesis. All of these critical roles make vitamin D important for multiple aspects of human health. 9
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  1. Liu X, Baylin A, Levy PD. Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications. British Journal of Nutrition. 2018;119(8):928-936.
  2. Holick MF. The vitamin D deficiency pandemic: a forgotten hormone important for health. Public health reviews. 2010;32(1):267-283.
  3. Amrein K, Scherkl M, Hoffmann M, et al. Vitamin D deficiency 2.0: an update on the current status worldwide. European journal of clinical nutrition. 2020;74(11):1498-1513.
  4. MacLaughlin J, Holick MF. Aging decreases the capacity of human skin to produce vitamin D3. J Clin Invest. 1985;76(4):1536-1538.)
  5. Kweder H, Eidi H. Vitamin D deficiency in elderly: Risk factors and drugs impact on vitamin D status. Avicenna J Med. 2018;8(4):139-146. doi:10.4103/ajm.AJM_20_18). 3. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/#h5
  6. Emmanuel M. K. Awumey, Devashis A. Mitra, Bruce W. Hollis, Rajiv Kumar, Norman H. Bell, Vitamin D Metabolism Is Altered in Asian Indians in the Southern United States: A Clinical Research Center Study, The Journal of Clinical Endocrinology & Metabolism. 1998; 83(1): 169–173, https://doi.org/10.1210/jcem.83.1.4514
  7. Castro JP, Penckofer S. The role of vitamin D in the health of Hispanic adults with diabetes. Hisp Health Care Int. 2014;12(2):90-8. doi: 10.1891/1540-4153.12.2.90. PMID: 24871915.
  8. Sassi F, Tamone C, D’Amelio P. Vitamin D: nutrient, hormone, and immunomodulator. Nutrients. 2018;10(11):1656.
  9. Hewlings SJ, Medeiros DM. Nutrition: Real People, Real Choices. Pearson Prentice Hall; 2009.
  10. Elliott ME, Binkley NC, Carnes M, Zimmerman DR, Petersen K, Knapp K, Behlke JM, Ahmann N, Kieser MA. Fracture risks for women in long-term care: high prevalence of calcaneal osteoporosis and hypovitaminosis D. Pharmacotherapy. 2003; Jun;23(6):702-10.
  11. Nair R, Maseeh A. Vitamin D: The “sunshine” vitamin. J Pharmacol Pharmacother. 2012; Apr;3(2):118-26.
  12. Bilezikian JP, Bikle D, Hewison M, et al.Mechanisms in Endocrinology: Vitamin D and COVID-19. European Journal of Endocrinology. 2020;183(5):R133-r147.
  13. van Etten E, Mathieu C. Immunoregulation by 1,25-dihydroxyvitamin D3: basic concepts. The Journal of steroid biochemistry and molecular biology. 2005;97(1-2):93-101.
  14. Ginde AA, Mansbach JM, Camargo CA, Jr. Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Archives of internal medicine. 2009;169(4):384-390.
  15. A Kempker, J., & S Martin, G. Vitamin D and sepsis: from associations to causal connections. Inflammation & Allergy-Drug Targets (Formerly Current Drug Targets-Inflammation & Allergy) (Discontinued). 2013; 12(4): 246-252.
  16. Zdrenghea, M. T., Makrinioti, H., Bagacean, C., Bush, A., Johnston, S. L., and Stanciu, L. A. Vitamin D modulation of innate immune responses to respiratory viral infections, Rev Med Virol. 2017; 27:e1909. doi: 10.1002/rmv.1909.
  17. Vetter V, Denizer G, Friedland LR, Krishnan J, Shapiro M. Understanding modern-day vaccines: what you need to know. Annals of medicine. 2018;50(2):110-120.
  18. Cannell JJ, Vieth R, Umhau JC, et al. Epidemic influenza and vitamin D. Epidemiology and infection. 2006;134(6):1129-1140.
  19. Martineau A R, Jolliffe D A, Hooper R L, Greenberg L, Aloia J F, Bergman P et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data BMJ. 2017; (356):i6583 doi:10.1136/bmj.i6583.
  20. Zabetakis I, Lordan R, Norton C, Tsoupras A. COVID-19: The Inflammation Link and the Role of Nutrition in Potential Mitigation. Nutrients. 2020 May 19;12(5):1466. doi: 10.3390/nu12051466. PMID: 32438620; PMCID: PMC7284818.
  21. Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. The Journal of clinical endocrinology and metabolism. 2011;96(1):53-58.
  22. Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr. 2003;77(1):204-210.
  23. Rosen CJ, Abrams SA, Aloia JF, Brannon PM, Clinton SK, Durazo-Arvizu RA, et al. IOM committee members respond to Endocrine Society vitamin D guidelines. J Clin Endocrinol Metab. 2012;97:1146-52.
  24. MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2011;96:1911-30.
  25. Amrein K, Scherkl M, Hoffmann M, et al. Vitamin D deficiency 2.0: an update on the current status worldwide. European journal of clinical nutrition. 2020;74(11):1498-1513.

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