{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:13:47Z","timestamp":1768868027069,"version":"3.49.0"},"reference-count":87,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2024,12,31]],"date-time":"2024-12-31T00:00:00Z","timestamp":1735603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background: Studies have shown a high prevalence of vitamin D deficiency in critically ill patients, and these patients are at higher risk for pneumonia and have increased incidence of sepsis and mortality. In this study, we reviewed available literature from randomized controlled trials (RCTs) on vitamin D supplementation in critically ill patients and summarized the evidence in this narrative review. Methods: Randomized controlled trials that included vitamin D supplementation as an intervention were eligible for inclusion. No limits were set regarding vitamin D dosage or route of administration, as well as for primary and secondary outcomes. A search was conducted in MEDLINE via PubMed for eligible RCTs. References from systematic reviews (SRs) and meta-analyses (MAs) were screened, and Clinicaltrials.gov was searched for ongoing studies. Results: A total of 21 RCTs involving 3166 patients were analyzed. There was a large heterogeneity in terms of patients\u2019 characteristics and inclusion criteria. Only six studies included patients with vitamin D levels &lt; 50 nmol\/L. Regarding clinically important outcomes, most of the studies did not show differences between the intervention and control group in terms of mortality, intensive care unit (ICU) or hospital length of stay (LoS). Conclusions: There is great variability in trial designs regarding the selection of patients, dosage, dosing intervals and routes of administration of vitamin D supplements. Better study designs are mandatory for future clinical research, with measuring and reporting basal vitamin D levels before randomization. Since variability in supplementation regimes limits the possibility of data synthesis, standardized protocols for vitamin D supplementation should be used in clinical trial settings.<\/jats:p>","DOI":"10.3390\/nu17010156","type":"journal-article","created":{"date-parts":[[2024,12,31]],"date-time":"2024-12-31T10:17:40Z","timestamp":1735640260000},"page":"156","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Vitamin D Supplementation in Critically Ill\u2014Narrative Review"],"prefix":"10.3390","volume":"17","author":[{"given":"Lenko","family":"Saric","sequence":"first","affiliation":[{"name":"Department of Anesthesiology, Reanimatology and Intensive Care, University Hospital Split, 21000 Split, Croatia"},{"name":"University Department of Health Studies, University of Split, 21000 Split, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5889-0478","authenticated-orcid":false,"given":"Josipa","family":"Domazet Bugarin","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology, Reanimatology and Intensive Care, University Hospital Split, 21000 Split, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Svjetlana","family":"Dosenovic","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology, Reanimatology and Intensive Care, University Hospital Split, 21000 Split, Croatia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,12,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1912","DOI":"10.1056\/NEJMc0809996","article-title":"Vitamin D deficiency in critically ill patients","volume":"360","author":"Lee","year":"2009","journal-title":"N. Engl. J. Med."},{"key":"ref_2","first-page":"275","article-title":"Vitamin D deficiency in the ICU: A systematic review","volume":"39","author":"Zajic","year":"2014","journal-title":"Minerva Endocrinol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"671","DOI":"10.1097\/CCM.0b013e318206ccdf","article-title":"Association of low serum 25-hydroxyvitamin D levels and mortality in the critically ill","volume":"39","author":"Braun","year":"2011","journal-title":"Crit. Care Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"273","DOI":"10.2174\/18715281113129990047","article-title":"Efficacy of high-dose vitamin D supplementation in the critically ill patients","volume":"12","author":"Perron","year":"2013","journal-title":"Inflamm. Allergy Drug Targets"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"769","DOI":"10.1016\/j.beem.2011.03.001","article-title":"Vitamin D metabolism and deficiency in critical illness","volume":"25","author":"Lee","year":"2011","journal-title":"Best Pract. Res. Clin. Endocrinol. Metab."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3170","DOI":"10.1097\/CCM.0b013e318260c928","article-title":"Association of low serum 25-hydroxyvitamin D levels and acute kidney injury in the critically ill","volume":"40","author":"Braun","year":"2012","journal-title":"Crit. Care Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"660","DOI":"10.1186\/s13054-014-0660-4","article-title":"Vitamin D deficiency as a risk factor for infection, sepsis and mortality in the critically ill: Systematic review and meta-analysis","volume":"18","author":"Groeneveld","year":"2014","journal-title":"Crit. Care"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"253","DOI":"10.2174\/18715281113129990049","article-title":"Vitamin D deficiency and acute lung injury","volume":"12","author":"Parekh","year":"2013","journal-title":"Inflamm. Allergy Drug Targets"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1056\/NEJMra070553","article-title":"Vitamin D deficiency","volume":"357","author":"Holick","year":"2007","journal-title":"N. Engl. J. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e17252","DOI":"10.1097\/MD.0000000000017252","article-title":"The association between vitamin D deficiency and community-acquired pneumonia: A meta-analysis of observational studies","volume":"98","author":"Zhou","year":"2019","journal-title":"Medicine"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1109","DOI":"10.1210\/er.2018-00126","article-title":"Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions","volume":"40","author":"Bouillon","year":"2019","journal-title":"Endocr. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e003176","DOI":"10.1136\/bmjgh-2020-003176","article-title":"Effect of micronutrient supplements on influenza and other respiratory tract infections among adults: A systematic review and meta-analysis","volume":"6","author":"Abioye","year":"2021","journal-title":"BMJ Glob. Health"},{"key":"ref_13","first-page":"548","article-title":"Effect of Oral Versus Intramuscular Vitamin D Replacement on Oxidative Stress and Outcomes in Traumatic Mechanical Ventilated Patients Admitted to Intensive Care Unit","volume":"35","author":"Hasanloei","year":"2020","journal-title":"Nutr. Clin. Pract. Off. Publ. Am. Soc. Parenter. Enter. Nutr."},{"key":"ref_14","first-page":"4048","article-title":"Editorial\u2014Vitamin D status: A key modulator of innate immunity and natural defense from acute viral respiratory infections","volume":"24","author":"Fabbri","year":"2020","journal-title":"Eur. Rev. Med. Pharmacol. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2335","DOI":"10.1007\/s00198-014-2734-1","article-title":"The association between critical illness and changes in bone turnover in adults: A systematic review","volume":"25","author":"Orford","year":"2014","journal-title":"Osteoporos. Int."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1186\/s13054-017-1657-6","article-title":"The association of time and medications with changes in bone mineral density in the 2 years after critical illness","volume":"21","author":"Orford","year":"2017","journal-title":"Crit. Care"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"282","DOI":"10.1097\/CCM.0000000000002095","article-title":"Vitamin D Deficiency in Human and Murine Sepsis","volume":"45","author":"Parekh","year":"2017","journal-title":"Crit. Care Med."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1017\/S0029665111001650","article-title":"Vitamin D and immune function: An overview","volume":"71","author":"Hewison","year":"2012","journal-title":"Proc. Nutr. Soc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1210\/er.2012-1012","article-title":"The roles of vitamin D in skeletal muscle: Form, function, and metabolism","volume":"34","author":"Girgis","year":"2013","journal-title":"Endocr. Rev."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"864370","DOI":"10.1155\/2015\/864370","article-title":"Optimal Vitamin D Supplementation Levels for Cardiovascular Disease Protection","volume":"2015","author":"Lugg","year":"2015","journal-title":"Dis. Markers"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1136\/thoraxjnl-2014-206680","article-title":"Vitamin D deficiency contributes directly to the acute respiratory distress syndrome (ARDS)","volume":"70","author":"Dancer","year":"2015","journal-title":"Thorax"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1097\/MCC.0000000000000849","article-title":"Vitamin D in critical care: Where are we now and what is next?","volume":"27","author":"Amrein","year":"2021","journal-title":"Curr. Opin. Crit. Care"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1016\/j.nut.2018.11.001","article-title":"Vitamin D in the ICU: More sun for critically ill adult patients?","volume":"61","author":"Langlois","year":"2019","journal-title":"Nutrition"},{"key":"ref_24","first-page":"1242","article-title":"Treatment With 25-Hydroxyvitamin D3 (Calcifediol) Is Associated With a Reduction in the Blood Neutrophil-to-Lymphocyte Ratio Marker of Disease Severity in Hospitalized Patients With COVID-19: A Pilot Multicenter, Randomized, Placebo-Controlled, Double-Blinded Clinical Trial","volume":"27","author":"Maghbooli","year":"2021","journal-title":"Endocr. Pract. Off. J. Am. Coll. Endocrinol. Am. Assoc. Clin. Endocrinol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"102230","DOI":"10.1016\/j.dsx.2021.102230","article-title":"Spurious undermining of the adjuvant role of vitamin D in COVID-19","volume":"15","author":"Pal","year":"2021","journal-title":"Diabetes Metab. Syndr."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1007\/s40618-021-01614-4","article-title":"Vitamin D supplementation and clinical outcomes in COVID-19: A systematic review and meta-analysis","volume":"45","author":"Pal","year":"2021","journal-title":"J. Endocrinol. Investig."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1097\/MCO.0000000000000147","article-title":"Vitamin D supplementation in the ICU patient","volume":"18","author":"Christopher","year":"2015","journal-title":"Curr. Opin. Clin. Nutr. Metab. Care"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Lan, S.H., Lai, C.C., Chang, S.P., Lu, L.C., Hung, S.H., and Lin, W.T. (2020). Vitamin D supplementation and the outcomes of critically ill adult patients: A systematic review and meta-analysis of randomized controlled trials. Sci. Rep., 10.","DOI":"10.1038\/s41598-020-71271-9"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1053","DOI":"10.1001\/jama.2020.26848","article-title":"Effect of a Single High Dose of Vitamin D3 on Hospital Length of Stay in Patients with Moderate to Severe COVID-19: A Randomized Clinical Trial","volume":"325","author":"Murai","year":"2021","journal-title":"JAMA"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.jcrc.2016.10.029","article-title":"Vitamin D and outcomes in adult critically ill patients. A systematic review and meta-analysis of randomized trials","volume":"38","author":"Putzu","year":"2017","journal-title":"J. Crit. Care"},{"key":"ref_31","first-page":"CD015043","article-title":"Vitamin D supplementation for the treatment of COVID-19: A living systematic review","volume":"5","author":"Stroehlein","year":"2021","journal-title":"Cochrane Database Syst. Rev."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1210\/jc.2010-2704","article-title":"The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: What clinicians need to know","volume":"96","author":"Ross","year":"2011","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1911","DOI":"10.1210\/jc.2011-0385","article-title":"Evaluation, treatment, and prevention of vitamin D deficiency: An Endocrine Society clinical practice guideline","volume":"96","author":"Holick","year":"2011","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"939","DOI":"10.1017\/S1368980011000590","article-title":"The IOM D-lemma","volume":"14","author":"Holick","year":"2011","journal-title":"Public Health Nutr."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1017","DOI":"10.1038\/s41591-020-0968-3","article-title":"Extrapulmonary manifestations of COVID-19","volume":"26","author":"Gupta","year":"2020","journal-title":"Nat. Med."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1002\/ehf2.13136","article-title":"Myocardial injury in severe COVID-19 is similar to pneumonias of other origin: Results from a multicentre study","volume":"8","author":"Jirak","year":"2021","journal-title":"ESC Heart Fail."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1186\/s13054-022-04139-1","article-title":"Administration of vitamin D and its metabolites in critically ill adult patients: An updated systematic review with meta-analysis of randomized controlled trials","volume":"26","author":"Menger","year":"2022","journal-title":"Crit. Care"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1238","DOI":"10.1016\/j.clnu.2017.05.006","article-title":"Vitamin D supplementation in the critically ill: A systematic review and meta-analysis","volume":"37","author":"Langlois","year":"2018","journal-title":"Clin. Nutr."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"853","DOI":"10.5005\/jp-journals-10071-24260","article-title":"Does Vitamin D Improve All-cause Mortality in Critically Ill Adults? An Updated Systematic Review and Meta-analysis of Randomized Controlled Trials","volume":"26","author":"Kaur","year":"2022","journal-title":"Indian J. Crit. Care Med."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Peng, L., Li, L., Wang, P., Chong, W., Li, Y., Zha, X., Deng, H., Fan, H., and Zhang, Y. (2020). Association between Vitamin D supplementation and mortality in critically ill patients: A systematic review and meta-analysis of randomized clinical trials. PLoS ONE, 15.","DOI":"10.1371\/journal.pone.0243768"},{"key":"ref_41","doi-asserted-by":"crossref","unstructured":"Gao, Z., Xie, J., Li, C., Liu, L., and Yang, Y. (2022). High Dose Vitamin D3 Supplementation Is Not Associated with Lower Mortality in Critically Ill Patients: A Meta-Analysis of Randomized Control Trials. Front. Nutr., 9.","DOI":"10.3389\/fnut.2022.762316"},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Cao, M., He, C., Gong, M., Wu, S., and He, J. (2023). The effects of vitamin D on all-cause mortality in different diseases: An evidence-map and umbrella review of 116 randomized controlled trials. Front. Nutr., 10.","DOI":"10.3389\/fnut.2023.1132528"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Shen, H., Mei, Y., Zhang, K., and Xu, X. (2021). The Effect of Vitamin D Supplementation on Clinical Outcomes for Critically Ill Patients: A Systemic Review and Meta-Analysis of Randomized Clinical Trials. Front. Nutr., 8.","DOI":"10.3389\/fnut.2021.664940"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"909","DOI":"10.1016\/j.chest.2021.03.046","article-title":"Effect of Early High-Dose Vitamin D3 Repletion on Cognitive Outcomes in Critically Ill Adults","volume":"160","author":"Han","year":"2021","journal-title":"Chest"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1007\/s40261-020-00896-5","article-title":"Neuroprotective Role of Oral Vitamin D Supplementation on Consciousness and Inflammatory Biomarkers in Determining Severity Outcome in Acute Traumatic Brain Injury Patients: A Double-Blind Randomized Clinical Trial","volume":"40","author":"Sharma","year":"2020","journal-title":"Clin. Drug Investig."},{"key":"ref_46","first-page":"59","article-title":"High Dose Vitamin D Administration in Ventilated Intensive Care Unit Patients: A Pilot Double Blind Randomized Controlled Trial","volume":"4","author":"Han","year":"2016","journal-title":"J. Clin. Transl. Endocrinol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"4623","DOI":"10.1210\/jc.2003-030358","article-title":"Bone turnover in prolonged critical illness: Effect of vitamin D","volume":"88","author":"Vanhove","year":"2003","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2529","DOI":"10.1056\/NEJMoa1911124","article-title":"Early High-Dose Vitamin D(3) for Critically Ill, Vitamin D-Deficient Patients","volume":"381","author":"Ginde","year":"2019","journal-title":"N. Engl. J. Med."},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Bychinin, M.V., Klypa, T.V., Mandel, I.A., Yusubalieva, G.M., Baklaushev, V.P., Kolyshkina, N.A., and Troitsky, A.V. (2022). Effect of vitamin D3 supplementation on cellular immunity and inflammatory markers in COVID-19 patients admitted to the ICU. Sci. Rep., 12.","DOI":"10.1038\/s41598-022-22045-y"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1520","DOI":"10.1001\/jama.2014.13204","article-title":"Effect of high-dose vitamin D3 on hospital length of stay in critically ill patients with vitamin D deficiency: The VITdAL-ICU randomized clinical trial","volume":"312","author":"Amrein","year":"2014","journal-title":"JAMA"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1164\/rccm.201405-0988OC","article-title":"Randomized controlled trial of calcitriol in severe sepsis","volume":"190","author":"Leaf","year":"2014","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_52","first-page":"1254","article-title":"Effect of Vitamin D Supplementation on Procalcitonin as Prognostic Biomarker in Patients with Ventilator Associated Pneumonia Complicated with Vitamin D Deficiency","volume":"16","author":"Miroliaee","year":"2017","journal-title":"Iran. J. Pharm. Res."},{"key":"ref_53","first-page":"1067","article-title":"Effect of High-Dose Vitamin D on Duration of Mechanical Ventilation in ICU Patients","volume":"18","author":"Miri","year":"2019","journal-title":"Iran. J. Pharm. Res."},{"key":"ref_54","first-page":"1147","article-title":"Effect of Early Administration of Vitamin D on Clinical Outcome in Critically Ill Sepsis Patients: A Randomized Placebo-controlled Trial","volume":"25","author":"Bhattacharyya","year":"2021","journal-title":"Indian J. Crit. Care Med."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"em133","DOI":"10.29333\/ejgm\/94224","article-title":"Vitamin D supplements\u2019 effect on expediting the weaning process in patients with the stroke","volume":"16","author":"Yousefian","year":"2019","journal-title":"Electron. J. Gen. Med."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"1219","DOI":"10.1016\/j.nut.2015.03.008","article-title":"Dose-response effect of ergocalciferol therapy on serum 25-hydroxyvitamin D concentration during critical illness","volume":"31","author":"Dickerson","year":"2015","journal-title":"Nutrition"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"101271","DOI":"10.1016\/j.eujim.2020.101271","article-title":"High dose vitamin D improves total serum antioxidant capacity and ICU outcome in critically ill patients\u2014A randomized, double-blind clinical trial","volume":"42","author":"Sistanizad","year":"2021","journal-title":"Eur. J. Integr. Med."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"1103","DOI":"10.3171\/2018.11.JNS182713","article-title":"The effect of supplementation of vitamin D in neurocritical care patients: RandomizEd Clinical TrIal oF hYpovitaminosis D (RECTIFY)","volume":"133","author":"Karsy","year":"2019","journal-title":"J. Neurosurg."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"R104","DOI":"10.1186\/cc10120","article-title":"Short-term effects of high-dose oral vitamin D3 in critically ill vitamin D deficient patients: A randomized, double-blind, placebo-controlled pilot study","volume":"15","author":"Amrein","year":"2011","journal-title":"Crit. Care"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"396","DOI":"10.1111\/ijcp.12795","article-title":"Effect of vitamin D on stress-induced hyperglycaemia and insulin resistance in critically ill patients","volume":"70","author":"Alizadeh","year":"2016","journal-title":"Int. J. Clin. Pract."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"1928","DOI":"10.1097\/CCM.0000000000001148","article-title":"Effect of Cholecalciferol Supplementation on Vitamin D Status and Cathelicidin Levels in Sepsis: A Randomized, Placebo-Controlled Trial","volume":"43","author":"Quraishi","year":"2015","journal-title":"Crit. Care Med."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1177\/0148607116678197","article-title":"High-Dose Vitamin D(3) Administration Is Associated with Increases in Hemoglobin Concentrations in Mechanically Ventilated Critically Ill Adults: A Pilot Double-Blind, Randomized, Placebo-Controlled Trial","volume":"42","author":"Smith","year":"2018","journal-title":"J. Parenter. Enter. Nutr."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/j.nut.2017.02.002","article-title":"Impact of high-dose vitamin D(3) on plasma free 25-hydroxyvitamin D concentrations and antimicrobial peptides in critically ill mechanically ventilated adults","volume":"38","author":"Han","year":"2017","journal-title":"Nutrition"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"2313","DOI":"10.1097\/CCM.0000000000001201","article-title":"A Randomized Study of a Single Dose of Intramuscular Cholecalciferol in Critically Ill Adults","volume":"43","author":"Nair","year":"2015","journal-title":"Crit. Care Med."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"744","DOI":"10.1038\/s41430-017-0047-0","article-title":"Oxidative stress in critically ill ventilated adults: Effects of vitamin D(3) and associations with alveolar macrophage function","volume":"72","author":"Han","year":"2018","journal-title":"Eur. J. Clin. Nutr."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1055\/a-1114-6072","article-title":"Effect of Intravenous 25OHD Supplementation on Bone Turnover and Inflammation in Prolonged Critically Ill Patients","volume":"52","author":"Ingels","year":"2020","journal-title":"Horm. Metab. Res."},{"key":"ref_67","first-page":"121","article-title":"Guidelines for the prevention, detection and therapy of vitamin D deficiency in adults","volume":"138","author":"Vrdoljak","year":"2016","journal-title":"Lije\u010d. Vjesn."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.3945\/jn.115.227728","article-title":"National Estimates of Serum Total 25-Hydroxyvitamin D and Metabolite Concentrations Measured by Liquid Chromatography-Tandem Mass Spectrometry in the US Population during 2007\u20132010","volume":"146","author":"Schleicher","year":"2016","journal-title":"J. Nutr."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"1033","DOI":"10.3945\/ajcn.115.120873","article-title":"Vitamin D deficiency in Europe: Pandemic?","volume":"103","author":"Cashman","year":"2016","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"R47","DOI":"10.1186\/cc13790","article-title":"Vitamin D status and its association with season, hospital and sepsis mortality in critical illness","volume":"18","author":"Amrein","year":"2014","journal-title":"Crit. Care"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1017\/S0954422421000251","article-title":"Vitamin D and acute and severe illness\u2014A mechanistic and pharmacokinetic perspective","volume":"36","author":"Schoenmakers","year":"2023","journal-title":"Nutr. Res. Rev."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"V64","DOI":"10.1359\/jbmr.07s221","article-title":"Vitamin D toxicity, policy, and science","volume":"22","author":"Vieth","year":"2007","journal-title":"J. Bone Miner. Res."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1111\/nure.12090","article-title":"Guidelines for optimizing design and analysis of clinical studies of nutrient effects","volume":"72","author":"Heaney","year":"2014","journal-title":"Nutr. Rev."},{"key":"ref_74","doi-asserted-by":"crossref","unstructured":"Pludowski, P. (2023). Supplementing Vitamin D in Different Patient Groups to Reduce Deficiency. Nutrients, 15.","DOI":"10.3390\/nu15173725"},{"key":"ref_75","first-page":"e14649","article-title":"Insufficient evidence for vitamin D use in COVID-19: A rapid systematic review","volume":"75","author":"Atallah","year":"2021","journal-title":"Int. J. Clin. Pract."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"1383","DOI":"10.1038\/s41430-021-00984-5","article-title":"The effect of high-dose parenteral vitamin D3 on COVID-19-related inhospital mortality in critical COVID-19 patients during intensive care unit admission: An observational cohort study","volume":"75","author":"Guven","year":"2021","journal-title":"Eur. J. Clin. Nutr."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1093\/qjmed\/hcab009","article-title":"Vitamin D supplementation, COVID-19 and disease severity: A meta-analysis","volume":"114","author":"Shah","year":"2021","journal-title":"QJM Mon. J. Assoc. Physicians"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1016\/S2213-8587(21)00051-6","article-title":"Vitamin D supplementation to prevent acute respiratory infections: A systematic review and meta-analysis of aggregate data from randomised controlled trials","volume":"9","author":"Jolliffe","year":"2021","journal-title":"Lancet Diabetes Endocrinol."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"4619","DOI":"10.1210\/jc.2013-2653","article-title":"Clinical review: The role of the parent compound vitamin D with respect to metabolism and function: Why clinical dose intervals can affect clinical outcomes","volume":"98","author":"Hollis","year":"2013","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"722","DOI":"10.1056\/NEJM198203253061206","article-title":"Vitamin-D synthesis and metabolism after ultraviolet irradiation of normal and vitamin-D-deficient subjects","volume":"306","author":"Adams","year":"1982","journal-title":"N. Engl. J. Med."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"644","DOI":"10.1093\/ajcn\/42.4.644","article-title":"Vitamin D absorption in healthy subjects and in patients with intestinal malabsorption syndromes","volume":"42","author":"Lo","year":"1985","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"E447","DOI":"10.1210\/jc.2010-2230","article-title":"Vitamin D(3) is more potent than vitamin D(2) in humans","volume":"96","author":"Heaney","year":"2011","journal-title":"J. Clin. Endocrinol. Metab."},{"key":"ref_83","first-page":"87","article-title":"Suntanning and cutaneous synthesis of vitamin D3","volume":"116","author":"Matsuoka","year":"1990","journal-title":"J. Lab. Clin. Med."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"2341","DOI":"10.1002\/jbmr.463","article-title":"Vitamin D supplementation during pregnancy: Double-blind, randomized clinical trial of safety and effectiveness","volume":"26","author":"Hollis","year":"2011","journal-title":"J. Bone Miner. Res."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"i6583","DOI":"10.1136\/bmj.i6583","article-title":"Vitamin D supplementation to prevent acute respiratory tract infections: Systematic review and meta-analysis of individual participant data","volume":"356","author":"Martineau","year":"2017","journal-title":"BMJ"},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"154753","DOI":"10.1016\/j.metabol.2021.154753","article-title":"The link between COVID-19 and VItamin D (VIVID): A systematic review and meta-analysis","volume":"119","author":"Bassatne","year":"2021","journal-title":"Metab. Clin. Exp."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"907","DOI":"10.1080\/14787210.2022.2035217","article-title":"COVID-19 and vitamin D (Co-VIVID study): A systematic review and meta-analysis of randomized controlled trials","volume":"20","author":"Varikasuvu","year":"2022","journal-title":"Expert Rev. Anti-Infect. 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