Abstract: nutrients Commentary Vitamin D Supplementation to Prevent COVID-19 Infections and Deaths—Accumulating Evidence from Epidemiological and Intervention Studies Calls for Immediate Action Hermann Brenner 1,2 1 2



 Citation: Brenner, H. Vitamin D Supplementation to Prevent COVID-19 German Cancer Research Center, Division of Clinical Epidemiology and Aging Research, 69120 Heidelberg, Germany; h.brenner@dkfz.de; Tel.: +49-6221-42-1300 Network Aging Research, Heidelberg University, 69115 Heidelberg, Germany Abstract: The COVID-19 pandemic poses an unprecedented threat to human health, health care systems, public life, and economy around the globe. The repertoire of effective therapies for severe courses of the disease has remained limited. A large proportion of the world population suffers from vitamin D insufficiency or deficiency, with prevalence being particularly high among the COVID-19 high-risk populations. Vitamin D supplementation has been suggested as a potential option to prevent COVID-19 infections, severe courses, and deaths from the disease, but is not widely practiced. This article provides an up-to-date summary of recent epidemiological and intervention studies on a possible role of vitamin D supplementation for preventing severe COVID-19 cases and deaths. Despite limitations and remaining uncertainties, accumulating evidence strongly supports widespread vitamin D supplementation, in particular of high-risk populations, as well as high-dose supplementation of those infected. Given the dynamics of the COVID-19 pandemic, the benefit–risk ratio of such supplementation calls for immediate action even before results of ongoing large-scale randomized trials become available. Keywords: COVID-19; mortality; prevention; supplementation; vitamin D Infections and Deaths—Accumulating Evidence from Epidemiological and Intervention Studies Calls for Immediate Action. Nutrients 2021, 13, 411. https://doi.org/10.3390/nu13020411 Academic Editor: Spyridon Karras Received: 28 December 2020 Accepted: 24 January 2021 Published: 28 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://