Can taking a vitamin D supplement prevent infection with the virus that causes the coronavirus disease 2019 (COVID-19)?
Answer From William F. Marshall, III M.D.
There isn't enough data to recommend use of vitamin D to prevent infection with the virus that causes COVID-19 or to treat COVID-19, according to the National Institutes of Health and the World Health Organization.
Several recent studies have looked at the impact of vitamin D on COVID-19. One study of 489 people found that those who had a vitamin D deficiency were more likely to test positive for the virus that causes COVID-19 than people who had normal levels of vitamin D.
Other research has observed high rates of vitamin D deficiency in people with COVID-19 who experienced acute respiratory failure. These people had a significantly higher risk of dying. And a small, randomized study found that of 50 people hospitalized with COVID-19 who were given a high dose of a type of vitamin D (calcifediol), only one needed treatment in the intensive care unit. In contrast, among the 26 people with COVID-19 who weren't given calcifediol, 13 needed to be treated in the intensive care unit.
In addition, vitamin D deficiency is common in the United States, particularly among Hispanic and Black people. These groups have been disproportionately affected by COVID-19. Vitamin D deficiency is also more common in people who are older, people who have a body mass index of 30 or higher (obesity), and people who have high blood pressure (hypertension). These factors also increase the risk of severe COVID-19 symptoms.
However, in recent years two randomized clinical trials that studied the effects of vitamin D supplementation had less hopeful results. In both trials, high doses of vitamin D were given to people who had vitamin D deficiencies and were seriously ill — not with COVID-19. Vitamin D didn't reduce the length of their hospital stays or their mortality rates when compared with those given a placebo.
Further research is needed to determine what role, if any, vitamin D and vitamin D deficiency might play in the prevention of and treatment of COVID-19.
In the meantime, if you have a vitamin D deficiency, talk to your doctor about whether a supplement might be right for you. If you're concerned about your vitamin D level, ask your doctor about getting it checked.
Feb. 10, 2021
William F. Marshall, III M.D.
See more Expert Answers
- Meltzer DO, et al. Association of vitamin D status and other clinical characteristics with COVID-19 test results. JAMA Network Open. 2020; doi:10.1001/jamanetworkopen.2020.19722.
- Carpagnano GE, et al. Vitamin D deficiency as a predictor of poor prognosis in patients with acute respiratory failure due to COVID-19. Journal of Endocrinological Investigation. 2020; doi:10.1007/s40618-020-01370-x.
- Castillo ME, et al. Effect of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study. The Journal of Steroid Biochemistry and Molecular Biology. 2020; doi:10.1016/j.jsbmb.2020.105751.
- Bergman P. The link between vitamin D and COVID-19: Distinguishing facts from fiction. Journal of Internal Medicine. 2020; doi:10.1111/joim.13158.
- Vitamin D. National Institutes of Health. https://www.covid19treatmentguidelines.nih.gov/adjunctive-therapy/vitamin-d/. Accessed Sept. 9, 2022.
- Coronavirus disease — Answers. World Health Organization. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/coronavirus-disease-answers?query=vitamin+D. Accessed Sept. 23, 2020.