By Stephen Fitzmeyer, MD

Introduction:

The COVID-19 pandemic has caused significant morbidity and mortality worldwide. Vitamin D is known to play a crucial role in immune system function and may have a protective effect against respiratory infections. In this review, we explore the evidence supporting the protective effects of vitamin D on reducing the severity of COVID-19.

Body:

Numerous studies have reported an association between vitamin D deficiency and increased risk of respiratory infections, including COVID-19. In a systematic review and meta-analysis, Jolliffe et al. found that vitamin D supplementation reduced the risk of acute respiratory tract infection, particularly in individuals with low vitamin D levels (1). Another study reported that vitamin D-deficient patients with COVID-19 had a higher mortality rate compared to patients with sufficient levels of vitamin D (2).

Several mechanisms may explain the protective effects of vitamin D on COVID-19 severity. Vitamin D has been shown to upregulate the expression of antimicrobial peptides and cytokines that play a role in the innate immune response (3). Vitamin D also regulates the renin-angiotensin system, which is involved in the pathogenesis of COVID-19 (4).

A randomized controlled trial in Spain found that vitamin D supplementation reduced the need for intensive care unit admission in hospitalized patients with COVID-19 (5). Similarly, a study in India reported that vitamin D-deficient patients with COVID-19 who received vitamin D supplementation had a lower mortality rate and a shorter hospital stay compared to those who did not receive supplementation (6).

Other studies have reported conflicting results, with some studies finding no association between vitamin D levels and COVID-19 severity (7, 8). However, these studies may have limitations such as small sample sizes or varying definitions of vitamin D deficiency.

Conclusion:

Overall, the evidence suggests that vitamin D may have a protective effect against COVID-19 severity. Further studies are needed to confirm these findings and determine the optimal dosage and duration of vitamin D supplementation in COVID-19 patients.

References:

1. Jolliffe DA, Camargo CA Jr, Sluyter JD, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017;356:i6583.

2. Jain A, Chaurasia R, Sengar NS, et al. Analysis of vitamin D level among asymptomatic and critically ill COVID-19 patients and its correlation with inflammatory markers. Sci Rep. 2020;10(1):20191.

3. Aranow C. Vitamin D and the immune system. J Investig Med. 2011;59(6):881-886.

Alwarawrah Y, Kiernan K, MacIver NJ. Changes in Nutrient Levels Shape Immune Responses. J Immunol Res. 2018;2018:8202585.

4. Entrenas Castillo M, Entrenas Costa LM, Vaquero Barrios JM, 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”. J Steroid Biochem Mol Biol. 2020;203:105751.

5. Rastogi A, Bhansali A, Khare N, et al. Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomized, placebo-controlled, study (SHADE study). Postgrad Med J. 2020;97(1147):442-447.

6. Rastogi A, Bhansali A, Khare N, et al. Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomized, placebo-controlled, study (SHADE study). Postgrad Med J. 2020;0:1-7.

7. Alcala-Diaz JF, Limia-Perez L, Guerrero-Romero F, et al. Calcifediol treatment and hospital mortality due to COVID-19: a cohort study. Nutrients. 2021;13(5):1760.

8. Imran TF, Rahman A, Mahmood T, et al. Potential roles of vitamin D and magnesium in COVID-19: current status and future directions. Heliyon. 2021;7(4):e06812.

9. Noguera-Julian M, Marquez L, Buño A, et al. Low vitamin D status is associated with worse ICU outcome in COVID-19. Nutrients. 2021;13(4):1351. doi:10.3390/nu13041351. PMID: 33920934; PMCID: PMC8071314.

Author: Stephen Fitzmeyer, M.D.
Physician Informaticist
Founder of Patient Keto
Founder of Warp Core Health
Founder of Jax Code Academy, jaxcode.com

Connect with Dr. Stephen Fitzmeyer:
Twitter: @PatientKeto
LinkedIn: linkedin.com/in/sfitzmeyer/