Vitamin C Supplementation for the Treatment of COVID-19: A Systematic Review and Meta-Analysis

Nutrients

Oct 2022

DOI: 10.3390/nu14194217

Citations:35

Influential Citations:3

Systematic Reviews / Meta-Analyses

Enhanced Details

Methods

Adults (≥18 years) with COVID-19; mixed sexes; included both randomized controlled trials and non-randomized (prospective and retrospective) trials; English-language publications.

Results

Vitamin C supplementation reduces hospital mortality in COVID-19, especially in randomized trials where in-hospital mortality was significantly lower with vitamin C (23.9% vs 35.8%; OR 0.44; p=0.003). One-month mortality was also lower in vitamin C groups (OR 0.48; p<0.001). Oral administration showed mortality benefit; intravenous did not reach significance. ICU length of stay tended to be longer with vitamin C, while overall hospital length of stay showed no difference. Acute kidney injury occurred less often with vitamin C (OR 0.56). Low-dose regimens were most effective and safe. However, due to study heterogeneity and evolving standard of care, results are not enough to change guidelines; more randomized trials are needed.

Limitations

High heterogeneity across studies; mix of randomized and non-randomized designs; variable dosing, routes, and co-treatments; evolving standard of care; some studies used combination therapies; limited randomized trial data for certain outcomes.

Abstract

Since the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe respiratory syndrome coronavirus 2 (SARS-CoV-2), millions of people have died, and the medical system has faced significant difficulties. Our purpose was to perform a meta-analysis to estimate the effect of vitamin C on in-hospital mortality and the ICU or hospital length of stay for patients diagnosed with COVID-19. We conducted a systematic review with meta-analysis in the following databases: PubMed, Web of Science, Scopus and Cochrane Central Register of Controlled Trials. We included studies that evaluated the effect of vitamin C supplementation, compared with standard treatment in COVID-19 patients who are ≥18 y of age. Nineteen trials were included in the meta-analysis. In-hospital mortality with and without vitamin C supplementation was 24.1% vs. 33.9% (OR = 0.59; 95%CI: 0.37 to 0.95; p = 0.03), respectively. Sub-analysis showed that, in randomized clinical trials, in-hospital mortality varied and amounted to 23.9% vs. 35.8% (OR = 0.44; 95%CI: 0.25 to 0.76; p = 0.003), respectively. In the non-randomized trials, in-hospital mortality was 24.2% vs. 33.5% (OR = 0.72; 95%CI: 0.38 to 1.39; p = 0.33), respectively. The ICU length of stay was longer in patients treated with vitamin C vs. standard therapy, 11.1 (7.3) vs. 8.3 (4.7) days (MD = 1.91; 95%CI: 0.89 to 2.93; p < 0.001), respectively. Acute kidney injury in patients treated with and without vitamin C varied and amounted to 27.8% vs. 45.0% (OR = 0.56; 95%CI: 0.40 to 0.78; p < 0.001), respectively. There were no differences in the frequency of other adverse events among patients’ treatment with and without vitamin C (all p > 0.05). The use of vitamin C reduces hospital mortality. The length of stay in the ICU is longer among patients treated with vitamin C. In terms of patient safety, vitamin C has an acceptable profile. Low doses of vitamin C are effective and safe. Despite some evidence of the usefulness of vitamin C in modifying the course of COVID-19, it is too early to modify guidelines and recommendations. Further studies, in particular randomized clinical trials, are necessary. show less