Background: Despite global efforts to treat and alleviate the outcomes of COVID-19, no consensus has been reached regarding the optimal approach. Some nutrients have been known to be vital for the integrity of the immune system. Although limited interventional studies support this idea, the findings of some cross-sectional and case studies have been encouraging. Aim: The present study will seek to determine the effectiveness of nutritional interventions on the outcomes of COVID-19. Methods: Electronic databases including PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar will be searched for articles published from October 1st, 2019, to January 12th, 2022. Different study designs, both randomized and nonrandomized trials, cross-sectional or cohort studies, and pre and post-interventions will be included. Screening, selection, and extraction of data as well as quality assessment of included studies, will be carried out by two separate reviewers. Any potential conflicts will be resolved through discussion. An appropriate risk of bias assessment tool will be used to appraise the included studies. Then, the results will be synthesized and pooled for meta-analysis. If the meta-analysis is not performed, the reason will be provided. After summarizing the results and providing conclusions, the specific features associated with effective interventions will be presented based on the power of each study.
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