Table 1.

Summary of articles analysed in this article, discussing the relationship between nutrition or supplements, and COVID-19.

Reference	Article Type	Finding Summary
Butler and Barrientos, 2020 [17]	Article	The author suggests prioritising healthy diets to reduce COVID-19 susceptibility and long-term complications, as an impaired immune system leads to chronic inflammation and lowers host defence against viruses.
Alexander et al. [18]	Review	Sufficient amount of zinc, selenium, and vitamin D is required for resistance to immunological functions and inflammation reductions. Therefore, the authors proposed that dietary intervention be used as a means to provide an adequate status to protect and slow the progression of COVID-19. However, observational outcomes are still weak, with more early-stage administrations recommended.
Budhwar et al., 2020 [19]	Review	In the review, it was suggested that consumption of immunity-boosting foods could help avoid respiratory infections or reduce disease-related complications. A thorough evaluation of nutritional status in infected patients could prove to be beneficial in finding a specific dietary intervention method.
Alagawany et al., 2021 [20]	Review	Vitamins and particular microminerals may be useful in increasing immunity against viral infections and improving disease outcomes.
Iddir et al., 2020 [14]	Review	In this review, the author suggests the importance of using optimal levels of relevant nutrients such as vitamin A, C, D, and zinc to reduce inflammation and oxidative stress, resulting in a strengthened immune system against COVID-19.
Zabetakis et al., 2020 [21]	Review	Strong emphasis on the importance of a healthy diet as a mitigation strategy in maintaining the immune system, highlighting evidence around various different food categories.
Adams et al., 2020 [22]	Article	The article drew attention to the lack of direct evidence linking supplements and COVID-19, pointing to evidence-based guidelines for treatment decisions instead.
Gasmie et al., 2020 [23]	Review	The effects of individual nutrient deficiency status increase virus susceptibility. Patients with specific nutrient deficiencies could benefit from supplementation, and determining nutritional statuses could prove critical.
Cena et al., 2020 [24]	Mini review	In this mini review, the author highlights the link between chronic inflammation and COVID-19 and suggests the use of dietary supplements to mitigate the effects.
Angelidi et al., 2020 [25]	Editorial	The author explores the evidence regarding the Mediterranean diet’s properties in managing COVID-19 and preventing infection.
Shah et al., 2021 [26]	Meta-analysis	The meta-analysis reviewed encouraging data around the role of vitamin D in improving COVID-19 severity in hospitalised patients.
Lordan, 2021 [27]	Review	The overall state of nutraceuticals and dietary supplements in the midst of the COVID-19 pandemic is assessed, with a particular focus on vitamin D.
Carr and Rowe, 2020 [28]	Editorial	Due to low costs and high potential, vitamin C appears to be a prime candidate for anti-inflammatory and antiviral therapeutical administration.
Hathaway et al., 2020 [29]	Review	With its anti-inflammatory and immunomodulatory effects, omega-3 fatty acids could play a role in deciding the clinical outcome in the COVID-19 pandemic.
Rogero et al., 2020 [30]	Literature review	In this review, both the beneficial and adverse effects of omega-3 fatty acids were appraised.
Skalny et al., 2020 [31]	Review	Inadequate zinc supply may increase susceptibility to infectious diseases of the respiratory tract. Existing data on the efficiency of zinc supplements and their anti-inflammatory effects supports zinc’s status as adjuvant therapy for COVID-19.
Finzi, 2020 [32]	Case report	Though the sample size was limited, patients receiving high-dose zinc therapies showed significant improvement.