Table 2.

Foods, bioactive compounds, their effects and other considerations

Food	Bioactive compounds	Effects	Considerations
Açai Berry (Euterpe oleracea)	Flavonoids (pp. anthocyanins)	Antioxidant Anti-inflammatory	Increased antioxidant enzyme activity, vasodilator, and antidiabetic effect. Açai berry plays a role in the prevention and in the treatment of comorbidities that may aggravate COVID-19 symptoms [161, 162]
Citric Fruits	Polyphenols/vitamin C	Antioxidant Immunomodulator	Vitamin C improves chemotaxis, improves neutrophil phagocytic capacity and oxidative death, and supports lymphocyte proliferation and function. Polyphenols have an important antioxidant and anti-inflammatory function [50, 163]
Cocoa (Theobroma cacao)	Flavonoids (pp. Catechins)	Antioxidant Anti-inflammatory Antiviral	Cell protection against free radicals and unscheduled apoptosis. Evidence shows cocoa's protective action against some influenza strains [164, 165]
Garlic (Allium sativum L.)	Allicin and thiosulfinates	Antibiotic Antifungal Antivirals Anti-inflammatory	Protective action against the flu virus (in addition to other viruses such as cytomegalovirus and herpes) [166–168]
Ginger (Zingiber officinale Roscoe)	Gingerols	Antioxidant Anti-inflammatory	In addition to the anti-inflammatory property, there is evidence that indicates an improvement in respiratory function, shorter duration of mechanical ventilation and shorter intensive care unit hospitalization in patients with Acute Respiratory Distress Syndrome [169, 170]
Grapes and grapes-derived products	Resveratrol	Antioxidant Anti-inflammatory	In addition to the already known properties of resveratrol in chronic non-communicable diseases, evidence shows immunomodulatory functions and infectious disease prevention. The protective effect in vitro studies with coronavirus (less cell death, less cytotoxicity and greater cell viability after treatment with resveratrol). At higher doses, Resveratrol contributes to reducing viral replication [171, 172]
Kefir	Probiotics	Antimicrobial Immunomodulator Anti-inflammatory	Kefir is associated with a healthy microbiota (as a pathogen barrier). Some benefits, such as increased macrophage activity and cytokine production, are related to immunomodulatory effects [173, 174]
Linseed (Linum usitatissimum L.) and Linseed oil	Polyunsaturated fatty acids (Ω-3)	Anti-inflammatory Immunomodulator	Due to its fatty acid content, linseed has an anti-inflammatory effect (the increase of anti-inflammatory properties substances and the decrease in inflammatory cytokines) [175–177]
Propolis	Phenolic compounds (pp. flavonoids)	Antimicrobial Antiviral Antifungal Antioxidant Anti-inflammatory	Although there is no sufficient clinical studies, experimental and in vitro studies show propolis as a potentially protective factor against various infections and is related to the healing process [178–180]
Turmeric (Curcuma longa)	Curcuminoid pigments (Curcumin)	Antivirals Anti-inflammatory Antioxidant	Anti-inflammatory and antioxidant properties, as well as action against various viruses, bacteria, and fungi. Besides that, a study correlates curcumin analogs as a treatment of influenza [130, 181, 182]