Copyright ©The Author(s) 2021.
World J Gastroenterol. Sep 14, 2021; 27(34): 5682-5699
Published online Sep 14, 2021. doi: 10.3748/wjg.v27.i34.5682
Table 1 Ongoing clinical trials of antioxidant supplementation in coronavirus disease 2019 patients
Antioxidants and nutrients
Plant and/or animal sources
Potential target pathways
Recommended dietary intake; Effective dose for respiratory infection)
Registered clinical trials of COVID-19, rial number
Intervention dose
Primary outcome
Vitamin A Carrots (raw); Cantaloupe; Mango; Salmon; EggsRole in immune competence; Immunomodulatory action900/700 μg M/FIRCT20200319046819N1[49]25000 IU vitamin A and 600000 IU vitamin D per day, 300 IU vitamin E twice a week, 2000 mg vitamin C 4 times in a day, amp vitamin B; Soluvit in a day, for 1 wkWeight, height, BMI; Severity of pulmonary involvement (CT scan); Respiratory support (invasive or non-invasive); WBC, CRP, IL6, TNF-α, IFN-γ, ESR; Body temperature; Organ involvement; Hospital duration; Mortality
Vitamin DPortabella mushrooms; Dairy products; Eggs; FishMaintenance of cell physical barrier integrity; Increased antimicrobial protein production; Anti-inflammatory state; ACE2 and other members of the RAS expression5- 15 μg; 20-50 μg[60]NCT04334005[61]25000 IU vitamin DMortality, all-cause mortality within 14 d
NCT04344041[62]400000 IU/or 50000 IUSerum 25(OH)D3 changes during treatment
NCT04636086[63]50000 IU vitamin D ; 25000 IU vitamin D ; Days 1-4, 8,15, 22, 29 and 36Vitamin D serum concentration, clinical improvement, biological markers
NCT04621058[64]D deficiency (< 30 ng/mL) 0.532 mg vitamin D (< 40 ng/mL): 0.266 mg vitamin DMortality reduction, lent of hospital reduction
NCT04483635[65]100000 IU vitamin D tab. baseline + 10000 IU/wk; 16 wk Change in incidence laboratory-confirmed COVID-19 infection
NCT04386850[66]25 µg 25(OH)D3; 2 mo Hospitalization, disease duration, death, mortality, ventilation
Vitamin COranges; Lemon; Green and red peppers; Tomato; Broccoli; Brussel sprouts; Cabbage; Cauliflower; Spinach; Sweet potato; Winter squashAntioxidant capacity; Immunomodulatory effects on interferon production; Cytokine production down-regulation40-80 mg; 6–8 g[77]NCT04323514[74]10 g vitamin C infusionHospital mortality
NCT04530539[75]1000 mg vitamin CSeverity of symptoms
NCT04682574[76]30 g/d 2 d with standard treatmentPartial pressure of oxygen in arterial blood to fraction of inspired oxygen
Vitamin ESunflower seeds; Nuts; Almonds; Blueberries; Kivi; BroccoliAntioxidant action; Immunomodulatory effects7–10 mg; 30–200 mg[82]
ZincPumpkin and squash seeds nuts; Soybean; Beef; Mollusks; LambReduces ROS in viral infections; Replication inhibition; Immunomodulatory effects; Antibody production; NK cell activity; Cytokine production by mononuclear cells; Chemotaxis response reduction; Neutrophil respiratory burst reduction 8–14 mg; 30–50 mg[43]NCT04335084[90]Zinc, vitamin D, vitamin C 12 wk and hydroxychloroquine for 1 dPrevention of COVID-19 symptoms recorded in a daily diary
Selenium Sunflower seeds; Coconut meat; Mollusks; Salmon; Turkey; HamAntioxidant balanceROS balance in inflammatory processes 60–70 mg
CopperCashew nuts; Tofu; Mushrooms; Beef; Oyster; Cereals; Roots, tubers: Sweet potato; QuinoaRole in immunity antimicrobial action due to copper toxicity; Enhance macrophage activity in lung infection900 μg
CurcuminRhizome of turmeric (Curcuma longa)Antioxidant capacity; Virus-ACE2 interaction reduction; ACE2 level increase; Antiviral activities SARS-CoV-2 protease, spike glycoprotein-RBD and PD-ACE2 bindingIRCT20200611047735N1[114]160 mg curcumin; 2 wkImmune responses (IFN-γ, IL-17, IL-4 and TGF-β)
IRCT20121216011763N46[115]1000 mg curcumin + 10 mg piperine twice/day, 2 wkClinical symptoms, duration, severity, inflammatory mediators
SilymarinMilk thistle (Silybum marianum)Antioxidant capacity; Anti-inflammatory; p38 MAPK pathway antiviral NCT04394208[116]420 mg/d; 3 divided dosesClinical outcome duration of mechanical ventilation hospitalization