A study conducted by researchers from Old Dominion University (USA) and Sapienza University in Rome (Italy) has shown that the co-administration of Vitamin C and quercetin from onions exerts a synergistic action due to its antiviral and immunomodulatory properties, recommending its use both preventively and in patients with COVID-
19 as a complementary supplement to the pharmacological treatments used.
Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (COVID-19). Colunga Biancatelli RML, Berrill M, Catravas JD, Marik PE. Front Immunol. 2020; 11:1451. Published 2020 Jun 19.doi:10.3389/fimmu.2020.01451