Quercetin’s antiviral effects keep rhinoviruses (those that cause the common cold) from replicating. – Journal of Medicinal Food (1)
Quercetin is a plant pigment (flavonoid). It is found in many plants and foods such as red wine, onions, green tea, apples, berries, and many others. According to many studies, quercetin is an antiviral substance with many health benefits. Specifically, quercetin has been shown to act against the viruses that cause the common cold (1).
“Q7G (quercetin) … inhibited virus replication in the initial stage of virus infection by indirect interaction with virus particles, and ribavirin (a common antiviral drug) had a relative weaker efficacy compared to Q7G. Therefore, these data suggest that Q7G exerted its anti-HRV2 effect (HRV2 is a rhinovirus, the family of viruses that causes common colds) via the inhibition of virus replication in the early stage… (1).”
WebMD notes on its website that “Quercetin is used for treating conditions of the heart and blood vessels including ‘hardening of the arteries’ (atherosclerosis), high cholesterol, heart disease, and circulation problems. It is also used for diabetes, cataracts, hay fever, peptic ulcer, schizophrenia, inflammation, asthma, gout, viral infections, chronic fatigue syndrome (CFS), preventing cancer, and for treating chronic infections of the prostate. Quercetin is also used to increase endurance and improve athletic performance (2).”
In addition to properties that work against the common cold, quercetin also works against the flu virus according to another study. “Quercetin-3-O-β-D-glucuronide also showed to possess inhibitory activity against influenza A virus (FLUAV) (3).” The study was published in September, 2011 in the medical journal Fitoterapia.
The bottom line?
Quercetin appears to have many antiviral properties that are effective against cold viruses.
(1) Song JH1, Park KS, Kwon DH, Choi HJ. “Anti-human rhinovirus 2 activity and mode of action of quercetin-7-glucoside from Lagerstroemia speciosa.” J Med Food. 2013 Apr;16(4):274-9. doi: 10.1089/jmf.2012.2290.
(2) WebMD.com – QUERCETIN. Natural Medicines Comprehensive Database Professional Version. © Therapeutic Research Faculty 2009.
(3) Hanan Polansky, Edan Itzkovitz “Gene-Eden-VIR Is Antiviral: Results of a Post Marketing Clinical Study” Pharmacy & Pharmacology Vol.4 No.6A, September 2013