This 2016 review compiled both in vitro and in vivo studies with epidemiological and observational studies that demonstrate quercetin’s potential therapeutic value. While the in vitro studies draw a clear mechanism of action of quercetin in the management of allergies through inhibition of mast cell histamine release, prostaglandin and leukotriene release. Human clinical evidence is related to the epidemiological and observational studies that draw a correlation between the consumption of foods high in flavonoids particularly quercetin such as apples, pears, and opinions and decreased incidence of asthma and food sensitivities.
Mlcek J, Jurikova T, Skrovankova S, Sochor J. Quercetin and Its Anti-Allergic Immune Response. Molecules. 2016;21(5):623. Published 2016 May 12. doi:10.3390/molecules21050623