Quercetin: A Real Flavonoid, Barely Absorbed, Oversold as an Antihistamine

Summary

Quercetin is a genuine dietary flavonoid with reproducible in-vitro and animal anti-inflammatory and mast-cell-stabilising activity and a clean, plausible mechanism, but its human outcome evidence is thin and does not carry the marketing: oral bioavailability from capsules is only about 1 to 2 percent, the flagship cold-prevention trial was null on its primary endpoint and only "worked" in a post-hoc subgroup, the antihistamine and allergy claim is largely preclinical and anecdotal, the senolytic dasatinib-plus-quercetin work is tiny early-phase research using a prescription chemotherapy drug