16.7 mg — A plant flavonoid studied for inflammation and antioxidant activity, at a dose well below typical research amounts.
Quercetin is dosed at 16.7mg per serving -- just over 1% of the total 1,383mg. Published research has used doses up to 1,000mg daily in some studies, roughly sixty times what's in this formula. Treat this as a minor contributor rather than a headline reason to choose this product.