Natural Products Show Promise Against COVID-19 Via Iron Chelation
Alpha lipoic acid would be the first choice here. It has good bioavailability, followed by caffeic acid. Quercetin has poorer bioavailability due to extensive first pass metabolism. Curcumin collects mainly in the intestinal tract and has very low bioavailability elsewhere, but some companies combine it with piperine in an attempt to increase its absorption.