Quercetin, a predominant dietary flavonoid, primarily exists as glycosides and undergoes enzymatic and microbial transformations that influence its bioavailability. This review highlights key factors affecting bioavailability, including glycoside structure, co-ingestion with fats, and chemical modifications such as prenylation, which may enhance lymphatic transport. Quercetin and its metabolites have been associated with antioxidant and anti-inflammatory effects, which may contribute to the prevention of atherosclerosis, particularly through the local conjugation of quercetin derivatives. A comprehensive understanding of these mechanisms is imperative for maximizing the health benefits of dietary polyphenols.