Recent advances and application challenges of quercetin-loaded delivery systems: from material selection to bioavailability

• Materials, response types and challenge of quercetin delivery are highlighted • Quercetin intake dose is affected by dietary habits, sources and individual variations • Intestinal-targeted systems enhance quercetin's oral bioavailability effectively • Leverage the two-edged interaction of quercetin-food to develop its strengths Quercetin is a flavonoid with numerous health benefits. However, its low bioavailability significantly limits its application. Recently, delivery systems have been devised to enhance the bioavailability of quercetin, involving various strategies such as material selection, carrier design, and practical applications. Consequently, a comprehensive understanding of quercetin-loaded delivery systems is required. In this review, we summarize the applications of three major food-derived material categories (proteins, polysaccharides, and lipids) in quercetin-loaded delivery systems. We then focus on delivery systems that are responsive to environmental stimuli, such as pH- and enzyme-responsive delivery systems. It is worth mentioning that small-intestine-targeted delivery systems, including mucus permeation and mucoadhesive systems, were first discussed in a review of quercetin delivery. Finally, the practical application challenges, limitations and recommendations of the available studies are discussed in detail. It is crucial to acknowledge that quercetin may have two-edged interactions with the components within the delivery system, necessitating a nuanced approach for carrier design. This review not only advances our understanding of quercetin function but also paves the way for more effective and targeted nutritional interventions.