Opportunities and challenges in enhancing the bioavailability and bioactivity of dietary flavonoids: A novel delivery system perspective

Flavonoids have multiple favorable bioactivities including antioxidant, anti-inflammatory, and antitumor. Currently, flavonoid-containing dietary supplements are widely tested in clinical trials for the prevention and/or treatment of multiple diseases. However, the clinical application of flavonoids is largely compromised by their low bioavailability and bioactivity, probably due to their poor aqueous solubility, intensive metabolism, and low systemic absorption. Therefore, formulating flavonoids into novel delivery systems is a promising approach for overcoming these drawbacks. In this review, we highlight the opportunities and challenges in the clinical use of dietary flavonoids from the perspective of novel delivery systems. First, the classification, sources, and bioactivity of dietary flavonoids are described. Second, the progress of clinical research on flavonoid-based dietary supplements is systematically summarized. Finally, novel delivery systems developed to improve the bioavailability and bioactivity of flavonoids are discussed in detail to broaden the clinical application of dietary flavonoids.