Flavonoid compositions containing the flavonoid quercetin and/or derivatives of quercetin are disclosed. The flavonoid compositions are formulated to improve the bioavailability of quercetin. Also provided herein are methods for improving athletic performance, improving cardiovascular health, and aiding in immune response and methods of improving athletic performance, improving bone health, preventing fatigue, reducing recovery time after exercise, countering oxidative stress, and/or boosting energy.