Life Extension Bio-Quercetin offers highly absorbable support for immune, cardiovascular and endothelial health. Quercetin is an antioxidant flavonoid that may boost energy and muscle recovery; it may also support respiratory health and weight management. Bio-Quercetin from Life Extension uses quercetin encased in a plant-derived phytosome, making it up to 50 times more absorbable than standard quercetin.