What is a Flavonoid?

What is a Flavonoid?

Flavonoids are natural compounds obtained in the human diet from the ingestion of plant products, and have been widely recognised for their antioxidant properties discovered more than 40 years ago and published in 23,000 scientific articles to date.

Quercetin is the most abundant flavanoid in the human diet and is derived from plant-based food products including onions, apples, blueberries, kale, broccoli, tea and red wine. The beneficial effects of quercetin on inflammation and immunity have been well-documented based on results obtained from lab-based and animal studies and several randomised clinical trials have been undertaken in humans to demonstrate Quercetin's effect in modulating immune function.

Research indicates that Quercetin may reduce the incidence of viral upper respiratory tract infection in the immediate post-exercise period following intensive exercise and in individuals suffering from high mental stress, conditions in which it is known that immune function is decreased and the incidence of viral infections is higher.


1. Pérez-Cano, F., & Castell, M. (2016). Flavonoids, Inflammation and Immune System. Nutrients, 8(10),

2. Li, Y., Yao, J., Han, C., Yang, J., Chaudhry, M., Wang, S., Liu, H., & Yin, Y. (2016). Quercetin, Inflammation and Immunity. Nutrients, 8(3),

3. Heinz, S., Henson, D., Austin, M., Jin, F., & Nieman, D. (2010). Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial. Pharmacological Research, 62(3), 237-242.

4. MAYER, E. (2007). Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise. Medicine & Science in Sports & Exercise, 39(9), 1561-1569.