2003, David Hoffmann, Medical Herbalism: The Science and Practice of Herbal Medicine, page 104:
Quercetin has gained the attention of the supplement industry, and is now widely promoted as a natural anti-inflammatory and antioxidant magic bullet.
2005, James Braly, Patrick Holford, Hidden Food Allergies, page 101:
The one daily supplement that often reduces allergic symptoms across the board is the phytonutrient quercetin, a chemical compound known as a bioflavonoid and found in plants.
2014, Masuko Kobori, “14: Dietary Quercetin and other Polyphenols: Attenuation of Obesity”, in Ronald Ross Watson, Victor R. Preedy, Sherma Zibadi, editors, Polyphenols in Human Health and Disease, volume 1, page 168:
In plasma, quercetin mostly exists as glucuronated, sulfated, and/or methylated quercetin conjugates.
One study, for example, found that eating a diet rich in quercetin, found in green tea, broccoli and red wine, might help protect against lung cancer, especially in heavy smokers.