Quercetin is a non-citrus bioflavonoid that works in synergy with Vitamin C. Bioflavonoids are naturally present in fruit, vegetables and herbs, and are a class of powerful phytochemicals. Exclusive to Solgar, Quercetin complex is a proprietary formula and contains additional natural plant bioflavonoids, powerful antioxidants that naturally accompany Vitamin C in fruits and vegetables. This complex is a unique formula that utilises a premium patented, non-acidic, form of vitamin C, Ester C known as "The Better Vitamin C". The highly absorbable Ester C is also gentle on the stomach compared to traditional forms of vitamin C, which is less likely to irritate and making this product a good choice for everyone. In addition, the complex includes Bromelain and natural bioflavanoids. Bromelain has been added to this specialised formula. Bromelain is a digestive enzyme found naturally in pineapples.