Quercetin is a flavenol found in many fruits and vegetables. Quercetin supplements are often sold to naturally support health. This complex provides 250 mg of quercetin per 2 tablets. In this complex there is also: Vitamin C (as Ester C) 150mg Ð this has been included to support the normal functioning of the immune system and the reduction of tiredness & fatigue Vitamin B5 100mg Ð to contribute to the normal synthesis of steroid hormones. The complex also contains the following supportive ingredients, which all have a long history of use in natural medicine: MSM Ð 250mg; Pine Bark Extract Ð 50mg and Liquorice extract equivalent to 250mg.