Flavonoids, common substances in the daily diet, comprise a large group of low-molecular-weight polyphenolic secondary plant metabolites and are included in various vegetables, fruits and beverages. Flavanoids share a common structure consisting of two aromatic rings that are bound together by three carbon atoms that form an oxygenated heterocycle. They exert several biological benefits for humans, such as antioxidant, anti-inflammatory, anti-bacterial, anti-viral, anti-angionic, anti-allergic and immune- modulating effects. An appropriate intake of flavonoids may therefore be expected to prevent chronic diseases including allergic diseases. (Tanaka, OA Alternative Medicine).