It is well known that many plants are rich in polyphenols with anti-oxidant, anti-atherogenic, anti-diabetic, anti-cancer, anti-viral, and anti-inflammatory properties. These compounds are secondary metabolites with the ability to donate electrons to free radicals through different mechanisms. In recent years, a large number of studies have attributed a protective effect to polyphenols and foods containing these compounds (e.g. plants, vegetables, cereals, tea, coffee or chocolate). Polyphenolic compounds have been described to inhibit cancer development and propagation, being used as chemopreventive agents.