Polyphenols are a structural class of natural and synthetic, organic chemicals characterized mainly by the presence of phenol structural units. Numerous epidemiological and experimental studies have strongly suggested their beneficial effects for human health. This view is supported by their biological activities, which are associated with chemical and biochemical properties, including the ability to act as antioxidants, their antineoplastic effect and the regulation of gene expression in chronic degenerative diseases. These mechanisms of action could account for their preventive and therapeutic uses in human subjects. Moreover, in some therapeutic uses, such as antineoplastic effect, a prooxidant therapeutic action has been suggested. In the diet, numerous compounds could participate in the beneficial properties, and this likely could result in synergistic effects because the whole effect is better than the separately action of each compound. However, the pharmacokinetic and pharmacodynamic properties of these bioactive micronutrients are yet to be further characterized. More research is required to fully establish the therapeutic use of polyphenols against human disease. Based on biological and pharmacological properties of polyphenols both as diet components and supplements, the objective of this work is to show an updated version about the role that polyphenols could play in several chronic diseases such as hypertension, diabetes mellitus, cancer and neurodegenerative disorders.