Health professionals presently recognise that the foods called functional can have a major role in health enhancement. Recently, many developments have been arising in this area. Researchers, food technologists and industrialists are aimed at identifying new functional foods and nutraceuticals, which can be included in diets with the general purpose of improving health or with a specific objective of helping to treat some diseases. The list of potential health substances is continuously growing, and includes a wide variety of substances that are recognized to have a positive role in the pathogenesis of many diseases. In recent years, many studies have been conducted by researchers all around the world to investigate the effects of these substances on human health, either with in vitro tests or with clinical trials. The amount of publications in this field is very extensive and an updated revision of the results obtained is of great interest to help identifying the real benefits, and to confirm or contradict some myths that might be installed. The present book gives an updated contribution to the knowledge regarding foods which may play a role in maintaining human health or fighting disease, showing their benefits, and evidencing in what way human diet can be manipulated to achieve certain objectives. The updated information that is provided here will certainly help people in general and professionals in particular, to make appropriate choices concerning what to eat.