ABSTRACT
A healthy diet is essential for the sustenance of human life. In the past, food was regarded simply as a source of energy at a time when strenuous manual labor involving high energy consumption was the norm. In many parts of the world, this concept of food did not change until after the Second World War when people became engaged in more sedentary occupations and lifestyles. In this modern era, food has assumed a whole new meaning and has increasingly become a cultural and social phenomenon rather than a basic activity to ensure survival. It is no longer sufcient for a healthy diet to provide only the major nutrients at adequate levels; a healthy diet should also be able to optimize health and help the body to ght diseases. In other words, besides supplying nutrients at adequate quantities and quality, a healthy diet should have additional functional attributes. Such protection is achieved by the presence of bioactive compounds contained in certain foods, which we now refer to as “functional foods.” This intrinsic relationship between diet and health has been known for over 2000 years, even in the days of the famous Greek physician, Hippocrates (400 bc), who wrote the advice quoted at the beginning of this chapter. Other ancient scholars also recognized the link between diet and good health as evidenced by early medical treatises written by Cicero (about 44 bc), Galen (about 180 ad), and Avicenna (about 1000 ad), but the rst medical insight into the link among longevity, quality of life, and diet was attributed to Alvise Cornaro in his “Discourses on the Sober Life” about 1560. The utility of his work was, however, limited by the fact that his suggestions were based on personal experiences rather than on objective observations. It is interesting to note that his recommendations at that time are similar to the recent theory of caloric restriction but the link is likely a casual one.1
