A balanced and healthy diet is prerequisite for a good health and well-being. However, dietary natural or introduced components can contribute in high extent to the development of certain diseases, such as in the case of carcinogenesis and cardiovascular illness, or may postpone or counteract their development in individuals' with high genetic susceptibility. To humans, a balanced diet represents the source of energy, building and functional elements, as well as a pleasure. On the other hand under certain circumstances of diets can include acute or chronic poisoning and provoke numerous adverse reactions ranging from mild discomfort to death. This book presents scientific facts and evidences that will help the readership to create its own picture and attitude about nutrition, since the essence of the food safety can not be discussed excluding the individually coloured philosophical approach.