At present, two important factors contributing to diseases are environmental and genetic factors. The gene is a well defined component distributing to many disorders. This is important genetic parameter. Focusing on environmental factor, nutrition is an important parameter. The interrelationship between gene and nutrition is well defined. The focus on gene and nutrition leads to new emerging sciences, nutrigenetics and nutrigenomics. In the book, the authors focus on research and report on these aspects. The subjects in nutrigenetics and nutrigenomics are presented and discussed.