The intestinal tract is the largest immunological organ, which is responsible for the first line of defense by preventing the invasion of pathogenic microorganism and neutralizing pathogenic materials such as toxin. Simultaneously, it does not respond to harmless or beneficial antigens such as foods and intestinal commensal bacteria. These harmonized immune responses are critical for the maintenance of intestinal homeostasis and hence disruption of the system would lead to the development of immune diseases such as inflammatory bowel disease and food allergy. Especially dietary lipids among the dietary components have been studied for a long time, and it is considered that dietary lipids are important factors for regulating the development of allergy and inflammation. As analytical techniques of lipid metabolites have been highly developed in recent years, it has become clear that some lipid metabolites derived from dietary oils have strong physiological functions including the control of allergic and inflammatory diseases. These findings are currently leading to the new methods for preventing and treating allergic and inflammatory diseases by using lipid metabolites. In this article, we introduce the control of allergic and inflammatory diseases by dietary lipids and its metabolites
