Searching for the Definition, Terminology and Classification of Dietary Fiber and the New Proposal from Japan

The present review refers to the proposal for resolving the confusion on concept of dietary fiber in the world. The working committee established by Japanese Association for Dietary Fiber Research (JDF) in 1997 first overviewed the changes of discussions on the definition, terminology and classification of dietary fiber conducted in different countries since 1972. Further reviewing has been carried out concerning the physiological significance and classification of new indigestible substances appearing year by year with the proceedings of the researches in this field. Based on the discussions, the committee members agreed that the term "dietary fiber" is inappropriate as a term which covers all indigestible components. The "luminacoids" was designed, as a comprehensive term that covers all such components, including dietary fiber in the conventional meaning. This comprehensive terminology should be classified into starch and non-starch components. Dietary fiber is a major component of non-starch substances and can be sub-classified into polysaccharides and lignin. Thus, the definition of "luminacoids" is proposed as follows: "dietary components which are not digested and/or absorbed in the human small intestine and which exert physiological effect that are useful in maintaining good health via the gastrointestinal tract". After presenting the proposal to the Annual Meeting of JDF in 1998 and 1999, it was finally approved at the 6th Annual Meeting in November 2000. We further describe the significance of new proposal by JDF , and also compare and discuss about these advantages and drawbacks of each revised definition of dietary fiber proposed currently by five international organizations and other investigators.