The editors have designed this book to serve both as a textbook on fiber in nutrition and, we hope, as the first complete reference on the subject. For the past 25 years, the study of plant fibers and their effect on human physiology has generally been relegated to a low-priority status. Recently, however, this area of research has enjoyed a renaissance unparalleled in the history of the food and nutritional sciences, a reawakening which has occurred primarily as a result of epidemiology reports that suggested a positive relationship between plant fiber ingestion and health. As interest among the scientific community increased and new research programs were initiated to test objectively the epidemiological hypotheses, major gaps in the fundamental pool of kwledge became apparent. To compound the difficulty, scientists often did t agree upon what fiber is. Some investigators restricted their definition to the structural polymers of the plant, while others expanded theirs to include the entire plant cell wall with all its fibrous and associated nfibrous substances. As a result, research that was performed and reported frequently only obscured the issue still further; at best it exposed whole new areas of igrance in a field once considered too uninteresting to pursue. Despite volumius research, scientists generally have still t been able to identify with certainty the specific component(s) of the plant cell-wall system that causes the various observed physiological effects. In fact, they do t yet agree upon the menclatures involved.