Specific physiological effects are not part of the definitions because new beneficial effects of nondigestible carbohydrates will continue to be discovered. Furthermore, the aim of this activity was to promulgate definitions that have overall long-term applicability. Thus specific physiological benefits are not included because such a definition would become quickly outdated as new health effects become established. It is anticipated that acceptable physiological benefits will be identified during implementation of the proposed definitions.
Physiological effects of some ingested Dietary Fibers and some Added Fibers include attenuation of postprandial blood glucose concentration and blood cholesterol concentration and improved laxation. Available data suggest that the addition of fiber sources that are viscous are capable of altering blood glucose and cholesterol concentrations (Anderson et al., 1999; Jenkins et al., 1978, 2000). Fiber sources that are slowly, incompletely, or essentially not fermented in the large intestine provide bulk and therefore optimize laxation (Birkett et al., 1997; Cummings, 1997). These two physicochemical properties, viscosity and fermentability, are recommended as meaningful alternative characteristics for the terms soluble and insoluble fiber to distinguish Dietary Fibers and Added Fibers that modulate gastric and small bowel function from those that provide substantial stool bulk. It is recommended that the terms soluble and insoluble fiber be phased out and replaced with the appropriate physicochemical property as the characterization of the properties of various fibers becomes standardized.