cose in legumes, and the low molecular weight fructans in foods, such as Jerusalem artichoke and onions.
Added Fiber consists of isolated or extracted nondigestible carbohydrates that have beneficial physiological effects in humans. Added Fibers may be isolated or extracted using chemical, enzymatic, or aqueous steps. Synthetically manufactured or naturally occurring isolated oligosaccharides and manufactured resistant starch are included in this definition. Also included are those naturally occurring polysaccharides or oligosaccharides usually extracted from their plant source that have been modified, for example to a shorter polymer length or to a different molecular arrangement. Although it has been inadequately studied, animal-derived carbohydrates such as connective tissue are generally regarded as nondigestible. The fact that animal-derived carbohydrates are not of plant origin forms the basis for including animal-derived, nondigestible carbohydrates in the Added Fiber category. Isolated, manufactured, or synthetic oligosaccharides of three or more degrees of polymerization are considered to be Added Fiber. Nondigestible monosaccharides, disaccharides, and sugar alcohols are not considered to be Added Fiber because they fall under “carbohydrates” on the food label.
Nondigestible carbohydrates are frequently isolated to concentrate a desirable attribute of the mixture from which it was extracted. Distinguishing a category of Added Fiber allows for the desirable characteristics of such components to be highlighted. In the relatively near future, plant and animal synthetic enzymes may be produced as recombinant proteins, which in turn may be used in the manufacture of fiber-like materials. The definition will allow for the inclusion of these materials and will provide a viable avenue to synthesize specific oligosaccharides and polysaccharides that are part of plant and animal tissues.
Three established physiological effects of Added Fibers are recognized at this time as beneficial to human health. These are attenuation of postprandial blood glucose concentrations, attenuation of blood cholesterol concentrations, and improved laxation. Rapidly changing lumenal fluid balance resulting from large amounts of nondigestible mono- and disaccharides or low molecular weight oligosaccharides, such as what occurs when sugar alcohols are consumed, is not considered a mechanism of laxation for Added Fibers.
Nondigestible carbohydrates may influence specific aspects of immune function, particularly since the small intestine embodies quantitatively the largest proportion of immune tissue in mammals (Kelly and Coutts, 2000; McKay and Perdue, 1993). Furthermore, nearly all fibers are fermented to some extent, producing short-chain fatty acids for which a variety of physiologic roles are being identified (Bugaut and Bentejac, 1993; Fleming and Yeo, 1990; Mortensen and Clausen, 1996). However, insufficient data and a lack of consistency in available experimental results limit recognition of some beneficial physiological effects