Dietary Reference Intakes Proposed Definition of Dietary Fiber (2001) / Chapter Skim
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III. Issues in Defining Dietary Fiber
III. Issues in Defining Dietary Fiber
Pages 12-21
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From page 12... ...
Currently in the United States, but not in Canada, if these products assay as fiber by accepted methods, they are included as part of the total fiber content of foods. Fur~ermore, Were are few data from human studies comparing animal-based with plant-based fibers using physiological endpoints.
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From page 13... ...
Quantitation of fructans will be incomplete, even if the constituent monosaccharides of fructans are measured by a procedure that does not include ethanol precipitation, because the fructose component of fructans is labile in many acid hydrolysis procedures used during fiber analysis. Furthermore, fructose can be reduced to sorbitol and mannitol during preparation of derivatives for gas chromatographic analysis.
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From page 14... ...
, 2000 Hignett, 2000 (U.K. Yes Some inulin No Food Standards Agency)
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From page 15... ...
PROPOSED DEFINITION OFDIETARY FIBER 15 Intact, Naturally Resistant to Specifies Occurring Food Human En- Physiologi Lignin Resistant Starch Sources Only zyrnes cat Effect Yes Not considered Not specifically Yes No listed Yes Not specifically Yes Yes No listed Yes Some No No No Yes No Yes Yes No Implied Implied No Implied No Yes Yes No Yes No Yes Yes No Yes No Yes Yes No Yes No Yes Some No Yes No Yes Yes No Yes No Yes Some No No No Yes Some No No No No No No No No Yes Some Implied Implied No Yes Some No No No Yes Some No No No Yes Yes No Yes Yet Yes Some No No No continued
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From page 16... ...
Furthermore, although lignin is present in the human food supply in very small amounts, animal research with high fiber feeds has shown that lignin affects the physiological effects of dietary fiber. For exan~le, lignin hinders fermentation of fiber polysaccharides in ruminants (Titgemeyer et al., 1991~.
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From page 17... ...
Resistant starch resulting from normal processing of a foodstuff is a more modest contributor to a typical daily intake. Starches specifically manufactured to be resistant to endogenous human digestion are a rapidly growing segment of commercially available resistant starches.
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From page 18... ...
In some instances, fibers isolated from plants or manufactured chemically or synthetically have demonstrated more powerful beneficial physiological effects than a food source of the fiber polysaccharide; in other instances, isolation from the plant matrix decreases physiological benefit. Specificity of the various dietary fiber definitions with respect to non- or undigestibilty of the material vanes among definitions (Table 3~.
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From page 19... ...
By comparing effects of many different fiber sources, it has become apparent that those fibers that are slowly, incompletely, or not fermented significantly increase stool output; these fibers usually analyze as insoluble fibers and contrast with soluble fibers, most of which are rapidly fennented. Correlational epidemiological evidence suggests a relationship between dietary fiber intake and colon cancer incidence (frock et al., 1990)
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From page 20... ...
Although intervention trials suggest an ability of fiber to reduce blood estrogen concentration, which is a risk factor for the development of breast cancer (Rose et al., 1991) , data are not sufficient to suggest that high fiber diets lower breast cancer risk.
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From page 21... ...
However, what data exist on the physiological differences seen when polymeric chain length and viscosity are reduced suggest that the glycemic and cholesterollowering effects of fiber may be reduced or lost (Favier et al., 1997; Jenkins et al., 1978; Lund et al., 1989; Wood et al., 1994~. Therefore, the advantages of improved palatability and ease of use must be weighed against potential loss of physiological effect for fibers that have a shorter chain length and reduced viscosity.
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