POLYPHENOLS AS DIETARY FIBER ASSOCIATED COMPOUNDS - COMPARATIVE-STUDY ON IN-VIVO AND IN-VITRO PROPERTIES

A comparative study between dietary fiber (DF) and polyphenols (PP) in terms of degradability and physiological properties was performed. Eight groups of Wistar rats were fed either a control diet free of DF and PP or diets containing DF constituents [cellulose (C), pectins (P), and lignin (L)] or PP, both soluble [catechin (CA) and tannic acid (TA)] and insoluble [condensed tannins (CT)]. A significant increase in the total stool output and in the water and fat content of feces was observed. Protein digestibility was significantly reduced. Intestinal degradation of the soluble compounds (P, CA, and TA) was almost complete. C was partially digested; L and CT were highly resistant. In vitro fermentation assays were performed, showing the different susceptibilities of the DF constituents and the polyphenolic compounds to fermentation and the inhibitory effect of TA and L on colonic microflora.