title: Effects of dietary fibre and tannins from apple pulp on the composition of faeces in rats.
abstract: The present study was undertaken to explore the effect of apple pulp on weight and composition of faeces. This material is rich in dietary fibre (DF; 620 g dry matter/kg) and contains appreciable amounts of polyphenols. Recent reports indicate that both condensed tannins (CT) and soluble polyphenols form cross-links with protein and inhibit digestive enzymes, affecting the protein digestibility, and may produce a stimulation of endogenous nitrogen excretion. Two groups of male Wistar rats were fed on either a control diet free of DF or a diet containing 100 g apple pulp DF/kg during 7 d after a 4 d adaptation period. Body-weight and food intake were monitored daily and faeces and urine were collected once daily. DF, water content and polyphenolic compounds were measured in faeces, and N content in both faeces and urine. Faecal weight increased in the fibre group by 280 and 240% when compared with wet and dry faecal weights of animals fed on the fibre-free diet. Soluble dietary fibre (SDF) excreted in faeces was 10.9% of the SDF ingested, which suggested a low resistance to fermentation of this fraction. Of the insoluble DF, 43% of the ingested fibre was fermented. Polyphenols were degraded in the intestinal tract. Of the ingested CT, 68.6% was recovered in faeces, while the soluble polyphenols were extensively degraded (85.7% of that ingested). On the other hand, a higher faecal N excretion was observed for the fibre-fed group, suggesting a decrease in the digestibility of the dietary protein and lower apparent digestibility of the dietary protein and lower apparent digestibility and N balance indices.
authors.affiliation: Instituto de Nutricion y Bromatologia, CSIC-UCM, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Bravo
authors.forename: F
authors.initials: F
authors.lastname: Saura-Calixto
authors.forename: I
authors.initials: I
authors.lastname: Goni
mesh_terms: D000818:Animals; D001835:Body Weight; D004043:Dietary Fiber / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism; D005243:Feces / Q000737:chemistry*; D005285:Fermentation / Q000502:physiology; D005419:Flavonoids; D005638:Fruit / Q000378:metabolism*; D008297:Male; D009584:Nitrogen / Q000032:analysis; D010636:Phenols / Q000378:metabolism; D011108:Polymers / Q000378:metabolism; D059808:Polyphenols; D051381:Rats; D011919:Rats, Inbred Strains; D013634:Tannins / Q000378:metabolism*; D014867:Water / Q000032:analysis
chemical_list: D004043:Dietary Fiber; D004044:Dietary Proteins; D005419:Flavonoids; D010636:Phenols; D011108:Polymers; D059808:Polyphenols; D013634:Tannins; D014867:Water; D009584:Nitrogen