British Journal of Nutrition

Full Papers

Effect of polydextrose on intestinal microbes and immune functions in pigs

Francesca Favaa1, Harri Mäkivuokkoa2, Hilkka Siljander-Rasia3, Heli Putaalaa2, Kirsti Tiihonena2, Julian Stowella4, Kieran Tuohya1, Glenn Gibsona1 and Nina Rautonena2 c1

a1 Food Microbial Sciences Unit, School of Food Biosciences, University of Reading, Reading, RG6 6BZ, UK

a2 Danisco Innovation, EnteroMix™ Research, Sokeritehtaantie 20, FIN-02460 Kantvik, Finland

a3 MTT Animal Production Research, Tervamäentie 179, FIN-05840 Hyvinkää, Finland

a4 Danisco Sweeteners, 41-51 Brighton Road, Redhill, RH1 6YS, UK


Dietary fibre has been proposed to decrease risk for colon cancer by altering the composition of intestinal microbes or their activity. In the present study, the changes in intestinal microbiota and its activity, and immunological characteristics, such as cyclo-oxygenase (COX)-2 gene expression in mucosa, in pigs fed with a high-energy-density diet, with and without supplementation of a soluble fibre (polydextrose; PDX) (30 g/d) were assessed in different intestinal compartments. PDX was gradually fermented throughout the intestine, and was still present in the distal colon. Irrespective of the diet throughout the intestine, of the four microbial groups determined by fluorescent in situ hybridisation, lactobacilli were found to be dominating, followed by clostridia and Bacteroides. Bifidobacteria represented a minority of the total intestinal microbiota. The numbers of bacteria increased approximately ten-fold from the distal small intestine to the distal colon. Concomitantly, also concentrations of SCFA and biogenic amines increased in the large intestine. In contrast, concentrations of luminal IgA decreased distally but the expression of mucosal COX-2 had a tendency to increase in the mucosa towards the distal colon. Addition of PDX to the diet significantly changed the fermentation endproducts, especially in the distal colon, whereas effects on bacterial composition were rather minor. There was a reduction in concentrations of SCFA and tryptamine, and an increase in concentrations of spermidine in the colon upon PDX supplementation. Furthermore, PDX tended to decrease the expression of mucosal COX-2, therefore possibly reducing the risk of developing colon cancer-promoting conditions in the distal intestine.

(Received June 05 2006)

(Revised January 08 2007)

(Accepted January 10 2007)


c1 *Corresponding author: Dr Nina Rautonen, fax +358-9-2982203, email


Abbreviations: COX, cyclo-oxygenase; FISH, fluorescent in situ hybridisation; G+C, guanine+cytosine; GI, gastrointestinal; PDX, polydextrose