Effect of polydextrose on intestinal microbes and immune functions in pigs

Abstract

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.

Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats

“…SCFAs are implicated in lipid and protein metabolism, colonic health, and immunity, suggesting that gut microflora may modulate host immune status through fermentation of dietary fiber to SCFAs (13). Polydextrose (PDX) and lactitol are fermentable peptic carbohydrates known to increase SCFA production (14,15,16). PDX, a synthetic oligosaccharide containing in average 12 randomly polymerized glucose units, is a commercially available dietary fiber widely used as a multi-purpose food supplement (14), while lactitol is a non-absorbable sugar alcohol produced industrially by lactose hydrogenation (16,17).…”

Polydextrose in Lipid Metabolism

“…Polydextrose has been reported to confer lipid modulating effects in human clinical intervention studies, as well as in animal studies. However, some of the characteristics of polydextrose are different to other soluble fibers, such as low viscosity, and sustained fermentation throughout the colon [11].…”

“…Fecal SCFA concentration measurements are not the best indicators of SCFA produced as the majority of fecal SCFA is absorbed rapidly by the colonic epithelial cells [99]. Polydextrose has been observed to increase the production of butyrate, acetate and propionate in vitro [18,[100][101][102], in rats [20], pigs [11], in dogs [103] and in humans [17,49]. When compared to other fibers, polydextrose produced similar quantities of SCFAs, and the molecular ratio of acetate/propionate/butyrate produced was found to be similar to that of fructo-oligosaccharides and xylo-oligosaccharides and other carbohydrates, such as inulin, pectin, and arabinose [104,105] while in other studies polydextrose produced less total SCFAs compared to FOS, inulin and GOS [102,106,107].…”

“…The lower production of SCFAs by polydextrose can be explained by the lower digestability of polydextrose and its more sustained fermentation throughout the gut due to its branched complex structure. Furthermore, polydextrose fermentation has been shown to reduce putrefactive microbial metabolites, or branched-chain fatty acids and biogenic amines produced from protein fermentation [11,20,49,100,101,[107][108][109] but the decrease of these in relation to lipid metabolism and absorption is unknown. Figure 2 shows an example of how fermentation of polydextrose increases the amount short chain fatty acids in an in vitro colon simulation both when the amount of polydextrose is increased, and when the simulation proceeds from vessel V1 representing proximal part of the colon towards the vessels representing more distal parts of the colon [108].…”

“…It is a branched molecule, and contains all different combinations of -and -linked 12, 13, 14 and 16 glycosidic linkages ( Figure 1) [7,8]. As polydextrose is only partially digested during gastrointestinal transit, it acts as a substrate for saccharolytic fermentation throughout the colon, even to the distal parts [9][10][11][12]. Polydextrose has a low caloric value: about 1 kcal/g, and it is widely used as a bulking agent and to replace the structure and texture of sucrose in low-calorie products by the food industry in confectionery applications, in pastry and bread, in dairy products, meat products, pasta and noodles, and in beverages [7,13].…”