Comparison of the Effects of Longer Chain Inulins with Different Degrees of Polymerization on Colonic Fermentation in a Mixed Culture of Swine Fecal Bacteria

Abstract

The complex human large bowel microbiome is critical for health and its growth and metabolic activity is highly dependent on substrate availability (1, 2). Quantitatively, the major carbon and energy sources are nondigestible dietary carbohydrates (fiber), undigested proteins and host mucopolysaccharides (3,4). The main fiber carbohydrates are non starch polysaccharides (NSP) and resistant starches (RS) which are fermented to short-chain fatty acids (SCFAs) leading to a lowering of pH, which is thought to protect against the absorption of cytotoxic and genotoxic bacterial products. Of the three major SCFAs, acetate, propionate and butyrate, the last is thought to be especially important for the maintenance of optimal colonic function and protection against serious large bowel disease in the long term.Recently, inulin-type fructans (b-(2,1)-linked fructosyl residues) have attracted industrial and scientific attention. These fiber components are produced mostly from chicory roots and are fermented extensively by the large bowel microbiome. Fructans are classified to their degree of polymerization (DP) as oligofructose (average DP of 4, ranging from 2 to 8) or longer chain inulins (average DP10, ranging from 2 to 60). The latter are subdivided into granulated inulin (GR; average DP of 10, ranging from 2 to 60), and high-performance inulin (HP; average DP of 24, ranging from 10 to 60) as well as Synergy 1, a specific 1 : 1 mixture of oligofructose and the HP-inulin. It has been established that both the rate and end products of gut microbial fermentation of fructans are affected profoundly by DP (5, 6). Short-chain saccharides are likely to be fermented more rapidly than longer ones (7,8). Previously we have shown in rats that an inulin-type fructan (inulin-Tokachi, average DP of 15, range 2-60) was fermented throughout the colon more slowly than inulin-GR (average DP of 10) but faster than inulin-HP (average DP of 24) (9). This difference translated to in differences in the number of colonic microbial species and hypolipidemic response (9). Summary The effects of inulin with three different degrees of polymerization (DP) on microbial dietary fiber fermentation were compared in an in vitro simulator of the porcine large bowel. The three inulin isolates had a DP of 15 (from chicory grown in Hokkaido, Japan), and 10 and 24 (from Orafti, Belgium), while cellulose was used as a control. The Lactobacillus level in the DP 10 group at 48 h and bifidobacteria levels in the DP 15 and DP 24 groups at 24 and 48 h were significantly higher than in the carbohydrate-free and cellulose groups. The SCFA concentrations in all the inulin groups were significantly higher than in the carbohydrate-free and cellulose groups at 24 and 48 h. Ammonia nitrogen concentrations in all the inulin groups were significantly lower than those in the carbohydrate-free and cellulose groups at 24 and 48 h. The three different inulin types were fermentable by gut microbiota as indicated by substantial increases in SCFA. In particular, inulin DP 15 exhi...

The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides

“…Although it is possible that the increase in body and submandibular gland tissue might affect the duration of FOS feeding time, our results strongly suggest that ingestion of FOS increased salivary IgA secretion by high levels of SCFA in the large intestine. Since ingestion of FOS increases SCFA levels in the large intestine at short (e.g., 12 h) and long times (e.g., 27 weeks) [44,45], continuous ingestion of FOS is expected to increase IgA levels in the large intestine of humans.…”

Effect of diets varying in the type of dietary fibre and its combination with polyphenols on gut function, microbial activity and antioxidant status in rats

“…The mechanism responsible for dietary effects of OLIOGOF may be related to stimulation of bacterial growth (especially bifidobacteria). Such changes within the gut microflora may promote both colonic and systemic health (Han et al, 2014). Oligofructose can be rapidly and completely fermented by the colonic microflora with the production of acetate and other SCFA.…”

“…It is plausible, that the latter was related to the increased accumulation of digesta in the caecum. Indeed, the chicory products, and other products that contain prebiotic fructans, oligofructose and inulin, were shown to exert a stimulatory effect on gastrointestinal bacteria and SCFA production (Louis et al, 2007;Han et al, 2014).…”

Genome of Bifidobacteria and Carbohydrate Metabolism

“…A recent study ( Stiverson et al ., 2014 ) demonstrated that a commercial formulation of long chain inulin (Beneo® Synergy 1) exerted a bifidogenic effect by increasing total bifidobacteria and more specifically B. longum in infant microbiota. A study performed with pig fecal microbiota showed that long chain inulin increased total bifidobacteria ( Han et al ., 2014 ). In this study, it was suggested that animal bifidobacterial strains were better able to metabolize inulin than human strains, especially long chain inulin (Average DP of 25).…”