Sa2055 Comparison of Fermentation and Fecal Microbiota Profiles of Wheat Dextrin, Inulin and Partially Hydrolyzed Guar Gum Using an In Vitro Digestion Pretreatment and In Vitro Batch Fermentation System Model

Abstract

Objective: Fiber supplements may increase fiber intake for those unable to reach recommended amounts through the diet. Colonic microbiota ferment fibers, producing metabolites such as short chain fatty acids (SCFAs) and gases. SCFAs and low colonic pH provide potential health benefits; however excess gas has decreased tolerance In Vivo. Fiber source influences fermentation rates and physiological effects. This study compared fermentation and microbiota profiles of three dietary fibers after digestion with salivary amylase and pepsin to mimic physiologic fermentation and to predict physiological benefits and tolerance In Vivo. Methods: Wheat dextrin (WD), inulin, and partially hydrolyzed guar gum (PHGG) underwent In Vitro digestion and fermentation. Each fiber (0.5 g) was fermented in triplicate including a control group with no fiber for 0, 4, 8, 12, and 24 h and was used for analysis of pH, gas volume, hydrogen and methane gases, and SCFA concentrations. Quantitative PCR was used to measure bifidobacteria and lactobacilli CFUs at 24 h. Data analysis was completed using an ANOVA procedure by SAS. Statistical significance was achieved when P-value < 0.05. No statistical analysis was done on microbiota results due to small sample size. Summary of Results: WD produced the least volume of gas during fermentation at 8, 12, and 24 h (P < 0.0001), while inulin produced the most at 8 h (P < 0.0001). Inulin reached its lowest pH value at 8 h (5.94 ± 0.05), PHGG at 12 h (5.98 ± 0.02), and WD at 24 h (6.17 ± 0.05). SCFA concentrations were not different, however differences in the proportion of SCFAs produced were observed at 24 h. Inulin andWD had a larger proportion of acetate (30% and 29% respectively), compared to PHGG (23%) (P < 0.0001). Propionate proportion from PHGG (53%) was larger than WD (48%) and inulin (33%) (P < 0.0001). Butyrate proportion from inulin (37%) was higher than PHGG (24%) and WD (23%) (P < 0.0001). A preliminary microbial analysis (CFU log 10/uL) showed WD with the largest CFU for bifidobacteria (6.12) and lactobacilli (7.15) compared with the control (4.92 and 6.35 respectively). Conclusions: Fermentation of WD produced less gas than inulin or PHGG, which may lead to better tolerance In Vivo. The fibers produced different proportions of acetate, propionate and butyrate and fecal pH values. Through the 24 h, pH values for WD consistently declined. Decreases in colonic pH may promote growth of beneficial bacteria. Butyrate is known to be a beneficial fuel source for colonocytes. The increased levels of bifidobacteria and lactobacilli suggest possible prebiotic effects that warrant further investigation. More research is required to determine the physiological benefits and tolerance of these fibers In Vivo. This study was supported by a research grant from Novartis Consumer Health Inc. Parsippany, New Jersey, USA.