Andrew J Hoffman

University of Saskatchewan, Saskatoon, Saskatchewan, Canada

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Publications (2)2.91 Total impact

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    ABSTRACT: To investigate the effect of 5 newly developed maize-based fibers on the activity and composition of the microbiota in the colon. The fibers tested were glucose-based and had variable structures, including 2 resistant starch preparations, soluble corn fiber, pullulan, and soluble fiber dextrin. The fibers were predigested, mono- and disaccharides were removed, and the residual polymer was used to assess the production of microbial metabolites and changes in composition of the microbiota using a dynamic, validated, in vitro model of the large intestine. Microbial metabolite analysis showed an increase in short-chain fatty acids for all fibers, with varying levels of butyrate production for each fiber. The greatest increase of butyrate, both in terms of absolute amounts and as a proportion of total short-chain fatty acids, was observed for pullulan. All fibers also reduced toxic metabolites from protein fermentation compared to the poorly fermentable control (cellulose). Microbial composition was assessed using a micro-array platform. All fibers showed increases of bifidobacteria and some Lactobacillus species, although different species were stimulated by different fibers. Pullulan showed the largest increase of bifidobacteria. All fibers showed prebiotic activity in terms of increases in growth and/or activity of beneficial microbes. In addition, compared to the control, health-promoting metabolites were produced in higher amounts, while putrefactive metabolites were reduced for all fibers. The importance of the findings lies in the fact that the newly developed, maize-based fibers shift the intestinal environment to a healthier milieu, with increased health-promoting metabolites and health-beneficial microbes.
    No preview · Article · Dec 2009 · Journal of the American College of Nutrition
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    ABSTRACT: Postprandial hyperglycemia has been associated with increased oxidative stress and the development of diabetes, heart disease and all-cause mortality. To assess the effect of novel maize-based dietary fibers on postprandial glycemia and to assess the correlation between a rapid in vitro digestibility system and the blood glucose response. In a clinical study, 12 healthy volunteers were fed seven test beverages containing maize-based fiber ingredients (25g total carbohydrate) along with 2 control meals on separate occasions in random order. Capillary blood samples were obtained and the relative glycemic and insulinemic responses were assessed by calculating the incremental area under the 2 h blood response curves. In vitro digestibility studies of the test fibers and control were also undertaken to determine if these correlated with the clinical findings. All test fibers resulted in significantly lower glycemic and insulinemic responses for the incremental area under the curve (iAUC) and at all time points compared with the control (P < 0.05). The in vitro digestibility curves were comparable to the cumulative in vivo iAUCs. In vitro data expressed as percent digestion correlated significantly with the in vivo iAUC for the first 30min of the test meal (P < 0.05). These novel maize-based dietary fibers all produce lower postprandial glycemic and insulinemic responses than the control. While further assessment is necessary in beverage and foods containing these fibers, they may be effective in applications for dietary strategies to control diabetes and other chronic diseases. In addition, the in vitro digestibility assay correlated well with in vivo data and may be useful in guiding product development.
    No preview · Article · Dec 2008 · Journal of the American College of Nutrition