Date of Award
Doctor of Philosophy
Food Science and Human Nutrition
Resistant starches (RS) are complex partly indigestible carbohydrates that have shown promise in improving digestive health, lowering postprandial blood glucose (PPG) and insulin (PPI) concentrations among other beneficial health effects. There are four types of RS and a fifth type is emerging; although there is very little experimental data on the physiological responses of RS type V. Three experiments were constructed to test the overarching hypothesis that RS (type II and V) can favorably impact human physiological responses of PPG, PPI, and microbial fermentation in the colon with minimal gastrointestinal distress. Two of the three experiments were randomized blind crossover human feeding studies. Study one, restricted to PPG response, was conducted using conventional and novel crossbred corn starches (type II) fed to 11 participants in pudding product. Study two investigated the effects of stearic acid-modified RS and its parent high amylose starch in crackers on PPG, PPI, and microbial fermentation in 30 participants. The third experiment was an in vitro batch-fermentation of human fecal microbiota from lean and obese individuals. Short chain fatty acids (SCFA) fermentation patterns and shifts in pH were assessed with RS type V, type IV, and type II starch residues (SR) inoculated in brain heart infusion broth, brain heart infusion broth without dextrose, and a basal nutrient growth medium. Overall in vivo results supported the use of RS type II and type V to lower PPG, RS type II to lower PPI, and for type II and V to be more fermentable than type II, based on breath hydrogen production at 8 h after RS intake. Both types of RS were very well tolerated by participants based on gastrointestinal symptom scores after RS-containing meals. In vitro analysis of RS types V and II in anaerobic human fecal batch fermentations showed no differences in SCFA fermentation according to body mass index (BMI) of fecal donors or SR type. More investigation on the fermentability of RS type V is needed, but so far results support the role of both types of starches in lower PPG with favorable implications for people with diabetes and metabolic syndrome.
Haugabrooks, Esther, "Evaluating the use of resistant starch as a beneficial dietary fiber and its effect on physiological response of glucose, insulin, and fermentation" (2013). Graduate Theses and Dissertations. 13625.