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Title: The role of plant-based food structures on gastrointestinal digestion, colonic fermentation and glucose homeostasis
Author: Petropoulou, Aikaterini
ISNI:       0000 0004 7969 9124
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2019
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Evidence suggests that dietary resistant starch (RS) has a positive impact on controlling blood glucose levels possibly via increased colonic fermentation and production of short chain fatty acids (SCFA), and hence reducing susceptibility to T2D. Naturally occurring mutations of plants lacking the starch branching enzyme (SBE) result in lower digestible carbohydrate content and higher amounts of RS delivery to the colon (Bhattacharyya et al., 1990). Drawing on insights from basic plant science and genetics, this thesis aimed to improve our understanding of how the consumption of differently processed plant-based foods leads to physiological effects associated with health benefits. Wild type (RR) peas were used as the control and mutant (rr) peas as the intervention group. The effect of further processing and associated health outcomes was studied using and comparing pea flour and pea derived products from both genotypes (RR and rr). Study 1 investigated the effect of peas and pea flour on gastric emptying (GE) and acute glycaemia. GE analysis showed no differences between RR and rr peas or peas flour. However, analysis indicated different glucose kinetics. The rr genotype exhibited significantly lower glucose concentrations as opposed to the RR genotype. Study 2 investigated the effect of peas and pea flour on gastric and small intestinal digestion. Metabolomic profiling indicated different digestion patterns between the two genotypes: different glucose related biomarkers outcomes were observed with the rr genotype exhibiting lower concentrations. Study 3 investigated the effect of peas and pea flour consumption on colonic fermentation. The rr genotype significantly increased the production of SCFAs propionate and butyrate. Study 4 investigated the effect of 28 days of RR and rr pea derived products consumption on glucose homeostasis via a gut dependent mechanism. Glucose homeostasis parameters were not improved despite changes in gut microbiota composition between or within groups. The physico-chemical characteristics of the rr genotype coupled with limited starch digestibility (high RS content) had the greatest impact on lowering postprandial blood glucose in the acute studies. Changes in gut microbiota are a consequence of lower carbohydrate digestion in the small intestine and increased delivery of RS to the colon and did not alter glucose homeostasis biomarkers over 4 weeks of consumption.
Supervisor: Frost, Gary ; Chambers, Edward Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral