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Permanent link (DOI): https://doi.org/10.7939/R3GQ6R72X

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Blood Glucose-attenuating Effects of Pea-derived Fractions: Exploration of Mechanisms of Action in a Rat Model of Glucose Intolerance Open Access

Descriptions

Other title
Subject/Keyword
Incretins
Glucagon
Insulin resistance
Gut microbiota
Glycemia
Pulse grains
Pancreatic islets
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Hashemi, Seyede Zohre
Supervisor and department
Chan, Catherine B. (Agricultural, Food, and Nutritional Science/Physiology)
Examining committee member and department
Vine, Donna (Agricultural, Food, and Nutritional Science)
Boulé, Normand (Physical Education and Recreation)
Department
Department of Agricultural, Food, and Nutritional Science
Specialization
Nutrition and Metabolism
Date accepted
2015-08-14T10:30:51Z
Graduation date
2015-11
Degree
Doctor of Philosophy
Degree level
Doctoral
Abstract
Pulses, including dried peas, are nutrient-dense foods rich in fibre that have shown efficacy in improving glucose control in diabetic subjects. The seed coats, in spite of being the highly fibrous part, are sometimes discarded as a food-processing by-product. We hypothesized that supplementing high fat diets (HFD) with pea seed coats (PSC) would improve glucose tolerance mainly by modifying gut responses to glucose and reducing HFD-induced stress on pancreatic islets. A secondary hypothesis was that the glucose-lowering effects of these fractions would be retained following cooking. HFD-induced glucose intolerant Sprague Dawley rats were fed a HFD supplemented with raw or cooked PSC for 4 weeks. HFD and low fat diet with inclusion of cellulose as the fibre source were used as control diets. The results showed that, compared to HFD, cooked PSC diet improved glucose response, decreased postprandial insulin secretion and enhanced fasting GLP-1 and GIP response to glucose. Cooked PSC feeding also decreased fasting glucagon, which was associated with reduced alpha-cell mass. Microbial analysis revealed that PSC diets significantly altered the overall composition of gut microbiota and resulted in increased population of Lachnospiraceae, a butyrate-producing family of bacteria. Additionally, cooked PSC was found to increase the expression of mRNA encoding mucin proteins in the ileum and induce a trend toward decreased expression of ileal TLR2. The effect of pea/bean consumption on the B vitamin status was examined in normoglycemic humans, showing that blood concentrations of thiamine and folate were not affected by pulse-containing diets. Overall, our results demonstrated that cooked PSC feeding can reverse adverse effects of HFD on glucose homeostasis via gut- and islet-mediated mechanisms. In particular, cooked PSC feeding is associated with enhanced incretin secretion, reduced alpha-cell abundance and glucagon concentrations, beneficial alterations in the gut microbiota and finally up-regulated expression of protective genes involved in gut barrier function. The higher effectiveness of the cooked PSC as compared to raw PSC showed that cooking treatment enhanced beneficial impacts of these components on glucose homeostasis.
Language
English
DOI
doi:10.7939/R3GQ6R72X
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Hashemi, Z., Yang, K., Yang, H., Jin, A., Ozga, J., & Chan, C. B. (2015). Cooking enhances beneficial effects of pea seed coat consumption on glucose tolerance, incretin, and pancreatic hormones in high-fat-diet-fed rats. Applied Physiology, Nutrition, and Metabolism = Physiologie Appliquee, Nutrition Et Metabolisme, 40(4), 323-333.

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