Document Type

Thesis - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Health and Nutritional Sciences

First Advisor

Igor Sergeev


Targeting gut microbiota with diet, prebiotics, and probiotics are emerging as a promising intervention in the comprehensive nutritional approach to reducing obesity and metabolic disorders. Recent human and animal studies suggest that such intervention can promote health benefits by influencing the aspects of metabolism and immunity. However, study of the multi-role association between the diet, the host and the microbiota remains to be clarified. My dissertation attempts to clarify the problem of how gut microbiota (taxonomic composition and predicted functional capacities) affects obesity and metabolic disorders.
In chapter 2, I conducted a placebo-controlled intervention clinical trial to evaluate effects of a synbiotic supplement containing Bifidobacterium and Lactobacillus strains on the human gut microbiota in relation to changes in body composition and metabolic biomarkers in obesity, followed the weight loss program eating plan (a lowcarbohydrate, high-protein dietary pattern with reduced energy intake). The results obtained and bioinformatic analysis support the conclusion that the synbiotic supplement used in this study modulates the human gut microbiota by increasing abundance of beneficial microbial genera and that the supplement may also have beneficial effects on metabolic parameters in obesity.
In chapter 3, I characterized the effect of dairy products (cow, goat, and camel milk and fermented cheese and yogurt originated from cow milk and containing the wellestablished probiotic Clostridium butyricum) on taxonomic composition and relative abundance of the mouse gut microbiota and body weight. The results obtained and their bioinformatics analysis appear to support the conclusion that camel milk and the probiotic cow cheese induce changes the mouse gut microbiota, which are associated with the optimal weight gain in growing mice.
In chapter 4, I evaluate the effect of food at home (FAH) and food away from home (FAFH) diets on human gut microbiota. Substantial work has been done to study whether the FAH diet-induced microbial and immunity changes can protect mice against diabetes. The results obtained and their analysis suggest that the FAH can help to reduce risk of developing diabetes by increasing abundance of potentially beneficial microbial species, T regulatory cells, and decreasing IL-17 producing cells and blood glucose levels.
This dissertation explores a scope of studies on the effects of diet on gut microbiota and health outcomes including obesity and metabolic disorders taking into perspective diets such as food at home, dairy products, high-protein, low-carbohydrate, prebiotic and probiotic. The main outcome of our studies is identification of an effective and novel approach for the prevention and treatment of obesity and metabolic disorders that is based on modulating the human/mouse gut microbiota and increasing abundance of the microbial species that can be considered to be of benefit to their immune system and host.

Library of Congress Subject Headings

Gastrointestinal system -- Microbiology.
Obesity -- Prevention.
Obesity -- Treatment.
Metabolism -- Disorders -- Prevention.
Metabolism -- Disorders -- Treatment.



Number of Pages



South Dakota State University



Rights Statement

In Copyright