Shearer, JaneHartslief, Micaela2024-12-092024-12-092024-12-05Hartslief, M. (2024). Early life dairy exposure: influence on the gut microbiota and obesity susceptibility (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/120181Childhood obesity rates are increasing at a detrimental trajectory, leading to a serious health epidemic with related comorbidities that are likely to persist into adulthood (1,2). The causes of obesity are complex and influenced by a multitude of factors including diet, genetics and more recently dysbiosis of the gut microbiota (3,4). The gut microbiota is comprised of microorganisms residing in the gut, that have the ability to produce physiologically active substances such as vitamins and short-chain fatty acids and provide various health benefits through immune system regulation and removal of toxins (5). Mounting evidence suggests that dairy may play a protective role in obesity partially mediated through positive modulation of the gut microbiota (6,7). This study examined the role of dairy proteins, casein, whey and complete dairy (skim milk powder), and a plant-based alternative, soy, on gut microbiota composition, obesity susceptibility and insulin sensitivity. At weaning, 3-week-old pups (p=85), were randomized into 4 dietary protein intervention groups for 4-weeks: 1) complete dairy; 2) casein; 3) whey; 4) soy followed by a 5-week high-fat high-sucrose (HFHS) dietary challenge with the same proteins maintained. Microbial and metabolic outcomes assessed in this study included fecal microbial analysis (16s rRNA sequencing), body composition (NMR), glucose tolerance and insulin sensitivity. Dairy proteins compared to soy largely altered gut microbial profiles fostering improved metabolic function and enhanced insulin sensitivity. The impact on gut microbiota and metabolic results was protein dependent whereby early exposure to complete dairy demonstrated the most promising results improving body fat percentage and glucose tolerance while enriching beneficial probiotic microbial taxa, Lactobacillus in males while increasing Akkermansia in females. In contrast, following 5-week exposure to HFHS, there were limited differential effects on obesity, adiposity, sex hormones and glucose tolerance. Gut microbial profiles following HFHS dairy consumption, largely increased Bifidobacterium in males and maintained the increase of Akkermansia in females, however reduced alpha diversity. Taken together, dairy proteins play a significant role in positively modulating gut microbial profiles in a normal fat diet, fostering beneficial effects on body composition and glucose homeostasis.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Gut MicrobiotaDairy ProteinObesityInsulin ResistanceNutritionmaster thesis