Omega-3 fatty acids, gut microbiota and associated inflammatory outcomes

dc.check.opt-outNot applicableen
dc.check.reasonThis thesis is due for publication or the author is actively seeking to publish this materialen
dc.contributor.advisorStanton, Catherineen
dc.contributor.advisorRoss, R. Paulen
dc.contributor.advisorFitzgerald, Gerald F.en
dc.contributor.authorRobertson, Ruairi C.
dc.contributor.funderDepartment of Agriculture, Food and the Marineen
dc.contributor.funderMarine Instituteen
dc.contributor.funderEnterprise Irelanden
dc.description.abstractThe overall aim of this thesis was to investigate the potential of omega-3 polyunsaturated fatty acids (n-3 PUFA), particularly from algal sources, as regulators of gut microbiota development, behaviour and associated inflammatory and metabolic outcomes. In chapter 2, omega-3 supplemented (O3+), omega-3 deficient (O3-) and control diets were compared for their effect on behaviour and gut microbiota development in both adolescence and adulthood. O3- impaired communication, social and depressionrelated behaviours, whereas O3+ enhanced cognition. These behavioural changes were associated with alterations to gut microbiota composition and inflammatory outcomes such that O3- mice displayed an elevated Firmicutes:Bacteroidetes ratio and blunted systemic LPS responsiveness. Contrastingly, O3+ mice displayed greater fecal Bifidobacterium and Lactobacillus abundance and dampened hypothalamic-pituitaryadrenal axis activity. These results suggest that the beneficial effects of n-3 PUFA on neurobehavioural development are closely associated with comprehensive alterations in gut microbiota composition, HPA-axis activity and inflammation. Chapter 3 further assessed the role of n-3 PUFA on the cecal microbiota and metabolome. n-3 PUFA status induced subtle changes to the cecal microbiota in mothers and their offspring and, in addition, O3+ induced increased production of energy metabolites. O3- reduced production of short chain fatty acids. These results indicate that n-3 PUFA modulate cecal microbiota composition and function, which may have implications for chronic disease risk. In chapter 4, the transgenic fat-1 mouse model was utilised to examine the effects of maternal n-3 PUFA on offspring obesity risk. Offspring of mothers with a lower n-6/n-3 tissue ratio gained significantly less weight on a high fat diet. This reduced weight gain was associated with reduced gut permeability and changes to the gut microbiota and inflammatory outcomes. These results indicate that maternal n-3 PUFA status can significantly influence offspring adiposity through changes associated with gut microbiota. Algae are potent sources of n-3 PUFA and pose potential as alternative sustainable sources of such fatty acids than fish. However, little research has examined the effect of algae-derived n-3 PUFA on health. The aim of Chapter 5 was to screen the anti-inflammatory bioactivity of n-3 PUFA-rich algae lipid extracts. Exposure of the algae lipid extracts to lipopolysaccharide-stimulated THP-1 macrophages significantly reduced production of the pro-inflammatory cytokines IL-6 and IL-8 and the expression of a number of pro-inflammatory genes associated with toll-like receptor and chemokine activity. These data reveal that such n-3 PUFA-rich algae lipid extracts pose potential as anti-inflammatory functional ingredients. The aim of chapter 6 was to investigate the suitability of yoghurt as a food matrix in which to supplement an n-3 PUFA-rich lipid extract of Pavlova lutheri. Addition of the extract had little negative effect on the techno-functional properties of yoghurt. Furthermore, addition of the extract dose-dependently increased concentrations of n−3 PUFA. However, sensory analysis revealed that supplemented yoghurts were not well accepted. These results suggest that addition of this extract to yoghurt is a suitable method to increase n-3 PUFA concentration. Finally, Chapter 7 discusses the major findings and general conclusions arising from the work presented in this thesis.en
dc.description.sponsorshipTeagasc (NutraMara programme (Grant-Aid Agreement No. MFFRI/07/01)); Enterprise Ireland (SMART FOOD project: ‘Science Based ‘Intelligent’/Functional and Medical Foods for Optimum Brain Health, Targeting Depression and Cognition’ project (Ref No. 13/F/411) with the support of the Marine Institute and the Department of Agriculture, Food and the Marine (DAFM) in Ireland)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.identifier.citationRobertson, R. C. 2016. Omega-3 fatty acids, gut microbiota and associated inflammatory outcomes. PhD Thesis, University College Cork.en
dc.publisherUniversity College Corken
dc.rights© 2016, Ruairi C. Robertson.en
dc.subjectOmega-3 fatty acidsen
dc.titleOmega-3 fatty acids, gut microbiota and associated inflammatory outcomesen
dc.typeDoctoral thesisen
dc.type.qualificationnamePhD (Science)en
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