Impact of Diet Quality and Functional Food (Honey) on Gut Microbiota and Metabolic Health in Obesity

Understanding the impact of dietary patterns and functional foods on human health is crucial for the advancement of evidence-based nutrition choices. This dissertation investigates the effects of three a priori-defined healthful dietary patterns as well as a functional food, specifically Manuka honey, on gut health and metabolic markers in individuals with overweight and obesity. Two studies were conducted to explore these relationships. The first study, a post-hoc, cross-sectional analysis, compared the effects of three healthful dietary patterns: Healthy Eating Index-2010 (HEI-2010), Dietary Approaches to Stop Hypertension (DASH), and Mediterranean Dietary Pattern (MDP) on markers of intestinal permeability and gut microbiota in a predominantly female, African American cohort with obesity. Greater adherence to all three dietary patterns was associated with lower intestinal permeability measures (P < 0.05). Greater adherence to the DASH diet was correlated with favorable shifts in gut microbiota, including decreased Proteobacteria (r = −0.28, P = 0.004) and increased Verrucomicrobia (r = 0.30, P = 0.002) phylum abundance.The second study was a randomized, parallel-arm, controlled trial assessing the effects of daily consumption of one tablespoon of Manuka honey for four weeks on metabolic health and gut microbiota in individuals with overweight and obesity. Compared to sugar control, one tablespoon of Manuka honey consumption improved fasting insulin (P = 0.017) and increased abundance of Akkermansia and Faecalibacterium compared to the sugar-controlled group over 4 weeks. Overall, these findings suggest that increased adherence to healthful dietary patterns such as HEI, DASH, and MDP and the inclusion of functional foods like Manuka honey as a sugar substitute, are associated with favorable shifts in the gut microbiota and metabolic health in individuals who are overweight or obese.Advisor: Heather Rasmussem and Weiwen Chai