Assessing the Effects of Acute and Chronic Whole Apple Consumption on Metabolic Disease Risk Factors in Overweight and Obese Adults: Apple Study Protocol

 

Obesity is characterized by an altered gut microbial profile and corresponding underlying inflammatory state in which various gut- and adipose tissue-derived inflammatory signaling molecules (e.g. endotoxins, cytokines) affect metabolic processes central to the development of type 2 diabetes and cardiovascular disease. While this phenomenon is promoted by digestion of a high-fat meal, whole foods with proposed anti-inflammatory actions, such as apples, may be beneficial but have been less well-studied. Thus, this study will assess the effects of acute and chronic consumption of whole, raw, Ontario-grown Gala apples on the gut microbial profile and immunometabolism in overweight and obese adults. 60 overweight or obese participants in otherwise good health will be recruited. With 30 participants, we will conduct a randomized, crossover trial to assess the effects of acute (one time) consumption of 3 apples on the 2, 4 and 6h postprandial response to ingestion of 1 g fat/kg body weight. Plasma markers of metabolism (triglycerides, glucose, insulin) and inflammation (endotoxin, cytokines) will be measured. Fasted and 4h postprandial peripheral blood mononuclear cells (PBMCs) will be isolated from whole blood and stimulated with 10 ng/mL LPS for 24h to measure secreted cytokines. With all 60 participants, we will conduct a parallel-arm, randomized, controlled trial to assess the effects of chronic (6 week) daily consumption of 3 apples on fasted plasma markers of metabolism and inflammation, PBMC-secreted cytokines in response to LPS stimulation, and the gut microbial profile. This study will be the first to comprehensively assess apples as a dietary component for optimizing food-health relationships, especially those integral to the burgeoning obesity-health crisis.