Investigating the Potential Anti-inflammatory Effects and Mechanisms of Apple Consumption in Overweight and Obesity




Liddle, Danyelle M

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University of Guelph


Increased production of inflammatory signalling mediators causally links overweight and obesity to the development of comorbidities including cardiovascular disease, the current leading cause of death worldwide. This thesis utilized both in vitro and in vivo methodologies to study the potential for apples, a widely available, accepted and consumed fruit with a rich nutrient, fibre and polyphenol profile, to mitigate inflammation in overweight and obesity. In a randomized controlled trial with participants with overweight and obesity, we showed the regular consumption of 3 whole Gala apples (~200 g edible parts)/day for 6 weeks as part of the habitual diet reduced concentrations of various inflammatory biomarkers in plasma and secreted from cultured peripheral blood mononuclear cells (PBMC), as well as increased plasma total antioxidant capacity (TAC), all despite no changes in anthropometric measurements. Likewise, in a randomized crossover trial with participants with overweight and obesity, we showed the one-time consumption of the same apple intervention in combination with a high fat meal (providing 1 g fat/kg body weight) modestly modulated the acute postprandial systemic inflammatory response and reduced various inflammatory biomarkers secreted from PBMC, again consistent with increased plasma TAC. Finally, to gain mechanistic insight into our observed anti-inflammatory effects of regular and one-time whole apple consumption, we established an in vitro model designed to recapitulate the inflammatory and hypoxic microenvironment characteristic of overweight and obese adipose tissue to study the bioactivity of the apple polyphenols phloretin (PT) and phlorizin (PZ). We showed PT reduced adipocyte production of inflammatory biomarkers via a peroxisome proliferator-activated receptor-γ dependent mechanism, which in turn blunted markers of macrophage polarization to the M1 inflammatory phenotype; whereas PZ was less potent. Overall, these studies were the first to comprehensively investigate the potential anti-inflammatory effects of apples in conditions specific to overweight and obesity. This thesis provides support for apple consumption as a dietary strategy to disrupt the pathophysiology of overweight- and obesity-associated comorbidities driven by acute and chronic inflammation.



Overweight and obesity, Adipose tissue, Inflammation, Apples, Polyphenols


Danyelle M. Liddle, Xinjie Lin, Liam C. Cox, Emily M. Ward, Rufaida Ansari, Amanda J. Wright, Lindsay E. Robinson. Daily apple consumption reduces plasma and peripheral blood mononuclear cell-secreted inflammatory biomarkers in adults with overweight and obesity: A 6-week randomized, controlled, parallel-arm trial. American Journal of Clinical Nutrition. 2021
114(2):752-63 (doi: 10.1093/ajcn/nqab094)
Danyelle M. Liddle, Xinjie Lin, Emily M. Ward, Liam C. Cox, Amanda J. Wright, Lindsay E. Robinson. Apple consumption reduces markers of postprandial inflammation following a high fat meal in overweight and obese adults: A randomized, crossover trial. Food & Function. 2021
12(14):6348-62 (doi: 10.1039/d1fo00392e)
Danyelle M. Liddle, Meaghan E. Kavanagh, Amanda J. Wright, Lindsay E. Robinson. Apple flavonols mitigate adipocyte inflammation and promote angiogenic factors in LPS- and cobalt chloride-stimulated adipocytes, in part by a peroxisome proliferator-activated receptor-??-dependent mechanism. Nutrients. 2020;12(5):1386 (doi: 10.3390/nu12051386).