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

Abstract

ABSTRACT Background Obesity-associated low-grade inflammation contributes to the development of cardiovascular disease (CVD). Apples are rich in anti-inflammatory bioactives including polyphenols and fiber. Objectives We aimed to determine the effects of regular apple consumption on fasting plasma biomarkers of inflammation (primary outcome), endotoxemia, carbohydrate and lipid metabolism (glucose, insulin, triacylglycerol; secondary outcomes), and peripheral blood mononuclear cell (PBMC)-secreted cytokines (secondary outcome) in individuals with overweight and obesity. Methods A randomized, controlled, parallel-arm trial was conducted with n = 46 participants. After avoiding foods and beverages rich in polyphenols and fiber for 2 wk, participants consumed 3 whole Gala apples (∼200 g edible parts)/d as part of their habitual diet (n = 23) or avoided apples (control, n = 23) for 6 wk. All participants limited consumption of polyphenols and fiber during the 6-wk trial. Fasting blood samples were collected before and after 6 wk for analysis of plasma biomarkers and isolation of PBMCs, which were cultured for 24 h unstimulated or stimulated with LPS (10 ng/mL). Results Forty-four participants completed the trial (30 female, 14 male; mean ± SEM age: 45.4 ± 2.2 y; BMI: 33.4 ± 0.9 kg/m2). After ANCOVA and correcting for multiple comparisons, apples decreased fasting plasma C-reactive protein by 17.0% (range: 14.3%–19.6%, P = 0.005), IL-6 by 12.4% (range: 6.7%–17.5%, P < 0.001), and LPS-binding protein by 20.7% (range: 14.1%–26.4%, P < 0.001) compared with control. Apples also decreased PBMC-secreted IL-6 by 28.3% (range: 22.4%–33.5%, P < 0.001) and IL-17 by 11.0% (range 5.8–15.6%, P = 0.003) in the unstimulated condition compared with control. Exploratory analysis showed apples also increased plasma total antioxidant capacity by 9.6% (range: 1.7–18.9%, P = 0.002) compared with control. However, apples had no effect on anthropometric or other CVD risk markers. Conclusions Six-week daily whole Gala apple consumption may be an effective dietary strategy to mitigate the obesity-associated inflammation that exacerbates CVD risk, without weight loss. This trial was registered at clinicaltrials.gov as NCT03523403.