Wild blueberry (Vaccinium angustifolium) consumption improves inflammatory status in the obese Zucker rat model of the metabolic syndrome

The metabolic syndrome (MetS) is a major public health problem in the United States. Chronic inflammation is a critical component of the MetS, leading to dramatically increased risk of type II diabetes and cardiovascular disease. This study investigates the ability of a wild-blueberry-enriched diet to improve the proinflammatory status associated with MetS in the obese Zucker rat (OZR). Circulating levels of key inflammatory markers and their expression in the liver and abdominal adipose tissue were examined in OZR and its genetic control, the lean Zucker rat (LZR), after feeding a control or an 8% wild blueberry diet (WB) for 8 weeks from age 8 to 16 weeks. In the OZR, WB consumption resulted in decreased plasma concentrations of tumor necrosis factor (TNF)-α (−25.6%, P<.05), interleukin (IL)-6 (−14.9%, P<.05) and C-reactive protein (CRP) (−13.1%, P<.05) and increased adiponectin concentration (+21.8%, P<.05). Furthermore, expression of IL-6, TNF-α and nuclear factor (NF)-kB was down-regulated in both the liver (−65%, −59% and −25%, respectively) and the abdominal adipose tissue (−64%, −52% and −65%), while CRP expression was down-regulated only in the liver (−25%). In the abdominal adipose tissue, similar trends were also observed in LZR following WB treatment, with decreased liver expression of NF-kB, CRP, IL-6 and TNF-α (−24%, −16%, −21% and −50%) and increased adiponectin expression (+25%). Results of this study suggest that wild blueberry consumption exerts an overall anti-inflammatory effect in the OZR, a model of the metabolic syndrome.