Flavanol supplementation protects against obesity-associated increases in systemic interleukin-6 levels without inhibiting body mass gain in mice fed a high-fat diet

Abstract

Weight gain and obesity are associated with increased levels of proinflammatory cytokines. Studies have demonstrated the ability of dietary flavanols to reduce the severity of metabolic derangements due to high-fat (HF) feeding. The degree of polymerization of the flavanols appears to play a role in determining the extent of these protective effects. This study evaluated the preventative effects of grape seed and pine bark flavanol supplementation, with significantly different flavanol degree of polymerization, in the context of an HF diet. For 13 weeks, mice were given 35 mg/kg body weight per day grape seed or pine bark as part of an HF diet and compared to mice fed a low-fat diet and control HF diet. All flavanol-supplemented groups and the HF control incurred significantly higher weight gain compared to the lean control, and the grape seed group gained significantly more weight than the HF control. Increased weight gain of treatment groups was likely caused by hyperphagia. Despite lack of improvements to weight gain and glycemic control, it was observed that all flavanol treatment groups were able to significantly reduce interleukin-6 compared to HF control. The grape seed group, which gained the most weight overall, also exhibited the lowest levels of interleukin-6 compared to other groups. Overall, low-dose flavanol extract supplementation, regardless of mean degrees of polymerization, blunted cytokine production despite increased weight gain. This obesity-independent effect suggests flavanols may be used as complementary interventions to ameliorate increased inflammatory tone in the contexts of obesity and diabetes. Furthermore, flavanol-induced hyperphagia may have use for attenuation of cachexia.

Keywords: Cytokines; Flavanols; Glucose intolerance; Mean degree of polymerization (mDP); Procyanidins (PCs).