Dietary coconut water vinegar for improvement of obesity-associated inflammation in high-fat-diet-treated mice

Obesity has become a serious health problem worldwide. Various types of healthy food, including vinegar, have been proposed to manage obesity. However, different types of vinegar may have different bioactivities. This study was performed to evaluate the anti-obesity and anti-inflammatory effects of coconut water vinegar on high-fat-diet (HFD)-induced obese mice. Changes in the gut microbiota of the mice were also evaluated. To induce obesity, C57/BL mice were continuously fed an HFD for 33 weeks. Coconut water vinegar (0.08 and 2 ml/kg body weight) was fed to the obese mice from early in week 24 to the end of week 33. Changes in the body weight, fat-pad weight, serum lipid profile, expression of adipogenesis-related genes and adipokines in the fat pad, expression of inflammatory-related genes, and nitric oxide levels in the livers of the untreated and coconut water vinegar-treated mice were evaluated. Faecal samples from the untreated and coconut water vinegar-treated mice (2 ml/kg body weight) were subjected to 16S metagenomic analysis to compare their gut microbiota. The oral intake of coconut water vinegar significantly (p < 0.05) reduced the body weight, fat-pad weight, and serum lipid profile of the HFD-induced obese mice in a dose-dependent manner. We also observed up-regulation of adiponectin and down-regulation of sterol regulatory element-binding protein-1, retinol-binding protein-4, and resistin expression. The coconut water vinegar also reduced HFD-induced inflammation by down-regulating nuclear factor-κB and inducible nitric oxide synthase expression, which consequently reduced the nitric oxide level in the liver. Alterations in the gut microbiota due to an increase in the populations of the Bacteroides and Akkermansia genera by the coconut water vinegar may have helped to overcome the obesity and inflammation caused by the HFD. These results provide valuable insights into coconut water vinegar as a potential food ingredient with anti-obesity and anti-inflammatory effects.