Zinc supplementation reduces diet-induced obesity and improves insulin sensitivity in rats

Rates of obesity have been growing at alarming rates, compromising the health of the world population. Thus, the search for interventions that address the metabolic repercussions of obesity are necessary. Here we evaluated the metabolic and antioxidant effects of zinc and branched-chain amino acids (BCAA) supplementation on obese rats. Male Wistar rats were fed either a high-fat/high-fructose diet (HFD) or a standard diet (SD) for 19 weeks. From the fifteenth week until the end of the experiment, HFD- and SD-fed rats received zinc (6 mg/kg) or BCAA (750 mg/kg) supplementation. Body weight, abdominal fat, lipid profile, blood glucose, insulin, leptin, and hepatic transaminases were evaluated. In the liver, superoxide dismutase and catalase activities and lipid peroxidation were also analyzed. HFD-fed animals showed increased weight gain, abdominal fat pad, plasma insulin, leptin, and triglycerides levels in comparison with SD-fed rats. Zinc supplementation reduced all these parameters, suggesting a beneficial role for the treatment of obesity. BCAA, on the other hand, did not show any beneficial effect. Liver antioxidant enzymes and hepatic transaminases plasma levels did not change among groups. Lipid peroxidation was higher in HFD-fed rats and was not reverted by zinc or BCAA supplementation. In conclusion, zinc supplementation may be a useful strategy for the treatment of the metabolic dysfunction associated with obesity.