Combination of β-glucan and Morus alba L. Leaf Extract Promotes Metabolic Benefits in Mice Fed a High-Fat Diet

β-glucan (BG) and mulberry have received increasing attention for their benefits as natural sources of metabolic health. In the current study, we investigated the synergetic beneficial effects of BG and mulberry leaf extract (MLE) in mice fed a high-fat diet (HFD). Male C57BL6 mice were fed a HFD for twelve weeks to induce significant obesity and insulin resistance. BG and MLE were administrated orally throughout the feeding period. The administration of BG resulted in a significant reduction in body weight gain, perirenal fat mass, fasting insulin, serum lipids, serum inflammation markers, and fatty liver, showing systemic health improvement. Likewise, the administration of MLE showed benefits similar to BG, with the exception of body weight gain. In addition to the systemic benefits, the combination of BG and MLE resulted in a synergetic improvement in insulin sensitivity. Meanwhile, only the combination of BG and MLE significantly enhanced liver GST (Glutathione S-Transferase) activity and CuZn-SOD (Superoxide dismutase (Cu-Zn)) activity, resulting in a significant reduction in GSH/GSSG (Glutathione disulfide) and reactive oxygen species (ROS) levels in the liver. These results further confirm the beneficial effects of BG and MLE on metabolic disorders and show that the combination of BG and MLE has synergetic effects.