Fermented Black Soybean and Dehulled Adlay Improve Metabolic Syndrome via AMPK–SIRT1 Activation and Gut Microbiota Modulation

This study investigated the metabolic efficacy of<i>Bacillus subtilis</i>-fermented black soybean and dehulled adlay (FBA) compared to its unfermented black soybean and dehulled adlay (UFBA) in high-fat, high-fructose-diet (HFFD)-fed C57BL/6J mice. FBA supplementation exhibited superior effects in attenuating body weight gain, visceral adiposity, dyslipidemia, and hepatic steatosis while improving insulin sensitivity. These benefits were consistent with the modulation of hepatic AMPK-SIRT1 and PI3K-Akt signaling pathways, suggesting enhanced lipid oxidation and suppressed lipogenesis. Furthermore, FBA restructured the gut microbiota by reversing HFFD-induced dysbiosis, notably decreasing the Firmicutes-to-Bacteroidetes (F/B) ratio and specifically elevating cecal propionate levels. These findings demonstrate that fermentation significantly potentiates the bioactivity of the substrate, suggesting FBA as a potential dietary strategy that may attenuate metabolic syndrome (MetS) features.