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

This study investigated the metabolic efficacy ofBacillus subtilis-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.