Black rice bran obtained from gradient milling regulates triglyceride levels and gut microbiota ecological networks in high-fat fed mice

• Black rice bran interventions significantly reduced plasma and hepatic triglyceride levels. • Black rice bran attenuated hepatic steatosis, improved hepatic oxidative stress indices in HFD. • Black rice bran increased fecal levels of butyric acid and total short chain fatty acids in HFD. • Black rice bran intervention improved the gut microbiota composition and molecular ecological networks in HFD. This study investigated the effects of black rice bran obtained from gradient milling on the nutritional properties and gut microbiota in high-fat fed mice. Long-term intervention indicated that a 12-week black rice bran of whole grain and lightly milled black rice intervention significantly reduced plasma and hepatic triglyceride levels, attenuated hepatic steatosis, improved hepatic oxidative stress indices, lowered plasma levels of the inflammatory factor IL-1β, and increased fecal levels of butyric acid and total short chain fatty acids (SCFAs) in mice fed a high-fat diet (HFD). The whole grain and lightly milled black rice bran interventions significantly increased the microbial richness of cecum contents in HFD mice, and significantly decreased intestinal microbial Firmicutes/Bacteroidota (F/B). Furthermore, a comparison of the constructed gut microbial ecological networks in mice on HFD revealed that the whole grain and slightly milled black rice bran intervention (A–B) was likely to enhance the collaborative behavior of the gut microbiota, improve the overall stability based on increasing the complexity of the constructed molecular ecological networks (MENs), and enhance the overall sensitivity of the MENs to the changes in the host's triglycerides and low-density lipoproteins. These findings suggested that black rice, as an alternative staple food, holds potential for regulating triglyceride levels and gut microbiota in high-fat fed mice.