Isocaloric diets with varying protein levels affected energy metabolism in young adult Sprague-Dawley rats via modifying the gut microbes: A lipid imbalance was brought on by a diet with a particularly high protein content

Increased dietary protein stimulates amino acid catabolism via the gut microbiota and secondary bile acid production

Excess amino acids from a protein-rich diet are mainly catabolized in the liver. However, it is still unclear to what extent the gut microbiota may be involved in the mechanisms governing this catabolism. Therefore, the aim of this study was to investigate whether consumption of different dietary protein concentrations induces changes in the taxonomy of the gut microbiota, which may contribute to the regulation of hepatic amino acid catabolism. Consumption of a high-protein diet caused overexpression of HIF-1α in the colon and increase in mitochondrial activity, creating a more anaerobic environment that was associated with changes in the taxonomy of the gut microbiota promoting an increase in the synthesis of secondary bile acids, increased secretion of pancreatic glucagon. This effect was demonstrated in pancreatic islets, where secondary bile acids stimulated the expression of the PC2 enzyme that promotes glucagon formation. The increase in circulating glucagon was associated with an induction of the expression of hepatic amino acid-degrading enzymes, an effect attenuated by antibiotics. Thus, high protein intake in mice and humans induced the increase of different species in the gut microbiota with the capacity to produce secondary bile acids leading to an increase in secondary bile acids and glucagon levels, promoting amino acid catabolism.

Gut bacteria and host metabolism: The keys to sea cucumber (Apostichopus japonicus) quality traits

Gut bacteria have a significant impact on modern genetics and contribute to the improvement of aquatic germplasm, which is a key focus for breeders. However, the effects of complex interactions between gut bacteria community and phenotypic trait of aquatic products remain largely unknown. Here, we unravel the association between phenotypic trait, gut microbiota and host metabolic variables of 216 sea cucumbers (Apostichopus japonicus) by Metagenome-wide association studies (MWAS) and Weighted correlation network analysis (WGCNA) methods. Our findings reveal that a total of 14 microbial biomarkers and 201 metabolic markers considered being associated with polysaccharide and collagen content. Among them, Desulfobacterota has the capacity to facilitate the synthesis of octopamine within the neuroactive ligand-receptor metabolic pathway, subsequently influencing polysaccharide content. Additionally, the Lachnospiraceae_NK4A136_group was shown to enhance collagen content through the facilitation of glycine synthesis. In conclusion, this research indicating that precision microbiome management could be a strategy for develop strategies for cultivating high-quality aquatic germplasm.

Preventive effect of quinoa polysaccharides on lipopolysaccharide-induced inflammation in mice through gut microbiota regulation

Inflammation significantly influences the development of gastrointestinal (GI) diseases such as inflammatory bowel diseases (IBD)and ulcerative colitis, which disrupts normal digestive functions, leading to tissue damage and various symptoms. This research explores the preventive effects of quinoa polysaccharides (QPS) on lipopolysaccharide (LPS)-induced systemic acute inflammation in mice and their mechanism of action. The findings revealed that QPS alleviated LPS-induced inflammation symptoms, enhanced the mice behavior score and their immune organ index, reduced pro-inflammatory cytokines (IL-6, TNF-α and IL-1β) levels, elevated the expression level of tight junction proteins (ZO-1, MUC2). Additionally, the levels of superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) were improved via QPS administration. Further, our research suggested that QPS enhanced the diversity and abundance of gut microbiota compared to that of LPS mice, leading to an increase in the short-chain fatty acids in mice feces. Linear discriminant analysis (LDA) effect size (LEfSe) showed that QPS administration could lead to a range of gut biomarkers, promoting the enhancement of polysaccharide-metabolizing bacteria. The results of 16S rRNA sequencing indicated that QPS alleviates LPS-induced inflammation by enhancing the richness of beneficial bacteria such as Bacteroides and Lactobacillus. Linear discriminant analysis (LDA) effect size (LEfSe) showed that QPS administration could lead to a range of gut biomarkers, promoting the enhancement of polysaccharide-metabolizing bacteria. UPLC Q-TOF-MS was performed to analyze metabolites in the fecal samples. LPS administration significantly altered metabolite levels detected in mice feces in which some metabolites have decreased such as xanthosine and hypoxanthine while an increase in some metabolites in mice that received QPS, metabolomics analysis showed the beneficial effects of QPS primarily mediated via amino and bile acid-related metabolism pathways. Our research could offer the basis for further studies and applications of quinoa polysaccharides.

High-protein high-konjac glucomannan diets changed glucose and lipid metabolism by modulating colonic microflora and bile acid profiles in healthy mouse models

High protein and fiber diets are becoming increasingly popular for weight loss; however, the benefits or risks of high protein and fiber diets with a normal calorie level for healthy individuals still need to be elucidated. In this study, we explored the role and mechanisms of long-term high protein and/or konjac glucomannan diets on the metabolic health of healthy mouse models. We found that high konjac glucomannan contents improved the glucose tolerance of mice and both high protein and high konjac glucomannan contents improved the serum lipid profile but increased the TNF-α levels. In the liver, high dietary protein contents reduced the expression of the FASN gene related to fatty acid synthesis. Interactions of dietary protein and fiber were shown in the signaling pathways related to lipid and glucose metabolism of the liver and the inflammatory status of the colon, wherein the high protein and high konjac glucomannan diet downregulated the expression of the SREBF1 and FXR genes in the liver and downregulated the expression of TNF-α genes in the colon compared to the high protein diet. High konjac glucomannan contents reduced the colonic secondary bile acid levels including DCA and LCA; this was largely associated with the changed microbiota profile and also contributed to improved lipid and glucose homeostasis. In conclusion, high protein diets improved lipid homeostasis and were not a risk to metabolic health, while high fiber diets improved glucose and lipid homeostasis by modulating colonic microbiota and bile acid profiles, and a high protein diet supplemented with konjac glucomannan might improve hepatic lipid homeostasis and colonic inflammation in healthy mouse models through long-term intervention.