Dietary habits have been proven to help alter the composition of gut microbiota, and exploring the impact of nutritional patterns on gut microbiota changes can help protect gut health. However, few studies have focused on the dietary impact on the gut microbiota over an experimental timeframe. In this study, 16S rRNA gene sequencing was employed to investigate the gut microbiota of mice under different dietary patterns, including AIN-93G diet (Control), high protein diet (HPD), high fiber diet (HFD), and switch diet (Switch). The alpha diversity of the HPD group significantly decreased, but HFD can restore this decline. During HPD, some genera were significantly upregulated (e.g., Feacalibaculum) and downregulated (e.g., Parabacteroides). However, after receiving HFD, other genera were upregulated (e.g., Akkermansia) and downregulated (e.g., Lactobacillus). In addition, the interaction between pathogenic bacteria was more pronounced during HPD, while the main effect was probiotics during HFD. In conclusion, the plasticity exhibited by the gut microbiota was subject to dietary influences, wherein disparate dietary regimens hold pivotal significance in upholding the well-being of the host. Therefore, our findings provide new ideas and references for the relationship between diets and gut microbiota.

Excessive intake of protein has been considered as a factor leading to intestinal microecological disorder, but why and how intestinal microbes change under the high-protein diet (HPD) have yet to be fully elucidated. Here, we performed 16S rRNA gene amplicon sequencing and metagenomic sequencing on contents of cecum, colon and feces from two groups of mice with standard diet (SD) and HPD. And then the microbial alteration of composition and function were deeply analyzed by using several statistical models and bioinformatic methods. Among the three niches, the microbes in the colon are observed to show the most significant change with lower alpha-diversity and higher beta-diversity after HPD. In addition, this alteration of microbial structure may be related to the replacement process and co-occurring community. Most species are also enriched or impoverished in the colon during this process. After analyzing the functional genes related to protein and carbohydrate hydrolysis in different niches, we found that the carbon source provided by poor carbohydrates compared with the rich protein may be the potential factor driving the enrichment of mucin degraders and desulphaters in the colon under HPD. Therefore, our study provided a new insight to understand the underlying mechanism of HPD affecting intestinal health from the perspective of microbial functional ecology.

High-protein diet (HPD) and high-fiber diet (HFiD) are two common types of diet, and the transition from HPD to HFiD frequently happens in people who perform diet control. Gut microbiota provide a bridge between diet and health. However, most of the research left out the metabolic landscape change and gut microbial influence under this kind of altered diet. Here, we examined gut microbiome and metabolites change using multi-omics (16S rRNA gene sequencing, shotgun metagenomics, LC-MS/MS metabolomics), and machine-learning methods were introduced to capture the response of gut microbiota to altered diet and associate the variable metabolites and microbial factors. The results suggest that the conversion from HPD to HFiD improves the gut microbial diversity and promotes the pathways of tryptophan, galactose, fructose, and mannose metabolism, which are associated with different gut microbiota and special metabolites. Among them, Faecalibacterium rodentium and Akkermansia muciniphila indicate potential roles in the multi-metabolism. Although these findings are exploratory and hypothesis-generating, they provide a foundation for future mechanistic investigations and emphasize the importance of diverse diets.

Diet and gut microbiota are both important factors in the pathogenesis of Crohn’s disease, and changes in diet can lead to alteration in gut microbiome. However, there is still insufficient exploration on interaction within the gut microbiota under high-protein diet (HPD) intervention. We analyzed the gut microbial network and marker taxa from patients with Crohn’s disease in public database (GMrepo, https://gmrepo.humangut.info) combined with investigation of the changes of composition and function of intestinal microbiome in mice fed on HPD by metagenomic sequencing. The results showed that there was an indirect negative correlation between Escherichia coli and Lachnospiraceae in patients with Crohn’s disease, and Escherichia coli was a marker for both Crohn’s disease and HPD intervention. Besides, enriched HH_1414 (one of the orthologs in eggNOG) related to tryptophan metabolism was from Helicobacter, whereas reduced orthologs (OGs) mainly contributed by Lachnospiraceae after HPD intervention. Our research indicates that some compositional changes in gut microbiota after HPD intervention are consistent with those in patients with Crohn’s disease, providing insights into potential impact of altered gut microbes under HPD on Crohn’s disease.

Hirschsprung disease (HD) is a congenital disorder of intestinal motility characterized by the absence of enteric neurons at the end of the bowel [ 1]. HD affects 1 in 5,000 live-born infants and 90% of patients are diagnosed within the first year of life [ 2]. Adult HD patients present with symptoms that begin in adulthood or childhood due to failure of diagnosis [ 1, 3]. Patients with inflammatory bowel disease (IBD) are considered to be more susceptible to HD in infancy than those without IBD, with a relative risk ranging from 24 to 40 times higher [ 4]. However, the rare co-morbidity of IBD and adult HD presenting after childhood is prone to missed diagnosis. Here, we report a case in which a patient was diagnosed with stricturing Crohn’s disease (CD) at the first visit, and pathological examination after surgery revealed adult HD complicated by CD.