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Numerous animal studies have demonstrated that oral probiotics may have a beneficial role in preventing obesity, inflammatory bowel disease and even colorectal cancer, which are all associated with a high-fat diet (HFD). However, the underlying beneficial effects of combined probiotic and dietary intervention on the gut microbiota of 'non-patient' individuals previously on an HFD have yet to be fully elucidated. In the present study, fecal samples were obtained from 36 volunteers on a high-fat diet and after dietary intervention for 4 months, and 16S rDNA sequencing was applied to identify how probiotics and dietary intervention had altered the composition of the microbiota. The results demonstrated that probiotics treatment and dietary intervention in combination raised the diversity of lumen microbes compared with their individual applications. A markedly separated distribution (β-diversity) was observed, confirming the difference in gut microbiota composition among the treatment groups. Bacterial taxonomic analysis demonstrated that the relative abundance of 30 species was altered among the groups following dietary intervention and/or probiotic supplementation. The majority of the species that exhibited a population increase belonged to two butyrate-producing families, Ruminococcaceae and Lachnospiraceae, whereas the species with reduced populations mainly belonged to the Bacteroidaceae family. Collectively, these results suggest that combined probiotic and dietary intervention is able to improve the gut microbiota composition of human subjects on an HFD.

Environmental exposure, including a high-fat diet (HFD), contributes to the high prevalence of colorectal cancer by changing the composition of the intestinal microbiota. However, data examining the interaction between dietary habits and intestinal microbiota of the Chinese population is sparse. We assessed dietary habits using a food frequency questionnaire (FFQ) in native Chinese community volunteers. Based on the dietary fat content determined using the FFQ, the volunteers were divided into HFD group (≥40% of dietary calories came from fat) or low-fat diet (LFD) group (<40%). Fecal and colonic mucosal microbiota composition was determined using 16S rDNA based methods. In stool matter of HFD group, Prevotella and Abiotrophia showed significantly higher abundance, whereas unclassified genus of S24-7 (family level) of Bacteroidetes, Gemmiger, Akkermansia and Rothia were less abundant. On colonic mucosal tissue testing, unclassified genus of S24-7 showed significantly higher abundance while Bacteroides, Coprobacter, Abiotrophia, and Asteroleplasma were less abundant in HFD group. A high fat and low fiber diet in a native Chinese community may partially contribute to changes of intestinal microbiota composition that may potentially favor the onset and progression of gastrointestinal disorders including inflammatory, hyperplastic and neoplastic diseases.

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