OBJECTIVE: The main focus of this review is to discuss and summarise the major risk factors associated with urbanisation that affect human gut microbiota thus affecting human health.
METHODS: Multiple medical literature databases, namely PubMed, Google, Google Scholar, and Web of Science were used to find relevant materials for urbanisation and its major factors affecting human gut microbiota/microbiome. Both layman and Medical Subject Headings (MeSH) terms were used in the search. Due to the scarcity of the data, no limitation was set on the publication date. Relevant materials in the English language which include case reports, chapters of books, journal articles, online news reports and medical records were included in this review.
RESULTS: Based on the data discussed in the review, it is quite clear that urbanisation and its associated factors have long-standing effects on the human gut microbiota that result in alterations of gut microbial diversity and composition. This is a matter of serious concern as chronic inflammatory diseases are on the rise in urbanised societies.
CONCLUSION: A better understanding of the factors associated with urbanisation will help us to identify and implement new biological and social approaches to prevent and treat diseases and improve health globally by deepening our understanding of these relationships and increasing studies across urbanisation gradients.HIGHLIGHTSHuman gut microbiota have been linked to almost every important function, including metabolism, intestinal homeostasis, immune system, biosynthesis of vitamins, brain processes, and behaviour.However, dysbiosis i.e., alteration in the composition and diversity of gut microbiota is associated with the pathogenesis of many chronic conditions.In the 21st century, urbanisation represents a major demographic shift in developed and developing countries.During this period of urbanisation, humans have been exposed to many environmental exposures, all of which have led to the dysbiosis of human gut microbiota.The main focus of the review is to discuss and summarise the major risk factors associated with urbanisation and how it affects the diversity and composition of gut microbiota which ultimately affects human health.
METHODS: OVX rats were treated with TPEE at 125, 250, 500 mg/kg/day, or controls (pomegranate extract, 500 mg/kg/day; estradiol, 25 μg/kg/day) for 12 weeks. Gut microbiota analysis was conducted by extracting the microbial DNA from fecal samples and microbiome taxonomic profiling was carried out by using next-generation sequencing. The levels of serum biomarkers were analyzed using enzyme-linked immunosorbent assay (ELISA) kit. The prediction of functional biomarker of microbiota was performed using PICRUSt to investigate the potential pathways associated with gut health and serum lipid profile regulation. To study the correlation between gut microbiota composition and serum lipid levels, Spearman's correlation coefficients were defined and analyzed. Additionally, gas chromatography-mass spectrometry analysis was conducted to uncover additional physiologically active ingredients.
RESULTS: TPEE-treated OVX rats showed significant reduction in serum triglycerides (TG), total cholesterols (TCHOL), and LDL/VLDL levels but increase in HDL level. The alteration in the pathways involve in metabolism was the most common among the other KEGG categories. Particularly, TPEE also significantly reduced the relative abundance of sequences read associated with inflammatory bowel disease (IBD) and the peroxisome proliferator-activated receptor (PPAR) signalling pathway. TPEE intervention was seen to reduce the Firmicutes to Bacteroidetes (F/B) ratio in the OVX rats, denoting a reduction in microbial dysbiosis in the OVX rats. Correlation analysis at the phylum level revealed that Bacteriodetes and Proteobacteria were strongly correlated with serum TG, TCHOL and HDL levels. At the species level, Bifidobacterium pseudolongum group was seen to positively correlate with serum HDL level and negatively correlated with serum AST, ALT, LDL/VLDL, TCHOL, and TG levels.
CONCLUSIONS: TPEE treatment showed therapeutic benefits by improving the intestinal microbiota composition which strongly correlated with the serum lipid and cholesterol levels in the OVX rats.
RESULTS: Thirty Hy-Line Gray and thirty Lohmann Pink laying hens were used in this study to determine the impact of cecal microbial structure on odor production of laying hens. The hens were managed under the same husbandry and dietary regimes. Results of in vivo experiments showed a lower hydrogen sulfide (H2S) production from Hy-Line hens and a lower concentration of soluble sulfide (S2-) but a higher concentration of butyrate in the cecal content of the Hy-Line hens compared to Lohmann Pink hens (P 0.05). Significant microbial structural differences existed between the two breed groups. The relative abundance of some butyrate producers (including Butyricicoccus, Butyricimonas and Roseburia) and sulfate-reducing bacteria (including Mailhella and Lawsonia) were found to be significantly correlated with odor production and were shown to be different in the 16S rRNA and PCR data between two breed groups. Furthermore, some bacterial metabolism pathways associated with energy extraction and carbohydrate utilization (oxidative phosphorylation, pyruvate metabolism, energy metabolism, two component system and secretion system) were overrepresented in the Hy-Line hens, while several amino acid metabolism-associated pathways (amino acid related enzymes, arginine and proline metabolism, and alanine-aspartate and glutamate metabolism) were more prevalent in the Lohmann hens.
CONCLUSION: The results of this study suggest that genotype of laying hens influence cecal microbiota, which in turn modulates their odor production. Our study provides references for breeding and enteric manipulation for defined microbiota to reduce odor gas emission.
METHODS: A multi-center study of multi-ethnic Asian patients with IBS was conducted in two phases: (i) an initial cross-sectional gut microbiota composition study of IBS patients and healthy controls, followed by (ii) a single-arm 6-week dietary interventional study of the IBS patients alone, exploring clinical and gut microbiota changes.
RESULTS: A total of 34 adult IBS patients (IBS sub-types of IBS-D 44.1%, IBS-C 32.4%, and IBS-M 23.5%) and 15 healthy controls were recruited. A greater abundance of Parabacteroides species with lower levels of bacterial fermenters and short-chain fatty acids producers were found among IBS patients compared with healthy controls. Age and ethnicity were found to be associated with gut microbiota composition. Following a low FODMAP dietary intervention, symptom and quality of life improvement were observed in 24 (70.6%) IBS patients. Symptom improvement was associated with adherence to the low FODMAP diet (46.7% poor adherence vs 92.9% good adherence, P = 0.014), and gut microbiota patterns, particularly with a greater abundance of Bifidobacterium longum, Anaerotignum propionicum, and Blautia species post-intervention.
CONCLUSION: Gut microbiota variation in multi-ethnic IBS patients may be related to dietary intake and may be helpful to identify patients who are likely to respond to a low FODMAP diet.
RESULTS: We found that cumulative food intake was not changed in the group with 12 h daily fasting, but significantly decreased in the 16 and 20 h fasting groups. The composition of gut microbiota was altered by all these types of intermittent fasting. At genus level, 16 h fasting led to increased level of Akkermansia and decreased level of Alistipes, but these effects disappeared after the cessation of fasting. No taxonomic differences were identified in the other two groups.
CONCLUSIONS: These data indicated that intermittent fasting shapes gut microbiota in healthy mice, and the length of daily fasting interval may influence the outcome of intermittent fasting.