Human gut microbiota composition and its predicted functional properties in people with western and healthy dietary patterns

Diet quality and anxiety: a critical overview with focus on the gut microbiome

Anxiety disorders disproportionally affect females and are frequently comorbid with eating disorders. With the emerging field of nutritional psychiatry, focus has been put on the impact of diet quality in anxiety pathophysiology and gut microbiome underlying mechanisms. While the relationship between diet and anxiety is bidirectional, improving dietary habits could better facilitate the actions of pharmacological and psychological therapies, or prevent their use. A better understanding of how gut bacteria mediate and moderate such relationship could further contribute to develop personalized programs and inform probiotics and prebiotics manufacturing. To date, studies that look simultaneously at diet, the gut microbiome, and anxiety are missing as only pairwise relationships among them have been investigated. Therefore, this study aims at summarizing and integrating the existing knowledge on the dietary effects on anxiety with focus on gut microbiome. Findings on the effects of diet on anxiety are critically summarized and reinterpreted in relation to findings on (i) the effects of diet on the gut microbiome composition, and (ii) the associations between the abundance of certain gut bacteria and anxiety. This novel interpretation suggests a theoretical model where the relationship between diet and anxiety is mediated and/or modulated by the gut microbiome through multiple mechanisms. In parallel, this study critically evaluates methodologies employed in the nutritional field to investigate the effects of diet on anxiety highlighting a lack of systematic operationalization and assessment strategies. Therefore, it ultimately proposes a novel evidence-based approach that can enhance studies validity, reliability, systematicity, and translation to clinical and community settings.

Human gut microbiome, diet, and mental disorders

Diet is one of the most important external factor shaping the composition and metabolic activities of the gut microbiome. The gut microbiome plays a crucial role in host health, including immune system development, nutrients metabolism, and the synthesis of bioactive molecules. In addition, the gut microbiome has been described as critical for the development of several mental disorders. Nutritional psychiatry is an emerging field of research that may provide a link between diet, microbial function, and brain health. In this study, we have reviewed the influence of different diet types, such as Western, Mediterranean, vegetarian, and ketogenic, on the gut microbiota composition and function, and their implication in various neuropsychiatric and psychological disorders.

Optimization of Fermented Maize Stover for the Fattening Phase of Geese: Effect on Production Performance and Gut Microflora

To optimize the utilization of fermented maize stover (FMS) feed during the fattening phase of Xianghai flying geese (XFG), a total of 300 XFG at 125 days of age were randomly assigned to four dietary treatment groups with three replicates of 25 in each set. Group A was fed the basal fattening diet, while the B, C, and D groups were fed the basic fattening diet and diets supplemented with 5%, 10% or 15% FMS, respectively. The findings indicate that the production performance indicators (especially the dressed, eviscerated and breast muscle yield) of Group D closely resembled Group A more than Groups B and C. Intestinal morphometry found that the jejunal villus height and the villus height/crypt depth were significantly increased in Group D compared to Group A. Next, 16S rRNA amplicon sequencing of the extracted DNA revealed that beneficial microbiota (Coprococcus and Victivallis) showed increased abundance in Group D. Cecal flora function analysis further revealed that some amino acid and glycerol biosynthesis were found to be associated with growth performance in geese. These findings suggest that incorporating 15% FMS as a substitute for a portion of the feed during the fattening phase of XFG can effectively sustain their production performance, optimize the gut microbial community and morphometrical traits, provide new insight into using non-conventional feed resources to reduce feed cost and improve economic benefits in the breeding industry.

Comprehensive insight into the alterations in the gut microbiome and the intestinal barrier as a consequence of iron deficiency anaemia

BACKGROUND

Iron deficiency is the top leading cause of anaemia, whose treatment has been shown to deteriorate gut health. However, a comprehensive analysis of the intestinal barrier and the gut microbiome during IDA have not been performed to date. This study aims to delve further into the analysis of these two aspects, which will mean a step forward minimising the negative impact of iron supplements on intestinal health.

METHODS

IDA was experimentally induced in an animal model. Shotgun sequencing was used to analyse the gut microbiome in the colonic region, while the intestinal barrier was studied through histological analyses, mRNA sequencing (RNA-Seq), qPCR and immunofluorescence. Determinations of lipopolysaccharide (LPS) and bacteria-specific immunoglobulins were performed to assess microbial translocation.

RESULTS

Microbial metabolism in the colon shifted towards an increased production of certain amino acids, short chain fatty acids and nucleotides, with Clostridium species being enriched during IDA. Structural alterations of the colonic epithelium were shown by histological analysis. RNA-Seq revealed a downregulation of extracellular matrix-associated genes and proteins and an overall underdeveloped epithelium. Increased levels of serum LPS and an increased immune response against dysbiotic bacteria support an impairment in the integrity of the gut barrier during IDA.

CONCLUSIONS

IDA negatively impacts the gut microbiome and the intestinal barrier, triggering an increased microbial translocation. This study emphasizes the deterioration of gut health during IDA and the fact that it should be addressed when treating the disease.

Diets intervene osteoporosis via gut-bone axis

Osteoporosis is a systemic skeletal disease that seriously endangers the health of middle-aged and older adults. Recently, with the continuous deepening of research, an increasing number of studies have revealed gut microbiota as a potential target for osteoporosis, and the research concept of the gut-bone axis has gradually emerged. Additionally, the intake of dietary nutrients and the adoption of dietary patterns may affect the gut microbiota, and alterations in the gut microbiota might also influence the metabolic status of the host, thus adjusting bone metabolism. Based on the gut-bone axis, dietary intake can also participate in the modulation of bone metabolism by altering abundance, diversity, and composition of gut microbiota. Herein, combined with emerging literatures and relevant studies, this review is aimed to summarize the impacts of different dietary components and patterns on osteoporosis by acting on gut microbiota, as well as underlying mechanisms and proper dietary recommendations.

Experimental Capacity of Human Fecal Microbiota to Degrade Fiber and Produce Short-Chain Fatty Acids Is Associated with Diet Quality and Anthropometric Parameters

BACKGROUND

Short-chain fatty acids (SCFAs) are considered beneficial to human health. The associations between bacterial capacity to produce SCFAs, diet, and health are not fully understood.

OBJECTIVE

We aimed to evaluate the capacity of human fecal microbiota to produce SCFAs and to metabolize soluble and insoluble fiber and to study its associations with human diet, anthropometric parameters, and carbohydrate and lipid metabolism.

METHODS

A cross-sectional study was carried out with 200 adult participants. Diet was evaluated using food records. Capacity to produce acetate, butyrate, and propionate and to degrade soluble fiber were assessed in an ex vivo experiment where fecal samples were inoculated in a pectin-containing broth. Fecal β-glucosidase activity was measured to assess potential to degrade insoluble fiber.

RESULTS

The main dietary determinants of high capacity to metabolize fiber were high intake of vegetables, fruits, nuts, and seeds. After adjusting analyses for confounders, glucose and lipid parameters were not significantly associated with any of the studied microbial capacities, but the capacity to produce propionic acid was significantly associated with hip circumference (β = -0.018, P = 0.044), which was seen especially in people eating healthy.

CONCLUSIONS

We confirmed that high intake of fiber-rich products is positively associated with the capacity of fecal microbiota to degrade soluble and insoluble dietary fiber and that people eating healthy food might benefit from enhanced microbial capacity to produce propionic acid.

The interactive effects of psychosocial stress and diet composition on health in primates

Social disadvantage and diet composition independently impact myriad dimensions of health. They are closely entwined, as social disadvantage often yields poor diet quality, and may interact to fuel differential health outcomes. This paper reviews effects of psychosocial stress and diet composition on health in nonhuman primates and their implications for aging and human health. We examined the effects of social subordination stress and Mediterranean versus Western diet on multiple systems. We report that psychosocial stress and Western diet have independent and additive adverse effects on hypothalamic-pituitary-adrenal and autonomic nervous system reactivity to psychological stressors, brain structure, and ovarian function. Compared to the Mediterranean diet, the Western diet resulted in accelerated aging, nonalcoholic fatty liver disease, insulin resistance, gut microbial changes associated with increased disease risk, neuroinflammation, neuroanatomical perturbations, anxiety, and social isolation. This comprehensive, multisystem investigation lays the foundation for future investigations of the mechanistic underpinnings of psychosocial stress and diet effects on health, and advances the promise of the Mediterranean diet as a therapeutic intervention on psychosocial stress.

Microbiome and Diet in Colon Cancer Development and Treatment

ABSTRACT

Diet plays critical roles in defining our immune responses, microbiome, and progression of human diseases. With recent progress in sequencing and bioinformatic techniques, increasing evidence indicates the importance of diet-microbial interactions in cancer development and therapeutic outcome. Here, we focus on the epidemiological studies on diet-bacterial interactions in the colon cancer. We also review the progress of mechanistic studies using the experimental models. Finally, we discuss the limits and future directions in the research of microbiome and diet in cancer development and therapeutic outcome. Now, it is clear that microbes can influence the efficacy of cancer therapies. These research results open new possibilities for the diagnosis, prevention, and treatment of cancer. However, there are still big gaps to apply these new findings to the clinical practice.