Mediterranean-Like Dietary Pattern Associations With Gut Microbiome Composition and Subclinical Gastrointestinal Inflammation

Adherence to the Mediterranean diet can beneficially affect the gut microbiota composition: a systematic review

AIM

Dietary patterns could have a notable role in shaping gut microbiota composition. Evidence confirms the positive impact of the Mediterranean diet (MD), as one of the most studied healthy dietary patterns, on the gut microbiota profile. We conducted this systematic review to investigate the results of observational studies and clinical trials regarding the possible changes in the gut microbiota composition, metabolites, and clinical outcomes following adherence to MD in healthy cases or patients suffering from metabolic disorders.

METHODS

A systematic literature search was conducted on PubMed, Web of Science, and Scopus databases until October 2023. Two researchers separately screened the titles, abstracts, and then full-text of the articles and selected the relevant studies. Quality assessment of observational and interventional studies was performed by Newcastle-Ottawa and Cochrane checklists, respectively.

RESULTS

A total of 1637 articles were obtained during the initial search. Ultimately, 37 articles, including 17 observational and 20 interventional studies, were included in this systematic review. Ten observational and 14 interventional studies reported a correlation between MD adherence and microbiota diversity. Faecalibacterium and Prevotella were the most frequent bacterial genera with increased abundance in both observational and interventional studies; an Increment of Bacteroides genus was also reported in observational studies. Better glycemic control, lowering fat mass, better bowel movement, decreased bloating, inflammation, and hospitalization risk were the reported clinical outcomes.

CONCLUSION

Adherence to the MD is associated with significant beneficial changes in the gut microbiota diversity, composition, and functions and major clinical improvements in most populations.

Lower Diet Quality Associated with Subclinical Gastrointestinal Inflammation in Healthy United States Adults

BACKGROUND

Higher diet quality has been associated with lower risk of developing inflammatory bowel disease, but associations between diet and gastrointestinal (GI) inflammation in healthy adults prior to disease onset are understudied.

OBJECTIVES

The purpose of this project was to examine associations between reported dietary intake and markers of GI inflammation in a healthy adult human cohort.

METHODS

In a cross-sectional observational trial of 358 healthy adults, participants completed ≤3 unannounced 24-h dietary recalls using the Automated Self-Administered Dietary Assessment Tool and a Block 2014 Food Frequency Questionnaire to assess recent and habitual intake, respectively. Those who provided a stool sample were included in this analysis. Inflammation markers from stool, including calprotectin, neopterin, and myeloperoxidase, were measured by ELISA along with LPS-binding protein from plasma.

RESULTS

Recent and habitual fiber intake was negatively correlated with fecal calprotectin concentrations (n = 295, P = 0.011, 0.009). Habitual soluble fiber intake was also negatively correlated with calprotectin (P = 0.01). Recent and habitual legume and vegetable intake was negatively correlated with calprotectin (P = 0.013, 0.026, 0.01, 0.009). We observed an inverse correlation between recent Healthy Eating Index (HEI) scores and calprotectin concentrations (n = 295, P = 0.026). Dietary Inflammatory Index scores were calculated and positively correlated with neopterin for recent intake (n = 289, P = 0.015). When participants with clinically elevated calprotectin were excluded, recent and habitual fiber, legume, vegetable, and fruit intake were negatively correlated with calprotectin (n = 253, P = 0.00001, 0.0002, 0.045, 0.001, 0.009, 0.001, 0.004, 0.014). Recent total HEI score was inversely correlated with subclinical calprotectin (P = 0.003).

CONCLUSIONS

Higher diet quality may be protective against GI inflammation even in healthy adults. This trial was registered at clinicaltrials.gov as NCT02367287.

Preliminary Analysis of Gut Microbiome and Gastrointestinal Symptom Burden in Breast Cancer Patients Receiving Chemotherapy Compared to Healthy Controls

BACKGROUND

Alterations in the naturally occurring bacteria of the gut, known as the gastrointestinal (GI) microbiome, may influence GI symptoms in women with breast cancer.

OBJECTIVE

This work aims to describe GI symptom occurrence, duration, severity, and distress and measures of the GI microbiome among women with breast cancer receiving chemotherapy compared to age- and sex-matched healthy controls.

INTERVENTIONS/METHODS

22 women with breast cancer receiving chemotherapy and 17 healthy control women provided stool specimens and GI symptom data using the modified Memorial Symptom Assessment Scale (MSAS). The fecal microbiome was profiled by metagenomic sequencing of 16S Ribosomal RNA (rRNA). GI microbiome was compared between groups using alpha-diversity (Observed OTU number and Shannon index), beta-diversity (UniFrac distances), and relative abundance of select genera.

RESULTS

GI symptoms with high symptom reports among breast cancer patients included nausea, diarrhea, flatulence, dry mouth, taste change, and poor appetite. Indices of differential abundance (beta diversity) significantly distinguished between breast cancer patients and healthy controls. Unique bacterial features differentiating the 2 groups were Prevotella_9, Akkermansia, Lachnospira, Lachnospiraceae_NK4A136, Lachnoclostridium, and Oscillibacter.

CONCLUSIONS

Gut bacteria are associated with GI inflammation and mucus degradation, suggesting the potential role of the GI microbiome in GI symptom burden. Understanding the influence of GI bacteria on gut health and symptoms will help harness the enormous potential of the GI microbiome as a future diagnostic and therapeutic agent to reduce the symptom burden associated with chemotherapy.

The interaction between Mediterranean diet and intestinal microbiome: relevance for preventive strategies against frailty in older individuals

Age-related changes in intestinal microbiome composition and function are increasingly recognized as pivotal in the pathophysiology of aging and are associated with the aging phenotype. Diet is a major determinant of gut-microbiota composition throughout the entire lifespan, and several of the benefits of a healthy diet in aging could be mediated by the microbiome. Mediterranean diet (MD) is a traditional dietary pattern regarded as the healthy diet paradigm, and a large number of studies have demonstrated its benefits in promoting healthy aging. MD has also a positive modulatory effect on intestinal microbiome, favoring bacterial taxa involved in the synthesis of several bioactive compounds, such as short-chain fatty acids (SCFAs), that counteract inflammation, anabolic resistance, and tissue degeneration. Intervention studies conducted in older populations have suggested that the individual response of older subjects to MD, in terms of reduction of frailty scores and amelioration of cognitive function, is significantly mediated by the gut-microbiota composition and functionality. In this context, the pathophysiology of intestinal microbiome in aging should be considered when designing MD-based interventions tailored to the needs of geriatric patients.

Moderate variations in the human diet impact the gut microbiota in humanized mice

AIM

Drastic diet interventions have been shown to promote rapid and significant compositional changes of the gut microbiota, but the impact of moderate diet variations is less clear. Here, we aimed to clarify the impact of moderate diet variations that remain within the spectrum of the habitual human diet on gut microbiota composition.

METHODS

We performed a pilot diet intervention where five healthy volunteers consumed a vegetarian ready-made meal for three days to standardize dietary intake before switching to a meat-based ready-made western-style meal and high sugar drink for two days. We performed 16S rRNA sequencing from daily fecal sampling to assess gut microbiota changes caused by the intervention diet. Furthermore, we used the volunteers' fecal samples to colonize germ-free mice that were fed the same sterilized diets to study the effect of a moderate diet intervention on the gut microbiota in a setting of reduced interindividual variation.

RESULTS

In the human intervention, we found that fecal microbiota composition varied between and within individuals regardless of diet. However, when we fed the same diets to mice colonized with the study participants' feces, we observed significant, often donor-specific, changes in the mouse microbiota following this moderate diet intervention.

CONCLUSION

Moderate variations in the habitual human diet have the potential to alter the gut microbiota. Feeding humanized mice human diets may facilitate our understanding of individual human gut microbiota responses to moderate dietary changes and help improve individualized interventions.

Clinical trial: A Mediterranean diet is feasible and improves gastrointestinal and psychological symptoms in irritable bowel syndrome

BACKGROUND

Diet is fundamental to the care of irritable bowel syndrome (IBS). However, some approaches are not appropriate for individuals experiencing psychological symptoms.

AIMS

To assess feasibility of a Mediterranean diet in IBS and its impact on gastrointestinal and psychological symptoms.

METHODS

We recruited adults with Rome IV IBS and mild or moderate anxiety and/or depressive symptoms to an unblinded 6-week randomised controlled trial. Patients were randomised to Mediterranean diet counselling or habitual diet. We collected gastrointestinal and psychological symptom data, dietary data and stool samples for metagenomic sequencing.

RESULTS

We randomised 59 individuals (29 Mediterranean diet, 30 control); 48 completed the study. The Mediterranean Diet Adherence Screener score was higher in the Mediterranean diet group than controls at week 6 (7.5 [95% CI: 6.9-8.0] vs. 5.7 [5.2-6.3], p < 0.001), and there was a greater score increase than controls (2.1 [95% CI: 1.3-2.9] vs. 0.5 [95% CI: 0.1-1.0], p = 0.004), demonstrating Mediterranean diet feasibility. There was a greater proportion of gastrointestinal symptom responders in the Mediterranean diet group than controls (24/29, 83% vs. 11/30, 37%, p < 0.001) and depression responders (15/29, 52% vs. 6/30 20%, p = 0.015). There was no difference in FODMAP intake at week 6 (p = 0.51). Gastrointestinal adverse events were similar (p = 0.588). There were no differences in change in microbiome parameters between groups.

CONCLUSIONS

A Mediterranean diet is feasible in IBS and leads to improvement in gastrointestinal and psychological symptoms. Although this study was unblinded, these findings together with the broader benefits of the Mediterranean diet, provide strong impetus for future research in IBS. Australia New Zealand Clinical Trials Registry: ACTRN12620001362987.

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.

Using a Patient-Completed Food Frequency Questionnaire to Determine Mediterranean Diet Score in People with Inflammatory Bowel Disease

Purpose: To examine the level of agreement between a patient-completed food frequency questionnaire (FFQ) and assessment of usual intake by a registered dietitian (RD) to score adherence to a Mediterranean diet (MedD) in patients with inflammatory bowel disease (IBD).Methods: Patients with IBD completed a short FFQ and were subsequently interviewed by an RD. A 12-item MedD score (MDS), adapted from the Mediterranean Diet Adherence Screener (MEDAS), was calculated from the FFQ and RD assessments. To determine agreement between individual items, Cohen's kappa coefficients were calculated. Absolute agreement between assessment methods was quantified using a one-way random intra-class correlation coefficient for a single measure.Results: Forty-six patients with IBD participated. The mean FFQ-MDS was 4.59 (standard deviation [SD] = 1.65), and mean RD-MDS was 4.83 (SD = 1.53). Kappa coefficients for individual MEDAS items ranged from 0.41 to 0.78 (p < 0.01) between the FFQ- and RD-MDS. Most items demonstrated moderate to substantial agreement. The intra-class correlation coefficient for absolute agreement between the summed FFQ-MDS and RD-MDS was 0.71 (95% confidence interval: 0.52-0.83, p < 0.001), indicating moderate reliability.Conclusions: This patient-completed FFQ may be a promising tool in clinical practice and research and would benefit from additional evaluation to validate its use in patients with IBD.

Gut dysbiosis-related thrombosis in inflammatory bowel disease: Potential disease mechanisms and emerging therapeutic strategies

Patients with inflammatory bowel disease (IBD) have an increased risk of developing venous thromboembolic events, which have a considerable impact on morbidity and mortality. Chronic inflammation plays a crucial role in the pathogenesis of thrombotic events in patients with IBD. However, many unresolved questions remain, particularly regarding the mechanisms that determine the persistent inflammatory state independent of disease activity. This review explored the role of gut microbiota dysbiosis and intestinal barrier dysfunction, which are considered distinctive features of IBD, in determining pro-thrombotic tendencies. Gut-derived endotoxemia due to the translocation of bacterial lipopolysaccharides (LPS) from the intestine to the bloodstream and the bacterial metabolite trimethylamine-N-oxide (TMAO) are the most important molecules involved in gut dysbiosis-related thrombosis. The pathogenic prothrombotic pathways linked to LPS and TMAO have been discussed. Finally, we present emerging therapeutic approaches that can help reduce LPS-mediated endotoxemia and TMAO, such as restoring intestinal eubiosis, normalizing intestinal barrier function, and counterbalancing the effects of LPS and TMAO.

A Mediterranean Diet Pattern Improves Intestinal Inflammation Concomitant with Reshaping of the Bacteriome in Ulcerative Colitis: A Randomised Controlled Trial

BACKGROUND AND AIMS

Dietary patterns are important in managing ulcerative colitis [UC], given their influence on gut microbiome-host symbiosis and inflammation. We investigated whether the Mediterranean Diet Pattern [MDP] vs the Canadian Habitual Diet Pattern [CHD] would affect disease activity, inflammation, and the gut microbiome in patients with quiescent UC.

METHODS

We performed a prospective, randomised, controlled trial in adults [65% female; median age 47 years] with quiescent UC in an outpatient setting from 2017 to 2021. Participants were randomised to an MDP [n = 15] or CHD [n = 13] for 12 weeks. Disease activity [Simple Clinical Colitis Activity Index] and faecal calprotectin [FC] were measured at baseline and week 12. Stool samples were analysed by 16S rRNA gene amplicon sequencing.

RESULTS

The diet was well tolerated by the MDP group. At week 12, 75% [9/12] of participants in the CHD had an FC >100 μg/g, vs 20% [3/15] of participants in the MDP group. The MDP group had higher levels of total faecal short chain fatty acids [SCFAs] [p = 0.01], acetic acid [p = 0.03], and butyric acid [p = 0.03] compared with the CHD. Furthermore, the MDP induced alterations in microbial species associated with a protective role in colitis [Alistipes finegoldii and Flavonifractor plautii], as well as the production of SCFAs [Ruminococcus bromii].

CONCLUSIONS

An MDP induces gut microbiome alterations associated with the maintenance of clinical remission and reduced FC in patients with quiescent UC. The data support that the MDP is a sustainable diet pattern that could be recommended as a maintenance diet and adjunctive therapy for UC patients in clinical remission. ClinicalTrials.gov no: NCT0305371.

Diet as an epigenetic factor in inflammatory bowel disease

Inflammatory bowel disease (IBD) has as a main characteristic the exacerbation of the immune system against enterocytes, compromising the individual's intestinal microbiota. This inflammatory cascade causes several nutritional deficiencies, which further compromise immunological functioning and, as a result, worsen the prognosis. This vicious cycle can be interrupted as the patient's dietary pattern meets their needs according to their clinical condition, acting directly on the inflammatory process of IBD through the interaction of food, intestinal microbiota, and epigenome. Specific nutritional intervention for IBD has a crucial role in preventing and managing disease activity. This review addresses epigenetic modifications through dietary compounds as a mechanism for modulating the intestinal microbiota of patients with IBD.

The Association between Gut Microbiota and Depression in the Japanese Population

Depression is a leading cause of disease worldwide. The association between gut microbiota and depression has barely been investigated in the Japanese population. We analyzed Iwaki health check-up data collected from 2017 to 2019 and constructed generalized linear mixed models. The independent variable was the relative abundance of each of the 37 gut microbiota genera that were reported to be associated with depression. The dependent variable was the presence of depression assessed by the Center for Epidemiologic Studies Depression Scale. Potential confounders, including grip strength, gender, height, weight, smoking, and drinking habits, were adjusted in the regression models. Nine genera's regression coefficients (Alistipes, Blautia, Coprococcus, Dorea, Faecalibacterium, Holdemania, Lactobacillus, Mitsuokella, and Oscillibacter) showed statistical significance after multiple comparisons adjustment. Among these nine gut bacteria genera, Alistipes, Blautia, Coprococcus, Dorea, Faecalibacterium, and Oscillibacter were reported to be associated with butyrate production in the intestine. Our results indicate that gut microbiotas may influence the depression condition of the host via the butyrate-producing process.

The 2023 Impact of Inflammatory Bowel Disease in Canada: Epidemiology of IBD

Inflammatory bowel disease (IBD), consisting of Crohn's disease and ulcerative colitis, is recognized across the world, though Canada has among the highest burdens of IBD in the world. The Canadian Gastro-Intestinal Epidemiology Consortium (CanGIEC) led a six-province study that demonstrated the compounding prevalence of IBD in Canada from 400 per 100,000 in 2002 to 636 per 100,000 in 2014. The prevalence in 2023 is estimated at 825 per 100,000, meaning that over 320,000 people in Canada are living with IBD. Prevalence is forecasted to rise by 2.44% per year such that 1.1% of the population, 470,000 Canadians, will live with IBD by 2035. The overall incidence of IBD in 2023 is 30 per 100,000 person-years, indicating that over 11,000 Canadians will be newly diagnosed with IBD in 2023. Incidence is forecasted to rise by 0.58% per year up to 32.1 per 100,000 by 2035. The rising incidence of IBD is propelled by pediatric-onset IBD, which is rising by 1.23% per year from 15.6 per 100,000 in 2023 to 18.0 per 100,000 in 2035. In contrast, incidence rates among adults and seniors are relatively stable. Understanding the determinates of IBD has expanded through prospective cohort studies such as the Crohn's and Colitis Canada Genetic, Environmental, Microbial (CCC-GEM) project. Consensus recommendations towards diet, lifestyle, behavioural and environmental modifications have been proposed by international organizations with the goal of optimizing disease control and ultimately preventing the development of IBD. Despite these efforts, Canadian healthcare systems will need to prepare for the rising number of people living with IBD.

Epidemiology of Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including subtypes Crohn disease and ulcerative colitis is a chronic inflammatory disorder most often diagnosed in young adulthood. The incidence and prevalence of pediatric-onset IBD is increasing globally. IBD is likely caused by an interplay of multiple environmental factors resulting in a dysregulated mucosal response to the commensal intestinal microbiota in genetically predisposed individuals. This article provides an overview of pediatric IBD epidemiology and environmental risk factors associated with its development, such as the Hygiene Hypothesis, air pollution, greenspace and blue space, neonatal factors, antibiotics, and diet.

The Role of Diet and Gut Microbiota Interactions in Metabolic Homeostasis

Diet is a pivotal determinant in shaping the structure and function of resident microorganisms in the gut through different food components, nutritive proportion, and calories. The effects of diet on host metabolism and physiology can be mediated through the gut microbiota. Gut microbiota-derived metabolites have been shown to regulate glucose and lipid metabolism, energy consumption, and the immune system. On the other hand, emerging evidence indicates that baseline gut microbiota could predict the efficacy of diet intervention, highlighting gut microbiota can be harnessed as a biomarker in personalized nutrition. In this review, the alterations of gut microbiota in different dietary components and dietary patterns, and the potential mechanisms in the diet-microbiota crosstalk are summarized to understand the interactions of diet and gut microbiota on the impact of metabolic homeostasis.

Effect of Dietary Patterns on Inflammatory Bowel Disease: A Machine Learning Bibliometric and Visualization Analysis

AIMS

This study aimed to analyze the related research on the influence of dietary patterns on IBD carried out over the past 30 years to obtain the context of the research field and to provide a scientific basis and guidance for the prevention and treatment of IBD.

METHODS

The literature on the effects of dietary patterns on inflammatory bowel disease published over the past three decades was retrieved from the Web of Science Core Collection (WoSCC) database. CiteSpace, VOSviewer, the R software (version 4.3.0) bibliometrix package, the OALM platform, and other tools were used for the analyses.

RESULTS

The growth of scientific papers related to this topic can be divided into two stages: before and after 2006. Overall, the growth of the relevant literature was in line with Price's literature growth curve. Subrata Ghosh and Antonio Gasbarrini are the authors with the highest academic influence in the field, and Lee D.'s research results are widely recognized by researchers in this field. Among the 72 countries involved in the study, the United States contributed the most, while China developed rapidly with regard to research being carried out in this area. From a regional perspective, countries and institutions in North America, Europe, and East Asia have made the most significant contributions to this field and have the closest cooperation. Among the 1074 articles included in the study, the most influential ones tended to consider the mechanism of the effect of dietary patterns on IBD from the perspective of the microbiome. Multiple tools were used for keyword analysis and mutual verification. The results showed that NF-κB, the Mediterranean diet, fatty acids, fecal microbiota, etc., are the focus and trends of current research.

CONCLUSIONS

A Mediterranean-like dietary pattern may be a good dietary habit for IBD patients. Carbohydrates, fatty acids, and inulin-type fructans are closely related to IBD. Fatty acid, gut microbiota, NF-κB, oxidative stress, and endoplasmic reticulum stress are the hot topics in the study of the effects of dietary patterns on IBD and will be emerging research trends.

Investigating the Crime Scene-Molecular Signatures in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are without cure and troublesome to manage because of the considerable diversity between patients and the lack of reliable biomarkers. Several studies have demonstrated that diet, gut microbiota, genetics and other patient factors are essential for disease occurrence and progression. Understanding the link between these factors is crucial for identifying molecular signatures that identify biomarkers to advance the management of IBD. Recent technological breakthroughs and data integration have fuelled the intensity of this research. This research demonstrates that the effect of diet depends on patient factors and gut microbial activity. It also identifies a range of potential biomarkers for IBD management, including mucosa-derived cytokines, gasdermins and neutrophil extracellular traps, all of which need further evaluation before clinical translation. This review provides an update on cutting-edge research in IBD that aims to improve disease management and patient quality of life.

Diet-microbiota interaction in irritable bowel syndrome: looking beyond the low-FODMAP approach

BACKGROUND

Diet is one of the main modulators of the gut microbiota, and dietary patterns are decisive for gut-microbiota-related diseases, including irritable bowel syndrome (IBS). The low-FODMAP diet (LFD) is commonly used to treat IBS, but its long-term effects on microbiota, symptoms and quality of life (QoL) are unclear. Alternative dietary strategies promoting beneficial gut microbiota, combined with reduced symptoms and improved QoL, are therefore of interest.

AIMS

To review current evidence on the diet-microbiota-interaction as a modulator of IBS pathophysiology, and dietary management of IBS, with particular emphasis on strategies targeting the gut microbiota, beyond the LFD.

METHODS

Literature was identified through PubMed-searches with relevant keywords.

RESULTS

Dietary patterns with a low intake of processed foods and a high intake of plants, such as the Mediterranean diet, promote gut microbiota associated with beneficial health outcomes. In contrast, Western diets with a high intake of ultra-processed foods promote a microbiota associated with disease, including IBS. Increasing evidence points towards dietary strategies consistent with the Mediterranean diet being equal to the LFD in alleviating IBS-symptoms and having a less negative impact on QoL. Timing of food intake is suggested as a gut microbiota modulator, but little is known about its effects on IBS.

CONCLUSIONS

Dietary recommendations in IBS should aim to target the gut microbiota by focusing on improved dietary quality, considering the impact on both IBS-symptoms and QoL. Increased intake of whole foods combined with a regular meal pattern and limitation of ultra-processed foods can be beneficial strategies beyond the LFD.

Future Modulation of Gut Microbiota: From Eubiotics to FMT, Engineered Bacteria, and Phage Therapy

The human gut is inhabited by a multitude of bacteria, yeasts, and viruses. A dynamic balance among these microorganisms is associated with the well-being of the human being, and a large body of evidence supports a role of dysbiosis in the pathogenesis of several diseases. Given the importance of the gut microbiota in the preservation of human health, probiotics, prebiotics, synbiotics, and postbiotics have been classically used as strategies to modulate the gut microbiota and achieve beneficial effects for the host. Nonetheless, several molecules not typically included in these categories have demonstrated a role in restoring the equilibrium among the components of the gut microbiota. Among these, rifaximin, as well as other antimicrobial drugs, such as triclosan, or natural compounds (including evodiamine and polyphenols) have common pleiotropic characteristics. On one hand, they suppress the growth of dangerous bacteria while promoting beneficial bacteria in the gut microbiota. On the other hand, they contribute to the regulation of the immune response in the case of dysbiosis by directly influencing the immune system and epithelial cells or by inducing the gut bacteria to produce immune-modulatory compounds, such as short-chain fatty acids. Fecal microbiota transplantation (FMT) has also been investigated as a procedure to restore the equilibrium of the gut microbiota and has shown benefits in many diseases, including inflammatory bowel disease, chronic liver disorders, and extraintestinal autoimmune conditions. One of the most significant limits of the current techniques used to modulate the gut microbiota is the lack of tools that can precisely modulate specific members of complex microbial communities. Novel approaches, including the use of engineered probiotic bacteria or bacteriophage-based therapy, have recently appeared as promising strategies to provide targeted and tailored therapeutic modulation of the gut microbiota, but their role in clinical practice has yet to be clarified. The aim of this review is to discuss the most recently introduced innovations in the field of therapeutic microbiome modulation.

Targeting the aryl hydrocarbon receptor by gut phenolic metabolites: A strategy towards gut inflammation

The Aryl Hydrocarbon Receptor (AHR) is a ligand-dependent transcription factor able to control complex transcriptional processes in several cell types, which has been correlated with various diseases, including inflammatory bowel diseases (IBD). Numerous studies have described different compounds as ligands of this receptor, like xenobiotics, natural compounds, and several host-derived metabolites. Dietary (poly)phenols have been studied regarding their pleiotropic activities (e.g., neuroprotective and anti-inflammatory), but their AHR modulatory capabilities have also been considered. However, dietary (poly)phenols are submitted to extensive metabolism in the gut (e.g., gut microbiota). Thus, the resulting gut phenolic metabolites could be key players modulating AHR since they are the ones that reach the cells and may exert effects on the AHR throughout the gut and other organs. This review aims at a comprehensive search for the most abundant gut phenolic metabolites detected and quantified in humans to understand how many have been described as AHR modulators and what could be their impact on inflammatory gut processes. Even though several phenolic compounds have been studied regarding their anti-inflammatory capacities, only 1 gut phenolic metabolite, described as AHR modulator, has been evaluated on intestinal inflammatory models. Searching for AHR ligands could be a novel strategy against IBD.

Changes in Dietary Inflammatory Index Score over Time and Cancer Development in Rural Post-Menopausal Women

Inflammation plays a key role in cancer development. As an important modulator of inflammation, the role of diet should be explored. The purpose of this study was to determine the association between diets with a higher inflammatory potential, as measured by the Dietary Inflammatory Index (DII^®), and cancer development in a cohort of rural post-menopausal women. Dietary intake from a randomized controlled trial cohort of rural, post-menopausal women in Nebraska was used to compute energy-adjusted DII (E-DII^TM) scores at baseline and four years later (visit 9). A linear mixed model analysis and multivariate logistic regression evaluated the association between E-DII scores (baseline, visit 9, change score) and cancer status. Of 1977 eligible participants, those who developed cancer (n = 91, 4.6%) had a significantly larger, pro-inflammatory change in E-DII scores (Non-cancer: Δ 0.19 ± 1.43 vs. Cancer: Δ 0.55 ± 1.43, p = 0.02). After adjustment, odds of cancer development were over 20% higher in those with a larger change (more pro-inflammatory) in E-DII scores than those with smaller E-DII changes (OR = 1.21, 95% CI [1.02, 1.42], p = 0.02). Shifting to a more pro-inflammatory diet pattern over four years was associated with increased odds of cancer development, but not with E-DII at baseline or visit 9 alone.

Weighted Gene Co-Expression Network Analysis Identifies a Functional Guild and Metabolite Cluster Mediating the Relationship between Mucosal Inflammation and Adherence to the Mediterranean Diet in Ulcerative Colitis

Diet influences the pathogenesis and clinical course of inflammatory bowel disease (IBD). The Mediterranean diet (MD) is linked to reductions in inflammatory biomarkers and alterations in microbial taxa and metabolites associated with health. We aimed to identify features of the gut microbiome that mediate the relationship between the MD and fecal calprotectin (FCP) in ulcerative colitis (UC). Weighted gene co-expression network analysis (WGCNA) was used to identify modules of co-abundant microbial taxa and metabolites correlated with the MD and FCP. The features considered were gut microbial taxa, serum metabolites, dietary components, short-chain fatty acid and bile acid profiles in participants that experienced an increase (n = 13) or decrease in FCP (n = 16) over eight weeks. WGCNA revealed ten modules containing sixteen key features that acted as key mediators between the MD and FCP. Three taxa (Faecalibacterium prausnitzii, Dorea longicatena, Roseburia inulinivorans) and a cluster of four metabolites (benzyl alcohol, 3-hydroxyphenylacetate, 3-4-hydroxyphenylacetate and phenylacetate) demonstrated a strong mediating effect (ACME: -1.23, p = 0.004). This study identified a novel association between diet, inflammation and the gut microbiome, providing new insights into the underlying mechanisms of how a MD may influence IBD. See clinicaltrials.gov (NCT04474561).

Cardiometabolic health, diet and the gut microbiome: a meta-omics perspective

Cardiometabolic diseases have become a leading cause of morbidity and mortality globally. They have been tightly linked to microbiome taxonomic and functional composition, with diet possibly mediating some of the associations described. Both the microbiome and diet are modifiable, which opens the way for novel therapeutic strategies. High-throughput omics techniques applied on microbiome samples (meta-omics) hold the unprecedented potential to shed light on the intricate links between diet, the microbiome, the metabolome and cardiometabolic health, with a top-down approach. However, effective integration of complementary meta-omic techniques is an open challenge and their application on large cohorts is still limited. Here we review meta-omics techniques and discuss their potential in this context, highlighting recent large-scale efforts and the novel insights they provided. Finally, we look to the next decade of meta-omics research and discuss various translational and clinical pathways to improving cardiometabolic health.

Associations of adherence to Mediterranean-like diet pattern with incident rosacea: A prospective cohort study of government employees in China

Background

Despite of growing evidence on gastrointestinal comorbidities of rosacea, there was a lack of literatures regarding the role of diet on rosacea.

Objectives

To investigate the relationship between adherence to a Mediterranean-like diet pattern and the risk of incident rosacea.

Methods

This was a prospective cohort study of government employees aged >20 years conducted between January 2018 and December 2021 from five cities of Hunan province of China. At baseline, participants completed a food frequency questionnaire and participated in a skin examination. Presence of rosacea was determined by certified dermatologists. Subsequent skin examinations during follow-up were performed every one-year interval since the entry of the study. The Mediterranean diet score (MDS) was generated based on seven food groups (whole grains, red meats, fish, raw vegetables, legumes, fruits and nuts). Binary logistic regression models adjusted for potential confounders were used to estimate risks for incident rosacea.

Results

Of the 3,773 participants who completed at least two consecutive skin examinations, 3,496 were eligible for primary analyses. With a total follow-up of 8,668 person-years, we identified 83 incident rosacea cases. After full adjustments for covariates, the MDS was associated a decreased risk of incident rosacea (aOR: 0.84, 95% CI: 0.72, 0.99; P _trend = 0.037 for 1-point increment of MDS). In subgroup analyses by body mass index (BMI), this inverse association was consistently observed in the lowest and medium tertiles of BMI (<24.5 kg/m²), but not in the highest tertile of BMI (≥24.5 kg/m²), with a significant interaction effect (P < 0.001).

Conclusions

Our results suggested that adherence to a Mediterranean-like diet pattern might reduce the risk of incident rosacea among non-overweight individuals.

The diet rapidly and differentially affects the gut microbiota and host lipid mediators in a healthy population

BACKGROUND

Bioactive lipids produced by human cells or by the gut microbiota might play an important role in health and disease. Dietary intakes are key determinants of the gut microbiota, its production of short-chain (SCFAs) and branched-chain fatty acids (BCFAs), and of the host endocannabinoidome signalling, which are all involved in metabolic diseases. This hypothesis-driven longitudinal fixed sequence nutritional study, realized in healthy participants, was designed to determine if a lead-in diet affects the host response to a short-term dietary intervention. Participants received a Mediterranean diet (MedDiet) for 3 days, a 13-day lead-in controlled diet reflecting the average Canadian dietary intake (CanDiet), and once again a MedDiet for 3 consecutive days. Fecal and blood samples were collected at the end of each dietary phase to evaluate alterations in gut microbiota composition and plasma levels of endocannabinoidome mediators, SCFAs, and BCFAs.

RESULTS

We observed an immediate and reversible modulation of plasma endocannabinoidome mediators, BCFAs, and some SCFAs in response to both diets. BCFAs were more strongly reduced by the MedDiet when the latter was preceded by the lead-in CanDiet. The gut microbiota response was also immediate, but not all changes due to the CanDiet were reversible following a short dietary MedDiet intervention. Higher initial microbiome diversity was associated with reduced microbiota modulation after short-term dietary interventions. We also observed that BCFAs and 2-monoacylglycerols had many, but distinct, correlations with gut microbiota composition. Several taxa modulated by dietary intervention were previously associated to metabolic disorders, warranting the need to control for recent diet in observational association studies.

CONCLUSIONS

Our results indicate that lipid mediators involved in the communication between the gut microbiota and host metabolism exhibit a rapid response to dietary changes, which is also the case for some, but not all, microbiome taxa. The lead-in diet influenced the gut microbiome and BCFA, but not the endocannabinoidome, response to the MedDiet. A higher initial microbiome diversity favored the stability of the gut microbiota in response to dietary changes. This study highlights the importance of considering the previous diet in studies relating the gut microbiome with lipid signals involved in host metabolism. Video Abstract.

Dietary Exposures and Interventions in Inflammatory Bowel Disease: Current Evidence and Emerging Concepts

Diet is intimately linked to the gastrointestinal (GI) tract and has potent effects on intestinal immune homeostasis. Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the GI tract. The therapeutic implications of diet in patients with IBD have received significant attention in recent years. In this review, we provide a contemporary and comprehensive overview of dietary exposures and interventions in IBD. Epidemiological studies suggest that ultra-processed foods, food additives, and emulsifiers are associated with a higher incidence of IBD. Exclusion and elimination diets are associated with improved symptoms in patients with IBD, but no effects on objective markers of inflammation. Specific dietary interventions (e.g., Mediterranean, specific carbohydrate, high fiber, ketogenic, anti-inflammatory diets) have been shown to reduce symptoms, improve inflammatory biomarkers, and quality of life metrics to varying degrees, but these studies are limited by study design, underpowering, heterogeneity, and confounding. To date, there is no robust evidence that any dietary intervention alone may replace standard therapies in patients with IBD. However, diet may play an adjunct role to induce or maintain clinical remission with standard IBD therapies. The results of novel dietary trials in IBD such as personalized fiber, intermittent fasting, and time-restricted diets are eagerly awaited.

Dietary Intake and Systemic Inflammation: Can We Use Food as Medicine?

PURPOSE OF REVIEW

This review summarizes the current literature regarding the association between diet and systemic inflammation.

RECENT FINDINGS

Data in humans suggests that consumption of plant-based nutrients is associated with a reduction in systemic inflammation, while consumption of red meat and excessive dairy has the opposite effect and may increase risk of acute flares in those that suffer from certain chronic diseases like inflammatory bowel disease or psoriasis and certain cancers. There is a known association between diet and systemic inflammation; thus, we recommend that clinicians discuss plant-based, whole food diets with patients, particularly those that suffer from chronic inflammatory diseases as an adjunct treatment for these conditions. Future research should evaluate whether adherence to these types of diets is sustainable in the long term and how these changes affect important quality of life concerns.

Should the Mediterranean diet be recommended for inflammatory bowel diseases patients? A narrative review

Inflammatory bowel diseases (IBD) are chronic, progressive and relapsing inflammatory disorders of unknown etiology that may cause disability over time. Data from epidemiologic studies indicate that diet may play a role in the risk of developing and the course of IBD. It is known that the group of beneficial bacteria was reduced in the IBD and that the Mediterranean diet (MD)-which is defined as eating habits characterized by high consumption of plant foods, mainly cereals, vegetables, fruit as well as olive oil, and small portions of dairy products, sweets, sugar and meat products-affects gut microbiota, enriching beneficial bacteria, which support gut barrier function and reduce inflammation. Although several studies support different favorable effects of MD on IBD, adherence to MD by IBD patients is generally low, including patients from the Mediterranean Basin. Patients avoid many products which are elements of MD because there cause gastrointestinal symptoms. Patients should be encouraged to have a healthy and well-balanced diet according to individual tolerance of products. A good option seems to be good modified MD, changing hard-to-digest products to easy digest.

Roux-en-Y gastric bypass-induced perturbative changes in microbial communities and metabolic pathways in rats

Background

Obesity has become a global health and socioeconomic problem because of an inadequate balance between energy intake and energy expenditure. Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are the two most commonly used strategies for weight loss, which have been proven to benefit from gut microbiota restoration.

Methods

Rats received SG, RYGB, and sham operations for 10 weeks. At the end of the experiment, the fecal microbiota was analyzed using 16s rRNA gene sequencing. In addition, the shift in the plasma metabolism of rats that underwent RYGB surgery was analyzed using untargeted metabolomics. The crosstalk between microbiome and metabolites was revealed using metabolic pathway enrichment and integrated analysis.

Result

The SG surgery induced a modest shift in the gut microbiota relative to the RYGB. RYGB significantly decreased the alpha diversity and Firmicutes/Bacteroides (F/B) ratio and increased the proportion of Escherichia, Bacteroides, and Akkermansia genera compared to sham and SG operations. The predicted function of gut microbiota revealed that the RYGB surgery uniquely enhanced the capability of linoleic acid and sphingolipid metabolism. Furthermore, the circulating serine, phosphatidylcholine (PC) 20:5/22:5, riboflavin, L–carnitine, and linoleic acid were evaluated after RYGB surgery. In addition, the metabolic pathway enrichment and integrated analysis suggest that the RYGB induced Escherichia, Bacteroides, and Akkermansia might inhibit the sphingonine and phytosphingosine metabolisms from serine and promote the PC (20:5/22:5) metabolism to produce linoleic acid.

Conclusion

This comprehensive analysis not only revealed the difference in the gut microbiota shifts after SG and RYGB but also discovered the perturbative changes in microbial communities and metabolic pathways after RYGB surgery, which provided clues for improving the beneficial effect of RYGB in metabolic disease intervention via regulating bacterial-metabolite crosstalk.

Increasing adherence to the Mediterranean diet and lifestyle is associated with reduced fecal calprotectin and intra-individual changes in microbial composition of healthy subjects

The Mediterranean diet (MED) is associated with the modification of gut microbial composition. In this pilot study, we investigate the feasibility of a microbiota-targeted MED-based lifestyle intervention in healthy subjects. MED intervention integrating dietary counseling, a supporting mobile application, and daily physical activity measurement using step trackers was prospectively applied for 4 weeks. Blood and fecal samples were collected at baseline, after the 4-week intervention, and at 6 and 12 months. Blood counts, inflammatory markers, microbial and eukaryotic composition were analyzed. Dietary adherence was assessed using daily questionnaires. All 20 healthy participants (females 65%, median age 37), completed the 4-week intervention. Adherence to MED increased from 15.6 ± 4.1 (baseline) to 23.2 ± 3.6 points (4 weeks), p < .01, reflected by increased dietary fiber and decreased saturated fat intake (both p < .05). MED intervention modestly reduced fecal calprotectin, white blood cell, neutrophil, and lymphocyte counts, within the normal ranges (P < .05). Levels of butyrate producers including Faecalibacterium and Lachnospira were positively correlated with adherence to MED and the number of daily steps. Bacterial composition was associated with plant-based food intake, while fungal composition with animal-based food as well as olive oil and sweets. Increasing adherence to MED correlated with increased absolute abundances of multiple beneficial gut symbionts. Therefore, increasing adherence to MED is associated with reduction of fecal calprotectin and beneficial microbial alterations in healthy subjects. Microbiota targeted lifestyle interventions may be used to modify the intestinal ecosystem with potential implications for microbiome-mediated diseases.

Crohn’s Disease, Host–Microbiota Interactions, and Immunonutrition: Dietary Strategies Targeting Gut Microbiome as Novel Therapeutic Approaches

Crohn’s disease (CD) is a complex, disabling, idiopathic, progressive, and destructive disorder with an unknown etiology. The pathogenesis of CD is multifactorial and involves the interplay between host genetics, and environmental factors, resulting in an aberrant immune response leading to intestinal inflammation. Due to the high morbidity and long-term management of CD, the development of non-pharmacological approaches to mitigate the severity of CD has recently attracted great attention. The gut microbiota has been recognized as an important player in the development of CD, and general alterations in the gut microbiome have been established in these patients. Thus, the gut microbiome has emerged as a pre-eminent target for potential new treatments in CD. Epidemiological and interventional studies have demonstrated that diet could impact the gut microbiome in terms of composition and functionality. However, how specific dietary strategies could modulate the gut microbiota composition and how this would impact host–microbe interactions in CD are still unclear. In this review, we discuss the most recent knowledge on host–microbe interactions and their involvement in CD pathogenesis and severity, and we highlight the most up-to-date information on gut microbiota modulation through nutritional strategies, focusing on the role of the microbiota in gut inflammation and immunity.