Effects of a mediterranean diet on the gut microbiota and microbial metabolites: A systematic review of randomized controlled trials and observational studies

The Influence of an AI-Driven Personalized Nutrition Program on the Human Gut Microbiome and Its Health Implications

Background/Objectives: Personalized nutrition programs enhanced with artificial intelligence (AI)-based tools hold promising potential for the development of healthy and sustainable diets and for disease prevention. This study aimed to explore the impact of an AI-based personalized nutrition program on the gut microbiome of healthy individuals. Methods: An intervention using an AI-based mobile application for personalized nutrition was applied for six weeks. Fecal and blood samples from 29 healthy participants (females 52%, mean age 35 years) were collected at baseline and at six weeks. Gut microbiome through 16s ribosomal RNA (rRNA) amplicon sequencing, anthropometric and biochemical data were analyzed at both timepoints. Dietary assessment was performed using food frequency questionnaires. Results: A significant increase in richness (Chao1, 220.4 ± 58.5 vs. 241.5 ± 60.2, p = 0.024) and diversity (Faith's phylogenetic diversity, 15.5 ± 3.3 vs. 17.3 ± 2.8, p = 0.0001) was found from pre- to post-intervention. Following the intervention, the relative abundance of genera associated with the reduction in cholesterol and heart disease risk (e.g., Eubacterium coprostanoligenes group and Oscillobacter) was significantly increased, while the abundance of inflammation-associated genera (e.g., Eubacterium ruminantium group and Gastranaerophilales) was decreased. Alterations in the abundance of several butyrate-producing genera were also found (e.g., increase in Faecalibacterium, decrease in Bifidobacterium). Further, a decrease in carbohydrate (272.2 ± 97.7 vs. 222.9 ± 80.5, p = 0.003) and protein (113.6 ± 38.8 vs. 98.6 ± 32.4, p = 0.011) intake, as well as a reduction in waist circumference (78.4 ± 12.1 vs. 77.2 ± 11.2, p = 0.023), was also seen. Changes in the abundance of Oscillospiraceae_UCG_002 and Lachnospiraceae_UCG_004 were positively associated with changes in olive oil intake (Rho = 0.57, p = 0.001) and levels of triglycerides (Rho = 0.56, p = 0.001). Conclusions: This study highlights the potential for an AI-based personalized nutrition program to influence the gut microbiome. More research is now needed to establish the use of gut microbiome-informed strategies for personalized nutrition.

Contributions of Dietary Patterns and Factors to Regulation of Rheumatoid Disease

Rheumatoid arthritis (RA) is a systemic autoimmune disease that commonly causes pain in joints and the progressive destruction of cartilage and bone, which significantly reduces the quality of life and increases the social burden. However, there is still no cure for RA, so it is highly important to explore additional adjuvant treatment methods. Studies have indicated that malnutrition, changes in intestinal microbiota, and changes in immune status caused by dietary imbalance are directly related to the onset of RA, indicating that dietary intervention may offer a simple, economical, and practical avenue to relieve RA. Therefore, in this review, we discuss the pathogenesis of RA and summarize the influence of different dietary patterns on RA. In particular, we pointed out that high-fat, high-sugar, and high-salt diets contribute to RA progression, whereas the Mediterranean diet (MD) is beneficial for preventing RA. Furthermore, the ingredients of food, such as dietary fiber, probiotics, and vitamins, help reduce the level of inflammation and relieve joint pain, which may play critical roles in the treatment of RA. Therefore, dietary intervention provides a potential effective approach for adjuvant therapy of RA.

The association between the Mediterranean Diet and the prime diet quality score and new-diagnosed irritable bowel syndrome: a matched case-control study

Background

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder with multifactorial etiology. Dietary patterns, including the Mediterranean Diet (Med-Diet) and the Prime Diet Quality Score (PDQS), may play a role in IBS risk. This study examined the association between adherence to the Med-Diet and PDQS and new-diagnosed IBS in an Iranian population.

Methods

A matched case-control study was conducted on 170 newly diagnosed IBS patients and 340 age- and sex-matched controls recruited from outpatient clinics in Zanjan, Iran. Dietary intake was assessed using a semiquantitative food frequency questionnaire. The Med-Diet score and PDQS were calculated, with higher scores indicating better diet quality. Conditional logistic regression was used to determine the odds of IBS across quartiles of Med-Diet and PDQS, adjusting for sociodemographic and clinical factors.

Results

Higher adherence to the Med-Diet was associated with 51% lower odds of IBS (OR: 0.49; 95% CI: 0.30-0.73, P < 0.001) in the highest quartile compared to the lowest. Similarly, participants in the highest PDQS quartile showed a significantly 59% lower odds of IBS (OR: 0.41; 95% CI: 0.26-0.51, P < 0.001) compared to the lowest quartile. Both associations remained significant after adjusting for potential confounders, including total energy intake. These findings highlight the potential clinical relevance of dietary quality in IBS prevention.

Conclusion

Higher adherence to the Med-Diet and a higher PDQS were both inversely associated with IBS risk. Specifically, individuals with higher Med-Diet scores and higher PDQS scores had a lower risk of developing IBS compared to those with lower adherence or scores. These findings suggest a potential role of these dietary patterns in modulating IBS risk, although causal relationships cannot be established from this study.

Diet interventions for depression: Review and recommendations for practice

OBJECTIVE

this paper aims to present the evidence for the role of diet in the prevention and treatment of depression, review the potential underlying mechanisms and provide practice recommendations for mental health clinicians.

METHODS

A literature review was conducted through searches of PubMed with the search terms 'depression', 'diet', 'prevention', 'treatment' and 'mechanisms' and combinations thereof. Additional articles were identified through hand searching.

RESULTS

Greater adherence to several healthy dietary patterns, traditional diets such as the Mediterranean diet and other diets such as the DASH diet are associated with or can treat symptoms of depression. Several limitations of the research were noted, many of which relate to inherent challenges of studying diet. Mechanisms by which dietary intervention can influence mood include the gut microbiome, modulation of inflammatory processes, reduction in oxidative stress and modulation of hypothalamic-pituitary-adrenal axis function. Recommendations for mental health clinicians to enable translation of the evidence into practice are provided.

CONCLUSION

Diet can play an important role in preventing and treating depression. Mental health clinicians are well placed to provide dietary counselling and to use clinical judgement in choosing the specific approach that reflects the needs of the patient but are encouraged to refer to a specialist dietitian where necessary.

The Interplay of Nutrition, the Gut Microbiota and Immunity and Its Contribution to Human Disease

Nutrition, the gut microbiota and immunity are all important factors in the maintenance of health. However, there is a growing realization of the complex interplay between these elements coalescing in a nutrition-gut microbiota-immunity axis. This regulatory axis is critical for health with disruption being implicated in a broad range of diseases, including autoimmune disorders, allergies and mental health disorders. This new perspective continues to underpin a growing number of innovative therapeutic strategies targeting different elements of this axis to treat relevant diseases. This review describes the inter-relationships between nutrition, the gut microbiota and immunity. It then details several human diseases where disruption of the nutrition-gut microbiota-immunity axis has been identified and presents examples of how the various elements may be targeted therapeutically as alternate treatment strategies for these diseases.

The impact of dietary patterns on gut microbiota for the primary and secondary prevention of cardiovascular disease: a systematic review

BACKGROUND

Previous studies found that it is promising to achieve the protective effects of dietary patterns on cardiovascular health through the modulation of gut microbiota. However, conflicting findings have been reported on how dietary patterns impact gut microbiota in individuals either established or at risk of cardiovascular disease (CVD). Our systematic review aimed to explore the effect of dietary patterns on gut microbiota composition and on risk factors for CVD in these populations.

METHODS

We systematically searched seven databases, including PubMed/MEDLINE, MEDLINE (Ovid), Embase (Ovid), CINHAL (EBSCO), Web of Science, CNKI (Chinese), and Wanfang (Chinese), covering literature from inception to October 2024. Studies were included if they focused on adults aged 18 years and older with CVD or at least two CVD risk factors, implemented dietary pattern interventions, and incorporated outcomes related to microbiome analysis. The risk of bias for included studies was assessed using the revised Cochrane risk of bias tool (RoB2) for randomized trials and the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) for non-randomized studies. Changes in the relative abundance of the gut microbiome were summarized at various taxonomic levels, including phylum, class, order, family, genus, and species. Random-effects meta-analysis was conducted to analyze the mean difference in cardiometabolic parameters pre- and post-intervention.

RESULTS

Nineteen studies were identified, including 17 RCT and two self-controlled trails. Risk of bias across the studies was mixed but mainly identified as low and unclear. The most frequently reported increased taxa were Faecalibacterium (N = 8) with plant-rich diets, Bacteroides (N = 3) with restrictive diets, and Ruminococcaceae UCG 005 and Alistipes (N = 9) with the polyphenol-rich diets. The most frequently reported decreased taxa were Parabacteroides (N = 7) with plant-rich diets, Roseburia (N = 3) with restrictive diets, and Ruminococcus gauvreauii group (N = 6) with the polyphenol-rich diets. Plant-rich diets showed a significant decrease in total cholesterol (TC) with a mean difference of -6.77 (95% CI, -12.36 to -2.58; I2 = 84.7%), while restrictive diets showed a significant decrease in triglycerides (TG) of -22.12 (95% CI, -36.05 to -8.19; I2 = 98.4%).

CONCLUSIONS

Different dietary patterns showed distinct impacts on gut microbiota composition. Plant-rich diets promoted the proliferation of butyrate-producing bacteria, suggesting promising prospects for modulating gut microbiota and butyrate production through dietary interventions to enhance cardiovascular health. Further research is warranted to investigate the long-term effects of dietary patterns on clinical endpoints, such as CVD events or mortality.

REVIEW REGISTRATION

Registration number: CRD42024507660.

The impact of the Mediterranean diet on alleviating depressive symptoms in adults: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

High adherence to the Mediterranean diet (MD) has been associated with a reduced risk of depression in prospective cohort studies, but whether MD interventions are effective among adults with depression is uncertain.

OBJECTIVE

This study aimed to synthesize findings on the effects of MD interventions on the severity of depressive symptoms in adults with depression.

DATA SOURCES

PubMed, Cochrane CENTRAL, PsycINFO, Scopus, and Web of Science were systematically searched from database inception to March 2023. The Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines and the Cochrane recommendations were followed. We included randomized controlled trials (RCTs) comparing outcomes after MD interventions with outcomes for control conditions in adults with depressive disorders or depressive symptoms.

DATA EXTRACTION

Two authors extracted the data independently. The Sidik-Jonkman estimator, the I2 metric, and the prediction interval were used to estimate between-study heterogeneity. To determine the risk of bias and the certainty of evidence from RCTs, we used the Cochrane Collaboration's Risk of Bias 2 and Grades of Recommendation, Assessment, Development, and Evaluation tools, respectively.

DATA ANALYSIS

In total, 1507 participants (mean age range: 22.0 years-53.3 years) with depression were initially included in the 5 RCTs of this review. Compared with control conditions, MD interventions significantly reduced depressive symptoms among young and middle-aged adults with major depression or mild to moderate depressive symptoms (standardized mean difference: -0.53; 95% confidence interval: -0.90 to -0.16; I2 = 87.1%). The prediction interval ranged from -1.86 to 0.81. The overall risk of bias was within the range of "some concerns" to "high," while the certainty of evidence was low.

CONCLUSION

MD interventions appear to have substantial potential for alleviating depressive symptoms in people experiencing major or mild depression. However, to establish robust recommendations, there remains a need for high-quality, large-scale, and long-term RCTs.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022341895.

Pan-Cancer Insights: A Study of Microbial Metabolite Receptors in Malignancy Dynamics

BACKGROUND/OBJECTIVES

The role of the gut microbiome in cancer biology has become an increasingly prominent area of research, particularly regarding the role of microbial metabolites and their receptors (MMRs). These metabolites, through the various gut-organ axes, have been proven to influence several pathogenetic mechanisms. This study conducted a comprehensive pan-cancer analysis of MMR transcriptomic profiles across twenty-three cancer types, exploring the mechanisms through which they can influence cancer development and progression.

METHODS

Utilizing both cancer cell lines from CCLE (Cancer Cell Line Encyclopedia) and human tumor samples from TCGA (The Cancer Gene Atlas), we analyzed 107 MMRs interacting with microbial metabolites such as short-chain fatty acids, bile acids, indole derivatives, and others while studying their interactions with key known cancer genes.

RESULTS

Our results revealed that certain MMRs, such as GPR84 and serotonin receptors, are consistently upregulated in various malignancies, while others, like ADRA1A, are frequently downregulated, suggesting diverse roles in cancer pathophysiology. Furthermore, we identified significant correlations between MMR expression and cancer hallmark genes and pathways, including immune evasion, proliferation, and metastasis.

CONCLUSIONS

These findings suggest that the interactions between microbial metabolites and MMRs may serve as potential biomarkers for cancer diagnosis, prognosis, and therapy, highlighting their therapeutic potential. This study underscores the significance of the microbiota-cancer axis and provides novel insights into microbiome-based strategies for cancer treatment.

Associations Among Estrogens, the Gut Microbiome and Osteoporosis

PURPOSE OF THE REVIEW

The purpose of this Review was to summarize the evidence on the associations among estrogen status, cellular senescence, the gut microbiome and osteoporosis.

RECENT FINDINGS

Indicate that osteoporosis is a global public health problem that impacts individuals and society. In postmenopausal women, a decrease in estrogen levels is associated with a decrease in gut microbial diversity and richness, as well as increased permeability of the gut barrier, which allows for low-grade inflammation. The direct effects of estrogen status on the association between bone and the gut microbiome were observed in untreated and treated ovariectomized women. In addition to the direct effects of estrogens on bone remodeling, estrogen therapy could reduce the risk of postmenopausal osteoporosis by preventing increased gut epithelial permeability, bacterial translocation and inflammaging. However, in studies comparing the gut microbiota of older women, there were no changes at the phylum level, suggesting that age-related comorbidities may have a greater impact on changes in the gut microbiota than menopausal status does. Estrogens modify bone health not only by directly influencing bone remodeling, but also indirectly by influencing the gut microbiota, gut barrier function and the resulting changes in immune system reactivity.

The dietary inflammatory index (DII®) and human papillomavirus infection: a cross-sectional study of US women

BACKGROUND

Diet may influence susceptibility of human papillomavirus (HPV) infection by affecting inflammation and immunity. However, the association between HPV infection and the inflammatory potential of diet has not been investigated. The research aimed to examine the correlation between HPV status and the dietary inflammatory index (DII®).

METHODS

We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2003-2016 to investigate the correlation between DII and HPV status among 9,256 women aged 18-59 years. DII scores were calculated based on 24-hour dietary recall interviews. The association between HPV status and DII was analyzed using weighted logistic regression and restricted cubic spline (RCS).

RESULTS

Women with HPV infection exhibited higher DII scores than those without HPV infection. An increased likelihood of HPV infection was found to be significantly associated with higher DII scores (OR = 1.05, 95% CI: 1.01-1.09, P = 0.021), after full multivariate adjustment. Compared with the lowest tertile of DII scores, the ORs (95% CIs) for HPV infection were 1.20 (1.01, 1.42) and 1.27 (1.07, 1.51) for the second and third tertiles, respectively (P for trend = 0.006). RCS analysis showed a U-shaped relationship between DII and HPV infection, with a breakpoint identified at 0.13.

CONCLUSIONS

Our findings suggest that a pro-inflammatory diet is associated with an increased likelihood of HPV infection among women in the United States. Dietary interventions to reduce inflammation may help prevent HPV infection and related diseases.

Mediterranean Diet Effect on the Intestinal Microbiota, Symptoms, and Markers in Patients with Functional Gastrointestinal Disorders

The Mediterranean diet (MD) has beneficial effects on the intestinal microbiota by the promotion of bacteria associated with a healthy gut. However, its impact on intestinal fungi, among others, is still unknown, and how it affects digestive symptoms and different biomarkers in patients with gastrointestinal (GI) disorders has hardly been explored. The present study evaluated the effect of the MD on gut microbial diversity and structure and intestinal symptoms and biomarkers after 6 weeks of dietary intervention in 46 patients with GI disorders. Dysbiosis in fungal composition and diversity was observed, with a significantly lower abundance of Sordariomycetes, Leotiomycetes, and Orbiliomycetes; a significantly higher abundance of Saccharomycetes; the Chytridiomycota and Mucoromycota phyla were significantly reduced; and the bacterial microbiota remained unchanged. In addition, various GI disorders decreased and associations between stool consistency and intestinal permeability were found with the bacterial genera Alistipes and Roseburia. Thus, the data suggest that MD can alter the fungal intestinal microbiota and improve GI disorders.

The Effect of Dietary Types on Gut Microbiota Composition and Development of Non-Communicable Diseases: A Narrative Review

INTRODUCTION

The importance of diet in shaping the gut microbiota is well established and may help improve an individual's overall health. Many other factors, such as genetics, age, exercise, antibiotic therapy, or tobacco use, also play a role in influencing gut microbiota.

AIM

This narrative review summarizes how three distinct dietary types (plant-based, Mediterranean, and Western) affect the composition of gut microbiota and the development of non-communicable diseases (NCDs).

METHODS

A comprehensive literature search was conducted using the PubMed, Web of Science, and Scopus databases, focusing on the keywords "dietary pattern", "gut microbiota" and "dysbiosis".

RESULTS

Both plant-based and Mediterranean diets have been shown to promote the production of beneficial bacterial metabolites, such as short-chain fatty acids (SCFAs), while simultaneously lowering concentrations of trimethylamine-N-oxide (TMAO), a molecule associated with negative health outcomes. Additionally, they have a positive impact on microbial diversity and therefore are generally considered healthy dietary types. On the other hand, the Western diet is a typical example of an unhealthy nutritional approach leading to an overgrowth of pathogenic bacteria, where TMAO levels rise and SCFA production drops due to gut dysbiosis.

CONCLUSION

The current scientific literature consistently highlights the superiority of plant-based and Mediterranean dietary types over the Western diet in promoting gut health and preventing NCDs. Understanding the influence of diet on gut microbiota modulation may pave the way for novel therapeutic strategies.

Obesity-associated inflammation countered by a Mediterranean diet: the role of gut-derived metabolites

The prevalence of obesity has increased dramatically worldwide and has become a critical public health priority. Obesity is associated with many co-morbid conditions, including hypertension, diabetes, and cardiovascular disease. Although the physiology of obesity is complex, a healthy diet and sufficient exercise are two elements known to be critical to combating this condition. Years of research on the Mediterranean diet, which is high in fresh fruits and vegetables, nuts, fish, and olive oil, have demonstrated a reduction in numerous non-communicable chronic diseases associated with this diet. There is strong evidence to support an anti-inflammatory effect of the diet, and inflammation is a key driver of obesity. Changes in diet alter the gut microbiota which are intricately intertwined with human physiology, as gut microbiota-derived metabolites play a key role in biological pathways throughout the body. This review will summarize recent published studies that examine the potential role of gut metabolites, including short-chain fatty acids, bile acids, trimethylamine-N-oxide, and lipopolysaccharide, in modulating inflammation after consumption of a Mediterranean-like diet. These metabolites modulate pathways of inflammation through the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, toll-like receptor 4 signaling, and macrophage driven effects in adipocytes, among other mechanisms.

Effect of 1-year lifestyle intervention with energy-reduced Mediterranean diet and physical activity promotion on the gut metabolome and microbiota: a randomized clinical trial

BACKGROUND

The health benefits of the Mediterranean diet (MedDiet) have been linked to the presence of beneficial gut microbes and related metabolites. However, its impact on the fecal metabolome remains poorly understood.

OBJECTIVES

Our goal was to investigate the weight-loss effects of a 1-y lifestyle intervention based on an energy-reduced MedDiet coupled with physical activity (intervention group), compared with an ad libitum MedDiet (control group), on fecal metabolites, fecal microbiota, and their potential association with cardiovascular disease risk factors.

METHODS

A total of 400 participants (200 from each study group), aged 55-75 y, and at high cardiovascular disease risk, were included. Dietary and lifestyle information, anthropometric measurements, blood biochemical parameters, and stool samples were collected at baseline and after 1 y of follow-up. Liquid chromatography-tandem mass spectrometry was used to profile endogenous fecal metabolites, and 16S amplicon sequencing was employed to profile the fecal microbiota.

RESULTS

Compared with the control group, the intervention group exhibited greater weight loss and improvement in various cardiovascular disease risk factors. We identified intervention effects on 4 stool metabolites and subnetworks primarily composed of bile acids, ceramides, and sphingosines, fatty acids, carnitines, nucleotides, and metabolites of purine and the Krebs cycle. Some of these were associated with changes in several cardiovascular disease risk factors. In addition, we observed a reduction in the abundance of the genera Eubacterium hallii group and Dorea, and an increase in alpha diversity in the intervention group after 1 y of follow-up. Changes in the intervention-related microbiota profiles were also associated with alterations in different fecal metabolite subnetworks and some cardiovascular disease risk factors.

CONCLUSIONS

An intervention based on an energy-reduced MedDiet and physical activity promotion, compared with an ad libitum MedDiet, was associated with improvements in cardiometabolic risk factors, potentially through modulation of the fecal microbiota and metabolome. This trial was registered at https://www.isrctn.com/ as ISRCTN89898870 (https://doi.org/10.1186/ISRCTN89898870).

The Mediterranean Diet, Its Microbiome Connections, and Cardiovascular Health: A Narrative Review

The Mediterranean diet (MD), rich in minimally processed plant foods and in monounsaturated fats but low in saturated fats, meat, and dairy products, represents one of the most studied diets for cardiovascular health. It has been shown, from both observational and randomized controlled trials, that MD reduces body weight, improves cardiovascular disease surrogates such as waist-to-hip ratios, lipids, and inflammation markers, and even prevents the development of fatal and nonfatal cardiovascular disease, diabetes, obesity, and other diseases. However, it is unclear whether it offers cardiovascular benefits from its individual components or as a whole. Furthermore, limitations in the methodology of studies and meta-analyses have raised some concerns over its potential cardiovascular benefits. MD is also associated with characteristic changes in the intestinal microbiota, mediated through its constituents. These include increased growth of species producing short-chain fatty acids, such as Clostridium leptum and Eubacterium rectale, increased growth of Bifidobacteria, Bacteroides, and Faecalibacterium prausnitzii species, and reduced growth of Firmicutes and Blautia species. Such changes are known to be favorably associated with inflammation, oxidative status, and overall metabolic health. This review will focus on the effects of MD on cardiovascular health through its action on gut microbiota.

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.

Role of fermented dairy products in the health benefits of a mediterranean diet

Mediterranean diet includes fermented dairy products like yogurt and cheese. These foods provide calcium, phosphorus, fat, carbohydrates and protein, all nutrients influencing various systems including bone, cardiovascular system, intermediary metabolism, cancer, central nervous system, and inflammation. In addition, they contain prebiotics and provide probiotics which are capable of modifiying microbiota composition and metabolism, potentially acting also indirectly on the various systems. A large body of evidence indicates that fermented dairy products consumption significantly contributes to the beneficial effects of a Mediterranean diet on various systems' health.

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.

A novel Mediterranean diet-inspired supplement ameliorates cognitive, microbial, and metabolic deficits in a mouse model of low-grade inflammation

The Mediterranean diet (MD) and its bioactive constituents have been advocated for their neuroprotective properties along with their capacity to affect gut microbiota speciation and metabolism. Mediated through the gut brain axis, this modulation of the microbiota may partly contribute to the neuroprotective properties of the MD. To explore this potential interaction, we evaluated the neuroprotective properties of a novel bioactive blend (Neurosyn240) resembling the Mediterranean diet in a rodent model of chronic low-grade inflammation. Behavioral tests of cognition, brain proteomic analysis, 16S rRNA sequencing, and 1H NMR metabolomic analyses were employed to develop an understanding of the gut-brain axis interactions involved. Recognition memory, as assessed by the novel object recognition task (NOR), decreased in response to LPS insult and was restored with Neurosyn240 supplementation. Although the open field task performance did not reach significance, it correlated with NOR performance indicating an element of anxiety related to this cognitive change. Behavioral changes associated with Neurosyn240 were accompanied by a shift in the microbiota composition which included the restoration of the Firmicutes: Bacteroidota ratio and an increase in Muribaculum, Rikenellaceae Alloprevotella, and most notably Akkermansia which significantly correlated with NOR performance. Akkermansia also correlated with the metabolites 5-aminovalerate, threonine, valine, uridine monophosphate, and adenosine monophosphate, which in turn significantly correlated with NOR performance. The proteomic profile within the brain was dramatically influenced by both interventions, with KEGG analysis highlighting oxidative phosphorylation and neurodegenerative disease-related pathways to be modulated. Intriguingly, a subset of these proteomic changes simultaneously correlated with Akkermansia abundance and predominantly related to oxidative phosphorylation, perhaps alluding to a protective gut-brain axis interaction. Collectively, our results suggest that the bioactive blend Neurosyn240 conferred cognitive and microbiota resilience in response to the deleterious effects of low-grade inflammation.

How Different Are the Influences of Mediterranean and Japanese Diets on the Gut Microbiome?

The gut microbiome is a complex ecosystem, mainly composed of bacteria, that performs essential functions for the host. Its composition is determined by many factors; however, diet has emerged as a key regulator. Both the Mediterranean (MD) and Japanese (JD) diets have been associated with significant health benefits and are therefore considered healthy dietary patterns. Both are plant-based diets and although they have much in common, they also have important differences mainly related to total calorie intake and the consumption of specific foods and beverages. Thus, it has been hypothesized that they exert their beneficial properties through different nutrients and bioactive compounds that interact with gut microbes and induce specific changes on gut metabolic pathways. In this review, we present current data on the effects of the MD and JD on the gut microbiome. Furthermore, we aim to examine whether there are differences or shared effects on the gut microbiome of people who adhere to these dietary patterns.

Resveratrol and Gut Microbiota Synergy: Preventive and Therapeutic Effects

The role of an imbalanced high-fat diet in the pathophysiology of common chronic noncommunicable diseases has been known for years. More recently, the concept of 'gut microbiota' and the interaction between their composition and gut metabolites produced from the intake of dietary products have gained the focus of researchers, mostly from the perspective of the prevention of cardiovascular and metabolic disorders, which are still the leading cause of death globally. The aim of this work is to highlight the health benefits of the interaction between resveratrol (RSV), red grape polyphenol, and gut microbiota, through aspects of their therapeutic and preventive potentials. Since changed microbiota (mostly as a consequence of antibiotic overuse) contribute to the persistence of post ('long')-COVID-19 symptoms, these aspects will be covered too. Data were obtained from the electronic databases (MedLine/PubMed), according to specific keywords regarding the protective role of resveratrol, the gut microbiota, and their synergy. RSV exerts beneficial properties in the modulation of cardiovascular, metabolic, and post-COVID-19-related disorders. In healthy individuals, it maintains an ergogenic capacity, prevents oxidative stress, and modulates the inflammatory response. Overall, it improves quality of life. The RSV-gut-microbiota interaction is beneficial in terms of maintaining human health. Along with physical activity, it is key for the prevention of chronic noncommunicable diseases.

Role of the intestinal microbiota and diet in the onset and progression of colorectal and breast cancers and the interconnection between both types of tumours

Colorectal cancer (CRC) is among the leading causes of mortality in adults of both sexes worldwide, while breast cancer (BC) is among the leading causes of death in women. In addition to age, gender, and genetic predisposition, environmental and lifestyle factors exert a strong influence. Global diet, including alcohol consumption, is one of the most important modifiable factors affecting the risk of CRC and BC. Western dietary patterns promoting high intakes of xenobiotics from food processing and ethanol have been associated with increased cancer risk, whereas the Mediterranean diet, generally leading to a higher intake of polyphenols and fibre, has been associated with a protective effect. Gut dysbiosis is a common feature in CRC, where the usual microbiota is progressively replaced by opportunistic pathogens and the gut metabolome is altered. The relationship between microbiota and BC has been less studied. The estrobolome is the collection of genes from intestinal bacteria that can metabolize oestrogens. In a dysbiosis condition, microbial deconjugating enzymes can reactivate conjugated-deactivated oestrogens, increasing the risk of BC. In contrast, intestinal microorganisms can increase the biological activity and bioavailability of dietary phytochemicals through diverse microbial metabolic transformations, potentiating their anticancer activity. Members of the intestinal microbiota can increase the toxicity of xenobiotics through metabolic transformations. However, most of the microorganisms involved in diet-microbiota interactions remain poorly characterized. Here, we provide an overview of the associations between microbiota and diet in BC and CRC, considering the diverse types and heterogeneity of these cancers and their relationship between them and with gut microbiota.

The gut microbiome in the fight against obesity: The potential of dietary factors

Obesity as a global public health burden has experienced a drastic growing trend recently. The management of obesity is challenging because of its complex etiology, and various factors are involved in its development, such as genetic and environmental factors. Different approaches are available to treat and/or manage obesity, including diet, physical activity, lifestyle changes, medications, and surgery. However, some of these approaches have inherent limitations and are closely associated with adverse effects. Therefore, probing into a novel/safe approach to treat and/or manage obesity is of fundamental importance. One such approach gaining renewed interest is the potential role of gut microbiota in obesity and its effectiveness in treating this condition. However, there is a dearth of comprehensive compilation of data on the potential role of the gut microbiome in obesity, particularly regarding dietary factors as a therapeutic approach. Therefore, this review aims to provide an updated overview of the role of gut microbiota in obesity, further highlighting the importance of dietary factors, particularly diet, prebiotics, and probiotics, as potential complementary and/or alternative therapeutic options. Moreover, the association of gut microbiota with obese or lean individuals has also been discussed.

The role of the Mediterranean diet in modulating the gut microbiome: A review of current evidence

The Mediterranean diet (MedDiet) is recognized as one of the United Nations Educational, Scientific and Cultural Organization Intangible Cultural Heritage assets associated with lower rates of cardiometabolic diseases; lower prevalence of cancer, Alzheimer's disease, depression, and onset of inflammatory bowel disease; and more generally low-grade inflammation and mortality risks. Beyond being an input source of beneficial micronutrients, it recently has been discovered that the MedDiet plays a role in a more complex human microbiome-mediated mechanism. An interesting hypothesis suggests a bidirectional relationship between the MedDiet and the gut microbiome, where gut microbiota assembly and biosynthetic capacity are responsive to the diet; in return, the microbiome-reachable nutrients shape and modulate the microbiome toward a characteristic probiotic state. It can be speculated that that primary health benefits of the MedDiet exerted via the gut microbiome are mediated by the bioactive compounds transformed by the microbiome. Furthermore, it is possible that additional probiotic properties of the organisms promoted by diet adherence have secondary benefits. As more detailed omic-based studies take place, more evidence on the MedDiet as a core generic probiotic microbiome modulation strategy surface. However, individual-specific microbiome compositions might impose personal variations on the diet outcome. Therefore, a prospective strategy of a fine-tuned precision nutrition approach might deliver optimized benefits of the MedDiet.

Impact on Fecal Microbiota and Health-Related Markers of an Intervention Focused on Improving Eating Behavior in People at Risk of Food Insecurity

Non-communicable diseases are particularly prevalent among low-income individuals and are associated with the consumption of processed foods, fat, and sugars. This work aims to evaluate the impacts of a nutrition education intervention for low socio-economic individuals on sensory perception, health-related parameters and gut microbiota. Twenty low-income adults underwent a 4-week intervention. Dietary information (three 24 h recalls), detection thresholds and discrimination scores (salty and sweet), and severity of depressive symptoms (Beck Depression Inventory-II (BDI-II)) were collected. Fecal microbial composition and short chain fatty acids were determined by 16S ribosomal RNA-gene sequencing and gas chromatography, respectively. After the intervention, 35% of subjects presented higher compliance with dietary recommendations, increased consumption of vegetables and lignans and reduced consumption of processed meats and nitrosamines, together with depleted levels of Actinomycetota. Higher discrimination for salty and sweet and lower BDI-II scores were also obtained. This nutrition education intervention entailed changes in dietary intake towards healthier food options, reduced potentially carcinogenic compounds and improved scores for discrimination and severity of depressive symptoms. The confirmation of these results in future studies would enable the design of strategic policies contributing to the optimal nutrition of materially deprived families through affordable healthy plant-based interventions.

A Review of the Anti-Obesity Effects of Wild Edible Plants in the Mediterranean Diet and Their Active Compounds: From Traditional Uses to Action Mechanisms and Therapeutic Targets

Obesity is a long-term condition resulting from a continuous imbalance between the amount of energy consumed and expended. It is associated with premature mortality and contributes to a large portion of the global chronic disease burden, including diabesity, cardiovascular disease, hypertension, and some cancers. While lifestyle changes and dietary adjustments are the primary ways to manage obesity, they may not always be sufficient for long-term weight loss. In these cases, medication may be necessary. However, the options for drugs are limited due to their potential side effects. As a result, there is a need to identify safe and effective alternative treatments. Recently, dietary compounds, plants, and bioactive phytochemicals have been considered as promising sources for discovering new pharmacological agents to treat obesity and its related complications. These natural products can function independently or synergistically with other plants to augment their effects at various levels of the body. They can modulate appetite, lipase activity, thermogenesis and fat synthesis and degradation, satiation, adipogenesis, and adipocyte apoptosis. Additionally, targeting adipocyte growth and differentiation with diverse medicinal plants/diet is a significant strategy for devising new anti-obesity drugs that can intervene in preadipocytes, maturing preadipocytes, and mature adipocytes. Clinical trials have shown that the wild edible plants in the Mediterranean diet can reduce the risk of obesity and its related diseases. This review examines the effectiveness of the common components of the Mediterranean diet in managing obesity and its associated health issues. We conducted a comprehensive literature review using PubMed, Science Direct, Google Scholar, and Medline Plus to gather data on the therapeutic effects of the Mediterranean diet and phytochemicals in treating obesity and its associated diseases.

Translation of nutrigenomic research for personalised and precision nutrition for cancer prevention and for cancer survivors

Personalised and precision nutrition uses information on individual characteristics and responses to nutrients, foods and dietary patterns to develop targeted nutritional advice that is more effective in improving the diet and health of each individual. Moving away from the conventional 'one size fits all', such targeted intervention approaches may pave the way to better population health, including lower burden of non-communicable diseases. To date, most personalised and precision nutrition approaches have been focussed on tackling obesity and cardiometabolic diseases with limited efforts directed to cancer prevention and for cancer survivors. Advances in understanding the biological basis of cancer and of the role played by diet in cancer prevention and in survival after cancer diagnosis, mean that it is timely to test and to apply such personalised and precision nutrition approaches in the cancer area. This endeavour can take advantage of the enhanced understanding of interactions between dietary factors, individual genotype and the gut microbiome that impact on risk of, and survival after, cancer diagnosis. Translation of these basic research into public health action should include real-time acquisition of nutrigenomic and related data and use of AI-based data integration methods in systems approaches that can be scaled up using mobile devices.

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.

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.

Role of short chain fatty acids in gut health and possible therapeutic approaches in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are characterized by inflammation in the gastrointestinal tract and include Ulcerative Colitis and Crohn's Disease. These diseases are costly to health services, substantially reduce patients' quality of life, and can lead to complications such as cancer and even death. Symptoms include abdominal pain, stool bleeding, diarrhea, and weight loss. The treatment of these diseases is symptomatic, seeking disease remission. The intestine is colonized by several microorganisms, such as fungi, viruses, and bacteria, which constitute the intestinal microbiota (IM). IM bacteria promotes dietary fibers fermentation and produces short-chain fatty acids (SCFAs) that exert several beneficial effects on intestinal health. SCFAs can bind to G protein-coupled receptors, such as GPR41 and GPR43, promoting improvements in the intestinal barrier, anti-inflammatory, and antioxidant effects. Thus, SCFAs could be a therapeutic tool for IBDs. However, the mechanisms involved in these beneficial effects of SCFAs remain poorly understood. Therefore, this paper aims to provide a review addressing the main aspects of IBDs, and a more detailed sight of SCFAs, focusing on the main effects on different aspects of the intestine with an emphasis on IBDs.

Beneficial Effects of Anti-Inflammatory Diet in Modulating Gut Microbiota and Controlling Obesity

Obesity has consistently been associated with an increased risk of metabolic abnormalities such as diabetes, hyperlipidemia, and cardiovascular diseases, as well as the development of several types of cancer. In recent decades, unfortunately, the rate of overweight/obesity has increased significantly among adults and children. A growing body of evidence shows that there is a relationship between metabolic disorders such as obesity and the composition of the gut microbiota. Additionally, inflammation is considered to be a driving force in the obesity-gut microbiota connection. Therefore, it seems that anti-inflammatory nutrients, foods, and/or diets can play an essential role in the management of obesity by affecting the intestinal flora and controlling inflammatory responses. In this review, we describe the links between the gut microbiota, obesity, and inflammation, and summarize the benefits of anti-inflammatory diets in preventing obesity.

Essential Factors for a Healthy Microbiome: A Scoping Review

Recent discoveries of the purpose and potential of microbial interactions with humans have broad implications for our understanding of metabolism, immunity, the host−microbe genetic interactions. Bioavailability and bioaccessibility of phytonutrients in foods not only enrich microbial diversity in the lower human gastrointestinal tract (GIT) but also direct the functioning of the metagenome of the microbiota. Thus, healthy choices must include foods that contain nutrients that satisfy both the needs of humans and their microbes. Physical activity interventions at a moderate level of intensity have shown positive effects on metabolism and the microbiome, while intense training (>70% VO2max) reduces diversity in the short term. The microbiome of elite endurance athletes is a robust producer of short-chain fatty acids. A lifestyle lacking activity is associated with the development of chronic disease, and experimental conditions simulating weightlessness in humans demonstrate loss of muscle mass occurring in conjunction with a decline in gut short-chain fatty acid (SCFA) production and the microbes that produce them. This review summarizes evidence addressing the relationship between the intestinal microbiome, diet, and physical activity. Data from the studies reviewed suggest that food choices and physical fitness in developed countries promote a resource “curse” dilemma for the microbiome and our health.

An Infancy-Onset 20-Year Dietary Counselling Intervention and Gut Microbiota Composition in Adulthood

The randomized controlled Special Turku Coronary Risk Factor Intervention Project (STRIP) has completed a 20-year infancy-onset dietary counselling intervention to reduce exposure to atherosclerotic cardiovascular disease risk factors via promotion of a heart-healthy diet. The counselling on, e.g., low intake of saturated fat and cholesterol and promotion of fruit, vegetable, and whole-grain consumption has affected the dietary characteristics of the intervention participants. By leveraging this unique cohort, we further investigated whether this long-term dietary intervention affected the gut microbiota bacterial profile six years after the intervention ceased. Our sub-study comprised 357 individuals aged 26 years (intervention n = 174, control n = 183), whose gut microbiota were profiled using 16S rRNA amplicon sequencing. We observed no differences in microbiota profiles between the intervention and control groups. However, out of the 77 detected microbial genera, the Veillonella genus was more abundant in the intervention group compared to the controls (log2 fold-change 1.58, p < 0.001) after adjusting for multiple comparison. In addition, an association between the study group and overall gut microbiota profile was found only in males. The subtle differences in gut microbiota abundances observed in this unique intervention setting suggest that long-term dietary counselling reflecting dietary guidelines may be associated with alterations in gut microbiota.