A Pilot Study on the Metabolic Impact of Mediterranean Diet in Type 2 Diabetes: Is Gut Microbiota the Key?

Knowledge, Attitudes, and Behaviors around Dietary Fats among People with Type 2 Diabetes: A Systematic Review

This systematic review assesses the knowledge, attitudes, and behaviors (KAB) surrounding dietary fat intake among people with type 2 diabetes mellitus (T2DM) and healthcare professionals. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, four databases were searched to identify studies published between 1995 and 2023 reporting people with T2DM or healthcare professionals that measured KAB towards dietary fat. This work was registered at PROSPERO (CRD42020140247). Twenty-four studies were included. Studies assessed knowledge of people with T2DM and reported poor nutrition knowledge regarding the health effect of fat consumption. Two opposing attitudes towards dietary fat was reported: (1) dietary fat should be limited, (2) promoted dietary fat intake through a low-carbohydrate diet. Participants reported behaviors of limiting fat intake, including trimming visible fat or choosing lower-fat alternatives. Total fat intake ranged between 10 and 66% of participants' total energy intake, while saturated fat intake ranged between 10 and 17%. People with T2DM reported poor knowledge of dietary fats in particular, and they were frequently unable to identify high-fat food. Attitudes towards dietary fat were heterogenous, and regarding behaviors, saturated fat intake was higher than recommended. Future studies should assess the KAB of people with T2DM based on dietary fat subtypes.

Improved Gut Health May Be a Potential Therapeutic Approach for Managing Prediabetes: A Literature Review

Given the growing global threat and rising prevalence of type 2 diabetes mellitus (T2DM), addressing this metabolic disease is imperative. T2DM is preceded by prediabetes (PD), an intermediate hyperglycaemia that goes unnoticed for years in patients. Several studies have shown that gut microbial diversity and glucose homeostasis in PD or T2DM patients are affected. Therefore, this review aims to synthesize the existing literature to elucidate the association between high-calorie diets, intestinal permeability and their correlation with PD or T2DM. Moreover, it discusses the beneficial effects of different dietary interventions on improving gut health and glucose metabolism. The primary factor contributing to complications seen in PD or T2DM patients is the chronic consumption of high-calorie diets, which alters the gut microbial composition and increases the translocation of toxic substances from the intestinal lumen into the bloodstream. This causes an increase in inflammatory response that further impairs glucose regulation. Several dietary approaches or interventions have been implemented. However, only a few are currently in use and have shown promising results in improving beneficial microbiomes and glucose metabolism. Therefore, additional well-designed studies are still necessary to thoroughly investigate whether improving gut health using other types of dietary interventions can potentially manage or reverse PD, thereby preventing the onset of T2DM.

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.

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.

Gut Microbiota and Nutrition: Strategies for the Prevention and Treatment of Type 2 Diabetes

The prevalence of diabetes has increased in last decades worldwide and is expected to continue to do so in the coming years, reaching alarming figures. Evidence have shown that patients with type 2 diabetes (T2D) have intestinal microbial dysbiosis. Moreover, several mechanisms link the microbiota with the appearance of insulin resistance and diabetes. Diet is a crucial factor related to changes in the composition, diversity, and activity of gut microbiota (GM). In this review, the current and future possibilities of nutrient-GM interactions as a strategy to alleviate T2D are discussed, as well as the mechanisms related to decreased low-grade inflammation and insulin resistance. A bibliographic search of clinical trials in Pubmed, Web of Science, and Scopus was carried out, using the terms "gut microbiota, diet and diabetes." The data analyzed in this review support the idea that dietary interventions targeting changes in the microbiota, including the use of prebiotics and probiotics, can improve glycemic parameters. However, these strategies should be individualized taking into account other internal and external factors. Advances in the understanding of the role of the microbiota in the development of metabolic diseases such as T2D, and its translation into a therapeutic approach for the management of diabetes, are necessary to allow a comprehensive approach.

Respiratory and Gut Microbiome Modification during Respiratory Syncytial Virus Infection: A Systematic Review

BACKGROUND

Respiratory syncytial virus (RSV) infection is a major cause of lower respiratory tract infection, especially in infants, and increases the risk of recurrent wheezing and asthma. Recently, researchers have proposed a possible association between respiratory diseases and microbiome alterations. However, this connection has not been fully established. Herein, we conducted a systematic literature review to evaluate the reported evidence of microbiome alterations in patients with RSV infection.

METHODS

The systematic literature review on the association between RSV and microbiome in humans was conducted by searching PubMed, EMBASE, Scopus, and CINAHL from 2012 until February 2022. The results were analyzed qualitatively, focusing on the relationship between microbiome and RSV infection with available key microbiome-related parameters.

RESULTS

In the 405 articles identified by searching databases, 12 (Respiratory tract: 9, Gut: 2, Both: 1) articles in line with the research aims were eligible for this qualitative review. The types of samples for the respiratory tract microbiome and the sequencing methods utilized varied from study to study. This review revealed that the overall microbial composition in both the respiratory tract and gut in RSV-infected patients was different from that in healthy controls. Our generated results demonstrated an increase in the abundance of Haemophilus and Streptococcus, which could contribute to the distinctive separation based on the beta diversity in the respiratory tract.

CONCLUSIONS

The respiratory tract and gut microbiome changed in patients with RSV infection. Further research with a well-organized longitudinal design is warranted to clarify the impact of microbiome alterations on disease pathogenesis.

The Microbiota-Gut-Brain Axis in Metabolic Syndrome and Sleep Disorders: A Systematic Review

BACKGROUND

Over recent decades, a growing body of evidence has emerged linking the composition of the gut microbiota to sleep regulation. Interestingly, the prevalence of sleep disorders is commonly related to cardiometabolic comorbidities such as diabetes, impaired lipid metabolism, and metabolic syndrome (MetS). In this complex scenario, the role of the gut-brain axis as the main communicating pathway between gut microbiota and sleep regulation pathways in the brain reveals some common host-microbial biomarkers in both sleep disturbances and MetS. As the biological mechanisms behind this complex interacting network of neuroendocrine, immune, and metabolic pathways are not fully understood yet, the present systematic review aims to describe common microbial features between these two unrelated chronic conditions.

RESULTS

This systematic review highlights a total of 36 articles associating the gut microbial signature with MetS or sleep disorders. Specific emphasis is given to studies evaluating the effect of dietary patterns, dietary supplementation, and probiotics on MetS or sleep disturbances.

CONCLUSIONS

Dietary choices promote microbial composition and metabolites, causing both the amelioration and impairment of MetS and sleep homeostasis.

Dietary intervention improves metabolic levels in patients with type 2 diabetes through the gut microbiota: a systematic review and meta-analysis

Background

Poor dietary structure plays a pivotal role in the development and progression of type 2 diabetes and is closely associated with dysbiosis of the gut microbiota. Thus, the objective of this systematic review was to assess the impact of dietary interventions on improving gut microbiota and metabolic levels in patients with type 2 diabetes.

Methods

We conducted a systematic review and meta-analysis following the PRISMA 2020 guidelines.

Results

Twelve studies met the inclusion criteria. In comparison to baseline measurements, the high-fiber diet produced substantial reductions in FBG (mean difference -1.15 mmol/L; 95% CI, -2.24 to -0.05; I2 = 94%; P = 0.04), HbA1c (mean difference -0.99%; 95% CI, -1.93 to -0.03; I2 = 89%; P = 0.04), and total cholesterol (mean difference -0.95 mmol/L; 95% CI, -1.57 to -0.33; I2 = 77%; P = 0.003); the high-fat and low-carbohydrate diet led to a significant reduction in HbA1c (mean difference -0.98; 95% CI, -1.50 to -0.46; I2 = 0%; P = 0.0002). Within the experimental group (intervention diets), total cholesterol (mean difference -0.69 mmol/L; 95% CI, -1.27 to -0.10; I2 = 52%; P = 0.02) and LDL-C (mean difference -0.45 mmol/L; 95% CI, -0.68 to -0.22; I2 = 0%; P < 0.0001) experienced significant reductions in comparison to the control group (recommended diets for type 2 diabetes). However, no statistically significant differences emerged in the case of FBG, HbA1c, HOMA-IR, and HDL-C between the experimental and control groups. The high dietary fiber diet triggered an augmented presence of short-chain fatty acid-producing bacteria in the intestines of individuals with T2DM. In addition, the high-fat and low-carbohydrate diet resulted in a notable decrease in Bacteroides abundance while simultaneously increasing the relative abundance of Eubacterium. Compared to a specific dietary pattern, personalized diets appear to result in the production of a greater variety of beneficial bacteria in the gut, leading to more effective blood glucose control in T2D patients.

Conclusion

Dietary interventions hold promise for enhancing metabolic profiles in individuals with T2D through modulation of the gut microbiota. Tailored dietary regimens appear to be more effective than standard diets in improving glucose metabolism. However, given the limited and highly heterogeneous nature of the current sample size, further well-designed and controlled intervention studies are warranted in the future.

A Mobile Intervention Designed Specifically for Older Adults With Frailty to Support Healthy Eating: Pilot Randomized Controlled Trial

BACKGROUND

Frailty, a common geriatric syndrome, predisposes older adults to functional decline. No medications can alter frailty's trajectory, but nutritional interventions may aid in supporting independence.

OBJECTIVE

This paper presents a pilot randomized controlled trial to investigate the feasibility and efficacy of a mobile health intervention, "Olitor," designed to enhance adherence to the Mediterranean diet among older adults with frailty, requiring no external assistance.

METHODS

The study sample consisted of 15 participants aged 66-77 (mean 70.5, SD 3.96) years randomized into intervention (n=8; 8 females; mean 72.4, SD 4.8 years) and control groups (n=7; 6 females, 1 male; mean 70.0, SD 3.9 years). The intervention involved a patient-facing mobile app called "Olitor" and a secure web-based administrative dashboard. Participants were instructed to use the app at least weekly for 3 months, which provided feedback on their food choices, personalized recipe recommendations, and an in-app messaging feature. Using Mann-Whitney tests to compare change scores and Hedges g statistics to estimate effect sizes, the primary efficacy outcomes were adherence to the Mediterranean diet score and insulin resistance measures. Secondary outcomes included retention as a measure of feasibility, engagement level and user app quality ratings for acceptability, and additional metrics to evaluate efficacy. Models were adjusted for multiple comparisons.

RESULTS

The findings demonstrated a significant improvement in the Mediterranean diet adherence score in the intervention group compared to the control (W=50.5; adjusted P=.04) with median change scores of 2 (IQR 2-4.25) and 0 (IQR -0.50 to 0.50), respectively. There was a small and insignificant reduction in homeostasis model assessment of insulin resistance measure (W=23; adjusted P=.85). Additionally, there were significant increases in legume intake (W=54; adjusted P<.01). The intervention's effect size was large for several outcomes, such as Mediterranean diet adherence (Hedges g=1.58; 95% CI 0.34-2.67) and vegetable intake (Hedges g=1.14; 95% CI 0.08-2.21). The retention rate was 100%. The app's overall quality rating was favorable with an average interaction time of 12 minutes weekly.

CONCLUSIONS

This pilot study revealed the potential of the mobile intervention "Olitor" in promoting healthier eating habits among older adults with frailty. It demonstrated high retention rates, significant improvement in adherence to the Mediterranean diet, and increased intake of recommended foods. Insulin resistance showed a minor nonsignificant improvement. Several secondary outcomes, such as lower extremity function and Mediterranean diet knowledge, had a large effect size. Although the app's behavior change features were similar to those of previous digital interventions, the distinctive focus on theory-informed mechanistic measures involved in behavioral change, such as self-regulation, self-efficacy, and expected negative outcomes, may have enhanced its potential. Further investigations in a more diverse and representative population, focusing on individuals with impaired insulin sensitivity, are warranted to validate these preliminary findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05236712; https://clinicaltrials.gov/study/NCT05236712.

Partially Hydrolyzed Guar Gum Intake Supports the Gut Microbiota and Attenuates Inflammation during Influenza H1N1 Virus Infection in Mice

Partially hydrolyzed guar gum (PHGG) is a soluble dietary fiber that is effective for defecation control. It influences the gut microbiota, by which it is metabolized to yield short-chain fatty acids (SCFAs), and it was also recently shown to protect against influenza infection in humans. We here investigated the effects of PHGG in a mouse model of influenza H1N1 virus infection. Eight-week-old C57BL/6 mice were fed normal chow with or without PHGG (500 mg/kg per day) for 4 weeks, infected with H1N1 at 10 weeks of age, and analyzed at 12 weeks of age. Administration of PHGG attenuated the decline in body weight induced by H1N1 infection without affecting food intake. It also ameliorated intestinal atrophy and increased the production of SCFAs including acetic acid, propionic acid, and butyric acid in the cecum, thereby preventing the inhibitory effect of H1N1 infection on SCFA production. The H1N1-induced increases in the serum concentrations of inflammatory cytokines including interferon-γ and interleukin-6 and anti-inflammatory cytokine such as interleukin-10 were all inhibited by PHGG intake. In addition, PHGG administration attenuated inflammatory gene expression in the lung and promoted both natural killer cell activity and regulatory T-cell differentiation in the spleen. Our findings suggest that the consumption of PHGG may improve the gut environment and thereby limit the inflammatory response to H1N1 infection. They may thus provide the basis for novel dietary intervention strategies to suppress the excessive inflammation associated with virus infection.

Effects of Physical Activity and Nutrition Education on the Gut Microbiota in Overweight and Obese Children

Childhood obesity continues to represent a growing challenge, and it has been associated with gut microbiota dysbiosis. This study examines the gut microbiota composition in overweight and obese school children and assesses whether a 12-week multidisciplinary intervention can induce changes in the gut microbiota. The intervention, which combined recreational football and nutritional education, was implemented among 15 school children, aged 7-10 years, with a Body Mass Index ≥ 85th percentile. The children were assigned into two groups: Football Group (n = 9) and Nutrition and Football Group (n = 6). Faecal samples were collected at the beginning and end of the program and analysed by sequencing the 16S rRNA gene. Over the intervention, a significant decrease was found collectively for Bifidobacterium genera (p = 0.011) and for Roseburia genera in the Football Group (p = 0.021). The relative abundance of Roseburia (p = 0.002) and Roseburia faecis (p = 0.009) was negatively correlated with moderate to vigorous physical activity (MVPA), while Prevotella copri was positively correlated with MVPA (p = 0.010) and with the daily intake of protein (p = 0.008). Our findings suggest that a multidisciplinary intervention was capable of inducing limited but significant positive changes in the gut microbiota composition in overweight and obese school children.

The impact of Hafnia alvei HA4597™ on weight loss and glycaemic control after bariatric surgery - study protocol for a triple-blinded, blocked randomized, 12-month, parallel-group, placebo-controlled clinical trial

BACKGROUND

Subjects with obesity exhibit changes in gut microbiota composition and function (i.e. dysbiosis) that contribute to metabolic dysfunction, including appetite impairment. Although bariatric surgery is an effective treatment for obesity with a great impact on weight loss, some subjects show weight regain due to increased energy intake after the surgery. This surgery involves gut microbiota changes that promote appetite control, but it seems insufficient to completely restore the obesity-associated dysbiosis - a possible contributor for weight regain. Thus, modulating gut microbiota with probiotics that could improve appetite regulation as a complementary approach to post-operative diet (i.e. Hafnia alvei HA4597™), may accentuate post-surgery weight loss and insulin sensitivity.

METHODS

This is a protocol of a triple-blinded, blocked-randomized, parallel-group, placebo-controlled clinical trial designed to determine the effect of Hafnia alvei HA4597™ supplementation on weight loss and glycaemic control 1 year after bariatric surgery. Patients of Hospital CUF Tejo, Lisbon, that undergo Roux-en-Y gastric bypass are invited to participate in this study. Men and women between 18 and 65 years old, with a BMI ≥ 35 kg/m2 and at least one severe obesity-related comorbidity, or with a BMI ≥ 40 kg/m2, and who are willing to take 2 capsules of Hafnia alvei HA4597™ probiotic supplements (equivalent to 5 × 107 CFU) vs. placebo per day for 90 days are included in this study. Assessments are carried out at baseline, 3, 6, 9, and 12 months after the surgery. Loss of weight in excess and glycated haemoglobin are considered primary outcomes. In addition, changes in other metabolic and inflammatory outcomes, gut microbiota composition and metabolites, as well as gastrointestinal quality of life are also being assessed during the trial.

DISCUSSION

The evidence obtained in this study will provide relevant information regarding the profile of the intestinal microbiota of individuals with severe obesity and the identification of the risk/benefit ratio of the use of Hafnia alvei HA4597™ as an adjunctive treatment in the maintenance of metabolic and weight control one year after the surgical intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05170867. Registered on 28 December 2021.

Exploring the roles of intestinal flora in enhanced recovery after surgery

Striving to optimize surgical outcomes, the Enhanced Recovery After Surgery (ERAS) pathway mitigates patients' stress through the implementation of evidence-based practices during the pre-, intra-, and postoperative periods. Intestinal flora is a sophisticated ecosystem integrating with the host and the external environment, which serves as a mediator in diverse interventions of ERAS to regulate human metabolism and inflammation. This review linked gut microbes and their metabolites with ERAS interventions, offering novel high-quality investigative proponents for ERAS. ERAS could alter the composition and function of intestinal flora in patients by alleviating various perioperative stress responses. Modifying gut flora through multiple modalities, such as diet and nutrition, to accelerate recovery might be a complementary approach when exploring novel ERAS initiatives. Meanwhile, the pandemic of COVID-19 and the availability of promising qualitative evidence created both challenges and opportunities for the establishment of ERAS mode.

Mediterranean Diet and Obesity-related Disorders: What is the Evidence?

PURPOSE OF REVIEW

Obesity is a chronic disease, a major public health problem due to its association with non-communicable diseases and all-cause mortality. Indeed, people with obesity are at increased risk for a variety of obesity-related disorders including hypertension, dyslipidemia, type 2 diabetes mellitus, cardiovascular disease, and several cancers. Many popular diets with very different macronutrient composition, including the Mediterranean diet (MD), have been used, proposed, and studied for prevention and management of obesity. In particular, MD has been the subject of countless studies over the years and now boasts a large body of scientific literature. In this review, we aimed to update current knowledge by summarizing the most recent evidence on the effect of MD on obesity and obesity-related disorders.

RECENT FINDINGS

The negative effects of obesity are partly reversed by substantial weight loss that can be achieved with MD, especially when low-calorie and in combination with adequate physical activity. In addition, the composition of MD has been correlated with an excellent effect on reducing dyslipidemia. It also positively modulates the gut microbiota and immune system, significantly decreasing inflammatory mediators, a common ground for many obesity-related disorders. People with obesity are at increased risk for a variety of medical disorders including hypertension, dyslipidemia, type 2 diabetes mellitus, and cardiovascular disease. Therefore, there is an inevitable need for measures to manage obesity and its related disorders. At this point, MD has been proposed as a valuable nutritional intervention. It is characterized by a high consumption of vegetables, fruit, nuts, cereals, whole grains, and extra virgin olive oil, as well as a moderate consumption of fish and poultry, and a limited intake of sweets, red meat, and dairy products. MD proves to be the healthiest dietary pattern available to tackle obesity and prevent several non-communicable diseases, including cardiovascular disease and type 2 diabetes.

Dynamics of Gut Microbiota and Clinical Variables after Ketogenic and Mediterranean Diets in Drug-Naïve Patients with Type 2 Diabetes Mellitus and Obesity

Type 2 diabetes mellitus (T2DM), the most common form of diabetes, is a progressive chronic metabolic disease that has increasingly spread worldwide, enhancing the mortality rate, particularly from cardiovascular diseases (CVD). Lifestyle improvement through diet and physical activity is, together with drug treatment, the cornerstone of T2DM management. The Mediterranean diet (MD), which favors a prevalence of unprocessed vegetable foods and a reduction in red meats and industrial foods, without excluding any food category, is usually recommended. Recently, scientific societies have promoted a very low-calorie ketogenic diet (VLCKD), a multiphasic protocol that limits carbohydrates and then gradually re-introduces them, with a favorable outcome on body weight and metabolic parameters. Indeed, gut microbiota (GM) modifications have been linked to overweight/obesity and metabolic alterations typical of T2DM. Diet is known to affect GM largely, but only a few studies have investigated the effects of VLCKD on GM, especially in T2DM. In this study, we have compared anthropometric, biochemical, lifestyle parameters, the quality of life, and the GM of eleven patients with recently diagnosed T2DM and overweight or obesity, randomly assigned to two groups of six and five patients who followed the VLCKD (KETO) or hypocaloric MD (MEDI) respectively; parameters were recorded at baseline (T0) and after two (T2) and three months (T3). The results showed that VLCKD had more significant beneficial effects than MD on anthropometric parameters, while biochemical improvements did not statistically differ. As for the GM, despite the lack of significant results regarding the alpha and beta diversity, and the Firmicutes/Bacteroidota ratio between the two groups, in the KETO group, a significant increase in beneficial microbial taxa such as Verrucomicrobiota phylum with its members Verrucomicrobiae, Verrucomicrobiales, Akkermansiaceae, and Akkermansia, Christensenellaceae family, Eubacterium spp., and a reduction in microbial taxa previously associated with obesity (Firmicutes and Actinobacteriota) or other diseases (Alistipes) was observed both at T2 and T3. With regards to the MEDI group, variations were limited to a significant increase in Actinobacteroidota phylum at T2 and T3 and Firmicutes phylum at T3. Moreover, a metagenomic alteration linked to some metabolic pathways was found exclusively in the KETO group. In conclusion, both dietary approaches allowed patients to improve their state of health, but VLCKD has shown better results on body composition as well as on GM profile.

Impact of Beer and Nonalcoholic Beer Consumption on the Gut Microbiota: A Randomized, Double-Blind, Controlled Trial

Gut microbiota modulation might constitute a mechanism mediating the effects of beer on health. In this randomized, double-blinded, two-arm parallel trial, 22 healthy men were recruited to drink 330 mL of nonalcoholic beer (0.0% v/v) or alcoholic beer (5.2% v/v) daily during a 4-week follow-up period. Blood and faecal samples were collected before and after the intervention period. Gut microbiota was analyzed by 16S rRNA gene sequencing. Drinking nonalcoholic or alcoholic beer daily for 4 weeks did not increase body weight and body fat mass and did not changed significantly serum cardiometabolic biomarkers. Nonalcoholic and alcoholic beer increased gut microbiota diversity which has been associated with positive health outcomes and tended to increase faecal alkaline phosphatase activity, a marker of intestinal barrier function. These results suggest the effects of beer on gut microbiota modulation are independent of alcohol and may be mediated by beer polyphenols.

Myeloid-derived suppressor cells prevent disruption of the gut barrier, preserve microbiota composition, and potentiate immunoregulatory pathways in a rat model of experimental autoimmune encephalomyelitis

Over-activated myeloid cells and disturbance in gut microbiota composition are critical factors contributing to the pathogenesis of Multiple Sclerosis (MS). Myeloid-derived suppressor cells (MDSCs) emerged as promising regulators of chronic inflammatory diseases, including autoimmune diseases. However, it remained unclear whether MDSCs display any therapeutic potential in MS, and how this therapy modulates gut microbiota composition. Here, we assessed the potential of in vitro generated bone marrow-derived MDSCs to ameliorate experimental autoimmune encephalomyelitis (EAE) in Dark Agouti rats and investigated how their application associates with the changes in gut microbiota composition. MDSCs differentiated with prostaglandin (PG)E2 (MDSC-PGE2) and control MDSCs (differentiated without PGE2) displayed strong immunosuppressive properties in vitro, but only MDSC-PGE2 significantly ameliorated EAE symptoms. This effect correlated with a reduced infiltration of Th17 and IFN-γ-producing NK cells, and an increased proportion of regulatory T cells in the CNS and spleen. Importantly, both MDSCs and MDSC-PGE2 prevented EAE-induced reduction of gut microbiota diversity, but only MDSC-PGE2 prevented the extensive alterations in gut microbiota composition following their early migration into Payer's patches and mesenteric lymph nodes. This phenomenon was related to the significant enrichment of gut microbial taxa with potential immunoregulatory properties, as well as higher levels of butyrate, propionate, and putrescine in feces. This study provides new insights into the host-microbiota interactions in EAE, suggesting that activated MDSCs could be potentially used as an efficient therapy for acute phases of MS. Considering a significant association between the efficacy of MDSC-PGE2 and gut microbiota composition, our findings also provide a rationale for further exploring the specific microbial metabolites in MS therapy.

Type 2 diabetes, gut microbiome, and systems biology: A novel perspective for a new era

The association between the physio-pathological variables of type 2 diabetes (T2D) and gut microbiota composition suggests a new avenue to track the disease and improve the outcomes of pharmacological and non-pharmacological treatments. This enterprise requires new strategies to elucidate the metabolic disturbances occurring in the gut microbiome as the disease progresses. To this end, physiological knowledge and systems biology pave the way for characterizing microbiota and identifying strategies in a move toward healthy compositions. Here, we dissect the recent associations between gut microbiota and T2D. In addition, we discuss recent advances in how drugs, diet, and exercise modulate the microbiome to favor healthy stages. Finally, we present computational approaches for disentangling the metabolic activity underlying host-microbiota codependence. Altogether, we envision that the combination of physiology and computational modeling of microbiota metabolism will drive us to optimize the diagnosis and treatment of T2D patients in a personalized way.

The impact of dietary, surgical, and pharmacological interventions on gut microbiota in individuals with diabetes mellitus: A systematic review

AIMS

To conduct a systematic review assessing the association between dietary, surgical, and pharmacological interventions and changes in the gut microbiota of individuals with diabetes.

METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were searched focusing on the effects of dietary, bariatric surgery, and pharmacological interventions on gut microbiota in adults with diabetes. Studies were classified based on qualitative changes using a simple vote-counting method, evaluating reduction, no effect, or an increase in the gut microbiota outcomes.

RESULTS

6,004 studies were retained to review their titles and abstracts. A total of 149 full-text articles were reassessed, of which 49 were included in the final analysis. This review indicates that dietary, surgical, and pharmacological interventions increase or decrease bacterial populations from more than 60 families, genera, or species. In general, the interventions led to an increase in the bacterial population from phylum Firmicutes, mainly Lactobacillus species, compared to the gram-negative bacterial population from phylum Bacteroidetes.

CONCLUSIONS

The results of the included studies suggest that interventions aimed at reducing species related to uncontrolled diabetes and increasing species related to the healthy gut are potential adjuvants in treating diabetes; however, well-conducted interventional studies targeting gut microbiota are necessary.

Mediterranean diet diminishes the effects of Crohn's disease and improves its parameters: A systematic review

BACKGROUND

The pathogenesis and clinical course of Crohn's disease (CD) is influenced by diet. Mediterranean Diet (MD) helps Crohn's patients through many mechanisms.

AIMS

This study aimed to evaluate the effect of the MD on CD patients and to evaluate such effect on body parameters.

METHODS

PubMed, Science Direct, Web of Science, MEDLINE and Cochrane central library were searched for MD and CD from 2010 to 2020. Included studies met the following criteria: (1) male and female adults (18-75 years) with a confirmed diagnosis of CD; (2) MD as an intervention; (3) original interventional Trial, Cross-Sectional Analysis, or Prospective Cohort Studies.

RESULTS

Five studies were included, involving 83,564 participants. A small number of patients with CD fulfilled the P-MDS criteria, the overall scores were low, 4.7 and 4.5 for females and males respectively. Patients with an inactive disease whose adherence to MD was greater, the MD score was negatively correlated with disease activity (p <0.001) and positively with IBDQ (p = 0.008). Twenty-seven percent had a prevalence of impaired adherence to a MD (mMED score = 0-2), giving such a population a risk attributed to 12% for the later CD. Seventy-point reduction in CDAI + decreased fecal CRP / calprotectin, calprotectin <250 mcg/gm or >50% decrease from baseline and hsCRP < 5 mg/L or >50% from baseline.

CONCLUSIONS

MD showed anti-inflammatory properties. Adherence to MD was associated with improvement in CD patients and negatively correlated with the disease activity, in addition to a lower risk of developing CD later in life.

Intestinal Alkaline Phosphatase: A Review of This Enzyme Role in the Intestinal Barrier Function

Intestinal alkaline phosphatase (IALP) has recently assumed a special relevance, being the subject of study in the prevention and treatment of certain diseases related to leaky gut. This brush border enzyme (ecto-enzyme) plays an important role in the maintenance of intestinal microbial homeostasis and intestinal barrier function through its ability to dephosphorylate lipopolysaccharide (LPS). This review addresses how IALP and intestinal barrier dysfunction may be implicated in the pathophysiology of specific diseases such as inflammatory bowel disease, necrotizing enterocolitis, and metabolic syndrome. The use of IALP as a possible biomarker to assess intestinal barrier function and strategies to modulate IALP activity are also discussed.

Respiratory tract infections and gut microbiome modifications: A systematic review

Respiratory tract infections (RTIs) are extremely common and can cause gastrointestinal tract symptoms and changes to the gut microbiota, yet these effects are poorly understood. We conducted a systematic review to evaluate the reported evidence of gut microbiome alterations in patients with a RTI compared to healthy controls (PROSPERO: CRD42019138853). We systematically searched Medline, Embase, Web of Science, Cochrane and the Clinical Trial Database for studies published between January 2015 and June 2021. Studies were eligible for inclusion if they were human cohorts describing the gut microbiome in patients with an RTI compared to healthy controls and the infection was caused by a viral or bacterial pathogen. Dual data screening and extraction with narrative synthesis was performed. We identified 1,593 articles and assessed 11 full texts for inclusion. Included studies (some nested) reported gut microbiome changes in the context of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) (n = 5), influenza (H1N1 and H7N9) (n = 2), Tuberculosis (TB) (n = 4), Community-Acquired Pneumonia CAP (n = 2) and recurrent RTIs (rRTI) (n = 1) infections. We found studies of patients with an RTI compared to controls reported a decrease in gut microbiome diversity (Shannon) of 1.45 units (95% CI, 0.15-2.50 [p, <0.0001]) and a lower abundance of taxa (p, 0.0086). Meta-analysis of the Shannon value showed considerable heterogeneity between studies (I2, 94.42). Unbiased analysis displayed as a funnel plot revealed a depletion of Lachnospiraceae, Ruminococcaceae and Ruminococcus and enrichment of Enterococcus. There was an important absence in the lack of cohort studies reporting gut microbiome changes and high heterogeneity between studies may be explained by variations in microbiome methods and confounder effects. Further human cohort studies are needed to understand RTI-induced gut microbiome changes to better understand interplay between microbes and respiratory health.

Study to Explore Plant-Derived Trimethylamine Lyase Enzyme Inhibitors to Address Gut Dysbiosis

Lifestyle complications are major health concerns around the globe and are recognized as a major factor for the development of various chronic diseases such as obesity, diabetes, inflammatory bowel diseases, cancer, and cardiac diseases. An unhealthy diet and poor lifestyle impose a serious threat to human health. Numerous studies have suggested the role of human microbiota in human health and diseases. Microbiota resides in the human body symbiotically and the composition of microorganisms is crucial for maintaining the healthy state of an individual. A dysbiotic gut microbiome is responsible for the release of toxic metabolites such as trimethylamine, lipopolysaccharides, bile acids, and uremic toxins and is associated with impaired organ functions. Dietary and herbal intervention of dysbiosis proposes a promising strategy to counteract gut alterations and repairing of the microbial ecosystem and health. The objective of the present comparative study was to observe the effect of therapeutic herbs in gut dysbiosis. In silico studies were performed to identify human microbiota associated with various diseases, ADME, and toxicity properties of phytoconstituents of "Tinospora cordifolia" and "Ocimum sanctum." Furthermore, co-interaction studies were performed to observe the affinity of selected phytochemicals against choline trimethylamine lyase, a critical enzyme involved in dysbiosis-induced human diseases. The antimicrobial potential of phytocompounds was done by the disc diffusion method. In conclusion, our work discusses the herbal intervention of gut dysbiosis and proposes a natural, safe, and effective herbal formulation to correct microbial dysbiosis and associated diseases.

The Effect of Dietary Interventions on Chronic Inflammatory Diseases in Relation to the Microbiome: A Systematic Review

Chronic inflammation plays a central role in the pathophysiology of various non-communicable diseases. Dietary interventions can reduce inflammation, in part due to their effect on the gut microbiome. This systematic review aims to determine the effect of dietary interventions, specifically fiber intake, on chronic inflammatory diseases and the microbiome. It aims to form hypotheses on the potential mediating effects of the microbiome on disease outcomes after dietary changes. Included were clinical trials which performed a dietary intervention with a whole diet change or fiber supplement (>5 g/day) and investigated the gut microbiome in patients diagnosed with chronic inflammatory diseases such as cardiovascular disease (CVD), type 2 diabetes (T2DM), and autoimmune diseases (e.g., rheumatoid arthritis (RA), inflammatory bowel disease (IBD)). The 30 articles which met the inclusion criteria had an overall moderate to high risk of bias and were too heterogeneous to perform a meta-analysis. Dietary interventions were stratified based on fiber intake: low fiber, high fiber, and supplemental fiber. Overall, but most pronounced in patients with T2DM, high-fiber plant-based dietary interventions were consistently more effective at reducing disease-specific outcomes and pathogenic bacteria, as well as increasing microbiome alpha diversity and short-chain fatty acid (SCFA)-producing bacteria, compared to other diets and fiber supplements.