Feeding Systems and the Gut Microbiome: Gut-Brain Interactions With Relevance to Psychiatric Conditions

Probiotic and prebiotic interventions in eating disorders: A narrative review

AIMS

The review aimed to summarise and discuss findings focused on therapeutic probiotic and prebiotic interventions in eating disorders (ED).

METHODS

Using PubMed/MEDLINE, Cochrane Library, and Web of Science all published studies were retrieved until February 2023, following PRISMA guidelines. From the 111 initial studies, 5 met the inclusion criteria for this review.

RESULTS

All studies included in this narrative review were focused on anorexia nervosa (AN). Three longitudinal, randomised, controlled trials aimed to evaluate interventions with probiotics (Lactobacillus reuteri, yoghurt with Lactobacillus, and Streptococcus) in children and adolescents. These studies primarily emphasised medical outcomes and anthropometric measures following the administration of probiotics. However, the findings yielded mixed results in terms of short-term weight gain or alterations in specific immunological parameters. With a lower level of evidence, supplementation with synbiotics (probiotic + prebiotic) has been associated with improvements in microbiota diversity and attenuation of inflammatory responses.

CONCLUSIONS

Research on probiotics and prebiotics in ED is limited, primarily focussing on anorexia nervosa (AN). Their use in AN regarding medical and anthropometric outcomes needs further confirmation and future research should be warranted to assess their impact on psychological and ED symptomatology, where there is a notable gap in the existing literature.

Effects of probiotic supplementation with weight reducing intervention on anthropometric measures, body composition, eating behavior, and related hormone levels in patients with food addiction and weight regain after bariatric surgery: a study protocol for a randomized clinical trial

BACKGROUND

One of the unfortunate events after bariatric surgery is the weight regain, which occurs in some patients. Food addiction is an eating disorder related to the brain-intestinal axis and can be effective in weight regain after bariatric surgery. In addition, the gut microbiome plays a vital role in eating behaviors, including food addiction. So, this study will aim to evaluate the effects of probiotic supplementation with a weight-reducing diet and cognitive behavioral therapy on anthropometric measures, body composition, eating behavior, and related hormone levels, leptin, oxytocin, and serotonin, in patients with food addiction and weight regain after bariatric surgery.

METHODS

We will carry out a triple-blinded randomized clinical trial for 12 weeks to evaluate the effect of probiotic supplementation with a weight-reducing diet and cognitive behavioral therapy on anthropometric measures, body composition, eating behavior, and related hormone levels including leptin, oxytocin, and serotonin, in patients with food addiction and weight regain after bariatric surgery.

DISCUSSION

Based on the available evidence, probiotic supplementation by modifying the intestinal microbiome can improve food addiction and subsequent weight loss.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20220406054437N1 Registered on 2022-06-01.

Novel ketamine and zinc treatment for anorexia nervosa and the potential beneficial interactions with the gut microbiome

Anorexia nervosa (AN) is a severe illness with diverse aetiological and maintaining contributors including neurobiological, metabolic, psychological, and social determining factors. In addition to nutritional recovery, multiple psychological and pharmacological therapies and brain-based stimulations have been explored; however, existing treatments have limited efficacy. This paper outlines a neurobiological model of glutamatergic and γ-aminobutyric acid (GABA)-ergic dysfunction, exacerbated by chronic gut microbiome dysbiosis and zinc depletion at a brain and gut level. The gut microbiome is established early in development, and early exposure to stress and adversity contribute to gut microbial disturbance in AN, early dysregulation to glutamatergic and GABAergic networks, interoceptive impairment, and inhibited caloric harvest from food (e.g., zinc malabsorption, competition for zinc ions between gut bacteria and host). Zinc is a key part of glutamatergic and GABAergic networks, and also affects leptin and gut microbial function; systems dysregulated in AN. Low doses of ketamine in conjunction with zinc, could provide an efficacious combination to act on NMDA receptors and normalise glutamatergic, GABAergic and gut function in AN.

Association between Endometriosis, Irritable Bowel Syndrome and Eating Disorders: ENDONUT Pilot Study

Background and aim: Irritable bowel syndrome (IBS), eating disorders (ED) and endometriosis share common pathophysiological mechanisms, involving alterations of the gut−brain axis. The aim of the ENDONUT pilot study was to investigate an association between these three diseases by screening for IBS and ED in patients with endometriosis. Method: We included patients from the CIRENDO cohort (Inter-Regional North-West Cohort of women with ENDOmetriosis) with a recent documented diagnosis of endometriosis of less than 4 years, regardless of age, date of onset of symptoms, type of endometriosis (digestive or not), with or without endometriosis-related digestive surgery. Validated questionnaires were used to screen for IBS (Rome IV, Francis score), ED (SCOFF-F, EAT-26), and anxiety/depression (HAD). Anthropometric data and lifestyle habits were also collected. The primary composite endpoint was SCOFF-F and ROME-IV scores. Results: Among 100 patients meeting inclusion criteria, 54 patients completed all the questionnaires. Of these, 19 had a positive SCOFF-F score (35.2%), 26 had a positive ROME-IV score (48.1%), and 14 patients (25.9%) had both a positive SCOFF-F score and a positive ROME-IV score (p = 0.006). Patients with positive SCOFF-F and ROME-IV scores had significantly higher HAD-anxiety and depression scores (p < 0.05). Conclusion: These results suggest a significant association between IBS, ED and endometriosis. The prevalence of IBS and ED in our population is higher than in the general population. Larger studies are needed to confirm these results, to better understand this triad, and to improve the diagnostic and multidisciplinary therapeutic management of these patients.

Biodiversity Effects on Human Mental Health via Microbiota Alterations

The biodiversity hypothesis postulates that the natural environment positively affects human physical and mental health. We evaluate the latest evidence and propose new tools to examine the halobiont environment. We chose to target our review at neuropsychiatric disorders, including depression, anxiety, autism, dementia, multiple sclerosis, etc. because a green prescription (exposure to green spaces) was shown to benefit patients with neuropsychiatric disorders. Specifically, our review consists of three mini reviews on the associations exploring: (1) ecological biodiversity and human microbiota; (2) human microbiota and neuropsychiatric disorders; (3) ecological biodiversity and neuropsychiatric disorders. We conclude that the environment could directly transfer microbes to humans and that human studies support the gut microbiota as part of the pathophysiology of neuropsychiatric disorders. Overall, the results from the three mini reviews consistently support the biodiversity hypothesis. These findings demonstrated the plausibility of biodiversity exerting mental health effects through biophysiological mechanisms instead of psychological mechanisms alone. The idea can be further tested with novel biodiversity measurements and research on the effects of a green prescription.

Features of gut microbiota in patients with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a psychological disorder, which is characterized by the misunderstanding of body image, food restriction, and low body weight. An increasing number of studies have reported that the pathophysiological mechanism of AN might be associated with the dysbiosis of gut microbiota. The purpose of our study was to explore the features of gut microbiota in patients with AN, hoping to provide valuable information on its pathogenesis and treatment.

METHODS

In this cross-sectional study, from August 2020 to June 2021, patients with AN who were admitted into Peking University Third Hospital and Peking University Sixth Hospital ( n   =  30) were recruited as the AN group, and healthy controls (HC) were recruited from a middle school and a university in Beijing ( n   =  30). Demographic data, Hamilton Depression Scale (HAMD) scores of the two groups, and length of stay of the AN group were recorded. Microbial diversity analysis of gut microbiota in stool samples from the two groups was analyzed by 16S ribosomal RNA (rRNA) gene sequencing.

RESULTS

The weight (AN vs. HC, [39.31 ± 7.90] kg vs. [56.47 ± 8.88] kg, P  < 0.001) and body mass index (BMI, AN vs. HC, [14.92 ± 2.54] kg/m 2vs. [20.89 ± 2.14] kg/m 2 , P  < 0.001) of patients with AN were statistically significantly lower than those of HC, and HAMD scores in AN group were statistically significantly higher than those of HC. For alpha diversity, there were no statistically significant differences between the two groups; for beta diversity, the two groups differed obviously regarding community composition. Compared to HC, the proportion of Lachnospiraceae in patients with AN was statistically significantly higher (AN vs. HC, 40.50% vs. 31.21%, Z  = -1.981, P  = 0.048), while that of Ruminococcaceae was lower (AN vs. HC, 12.17% vs. 19.15%, Z  = -2.728, P  = 0.007); the proportion of Faecalibacterium (AN vs. HC, 3.97% vs. 9.40%, Z  = -3.638, P  < 0.001) and Subdoligranulum (AN vs. HC, 4.60% vs. 7.02%, Z  = -2.369, P  = 0.018) were statistically significantly lower, while that of Eubacterium_hallii_group was significantly higher (AN vs. HC, 7.63% vs. 3.43%, Z  = -2.115, P  = 0.035). Linear discriminant effect (LEfSe) analysis (LDA score >3.5) showed that o_Lachnospirales, f_Lachnospiraceae, and g_Eubacterium_hallii_group (o, f and g represents order, family and genus respectively) were enriched in patients with AN. Microbial function of nutrient transport and metabolism in AN group were more abundant ( P  > 0.05). In AN group, weight and BMI were significantly negatively correlated with the abundance of Bacteroidota and Bacteroides , while positively correlated with Subdoligranulum . BMI was significantly positively correlated with Firmicutes; HAMD scores were significantly negatively correlated with Faecalibacterium.

CONCLUSIONS

The composition of gut microbiota in patients with AN was different from that of healthy people. Clinical indicators have correlations with the abundance of gut microbiota in patients with AN.

Are the Effects of Malnutrition on the Gut Microbiota–Brain Axis the Core Pathologies of Anorexia Nervosa?

Anorexia nervosa (AN) is a disabling, costly, and potentially deadly illness. Treatment failure and relapse after treatment are common. Several studies have indicated the involvement of the gut microbiota–brain (GMB) axis. This narrative review hypothesizes that AN is driven by malnutrition-induced alterations in the GMB axis in susceptible individuals. According to this hypothesis, initial weight loss can voluntarily occur through dieting or be caused by somatic or psychiatric diseases. Malnutrition-induced alterations in gut microbiota may increase the sensitivity to anxiety-inducing gastrointestinal hormones released during meals, one of which is cholecystokinin (CCK). The experimental injection of a high dose of its CCK-4 fragment in healthy individuals induces panic attacks, probably via the stimulation of CCK receptors in the brain. Such meal-related anxiety attacks may take part in developing the clinical picture of AN. Malnutrition may also cause increased effects from appetite-reducing hormones that also seem to have roles in AN development and maintenance. The scientific background, including clinical, microbiological, and biochemical factors, of AN is discussed. A novel model for AN development and maintenance in accordance with this hypothesis is presented. Suggestions for future research are also provided.

PROBIOTIC SUPPLEMENTATION ATTENUATES BINGE EATING AND FOOD ADDICTION 1 YEAR AFTER ROUX-EN-Y GASTRIC BYPASS: A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL

AIM

The use of probiotics as adjuvants in the treatment of eating disorders, known as psychobiotics, has already been investigated as a means of modulating the microbiota-gut-brain axis. This study aimed to assess the effect of probiotic supplementation on binge eating and food addiction in subjects after Roux-en-Y gastric bypass surgery.

METHODS

This is a randomized, double-blind, placebo-controlled trial involving 101 patients who received probiotic (Lactobacillus acidophilus NCFM and Bifidobacterium lactis Bi-07) or placebo supplements for 90 days after bariatric surgery, starting on the seventh postoperative day. They were evaluated preoperatively (T0) and postoperatively at 90 days (T1) and 1 year (T2) after surgery. The Yale Food Addiction Scale (YFAS) and Binge Eating Scale (BES) were applied to assess food addiction and binge eating, respectively.

RESULTS

Before surgery, one-third of the patients presented with a food addiction and binge eating diagnosis. The number of symptoms of YFAS and the BES score decreased significantly in both groups at T1 compared to T0. However, a significant effect of treatment with probiotics was observed 1 year after surgery (T2). Both the number of symptoms of food addiction and the binge eating score were lower in the probiotic group than in the placebo group (p=0.037 and p=0.030, respectively).

CONCLUSION

The use of probiotic supplementation for 90 days in the immediate postoperative period may decrease food addiction symptoms and binge eating score up to 1 year after surgery compared to controls.

The Role of the Gut Microbiome, Immunity, and Neuroinflammation in the Pathophysiology of Eating Disorders

There is a growing recognition that both the gut microbiome and the immune system are involved in a number of psychiatric illnesses, including eating disorders. This should come as no surprise, given the important roles of diet composition, eating patterns, and daily caloric intake in modulating both biological systems. Here, we review the evidence that alterations in the gut microbiome and immune system may serve not only to maintain and exacerbate dysregulated eating behavior, characterized by caloric restriction in anorexia nervosa and binge eating in bulimia nervosa and binge eating disorder, but may also serve as biomarkers of increased risk for developing an eating disorder. We focus on studies examining gut dysbiosis, peripheral inflammation, and neuroinflammation in each of these eating disorders, and explore the available data from preclinical rodent models of anorexia and binge-like eating that may be useful in providing a better understanding of the biological mechanisms underlying eating disorders. Such knowledge is critical to developing novel, highly effective treatments for these often intractable and unremitting eating disorders.

Medication in AN: A Multidisciplinary Overview of Meta-Analyses and Systematic Reviews

Drugs are widely prescribed for anorexia nervosa in the nutritional, somatic, and psychiatric fields. There is no systematic overview in the literature, which simultaneously covers all these types of medication. The main aims of this paper are (1) to offer clinicians an overview of the evidence-based data in the literature concerning the medication (psychotropic drugs and medication for somatic and nutritional complications) in the field of anorexia nervosa since the 1960s, (2) to draw practical conclusions for everyday practise and future research. Searches were performed on three online databases, namely MEDLINE, Epistemonikos and Web of Science. Papers published between September 2011 and January 2019 were considered. Evidence-based data were identified from meta-analyses, if there were none, from systematic reviews, and otherwise from trials (randomized or if not open-label studies). Evidence-based results are scarce. No psychotropic medication has proved efficacious in terms of weight gain, and there is only weak data suggesting it can alleviate certain psychiatric symptoms. Concerning nutritional and somatic conditions, while there is no specific, approved medication, it seems essential not to neglect the interest of innovative therapeutic strategies to treat multi-organic comorbidities. In the final section we discuss how to use these medications in the overall approach to the treatment of anorexia nervosa.

[The Indian Ayurveda medicine-a meaningful supplement to psychiatric treatment?]

Ayurveda is a traditional Indian system of medicine that is more than 3000 years old, consisting mostly of a specific diet, oily infusions mainly in the area of the head, enemas, medicinal plants and yoga. It is based on a naturopathic and anthropological belief in association with the hinduistic religion. Ayurveda has been practiced very successfully in India but so far it has only been insufficiently appreciated by western medicine, especially psychiatry. An exception is Scharfetter from Zürich who wrote a review article on this topic in 1976. Nevertheless, it is probable that particularly the immunological mechanisms of psychotic and affective disorders can be influenced by the application of ayurvedic methods; however, the empirical data source, particularly with respect to randomized controlled trials and meta-analyses regarding psychiatric disorder symptoms is limited. Even if Ayurveda is applied in a highly individualized manner, this should be rapidly improved for further evidential assessment. First positive experiences in the neuropsychiatric field in Germany are already available.

Antidepressants Improve Negative Regulation of Toll-Like Receptor Signaling in Monocytes from Patients with Major Depression

OBJECTIVE

Changes in the brain's inflammatory status can lead to psychopathological responses, especially depression. Using animal models, recent studies have revealed that this pathology is due, in part, to innate immune responses of monocytes.

METHODS

We focus on the involvement of Toll-like receptors (TLRs) and expression of genes encoding their negative regulators, SOCS1, TOLLIP, SIGIRR, MyD88s, NOD2, and TNFAIP3, in CD14+ monocytes from 34 patients with major depressive disorder (MDD) and 33 healthy controls before and after treatment with antidepressants. We also seek to investigate their association with depression severity, measured by the 17-item Hamilton Depression Rating Scale (HAMD-17).

RESULTS

mRNA expression of all TLRs, except TLR3 and -5, was significantly higher in monocytes from patients with MDD than in those from controls. Conversely, the "brakes" in TLR signaling, including TOLLIP, MyD88s, NOD2, and TNFAIP3, were downregulated. In clinical findings, the remission group showed higher baseline TLR4 and lower baseline IRAK3 mRNA levels but only baseline elevated SOCS1 mRNA levels, which were inversely correlated with HAMD-17 scores, predicting worsened outcome in MDD patients. In addition, TNFAIP3 mRNA levels were increased by antidepressant treatment.

CONCLUSION

Collectively, our findings suggest a role for dysregulation of TLR signaling in monocytes in MDD and identify a balancing effect of antidepressants on this dysregulation.