Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial

Acupuncture ameliorates depression-like behavior of poststroke depression model rats through the regulation of gut microbiota and NLRP3 inflammasome in the colon

This study was conducted to examine the effects of acupuncture on gut microbiota and expression of NLRP3 inflammasome in the colon in poststroke depression (PSD) model rats. Sprague-Dawley male rats were randomized into four groups: sham surgery group, poststroke depression group, acupuncture group, and probiotics group. Acupuncture therapy at Baihui (GV20), Shenting (GV24), bilateral Zusanli (ST36) acupoints in the acupuncture group and probiotic gavage therapy in the probiotics group were performed once per day for 2 weeks. Behaviors of depression were assessed by using weight measurements, sucrose preference test, open field test, and forced swimming test. Histopathological alterations in the colon were determined by hematoxylin-eosin staining, the expression of NLRP3/ASC/caspase-1 pathway-related proteins was analyzed by western blotting. Serum levels of IL-1β and IL-18 were derived from ELISA. The 16S rRNA gene sequencing was performed to examine and analyze the differences of gut microbiota of rats among all groups. Acupuncture was effective to increase weight and ameliorate depressive-like behaviors in PSD rats. Acupuncture increased the diversity of gut microbiota, upregulated the abundance of Bifidobacteriaceae and Lactobacillaceae, and decreased the relative abundance of Peptostreptococcaceae, Rikenellaceae, Eggerthellaceae, and Streptococcaceae at family level. Acupuncture effectively improved the pathological changes in the colon. Meanwhile, acupuncture reduced NLRP3, ASC, caspase-1 protein expressions in the colon, and serum levels of IL-18 and IL-1β. Acupuncture may reduce depressive-like behaviors of PSD by regulating the gut microbiota and suppressing hyperactivation of NLRP3 inflammasome in the colon. Microbiota-gut-brain axis may be an effective target pathway for acupuncture treatment of PSD.

The researcher's guide to selecting biomarkers in mental health studies

Clinical mental health researchers may understandably struggle with how to incorporate biological assessments in clinical research. The options are numerous and are described in a vast and complex body of literature. Here we provide guidelines to assist mental health researchers seeking to include biological measures in their studies. Apart from a focus on behavioral outcomes as measured via interviews or questionnaires, we advocate for a focus on biological pathways in clinical trials and epidemiological studies that may help clarify pathophysiology and mechanisms of action, delineate biological subgroups of participants, mediate treatment effects, and inform personalized treatment strategies. With this paper we aim to bridge the gap between clinical and biological mental health research by (1) discussing the clinical relevance, measurement reliability, and feasibility of relevant peripheral biomarkers; (2) addressing five types of biological tissues, namely blood, saliva, urine, stool and hair; and (3) providing information on how to control sources of measurement variability.

A randomized, double-blind, placebo-controlled parallel trial to test the effect of inulin supplementation on migraine headache characteristics, quality of life and mental health symptoms in women with migraine

Migraine is a complex neurovascular disorder characterized by recurrent headache attacks that are often accompanied by symptoms such as vomiting, nausea, and sensitivity to sound or light. Preventing migraine attacks is highly important. Recent research has indicated that alterations in gut microbiota may influence the underlying mechanisms of migraines. This study aimed to investigate the effects of inulin supplementation on migraine headache characteristics, quality of life (QOL), and mental health symptoms in women with migraines. In a randomized double-blind placebo-controlled trial, 80 women with migraines aged 20 to 50 years were randomly assigned to receive 10 g day-1 of inulin or a placebo supplement for 12 weeks. Severity, frequency, and duration of migraine attacks, as well as depression, anxiety, stress, QOL, and headache impact test (HIT-6) scores, were examined at the start of the study and after 12 weeks of intervention. In this study, the primary outcome focused on the frequency of headache attacks, while secondary outcomes encompassed the duration and severity of headache attacks, QOL, and mental health. There was a significant reduction in severity (-1.95 vs. -0.84, P = 0.004), duration (-6.95 vs. -2.05, P = 0.023), frequency (-2.09 vs. -0.37, P < 0.001), and HIT-6 score (-10.30 vs. -6.52, P < 0.023) in the inulin group compared with the control. Inulin supplementation improved mental health symptoms, including depression (-4.47 vs. -1.45, P < 0.001), anxiety (-4.37 vs. -0.70, P < 0.001), and stress (-4.40 vs. -1.50, P < 0.001). However, no significant difference was observed between the two groups regarding changes in QOL score. This study provides evidence supporting the beneficial effects of inulin supplement on migraine symptoms and mental health status in women with migraines. Further studies are necessary to confirm these findings. Trial registration: Iranian Registry of Clinical Trials (https://www.irct.ir) (ID: IRCT20121216011763N58).

Christensenella minuta mitigates behavioral and cardiometabolic hallmarks of social defeat stress

Psychological stress during early development and adolescence may increase the risk of psychiatric and cardiometabolic comorbidities in adulthood. The gut microbiota has been associated with mental health problems such as depression and anxiety and with cardiometabolic disease, but the potential role of the gut microbiota in their comorbidity is not well understood. We investigated the effects and mode of action of the intestinal bacterium Christensenella minuta DSM 32891 on stress-induced mental health and cardiometabolic disturbances in a mouse model of social defeat stress. We demonstrate that administered C. minuta alleviates chronic stress-induced depressive, anxiogenic and antisocial behavior. These effects are attributed to the bacterium's ability to modulate the hypothalamic-pituitary-adrenal axis, which mediates the stress response. This included the oversecretion of corticosterone and the overexpression of its receptors, as well as the metabolism of dopamine (DA) and the expression of its receptors (D1, D2L and D2S). Additionally, C. minuta administration reduced chronically induced inflammation in plasma, spleen and some brain areas, which likely contribute to the recovery of physical and behavioral function. Furthermore, C. minuta administration prevented chronic stress-induced cardiovascular damage by regulating key enzymes mediating liver fibrosis and oxidative stress. Finally, C. minuta increased the abundance of bacteria associated with mental health. Overall, our study highlights the potential of microbiota-directed interventions to alleviate both the physical and mental effects of chronic stress.

Cutting-Edge iPSC-Based Approaches in Studying Host-Microbe Interactions in Neuropsychiatric Disorders

Gut microbiota (GM), together with its metabolites (such as SCFA, tryptophan, dopamine, GABA, etc.), plays an important role in the functioning of the central nervous system. Various neurological and psychiatric disorders are associated with changes in the composition of GM and their metabolites, which puts them in the foreground as a potential adjuvant therapy. However, the molecular mechanisms behind this relationship are not clear enough. Therefore, before considering beneficial microbes and/or their metabolites as potential therapeutics for brain disorders, the mechanisms underlying microbiota-host interactions must be identified and characterized in detail. In this review, we summarize the current knowledge of GM alterations observed in prevalent neurological and psychiatric disorders, multiple sclerosis, major depressive disorder, Alzheimer's disease, and autism spectrum disorders, together with experimental evidence of their potential to improve patients' quality of life. We further discuss the main obstacles in the study of GM-host interactions and describe the state-of-the-art solution and trends in this field, namely "culturomics" which enables the culture and identification of novel bacteria that inhabit the human gut, and models of the gut and blood-brain barrier as well as the gut-brain axis based on induced pluripotent stem cells (iPSCs) and iPSC derivatives, thus pursuing a personalized medicine agenda for neuropsychiatric disorders.

Prenatal Stress and Ethanol Exposure: Microbiota-Induced Immune Dysregulation and Psychiatric Risks

Changes in maternal gut microbiota due to stress and/or ethanol exposure can have lasting effects on offspring's health, particularly regarding immunity, inflammation response, and susceptibility to psychiatric disorders. The literature search for this review was conducted using PubMed and Scopus, employing keywords and phrases related to maternal stress, ethanol exposure, gut microbiota, microbiome, gut-brain axis, diet, dysbiosis, progesterone, placenta, prenatal development, immunity, inflammation, and depression to identify relevant studies in both preclinical and human research. Only a limited number of reviews were included to support the arguments. The search encompassed studies from the 1990s to the present. This review begins by exploring the role of microbiota in modulating host health and disease. It then examines how disturbances in maternal microbiota can affect the offspring's immune system. The analysis continues by investigating the interplay between stress and dysbiosis, focusing on how prenatal maternal stress influences both maternal and offspring microbiota and its implications for susceptibility to depression. The review also considers the impact of ethanol consumption on gut dysbiosis, with an emphasis on the effects of prenatal ethanol exposure on both maternal and offspring microbiota. Finally, it is suggested that maternal gut microbiota dysbiosis may be significantly exacerbated by the combined effects of stress and ethanol exposure, leading to immune system dysfunction and chronic inflammation, which could increase the risk of depression in the offspring. These interactions underscore the potential for novel mental health interventions that address the gut-brain axis, especially in relation to maternal and offspring health.

Strain-specific effects of probiotics on depression and anxiety: a meta-analysis

INTRODUCTION

Depression and anxiety are pervasive mental health disorders with substantial global burdens. Probiotics, live microorganisms known for their health benefits, have emerged as a potential therapeutic intervention for these conditions. This systematic review and meta-analysis aim to evaluate the strain-specific effects of probiotics on relieving depressive and anxiety symptoms while elucidating underlying mechanisms.

METHODS

EMBASE, Cochrane CENTRAL and PubMed/Medline were systematically queried to identify studies released until May 15, 2024. Randomized Controlled Trials (RCTs) that employed standardized assessment tools for depression and anxiety namely Beck Depression Inventory (BDI), Hamilton Depression Rating Scale (HAMD), Depression Anxiety Stress Scales (DASS), or Montgomery-Asberg Depression Rating Scale (MADRS) were included.

RESULTS

12 RCTs involving 707 participants were included. Seven RCTs utilizing the BDI questionnaire demonstrated a significant decrease in depressive symptoms favoring probiotics containing strains such as Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus salivarius, Bifidobacterium bifidum, Bifidobacterium lactis, Bifidobacterium breve, and Bifidobacterium longum (MD: -2.69, CI95%: -4.22/-1.16, p value: 0.00). Conversely, RCTs using HAMD showed a non-significant reduction in depressive symptoms (MD: -1.40, CI95%: -3.29/0.48, p value: 0.14). RCTs employing DASS and MADRS scales also showed no significant differences.

CONCLUSION

This meta-analysis offers valuable insights into the strain-specific effects of probiotics containing Lactobacillus and Bifidobacterium species on depressive and anxiety symptoms. While our findings suggest a significant reduction in depressive symptoms based on the BDI scale favoring probiotics, the lack of significant effects observed on the HAMD, DASS, and MADRS scales underscores the complexity inherent in these conditions. It is imperative to acknowledge the mixed results across different measurement scales, indicating the need for cautious interpretation. Therefore, we advocate for a nuanced understanding of probiotics' impacts on various dimensions of mood, emphasizing the necessity for further research.

"Inflamed" depression: A review of the interactions between depression and inflammation and current anti-inflammatory strategies for depression

Depression is a common mental disorder, the effective treatment of which remains a challenging issue worldwide. The clinical pathogenesis of depression has been deeply explored, leading to the formulation of various pathogenic hypotheses. Among these, the monoamine neurotransmitter hypothesis holds a prominent position, yet it has significant limitations as more than one-third of patients do not respond to conventional treatments targeting monoamine transmission disturbances. Over the past few decades, a growing body of research has highlighted the link between inflammation and depression as a potential key factor in the pathophysiology of depression. In this review, we first summarize the relationship between inflammation and depression, with a focus on the pathophysiological changes mediated by inflammation in depression. The mechanisms linking inflammation to depression as well as multiple anti-inflammatory strategies are also discussed, and their efficacy and safety are assessed. This review broadens the perspective on specific aspects of using anti-inflammatory strategies for treating depression, laying the groundwork for advancing precision medicine for individuals suffering from "inflamed" depression.

Exploring the gut-brain Axis: Potential therapeutic impact of Psychobiotics on mental health

One of the most challenging and controversial issues in microbiome research is related to gut microbial metabolism and neuropsychological disorders. Psychobiotics affect human behavior and central nervous system processes via the gut-brain axis, involving neuronal, immune, and metabolic pathways. They have therapeutic potential in the treatment of several neurodegenerative and neurodevelopmental disorders such as depression, anxiety, autism, attention deficit hyperactivity disorder, Alzheimer's disease, Parkinson's disease, schizophrenia, Huntington's disease, anorexia nervosa, and multiple sclerosis. However, the mechanisms underlying the interaction between psychobiotics and the abovementioned diseases need further exploration. This review focuses on the relationship between gut microbiota and its impact on neurological and neurodegenerative disorders, examining the potential of psychobiotics as a preventive and therapeutic approach, summarising recent research on the gut-brain axis and the potential beneficial effects of psychobiotics, highlighting the need for further research and investigation in this area.

Therapeutic modulation of the kynurenine pathway in severe mental illness and comorbidities: A potential role for serotonergic psychedelics

Mounting evidence points towards a crucial role of the kynurenine pathway (KP) in the altered gut-brain axis (GBA) balance in severe mental illness (SMI, namely depression, bipolar disorder, and schizophrenia) and cardiometabolic comorbidities. Preliminary evidence shows that serotonergic psychedelics and their analogues may hold therapeutic potential in addressing the altered KP in the dysregulated GBA in SMI and comorbidities. In fact, aside from their effects on mood, psychedelics elicit therapeutic improvement in preclinical models of obesity, metabolic syndrome, and vascular inflammation, which are highly comorbid with SMI. Here, we review the literature on the therapeutic modulation of the KP in the dysregulated GBA in SMI and comorbidities, and the potential application of psychedelics to address the altered KP in the brain and systemic dysfunction underlying SMI and comorbidities. Psychedelics might therapeutically modulate the KP in the altered GBA in SMI and comorbidities either directly, via altering the metabolic pathway by influencing the rate-limiting enzymes of the KP and affecting the levels of available tryptophan, or indirectly, by affecting the gut microbiome, gut metabolome, metabolism, and the immune system. Despite promising preliminary evidence, the mechanisms and outcomes of the KP modulation with psychedelics in SMI and systemic comorbidities remain largely unknown and require further investigation. Several concerns are discussed surrounding the potential side effects of this approach in specific cohorts of individuals with SMI and systemic comorbidities.

The effects of Lactobacillus plantarum PS128 in patients with major depressive disorder: an eight-week double-blind, placebo-controlled study

Major depressive disorder (MDD) is a complex mental disorder, potentially linked to the gut-microbiota-brain axis. Probiotics like Lactobacillus plantarum PS128 (PS128) may improve depressive symptoms by modulating the gut microbiota based on our previous open trial. We conducted an 8-week double-blind, placebo-controlled trial to investigate the impact of PS128 on depression severity, markers of inflammation and gut permeability, and the gut microbiota composition in 32 patients with MDD with stable antidepressant treatment but moderate symptom severity. Following the 8-week intervention, both the Hamilton Depression Rating Scale-17 score (HAMD), and Depression and Somatic Symptoms Scale (DSSS) showed a significant decrease in both groups (p<0.001). However, there was no significant difference in the change of depression severity between groups (p=0.203). Moreover, alterations in serum levels of high sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-α, and intestinal fatty acid binding protein, as well as changes in the gut microbiota composition, did not exhibit significant differences before and after intervention or between the groups. In comparison to the placebo group, our study did not find significant effects of PS128 on depressive symptoms, biomarkers of inflammation and gut permeability, and the overall gut microbiota composition. Nonetheless, we observed a potential impact of PS128 on the symbiosis of specific taxa. To comprehensively understand the psychophysiological effects of PS128 in patients with MDD, further research with a larger sample size is imperative.

Gut-Brain Axis: Role of Microbiome, Metabolomics, Hormones, and Stress in Mental Health Disorders

The influence of gut microbiome, metabolites, omics, hormones, and stress on general and mental health is increasingly being recognized. Ancient cultures recognized the importance of diet and gut health on the overall health of an individual. Western science and modern scientific methods are beginning to unravel the foundations and mechanisms behind some of the ancient beliefs and customs. The gut microbiome, an organ itself, is now thought to influence almost all other organs, ranging from the brain to the reproductive systems. Gut microbiome, metabolites, hormones, and biological sex also influence a myriad of health conditions that range from mental health disorders, obesity, gastrointestinal disorders, and cardiovascular diseases to reproductive health. Here, we review the history and current understanding of the gut-brain axis bidirectional talk in various mental health disorders with special emphasis on anxiety and depressive disorders, whose prevalence has increased by over 50% in the past three decades with COVID-19 pandemic being the biggest risk factor in the last few years. The vagal nerve is an important contributor to this bidirectional talk, but other pathways also contribute, and most remain understudied. Probiotics containing Lactobacillus and Bifidobacterium species seem to have the most impact on improvement in mental health symptoms, but the challenge appears to be maintaining sustained levels, especially since neither Lactobacillus nor Bifidobacterium can permanently colonize the gut. Ancient endogenous retroviral DNA in the human genome is also linked to several psychiatric disorders, including depression. These discoveries reveal the complex and intricately intertwined nature of gut health with mental health disorders.

Survival of Probiotic Bacterial Cells in the Upper Gastrointestinal Tract and the Effect of the Surviving Population on the Colonic Microbial Community Activity and Composition

Many health-promoting effects have been attributed to the intake of probiotic cells. However, it is important that probiotic cells arrive at the site of their activity in a viable state in order to exert their beneficial effects. Careful selection of the appropriate probiotic formulation is therefore required as mainly the type of probiotic species/strain and the administration strategy may affect survival of the probiotic cells during the upper gastrointestinal (GIT) passage. Therefore, the current study implemented Simulator of the Human Microbial Ecosystem (SHIME®) technology to investigate the efficacy of different commercially available probiotic formulations on the survival and culturability of probiotic bacteria during upper GIT passage. Moreover, Colon-on-a-Plate (CoaP™) technology was applied to assess the effect of the surviving probiotic bacteria on the gut microbial community (activity and composition) of three human donors. Significantly greater survival and culturability rates were reported for the delayed-release capsule formulation (>50%) as compared to the powder, liquid, and standard capsule formulations (<1%) (p < 0.05), indicating that the delayed-release capsule was most efficacious in delivering live bacteria cells. Indeed, administration of the delayed-release capsule probiotic digest resulted in enhanced production of SCFAs and shifted gut microbial community composition towards beneficial bacterial species. These results thus indicate that careful selection of the appropriate probiotic formulation and administration strategy is crucial to deliver probiotic cells in a viable state at the site of their activity (distal ileum and colon).

Probiotics and Paraprobiotics: Effects on Microbiota-Gut-Brain Axis and Their Consequent Potential in Neuropsychiatric Therapy

Neuropsychiatric disorders are clinical conditions that affect cognitive function and emotional stability, often resulting from damage or disease in the central nervous system (CNS). These disorders are a worldwide concern, impacting approximately 12.5% of the global population. The gut microbiota has been linked to neurological development and function, implicating its involvement in neuropsychiatric conditions. Due to their interaction with gut microbial communities, probiotics offer a natural alternative to traditional treatments such as therapeutic drugs and interventions for alleviating neuropsychiatric symptoms. Introduced by Metchnikoff in the early 1900s, probiotics are live microorganisms that provide various health benefits, including improved digestion, enhanced sleep quality, and reduced mental problems. However, concerns about their safety, particularly in immunocompromised patients, warrant further investigation; this has led to the concept of "paraprobiotics", inactivated forms of beneficial microorganisms that offer a safer alternative. This review begins by exploring different methods of inactivation, each targeting specific cellular components like DNA or proteins. The choice of inactivation method is crucial, as the health benefits may vary depending on the conditions employed for inactivation. The subsequent sections focus on the potential mechanisms of action and specific applications of probiotics and paraprobiotics in neuropsychiatric therapy. Probiotics and paraprobiotics interact with gut microbes, modulating the gut microbial composition and alleviating gut dysbiosis. The resulting neuropsychiatric benefits primarily stem from the gut-brain axis, a bidirectional communication channel involving various pathways discussed in the review. While further research is needed, probiotics and paraprobiotics are promising therapeutic agents for the management of neuropsychiatric disorders.

Depression clinical trials worldwide: a systematic analysis of the ICTRP and comparison with ClinicalTrials.gov

Major depressive disorder (MDD), commonly known as depression, affects over 300 million people worldwide as of 2018 and presents a wide range of clinical symptoms. The international clinical trials registry platform (ICTRP) introduced by WHO includes aggregated data from ClinicalTrials.gov and 17 other national registers, making it the largest clinical trial platform. Here we analysed data in ICTRP with the aim of providing comprehensive insights into clinical trials on depression. Applying a novel hidden duplicate identification method, 10,606 depression trials were identified in ICTRP, with ANZCTR being the largest non- ClinicalTrials.gov database at 1031 trials, followed by IRCT with 576 trials, ISRCTN with 501 trials, CHiCTR with 489 trials, and EUCTR with 351 trials. The top four most studied drugs, ketamine, sertraline, duloxetine, and fluoxetine, were consistent in both groups, but ClinicalTrials.gov had more trials for each drug compared to the non-ClinicalTrials.gov group. Out of 9229 interventional trials, 663 unique agents were identified, including approved drugs (74.5%), investigational drugs (23.2%), withdrawn drugs (1.8%), nutraceuticals (0.3%), and illicit substances (0.2%). Both ClinicalTrials.gov and non-ClinicalTrials.gov databases revealed that the largest categories were antidepressive agents (1172 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov) and nutrients, amino acids, and chemical elements (250 in ClinicalTrials.gov and 659 in non-ClinicalTrials.gov), indicating a focus on alternative treatments involving dietary supplements and nutrients. Additionally, 26 investigational antidepressive agents targeting 16 different drug targets were identified, with buprenorphine (opioid agonist), saredutant (NK2 antagonist), and seltorexant (OX2 antagonist) being the most frequently studied. This analysis addresses 40 approved drugs for depression treatment including new drug classes like GABA modulators and NMDA antagonists that are offering new prospects for treating MDD, including drug-resistant depression and postpartum depression subtypes.

Exploring the Potential of Probiotics and Prebiotics in Major Depression: From Molecular Function to Clinical Therapy

Major depressive disorder (MDD) represents a complex and challenging mental health condition with multifaceted etiology. Recent research exploring the gut-brain axis has shed light on the potential influence of gut microbiota on mental health, offering novel avenues for therapeutic intervention. This paper reviews current evidence on the role of prebiotics and probiotics in the context of MDD treatment. Clinical studies assessing the effects of prebiotic and probiotic interventions have demonstrated promising results, showcasing improvements in depression symptoms and metabolic parameters in certain populations. Notably, prebiotics and probiotics have shown the capacity to modulate inflammatory markers, cortisol levels, and neurotransmitter pathways linked to MDD. However, existing research presents varied outcomes, underscoring the need for further investigation into specific microbial strains, dosage optimization, and long-term effects. Future research should aim at refining personalized interventions, elucidating mechanisms of action, and establishing standardized protocols to integrate these interventions into clinical practice. While prebiotics and probiotics offer potential adjunctive therapies for MDD, continued interdisciplinary efforts are vital to harnessing their full therapeutic potential and reshaping the landscape of depression treatment paradigms.

Exploring the Multifaceted Therapeutic Potential of Probiotics: A Review of Current Insights and Applications

The interplay between human health and the microbiome has gained extensive attention, with probiotics emerging as pivotal therapeutic agents due to their vast potential in treating various health issues. As significant modulators of the gut microbiota, probiotics are crucial in maintaining intestinal homeostasis and enhancing the synthesis of short-chain fatty acids. Despite extensive research over the past decades, there remains an urgent need for a comprehensive and detailed review that encapsulates probiotics' latest insights and applications. This review focusses on the multifaceted roles of probiotics in promoting health and preventing disease, highlighting the complex mechanisms through which these beneficial bacteria influence both gut flora and the human body at large. This paper also explores probiotics' neurological and gastrointestinal applications, focussing on their significant impact on the gut-brain axis and their therapeutic potential in a broad spectrum of pathological conditions. Current innovations in probiotic formulations, mainly focusing on integrating genomics and biotechnological advancements, have also been comprehensively discussed herein. This paper also critically examines the regulatory landscape that governs probiotic use, ensuring safety and efficacy in clinical and dietary settings. By presenting a comprehensive overview of recent studies and emerging trends, this review aims to illuminate probiotics' extensive therapeutic capabilities, leading to future research and clinical applications. However, besides extensive research, further advanced explorations into probiotic interactions and mechanisms will be essential for developing more targeted and effective therapeutic strategies, potentially revolutionizing health care practices for consumers.

Examining immune-inflammatory mechanisms of probiotic supplementation in depression: secondary findings from a randomized clinical trial

We recently indicated that four-week probiotic supplementation significantly reduced depression along with microbial and neural changes in people with depression. Here we further elucidated the biological modes of action underlying the beneficial clinical effects of probiotics by focusing on immune-inflammatory processes. The analysis included a total of N = 43 participants with depression, from which N = 19 received the probiotic supplement and N = 24 received a placebo over four weeks, in addition to treatment as usual. Blood and saliva were collected at baseline, at post-intervention (week 4) and follow-up (week 8) to assess immune-inflammatory markers (IL-1β, IL-6, CRP, MIF), gut-related hormones (ghrelin, leptin), and a stress marker (cortisol). Furthermore, transcriptomic analyses were conducted to identify differentially expressed genes. Finally, we analyzed the associations between probiotic-induced clinical and immune-inflammatory changes. We observed a significant group x time interaction for the gut hormone ghrelin, indicative of an increase in the probiotics group. Additionally, the increase in ghrelin was correlated with the decrease in depressive symptoms in the probiotics group. Transcriptomic analyses identified 51 up- and 57 down-regulated genes, which were involved in functional pathways related to enhanced immune activity. We identified a probiotic-dependent upregulation of the genes ELANE, DEFA4 and OLFM4 associated to immune activation and ghrelin concentration. These results underscore the potential of probiotic supplementation to produce biological meaningful changes in immune activation in patients with depression. Further large-scale mechanistic trials are warranted to validate and extend our understanding of immune-inflammatory measures as potential biomarkers for stratification and treatment response in depression. Trial Registration: www.clinicaltrials.gov , identifier: NCT02957591.

An Assessment of the Knowledge, Attitude, and Practice of Probiotics and Prebiotics among the Population of the United Arab Emirates

Probiotics and prebiotics offer a range of advantageous effects on human health. The knowledge, attitudes, and practices (KAP) of individuals can impact their inclination to consume probiotics and prebiotics. The main objective of this study was to examine the KAP of the people in the United Arab Emirates (UAE) about probiotics and prebiotics consumption. Additionally, the study aimed to assess the impact of KAP and sociodemographic factors on the use of probiotics and prebiotics. In order to accomplish this objective, a verified online questionnaire was used with a five-point Likert scale and distributed using an online platform (Google Forms). A cross-sectional research, non-probability sampling was implemented, and G*Power statistical power analysis was used to estimate a sample size of 385 participants. A total of 408 replies were gathered. The population under study consisted of residents in the UAE between the ages of 18 to 64 years old, excluding populations under the age of 18 and those living outside the UAE. A total of 392 participants met the criteria for inclusion in this study. The research ethics committees of UAE University granted the study approval (ERSC_2024_4359), and the validity of the findings was confirmed through face-to-face interviews with around 50 individuals and a Cronbach's alpha test with result of 0.84. The statistical software SPSS version 29.0 for Mac OS was utilized to examine the relationships between KAP variables, including Chi-square tests and Pearson's correlation coefficients. The tests were selected based on their capacity to handle categorical and continuous data, respectively. The female population was 85.2% of the total, while the male population accounts for 14.8%. The age distribution of participants shows that the largest proportion, 68.4%, falls within the 18-24 age range. Out of the participants, 61.5% held a bachelor's degree. Most of the participants, 56.4%, were students, while 29.1% were employees. The average results indicate a significant inclination towards probiotics and prebiotics, as demonstrated by the scores above the midpoint for the six knowledge questions (M = 2.70), six attitude questions (M = 3.10), and six practice questions (M = 3.04). Several studies have examined this phenomenon; however, additional research comparing individuals in the UAE is necessary to fully comprehend the influence of KAP on the consumption of probiotics and prebiotics in the UAE.

Vitamin-mediated interaction between the gut microbiome and mitochondria in depression: A systematic review-based integrated perspective

Depression is one of the world's most prevalent mental disorders and its treatment remains suboptimal. Depression is a systemic disease with highly complex biological mechanisms. Emerging evidence points towards the involvement of mitochondria, microbiome and vitamins in its pathophysiology. Mitochondrial energy production was shown to be lowered in patients with depression. Mitochondrial energy production depends on vitamins, which are available from food, but are also synthesized by the gut microbiota. Several studies reported altered vitamin levels as well as changes in the gut microbiome composition and its vitamin metabolism in patients with depression. Therefore, the question of a connection between mitochondria and gut microbiome and vitamins influencing the mental health arises. This review aims to systematically investigate a combination of the topics - depression, mitochondria, microbiome, and vitamins - to generate an overview of a novel yet extremely complex and interconnected research field. A systematic literature search yielded 34 articles, and the results were summarized and bundled to develop this new integrative perspective on mitochondrial function mediated by the microbiome and microbiome-derived vitamins in depression. Furthermore, by discussing the research gaps this review aims to encourage innovative research approaches to better understand the biology of depression, which could result in optimized therapeutic approaches.

Lacticaseibacillus paracasei PS23 increases ghrelin levels and modulates microbiota composition: a post-hoc analysis of a randomized controlled study

Muscle damage can occur due to excessive, high-intensity, or inappropriate exercise. It is crucial for athletes and sports enthusiasts to have access to ways that expedite their recovery and alleviate discomfort. Our previous clinical trial demonstrated the anti-inflammatory and muscle damage-ameliorating properties of Lacticaseibacillus paracasei PS23 (PS23), prompting us to further explore the role of this probiotic in muscle damage recovery. This post-hoc analysis of a randomized controlled study investigated potential mediators between the intake of PS23 and the prevention of strength loss after muscle damage. We recruited 105 students from a sports university who had participated in the previously published clinical trial. These participants were randomly allocated to three groups, receiving capsuled live PS23 (L-PS23), heat-treated PS23 (HT-PS23), or a placebo over a period of six weeks. Baseline and endpoint measurements were taken for the levels of circulating ghrelin and other blood markers, stress, mood, quality of life, and the fecal microbiota. A significant increase in ghrelin levels was recorded in the L-PS23 group compared to the other groups. Additionally, both L-PS23 and HT-PS23 interventions led to positive shifts in the gut microbiota composition, particularly in elevated Lacticaseibacillus, Blautia, and Lactobacillus populations. The abundance of these bacteria was positively correlated with exercise performance and inversely correlated with inflammatory markers. In conclusion, dietary supplementation with PS23 may enhance exercise performance and influence muscle damage by increasing ghrelin levels and modulating the gut microbiota composition. Further clarification of the possible mechanisms and clinical implications is required.

From Gut to Brain: Unraveling the Intricate Link Between Microbiome and Stroke

Stroke, a neurological disorder, is intricately linked to the gut microbiota, influencing microbial composition and elevating the risk of ischemic stroke. The neuroprotective impact of short-chain fatty acids (SCFAs) derived from dietary fiber fermentation contrasts with the neuroinflammatory effects of lipopolysaccharide (LPS) from gut bacteria. The pivotal role of the gut-brain axis, facilitating bidirectional communication between the gut and the brain, is crucial in maintaining gastrointestinal equilibrium and influencing cognitive functions. An in-depth understanding of the interplay among the gut microbiota, immune system, and neurological outcomes in stroke is imperative for devising innovative preventive and therapeutic approaches. Strategies such as dietary adjustments, probiotics, prebiotics, antibiotics, or fecal transplantation offer promise in modulating stroke outcomes. Nevertheless, comprehensive research is essential to unravel the precise mechanisms governing the gut microbiota's involvement in stroke and to establish effective therapeutic interventions. The initiation of large-scale clinical trials is warranted to assess the safety and efficacy of interventions targeting the gut microbiota in stroke management. Tailored strategies that reinstate eubiosis and foster a healthy gut microbiota hold potential for both stroke prevention and treatment. This review underscores the gut microbiota as a promising therapeutic target in stroke and underscores the need for continued research to delineate its precise role and develop microbiome-based interventions effectively.

Probiotics as a Promising Therapy in Improvement of Symptoms in Children With ADHD: A Systematic Review

BACKGROUND

ADHD is widely recognized as the most prevalent neurodevelopmental disorder in children. Recently, the potential role of gut microbiota as an etiological factor in ADHD has gained attention. This systematic review aims to investigate the potential impact of probiotic supplements on alleviating ADHD symptoms and influencing behavior.

METHODS

PubMed, Web of Science, Cochrane Library, and SCOPUS were searched from inception to May 2023. Only randomized controlled trials that have suitable data of the effects of probiotics/synbiotics on children with ADHD were enrolled. The risk of bias of the included studies was assessed by Cochrane Collaboration risk of bias tool.

RESULTS

Five related randomized controlled trial were evaluated in the current review. Types of interventions ranged from single/multi strain probiotics to synbiotic. The duration of intervention in all of the studies were 2 to 3 months. The assessed outcomes were very diverse and different tools were used to report the symptoms in children. Among those which used Conners' Parent Rating Scale, a decrease in the total score occurred in the probiotic group, compared to the placebo group. An improvement in both intervention and control groups was seen in one study which used ADHD-Rating Scale.

CONCLUSION

In summary, the combined findings from the reviewed studies suggest that probiotic supplements might potentially serve as a complementary intervention for ADHD. However, given the small number of studies, limited sample sizes, and the diversity of probiotic strains, further research is needed to clarify the effects of probiotics in children with ADHD. The observed tolerability of probiotics is noteworthy as none of the studies report adverse effects.

Biological Significance of Probiotic Microorganisms from Kefir and Kombucha: A Review

(1) Background: The human microbiota is essential for maintaining a healthy body. The gut microbiota plays a protective role against pathogenic bacteria. Probiotics are live microorganisms capable of preventing and controlling gastrointestinal and balancing the immune system. They also aid in better nutrients and vitamins absorption. Examples of natural probiotic cultures are kefir and kombucha. (2) Methods: Therefore, the aim of this review was to address the beneficial properties of probiotic kefir and kombucha using a Boxplot analysis to search for scientific data in the online literature up to January 2024: (Latin American and Caribbean Health Sciences (LILACS), PubMed, Medical Literature Analysis (MED-LINE), Science Direct, Google Scholar/Google Academic, Bioline Inter-national and Springer Link). Boxplots showed the summary of a set of data "Index Terms-Keywords" on kefir and kombucha in three languages (English, Portuguese and Spanish). (3) Results: Google Scholar was the database with the highest number of articles found, when the search for the keywords used in the study (containing ~4 × 106-~4 million articles available). This was Followed by the Science Direct database, containing ~3 × 106-~3 million articles available, and the BVS databases-Biblioteca Virtual de Saúde (Virtual Health Library) e Lilacs, both containing a value of ~2 × 106-~2 million articles available. The databases containing the smallest number of articles found were Nutrients and Medline, both containing a value of ≤0.1 × 106-≤100 thousand articles. (4) Conclusions: Scientific studies indicate that kefir and kombucha certainly contain various functional properties, such as antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity, in addition to having a microbiological composition of probiotic bacteria and yeasts. Kefir and kombucha represent key opportunities in the food and clinic/medical fields.

Human Gut Microbiota for Diagnosis and Treatment of Depression

Nowadays, depressive disorder is spreading rapidly all over the world. Therefore, attention to the studies of the pathogenesis of the disease in order to find novel ways of early diagnosis and treatment is increasing among the scientific and medical communities. Special attention is drawn to a biomarker and therapeutic strategy through the microbiota-gut-brain axis. It is known that the symbiotic interactions between the gut microbes and the host can affect mental health. The review analyzes the mechanisms and ways of action of the gut microbiota on the pathophysiology of depression. The possibility of using knowledge about the taxonomic composition and metabolic profile of the microbiota of patients with depression to select gene compositions (metagenomic signature) as biomarkers of the disease is evaluated. The use of in silico technologies (machine learning) for the diagnosis of depression based on the biomarkers of the gut microbiota is given. Alternative approaches to the treatment of depression are being considered by balancing the microbial composition through dietary modifications and the use of additives, namely probiotics, postbiotics (including vesicles) and prebiotics as psychobiotics, and fecal transplantation. The bacterium Faecalibacterium prausnitzii is under consideration as a promising new-generation probiotic and auxiliary diagnostic biomarker of depression. The analysis conducted in this review may be useful for clinical practice and pharmacology.

A Narrative Review on Gut Microbiome Disturbances and Microbial Preparations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Implications for Long COVID

Myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS), and long COVID are complex, multisystemic and long-term disabling conditions characterized by debilitating post-exertional malaise and other core symptoms related to immune dysregulation resultant from post-viral infection, including mitochondrial dysfunction, chronic neuroinflammation and gut dysbiosis. The reported associations between altered microbiota composition and cardinal symptoms of ME/CFS and long COVID suggest that the use of microbial preparations, such as probiotics, by restoring the homeostasis of the brain-immune-gut axis, may help in the management of symptoms in both conditions. Therefore, this review aims to investigate the implications of alerted gut microbiome and assess the evidence supporting use of microbial-based preparations, including probiotics, synbiotics, postbiotics alone and/or in combination with other nutraceuticals in the management of fatigue, inflammation and neuropsychiatric and gastrointestinal symptoms among patients with ME/CFS and long COVID.

Therapeutic potential of lipid-lowering probiotics on the atherosclerosis development

Hypercholesterolemia is a critical risk factor for atherosclerosis, mostly attributed to lifestyle behavior such as diet. Recent advances have emphasized the critical effects of gastrointestinal bacteria in the pathology of hypercholesterolemia and atherosclerosis, suggesting that the gastrointestinal microbiome can therefore provide efficient therapeutic targets for preventing and treating atherosclerosis. Thus, interventions, such as probiotic therapy, aimed at altering the bacterial composition introduce a promising therapeutic procedure. In the current review, we will provide an overview of anti-atherogenic probiotics contributing to lipid-lowering, inhibiting atherosclerotic inflammation, and suppressing bacterial atherogenic metabolites.

Unraveling the Role of the Blood-Brain Barrier in the Pathophysiology of Depression: Recent Advances and Future Perspectives

Depression is a highly prevalent psychological disorder characterized by persistent dysphoria, psychomotor retardation, insomnia, anhedonia, suicidal ideation, and a remarkable decrease in overall well-being. Despite the prevalence of accessible antidepressant therapies, many individuals do not achieve substantial improvement. Understanding the multifactorial pathophysiology and the heterogeneous nature of the disorder could lead the way toward better outcomes. Recent findings have elucidated the substantial impact of compromised blood-brain barrier (BBB) integrity on the manifestation of depression. BBB functions as an indispensable defense mechanism, tightly overseeing the transport of molecules from the periphery to preserve the integrity of the brain parenchyma. The dysfunction of the BBB has been implicated in a multitude of neurological disorders, and its disruption and consequent brain alterations could potentially serve as important factors in the pathogenesis and progression of depression. In this review, we extensively examine the pathophysiological relevance of the BBB and delve into the specific modifications of its components that underlie the complexities of depression. A particular focus has been placed on examining the effects of peripheral inflammation on the BBB in depression and elucidating the intricate interactions between the gut, BBB, and brain. Furthermore, this review encompasses significant updates on the assessment of BBB integrity and permeability, providing a comprehensive overview of the topic. Finally, we outline the therapeutic relevance and strategies based on BBB in depression, including COVID-19-associated BBB disruption and neuropsychiatric implications. Understanding the comprehensive pathogenic cascade of depression is crucial for shaping the trajectory of future research endeavors.

The influence of the gut-brain axis on anxiety and depression: A review of the literature on the use of probiotics

This review aims to argue how using probiotics can improve anxiety and depressive behaviour without adverse effects, also exploring the impact of postbiotics on it. Specifically, probiotics have drawn more attention as effective alternative treatments, considering the rising cost of antidepressant and anti-anxiety drugs and the high risk of side effects. Depression and anxiety disorders are among the most common mental illnesses in the world's population, characterised by low mood, poor general interest, and cognitive or motor dysfunction. Thus, this study analysed published literature on anxiety, depression, and probiotic supplementation from PubMed and Scopus, focusing on the last twenty years. This study focused on the effect of probiotics on mental health as they have drawn more attention because of their extensive clinical applications and positive impact on various diseases. Numerous studies have demonstrated how the gut microbiota might be critical for mood regulation and how probiotics can affect host health by regulating the gut-brain axis. By comparing the different works analysed, it was possible to identify a strategy by which they are selected and employed and, at the same time, to assess how the effect of probiotics can be optimised using postbiotics, an innovation to improve mental well-being in humans.

Effectiveness of Psychobiotics in the Treatment of Psychiatric and Cognitive Disorders: A Systematic Review of Randomized Clinical Trials

In this study, a systematic review of randomized clinical trials conducted from January 2000 to December 2023 was performed to examine the efficacy of psychobiotics-probiotics beneficial to mental health via the gut-brain axis-in adults with psychiatric and cognitive disorders. Out of the 51 studies involving 3353 patients where half received psychobiotics, there was a notably high measurement of effectiveness specifically in the treatment of depression symptoms. Most participants were older and female, with treatments commonly utilizing strains of Lactobacillus and Bifidobacteria over periods ranging from 4 to 24 weeks. Although there was a general agreement on the effectiveness of psychobiotics, the variability in treatment approaches and clinical presentations limits the comparability and generalization of the findings. This underscores the need for more personalized treatment optimization and a deeper investigation into the mechanisms through which psychobiotics act. The research corroborates the therapeutic potential of psychobiotics and represents progress in the management of psychiatric and cognitive disorders.

A randomized, double-blinded, placebo-controlled clinical trial on Lactobacillus-containing cultured milk drink as adjuvant therapy for depression in irritable bowel syndrome

Irritable bowel syndrome (IBS) is frequently linked with coexisting mental illnesses. Our previous study discovered that 32.1% of IBS patients had subthreshold depression (SD), placing them at higher risk of developing major depression. Gut microbiota modulation through psychobiotics was found to influence depression via the gut-brain axis. However, the efficacy of lessening depression among IBS patients remains ambiguous. The study's aim was to investigate the roles of cultured milk drinks containing 109 cfu Lactobacillus acidophilus LA-5 and Lactobacillus paracasei L. CASEI-01 on depression and related variables among IBS participants with SD. A total of 110 IBS participants with normal mood (NM) and SD, were randomly assigned to one of four intervention groups: IBS-NM with placebo, IBS-NM with probiotic, IBS-SD with placebo, and IBS-SD with probiotic. Each participant was required to consume two bottles of cultured milk every day for a duration of 12 weeks. The following outcomes were assessed: depression risk, quality of life, the severity of IBS, and hormonal changes. The depression scores were significantly reduced in IBS-SD with probiotic and placebo from baseline (p < 0.001). Only IBS-SD with probiotic showed a significant rise in serotonin serum levels (p < 0.05). A significantly higher life quality measures were seen in IBS-SD with probiotic, IBS-SD with placebo, and IBS-NM with placebo (p < 0.05). All groups, both placebo and probiotic, reported significant improvement in IBS severity post-intervention with a higher prevalence of remission and mild IBS (p < 0.05). Dual strains lactobacillus-containing cultured milk drink via its regulation of relevant biomarkers, is a potential anti-depressive prophylactic agent for IBS patients at risk.

Approach to the diagnosis and management of dysbiosis

All microorganisms like bacteria, viruses and fungi that reside within a host environment are considered a microbiome. The number of bacteria almost equal that of human cells, however, the genome of these bacteria may be almost 100 times larger than the human genome. Every aspect of the physiology and health can be influenced by the microbiome living in various parts of our body. Any imbalance in the microbiome composition or function is seen as dysbiosis. Different types of dysbiosis are seen and the corresponding symptoms depend on the site of microbial imbalance. The contribution of the intestinal and extra-intestinal microbiota to influence systemic activities is through interplay between different axes. Whole body dysbiosis is a complex process involving gut microbiome and non-gut related microbiome. It is still at the stage of infancy and has not yet been fully understood. Dysbiosis can be influenced by genetic factors, lifestyle habits, diet including ultra-processed foods and food additives, as well as medications. Dysbiosis has been associated with many systemic diseases and cannot be diagnosed through standard blood tests or investigations. Microbiota derived metabolites can be analyzed and can be useful in the management of dysbiosis. Whole body dysbiosis can be addressed by altering lifestyle factors, proper diet and microbial modulation. The effect of these interventions in humans depends on the beneficial microbiome alteration mostly based on animal studies with evolving evidence from human studies. There is tremendous potential for the human microbiome in the diagnosis, treatment, and prognosis of diseases, as well as, for the monitoring of health and disease in humans. Whole body system-based approach to the diagnosis of dysbiosis is better than a pure taxonomic approach. Whole body dysbiosis could be a new therapeutic target in the management of various health conditions.

Hormetic Nutrition and Redox Regulation in Gut-Brain Axis Disorders

The antioxidant and anti-inflammatory effects of hormetic nutrition for enhancing stress resilience and overall human health have received much attention. Recently, the gut-brain axis has attracted prominent interest for preventing and therapeutically impacting neuropathologies and gastrointestinal diseases. Polyphenols and polyphenol-combined nanoparticles in synergy with probiotics have shown to improve gut bioavailability and blood-brain barrier (BBB) permeability, thus inhibiting the oxidative stress, metabolic dysfunction and inflammation linked to gut dysbiosis and ultimately the onset and progression of central nervous system (CNS) disorders. In accordance with hormesis, polyphenols display biphasic dose-response effects by activating at a low dose the Nrf2 pathway resulting in the upregulation of antioxidant vitagenes, as in the case of heme oxygenase-1 upregulated by hidrox® or curcumin and sirtuin-1 activated by resveratrol to inhibit reactive oxygen species (ROS) overproduction, microbiota dysfunction and neurotoxic damage. Importantly, modulation of the composition and function of the gut microbiota through polyphenols and/or probiotics enhances the abundance of beneficial bacteria and can prevent and treat Alzheimer's disease and other neurological disorders. Interestingly, dysregulation of the Nrf2 pathway in the gut and the brain can exacerbate selective susceptibility under neuroinflammatory conditions to CNS disorders due to the high vulnerability of vagal sensory neurons to oxidative stress. Herein, we aimed to discuss hormetic nutrients, including polyphenols and/or probiotics, targeting the Nrf2 pathway and vitagenes for the development of promising neuroprotective and therapeutic strategies to suppress oxidative stress, inflammation and microbiota deregulation, and consequently improve cognitive performance and brain health. In this review, we also explore interactions of the gut-brain axis based on sophisticated and cutting-edge technologies for novel anti-neuroinflammatory approaches and personalized nutritional therapies.

The Power of Psychobiotics in Depression: A Modern Approach through the Microbiota-Gut-Brain Axis: A Literature Review

The microbiota-gut-brain (MGB) axis is a complex communication network linking the gut, microbiota, and brain, influencing various aspects of health and disease. Dysbiosis, a disturbance in the gut microbiome equilibrium, can significantly impact the MGB axis, leading to alterations in microbial composition and function. Emerging evidence highlights the connection between microbiota alterations and neurological and psychiatric disorders, including depression. This review explores the potential of psychobiotics in managing depressive disorders, emphasizing their role in restoring microbial balance and influencing the MGB axis. Psychobiotics exhibit positive effects on the intestinal barrier, immune response, cortisol levels, and the hypothalamic-pituitary-adrenal (HPA) axis. Studies suggest that probiotics may serve as an adjunct therapy for depression, especially in treatment-resistant cases. This review discusses key findings from studies on psychobiotics interventions, emphasizing their impact on the gut-brain axis and mental health. The increasing acceptance of the expanded concept of the MGB axis underscores the importance of microorganisms in mental well-being. As our understanding of the microbiome's role in health and disease grows, probiotics emerge as promising agents for addressing mental health issues, providing new avenues for therapeutic interventions in depressive disorders.

The Role of Gut Microbiota, Nutrition, and Physical Activity in Depression and Obesity-Interdependent Mechanisms/Co-Occurrence

Obesity and depression are interdependent pathological disorders with strong inflammatory effects commonly found worldwide. They determine the health status of the population and cause key problems in terms of morbidity and mortality. The role of gut microbiota and its composition in the treatment of obesity and psychological factors is increasingly emphasized. Published research suggests that prebiotic, probiotic, or symbiotic preparations can effectively intervene in obesity treatment and mood-dysregulation alleviation. Thus, this literature review aims to highlight the role of intestinal microbiota in treating depression and obesity. An additional purpose is to indicate probiotics, including psychobiotics and prebiotics, potentially beneficial in supporting the treatment of these two diseases.

Accounting for the health risk of probiotics

Probiotics have long been associated with a myriad of health benefits, so much so that their adverse effects whether mild or severe, are often neglected or overshadowed by the enormous volume of articles describing their beneficial effects in the current literature. Recent evidence has demonstrated several health risks of probiotics that warrant serious reconsideration of their applications and further investigations. This review aims to highlight studies that report on how probiotics might cause opportunistic systemic and local infections, detrimental immunological effects, metabolic disturbance, allergic reactions, and facilitating the spread of antimicrobial resistance. To offer a recent account of the literature, articles within the last five years were prioritized. The narration of these evidence was based on the nature of the studies in the following order of preference: clinical studies or human samples, in vivo or animal models, in situ, in vitro and/or in silico. We hope that this review will inform consumers, food scientists, and medical practitioners, on the health risks, while also encouraging research that will focus on and clarify the adverse effects of probiotics.

Psychobiotics and the Microbiota-Gut-Brain Axis: Where Do We Go from Here?

The bidirectional relationship between the gut microbiota and the nervous system is known as the microbiota-gut-brain axis (MGBA). The MGBA controls the complex interactions between the brain, the enteric nervous system, the gut-associated immune system, and the enteric neuroendocrine systems, regulating key physiological functions such as the immune response, sleep, emotions and mood, food intake, and intestinal functions. Psychobiotics are considered tools with the potential to modulate the MGBA through preventive, adjunctive, or curative approaches, but their specific mechanisms of action on many aspects of health are yet to be characterized. This narrative review and perspectives article highlights the key paradigms needing attention as the scope of potential probiotics applications in human health increases, with a growing body of evidence supporting their systemic beneficial effects. However, there are many limitations to overcome before establishing the extent to which we can incorporate probiotics in the management of neuropsychiatric disorders. Although this article uses the term probiotics in a general manner, it remains important to study probiotics at the strain level in most cases.

Gut microbiome in atypical depression

BACKGROUND

Recent studies showed that immunometabolic dysregulation is related to unipolar major depressive disorder (MDD) and that it more consistently maps to MDD patients endorsing an atypical symptom profile, characterized by energy-related symptoms including increased appetite, weight gain, and hypersomnia. Despite the documented influence of the microbiome on immune regulation and energy homeostasis, studies have not yet investigated microbiome differences among clinical groups in individuals with MDD.

METHODS

Fifteen MDD patients with atypical features according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)-5, forty-four MDD patients not fulfilling the DSM-5 criteria for the atypical subtype, and nineteen healthy controls were included in the study. Participants completed detailed clinical assessment and stool samples were collected. Samples were sequenced for the prokaryotic 16S rRNA gene, in the V3-V4 variable regions. Only samples with no antibiotic exposure in the previous 12 months and a minimum of >2000 quality-filtered reads were included in the analyses.

RESULTS

There were no statistically significant differences in alpha- and beta-diversity between the MDD groups and healthy controls. However, within the atypical MDD group, there was an increase in the Verrucomicrobiota phylum, with Akkermansia as the predominant bacterial genus.

LIMITATIONS

Cross-sectional data, modest sample size, and significantly increased body mass index in the atypical MDD group.

CONCLUSIONS

There were no overall differences among the investigated groups. However, differences were found at several taxonomic levels. Studies in larger longitudinal samples with relevant confounders are needed to advance the understanding of the microbial influences on the clinical heterogeneity of depression.

The Gut Microbiome and Mental Health

The gut microbiome has been well researched in the past few years and may be a target for treating mental illness. Trillions of bacteria in the digestive system work with the brain, immune function, and endocrine pathways. This gut microbiome ecosystem mediates the interaction between the human being and the environment making its inclusion in holistic nursing essential. Changes in normal balance of the gut microbiome occur with diet, antibiotics and other medications, stress, cancer treatment, geography and environment, and current illnesses. When the microbiome is challenged a "dysbiotic" state leads to inadequate production of needed neurotransmitters such as serotonin and dopamine. Research has shown links between the dysbiosis, and the inflammatory response system that are known to contribute to depression, anxiety, and schizophrenia. Understanding the role of the gut microbiome can be beneficial to holistic nurses, providing a new tool to prevent, treat, or reduce symptoms of mental illness and improve general immune function. This innocuous holistic approach to mental wellness is becoming an important evidenced-based approach.

Beneficial effects of the probiotics and synbiotics supplementation on anthropometric indices and body composition in adults: A systematic review and meta-analysis

Studies have suggested that probiotics and synbiotics can improve body weight and composition. However, randomized controlled trials (RCTs) demonstrated mixed results. Hence, we performed a systematic review and meta-analysis to evaluate the effectiveness of probiotics and synbiotics on body weight and composition in adults. We searched PubMed/Medline, Ovid/Medline, Scopus, ISI Web of Science, and Cochrane library up to April 2023 using related keywords. We included all RCTs investigating the effectiveness of probiotics and/or synbiotics supplementation on anthropometric indices and body composition among adults. Random-effects models were applied for performing meta-analyses. In addition, we conducted subgroup analyses and meta-regression to explore the non-linear and linear relationship between the length of follow-up and the changes in each outcome. We included a total of 200 trials with 12,603 participants in the present meta-analysis. Probiotics or synbiotics intake led to a significant decrease in body weight (weighted mean difference [WMD]: -0.91 kg; 95% CI: -1.08, -0.75; p < 0.001), body mass index (BMI) (WMD: -0.28 kg/m2 ; 95% CI: -0.36, -0.21; p < 0.001), waist circumference (WC) (WMD: -1.14 cm; 95% CI: -1.42, -0.87; p < 0.001), waist-to-hip ratio (WHR) (WMD: -0.01; 95% CI: -0.01, -0.00; p < 0.001), fat mass (FM) (WMD: -0.92 kg; 95% CI: -1.05, -0.79; p < 0.001), and percentage of body fat (%BF) (WMD: -0.68%; 95% CI: -0.94, -0.42; p < 0.001) compared to controls. There was no difference in fat-free mass (FFM) and lean body mass (LBM). Subgroup analyses indicated that probiotics or synbiotics administered as food or supplement resulted in significant changes in anthropometric indices and body composition. However, compared to controls, FM and %BF values were only reduced after probiotic consumption. Our results showed that probiotics or synbiotics have beneficial effects on body weight, central obesity, and body composition in adults and could be useful as an add on to weight loss products and medications.

Probiotic, prebiotic, synbiotic and fermented food supplementation in psychiatric disorders: A systematic review of clinical trials

The use of probiotics, prebiotics, synbiotics or fermented foods can modulate the gut-brain axis and constitute a potentially therapeutic intervention in psychiatric disorders. This systematic review aims to identify current evidence regarding these interventions in the treatment of patients with DSM/ICD psychiatric diagnoses. Forty-seven articles from 42 studies met the inclusion criteria. Risk of bias was assessed in all included studies. Major depression was the most studied disorder (n = 19 studies). Studies frequently focused on schizophrenia (n = 11) and bipolar disorder (n = 5) and there were limited studies in anorexia nervosa (n = 4), ADHD (n = 3), Tourette (n = 1), insomnia (n = 1), PTSD (n = 1) and generalized anxiety disorder (n = 1). Except in MDD, current evidence does not clarify the role of probiotics and prebiotics in the treatment of mental illness. Several studies point to an improvement in the immune and inflammatory profile (e.g. CRP, IL6), which may be a relevant mechanism of action of the therapeutic response identified in these studies. Future research should consider lifestyle and dietary habits of patients as possible confounders that may influence inter-individual treatment response.

Role of Inflammatory Mechanisms in Major Depressive Disorder: From Etiology to Potential Pharmacological Targets

The involvement of central and peripheral inflammation in the pathogenesis and prognosis of major depressive disorder (MDD) has been demonstrated. The increase of pro-inflammatory cytokines (interleukin (IL)-1β, IL-6, IL-18, and TNF-α) in individuals with depression may elicit neuroinflammatory processes and peripheral inflammation, mechanisms that, in turn, can contribute to gut microbiota dysbiosis. Together, neuroinflammation and gut dysbiosis induce alterations in tryptophan metabolism, culminating in decreased serotonin synthesis, impairments in neuroplasticity-related mechanisms, and glutamate-mediated excitotoxicity. This review aims to highlight the inflammatory mechanisms (neuroinflammation, peripheral inflammation, and gut dysbiosis) involved in the pathophysiology of MDD and to explore novel anti-inflammatory therapeutic approaches for this psychiatric disturbance. Several lines of evidence have indicated that in addition to antidepressants, physical exercise, probiotics, and nutraceuticals (agmatine, ascorbic acid, and vitamin D) possess anti-inflammatory effects that may contribute to their antidepressant properties. Further studies are necessary to explore the therapeutic benefits of these alternative therapies for MDD.

Exploring the complex interplay: gut microbiome, stress, and leptospirosis

Leptospirosis, a re-emerging zoonotic disease, remains a significant global health concern, especially amid floods and disasters such as the Kakhovka Dam destruction. As is known, the stress that occurs in the conditions of military conflicts among civilian and military personnel significantly affects susceptibility to infectious diseases and possibly even influences their course. This review aims to explore how the gut microbiome and stress mediators (such as catecholamines and corticosteroids) might impact the leptospirosis disease course. The review opens new horizons for research by elucidating the connections between the gut microbiome, stress, and leptospirosis.

Mood and microbes: a comprehensive review of intestinal microbiota's impact on depression

Depression is considered a multifaceted and intricate mental disorder of growing concern due to its significant impact on global health issues. The human gut microbiota, also known as the "second brain," has an important role in the CNS by regulating it through chemical, immunological, hormonal, and neurological processes. Various studies have found a significant bidirectional link between the brain and the gut, emphasizing the onset of depression therapies. The biological and molecular processes underlying depression and microbiota are required, as the bidirectional association may represent a novel study. However, profound insights into the stratification and diversity of the gut microbiota are still uncommon. This article investigates the emerging evidence of a bacterial relationship between the gut and the brain's neurological system and its potential pathogenicity and relevance. The interplay of microbiota, immune system, nervous system neurotransmitter synthesis, and neuroplasticity transitions is also widely studied. The consequences of stress, dietary fibers, probiotics, prebiotics, and antibiotics on the GB axis are being studied. Multiple studies revealed the processes underlying this axis and led to the development of effective microbiota-based drugs for both prevention and treatment. Therefore, the results support the hypothesis that gut microbiota influences depression and provide a promising area of research for an improved knowledge of the etiology of the disease and future therapies.

BDNF/CREB signaling pathway contribution in depression pathogenesis: A survey on the non-pharmacological therapeutic opportunities for gut microbiota dysbiosis

Emerging evidence supports the gut microbiota and the brain communication in general health. This axis may affect behavior through modulating neurotransmission, and thereby involve in the pathogenesis and/or progression of different neuropsychiatric disorders such as depression. Brain-derived neurotrophic factor and cAMP response element-binding protein known as CREB/BDNF pathway plays have critical functions in the pathogenesis of depression as the same of mechanisms related to antidepressants. However, the putative causal significance of the CREB/BDNF signaling cascade in the gut-brain axis in depression remains unknown. Also interventions such as probiotics supplementation and exercise can influence microbiome also improve bidirectional communication of gut and brain. In this review we aim to explain the BDNF/CREB signaling pathway and gut microbiota dysfunction and then evaluate the potential role of probiotics, prebiotics, and exercise as a therapeutic target in the gut microbiota dysfunction induced depression. The current narrative review will specifically focus on the impact of exercise and diet on the intestinal microbiota component, as well as the effect that these therapies may have on the microbiota to alleviate depressive symptoms. Finally, we look at how BDNF/CREB signaling pathway may exert distinct effects on depression and gut microbiota dysfunction.

Depression-associated gut microbes, metabolites and clinical trials

Depression is one of the most prevalent mental disorders today. Over the past decade, there has been considerable attention given to the field of gut microbiota associated with depression. A substantial body of research indicates a bidirectional communication pathway between gut microbiota and the brain. In this review, we extensively detail the correlation between gut microbiota, including Lactobacillus acidophilus and Bifidobacterium longum, and metabolites such as short-chain fatty acids (SCFAs) and 5-hydroxytryptamine (5-HT) concerning depression. Furthermore, we delve into the potential health benefits of microbiome-targeted therapies, encompassing probiotics, prebiotics, and synbiotics, in alleviating depression. Lastly, we underscore the importance of employing a constraint-based modeling framework in the era of systems medicine to contextualize metabolomic measurements and integrate multi-omics data. This approach can offer valuable insights into the complex metabolic host-microbiota interactions, enabling personalized recommendations for potential biomarkers, novel drugs, and treatments for depression.

Probiotics for adults with major depressive disorder compared with antidepressants: a systematic review and network meta-analysis

CONTEXT

Despite recent advances in antidepressants in treating major depression (MDD), their usage is marred by adverse effects and social stigmas. Probiotics may be an efficacious adjunct or standalone treatment, potentially circumventing the aforementioned issues with antidepressants. However, there is a lack of head-to-head clinical trials between these 2 interventions.

OBJECTIVE

A systematic review and network meta-analysis was conducted to compare the efficacy and acceptability of these 2 interventions in treating MDD.

DATA SOURCES

Six databases and registry platforms for the clinical trial were systematically searched to identify the eligible double-blinded, randomized controlled trials published between 2015 and 2022.

DATA EXACTION

Two authors selected independently the placebo-controlled trials of antidepressants and microbiota-targeted interventions (prebiotics, probiotics, and synbiotics) used for the treatment of MDD in adults (≥18 years old). Standardized mean differences (SMDs) of depressive symptom scores from individual trials were pooled for network meta-analysis (PROSPERO no. CRD42020222305).

RESULTS

Forty-two eligible trials covering 22 interventions were identified, of which 16 were found to be effective in MDD treatment and the certainty of evidence was moderate to very low. When all trials were considered, compared with placebo, SMDs of interventions ranged from -0.16 (95% credible interval: -0.30, -0.04) for venlafaxine to -0.81 (-1.06, -0.52) for escitalopram. Probiotics were superior to brexpiprazole (SMD [95% credible interval]: -0.42 [-0.68, -0.17]), cariprazine (-0.44 [-0.69, -0.24]), citalopram (-0.37 [-0.66, -0.07]), duloxetine (-0.26, [-0.51, -0.04]), desvenlafaxine (-0.38 [-0.63, -0.14]), ketamine (-0.32 [-0.66, -0.01]), venlafaxine (-0.47 [-0.73, -0.23]), vilazodone (-0.37 [-0.61, -0.12]), vortioxetine (-0.39 [-0.63, -0.15]), and placebo (-0.62 [-0.86, -0.42]), and were noninferior to other antidepressants. In addition, probiotics ranked the second highest in the treatment hierarchy after escitalopram. Long-term treatment (≥8 weeks) using probiotics showed the same tolerability as antidepressants.

CONCLUSION

Probiotics, compared with antidepressants and placebo, may be efficacious as an adjunct or standalone therapy for treating MDD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020222305.

Adjuvant administration of probiotic effects on sexual function in depressant women undergoing SSRIs treatment: a double-blinded randomized controlled trial

BACKGROUND

According to the Institute of Health Metrics and Evaluation's Global Health Data Exchange (2023) it is estimated that 5% of all adults will experience depressive disorder. Amongst the general loss of pleasure and interest in everyday activities that are symptoms of low mood, reduced sexual desire and sexual dysfunction can be particularly overlooked. Human sexuality is complex, but finding solutions based on scientific evidence to limit the symptoms of depressive disorder and the iatrogenic impact of antidepressant treatment to improve this outcome is an important step in promoting psychological health and general wellbeing.

OBJECTIVE

The present study aimed is to provide scientific evidence to assess the effect of oral probiotic on sexual function in women with depressive disorder treated with Selective Serotonin Reuptake Inhibitors (SSRIs) in an Iranian population.

DESIGN

This study was a double-blind randomized clinical trial. Eligible women were assigned to lactofem plus SSRIs (n = 58) or SSRIs alone (n = 54). In group A, SSRI antidepressants were prescribed together with Lactofem, and in group B, SSRI antidepressants were prescribed alone. Lactofem including Lactobacillus acidophilus 2 × 109 cfu/g, Bifidobacterium bifidus 2 × 109 cfu/g, Lactobacillus rutri 2 × 109 cfu/g, Lactobacillus fermentum 2 × 109 cfu/g; capsule weight of 500 mg bio-capsule administered orally and daily. The duration of intervention in two groups was two months. All questionnaires were completed by the patients before and after the intervention. The Female Sexual Function Index (FSFI), Hamilton Depression Rating Scale and Larson's Sexual Satisfaction Questionnaire were used to evaluate sexual function, severity of depressive disorder and sexual satisfaction, respectively.

RESULTS

Based on the results of the present study, there was a statistically significant difference in sexual satisfaction and severity of depressive disorder between the groups before and after the intervention (P < 0.05). Also, our findings showed that after eight weeks, the Lactofem plus SSRIs group showed significant improvement in FSFI domains and total scores compared to SSRIs alone group (P < 0.05).

CONCLUSIONS

The results of the present study show that taking probiotics for eight weeks may improve the severity of depressive disorder, sexual function and sexual satisfaction in depressed women treated with SSRIs.

TRIAL REGISTRATION

ClinicalTrials.govidentifier: IRCT20160524028038N14 (19/12/2022).

The adolescent and young adult microbiome and its association with substance use: a scoping review

AIMS

The microbiome is a critical factor in health throughout human development. The aims of this scoping review are to (i) elucidate the differences between the youth (post-natal day 21-65 for rodents, 2-7 years for non-human primates, and 10-25 years for humans) microbiome with other life stages and (ii) identify youth-specific microbial changes associated with substance use.

METHODS

Peer-reviewed studies published up to May 2023 were identified in PubMed and SCOPUS and included gut and oral microbiome studies from rodents, non-human primates, and humans (N = 1733). Twenty-six articles were determined eligible based on inclusion criteria (aim 1: n = 19, aim 2: n = 7).

RESULTS

The adolescent and young adult oral and gut microbiomes are distinct compared to other life stages, within both non-human and human models. While there is limited research in this area, the microbiome appears to be vulnerable to substance use exposure earlier in life, including substances commonly initiated and escalated during adolescence and young adulthood (i.e. alcohol, cannabis, and tobacco).

CONCLUSIONS

Studies across the lifespan indicate that adolescence and young adulthood are distinct periods of development, where the microbiome is sensitive to exposures, including substance use. There is a need for more studies focused on the adolescent and young adult microbiome and substance use, as well as focused on the oral microbiome during this developmental period. Understanding the gut and oral microbiome during adolescence and young adulthood may provide insight into the pathophysiology of substance use disorders.

An updated overview on the relationship between human gut microbiome dysbiosis and psychiatric and psychological disorders

There is a lot of evidence establishing that nervous system development is related to the composition and functions of the gut microbiome. In addition, the central nervous system (CNS) controls the imbalance of the intestinal microbiota, constituting a bidirectional communication system. At present, various gut-brain crosstalk routes have been described, including immune, endocrine and neural circuits via the vagal pathway. Several empirical data have associated gut microbiota alterations (dysbiosis) with neuropsychiatric diseases, such as Alzheimer's disease, autism and Parkinson's disease, and with other psychological disorders, like anxiety and depression. Fecal microbiota transplantation (FMT) therapy has shown that the gut microbiota can transfer behavioral features to recipient animals, which provides strong evidence to establish a causal-effect relationship. Interventions, based on prebiotics, probiotics or synbiotics, have demonstrated an important influence of microbiota on neurological disorders by the synthesis of neuroactive compounds that interact with the nervous system and by the regulation of inflammatory and endocrine processes. Further research is needed to demonstrate the influence of gut microbiota dysbiosis on psychiatric and psychological disorders, and how microbiota-based interventions may be used as potential therapeutic tools.