Effects of inulin supplementation on inflammatory biomarkers and clinical symptoms of women with obesity and depression on a calorie-restricted diet: a randomised controlled clinical trial

Gut Microbiota: A New Challenge in Mood Disorder Research

The gut microbiome has emerged as a novel and intriguing focus in mood disorder research. Emerging evidence demonstrates the significant role of the gut microbiome in influencing mental health, suggesting a bidirectional communication between the gut and the brain. This review examines the latest findings on the gut-microbiota-brain axis and elucidates how alterations in gut microbiota composition can influence this axis, leading to changes in brain function and behavior. Although dietary interventions, prebiotics, probiotics, and fecal microbiota transplantation have yielded encouraging results, significant advances are needed to establish next-generation approaches that precisely target the neurobiological mechanisms of mood disorders. Future research must focus on developing personalized treatments, facilitated by innovative therapies and technological progress, which account for individual variables such as age, sex, drug history, and lifestyle. Highlighting the potential therapeutic implications of targeting the gut microbiota, this review emphasizes the importance of integrating microbiota research into psychiatric studies to develop more effective and personalized treatment strategies for mood disorders.

Nutritional Strategies in Major Depression Disorder: From Ketogenic Diet to Modulation of the Microbiota-Gut-Brain Axis

Major depressive disorder (MDD) is a leading cause of disability worldwide. While traditional pharmacological treatments are effective for many cases, a significant proportion of patients do not achieve full remission or experience side effects. Nutritional interventions hold promise as an alternative or adjunctive approach, especially for treatment-resistant depression. This review examines the potential role of nutrition in managing MDD through addressing biological deficits and modulating pathways relevant to its pathophysiology. Specifically, it explores the ketogenic diet and gut microbiome modulation through various methods, including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation. Numerous studies link dietary inadequacies to increased MDD risk and deficiencies in nutrients like omega-3 s, vitamins D and B, magnesium, and zinc. These deficiencies impact neurotransmitters, inflammation, and other biological factors in MDD. The gut-brain axis also regulates mood, stress response, and immunity, and disruptions are implicated in MDD. While medications aid acute symptoms, nutritional strategies may improve long-term outcomes by preventing relapse and promoting sustained remission. This comprehensive review aims to provide insights into nutrition's multifaceted relationship with MDD and its potential for developing more effective integrated treatment approaches.

Efficacy and safety of gut microbiome-targeted treatment in patients with depression: a systematic review and meta-analysis

BACKGROUND

The study aimed to comprehensively analyze and establish a framework for evaluating the efficacy of microbiome-targeted treatment (MTT) for depression.

METHODS

We searched PubMed, Embase, Cochrane Library, Web of Science, and the Chinese National Knowledge Infrastructure database for randomized controlled trials (RCTs) on MTT in treating depression until October 19, 2023. A meta-analysis was conducted to evaluate the efficacy and safety of MTT. Comprehensive subgroup analyses were undertaken to explore factors influencing MTT's efficacy in treating depression. This study was registered with PROSPERO (CRD42023483649).

RESULTS

The study selection process identified 51,570 studies, of which 34 met the inclusion criteria. The overall pooled estimates showed that MTT significantly improved depression symptoms (SMD -0.26, 95% CI [-0.32, -0.19], I2 = 54%) with acceptable safety. Subgroup analyses by geography showed that effectiveness was demonstrated in Asia (SMD -0.46, 95% CI [-0.56, -0.36], I2 = 36%), while no evidence of effectiveness was found in Europe (SMD -0.07, 95% CI [-0.19, 0.05], I2 = 55%), America (SMD -0.33, 95% CI [-0.67, 0.02], I2 = 60%), and Oceania (SMD 0.00, 95% CI [-0.18, 0.18], I2 = 0%). Besides, the efficacy was shown in depressed patients without comorbidities (SMD -0.31, 95% CI [-0.40, -0.22], I2 = 0%), whereas effectiveness was poor in those with digestive disorders, such as irritable bowel syndrome (SMD -0.37, 95% CI [-0.89, 0.16], I2 = 74%), chronic diarrhea (SMD -0.34, 95% CI [-0.73, 0.05]), and chronic constipation (SMD -0.23, 95% CI [-0.57, 0.11], I2 = 0%). In perinatal depressed patients, MTT was not effective (SMD 0.16, 95% CI [0.01, 0.31], I2 = 0%). It was found that < 8 weeks (SMD -0.33, 95% CI [-0.45, -0.22], I2 = 0%) and 8-12 weeks (SMD -0.34, 95% CI [-0.44, -0.23], I2 = 57%) MTT were effective, while > 12 weeks (SMD 0.02, 95% CI [-0.12, 0.17], I2 = 68%) MTT was ineffective.

CONCLUSIONS

Despite the overall effectiveness of MTT in treating depression and its acceptable safety profile, caution is warranted in drawing this conclusion due to limitations posed by the small sample size of included studies and heterogeneity. The efficacy of MTT for depression exhibits variation influenced by geography, patient comorbidities, and duration of administration.

Gut-brain axis as a bridge in obesity and depression: Mechanistic exploration and therapeutic prospects

A recent study by Wang et al, published in the World Journal of Psychiatry, provided preventative and therapeutic strategies for the comorbidity of obesity and depression. The gut-brain axis, which acts as a two-way communication system between the gastrointestinal tract and the central nervous system, plays a pivotal role in the pathogenesis of these conditions. Evidence suggests that metabolic byproducts, such as short-chain fatty acids, lipopolysaccharide and bile acids, which are generated by the gut microbiota, along with neurotransmitters and inflammatory mediators within the gut-brain axis, modulate the host's metabolic processes, neuronal regulation, and immune responses through diverse mechanisms. The interaction between obesity and depression via the gut-brain axis involves disruptions in the gut microbiota balance, inflammatory immune responses, and alterations in the neuroendocrine system. Modulating the gut-brain axis, for example, through a ketogenic diet, the use of probiotics, and the supplementation of antioxidants, offers new remedial approaches for obesity and depression. Future research that explores the mechanisms of the gut-brain axis is needed to provide more evidence for clinical treatment.

Inulin: a multifaceted ingredient in pharmaceutical sciences

Inulin, a naturally occurring polysaccharide derived from plants such as chicory root, has emerged as a significant ingredient in pharmaceutical sciences due to its diverse therapeutic and functional properties. This review explores the multifaceted applications of inulin, focusing on its chemical structure, sources, and mechanisms of action. Inulin's role as a prebiotic is highlighted, with particular emphasis on its ability to modulate gut microbiota, enhance gut health, and improve metabolic processes. The review also delves into the therapeutic applications of inulin, including its potential in managing metabolic health issues such as diabetes and lipid metabolism, as well as its immune-modulating properties and benefits in gastrointestinal health. Furthermore, the article examines the incorporation of inulin in drug formulation and delivery systems, discussing its use as a stabilizing agent and its impact on enhancing drug bioavailability. Innovative inulin-based delivery systems, such as nanoparticles and hydrogels, are explored for their potential in controlled release formulations. The efficacy of inulin is supported by a review of clinical studies, underscoring its benefits in managing conditions like diabetes, cardiovascular health, and gastrointestinal disorders. Safety profiles, regulatory aspects, and potential side effects are also addressed. This comprehensive review concludes with insights into future research directions and the challenges associated with the application of inulin in pharmaceutical sciences.

The effect of prebiotic supplementation on serum levels of tryptophan and kynurenine in obese women with major depressive disorder: a double-blinded placebo-controlled randomized clinical trial

OBJECTIVE

The objective of the present study was to examine the effect of calorie restricted diet (CRD) plus inulin supplementation on serum levels of tryptophan (Trp), kynurenine (Kyn) and Trp/Kyn ratio in obese women with major depressive disorder (MDD).

RESULTS

In this double-blind placebo-controlled randomized clinical trial, 51 obese women (BMI = 30-40 kg/m2) with mild MDD were assessed for depression level using Hamilton depression rating scale (HDRS). The patients were randomly allocated into either "Prebiotic group" (received 10 g/day inulin) or "Placebo group" (received 10 g/day maltodextrin). All participants also received individualized CRD. Fasting serum levels of Trp, Kyn, and Trp/Kyn ratio were assessed at baseline and after 8 weeks. Results showed slightly greater increases in serum levels of Trp and Trp/Kyn ratio as well as reductions in serum level of Kyn and HDRS score in prebiotic group than placebo group. However, between group differences in these parameters as well as HDRS score were not statistically significant after adjusting for baseline variables at the end of the trial. Results indicates that CRD accompanied by inulin supplementation (10 g/day) did not influence serum levels of Trp, Kyn and Trp/Kyn ratio as well as HDRS score after 8 weeks.

TRIAL REGISTRATION

The trial was registered in the Iranian registry of clinical trials at 2018-08-02 ( https://www.irct.ir/ ; registration number: IRCT20100209003320N15).

Intestinal Barrier Impairment, Preservation, and Repair: An Update

BACKGROUND/OBJECTIVES

Our objective was to review published studies of the intestinal barrier and permeability, the deleterious effects of dietary components (particularly fat), the impact of altered intestinal permeability in disease models and human diseases, the role of the microbiome and epigenomics in control of barrier function, and the opportunities to restore normal barrier function with dietary interventions and products of the microbiota.

METHODS

We conducted a literature review including the following keywords alone or in combination: intestinal barrier, permeability, microbiome, epigenomics, diet, irritable bowel syndrome, inflammatory bowel disease, probiotics.

RESULTS

Intestinal permeability is modified by a diet including fat, which increases permeability, and nutrients such as fiber, glutamine, zinc, vitamin D, polyphenols, emulsifiers, and anthocyanins, which decrease permeability. There is significant interaction of the microbiome and barrier function, including the inflammatory of luminal/bacterial antigens, and anti-inflammatory effects of commensals or probiotics and their products, including short-chain fatty acids. Epigenomic modification of barrier functions are best illustrated by effects on junction proteins or inflammation. Detailed documentation of the protective effects of diet, probiotics, prebiotics, and microbiota is provided.

CONCLUSION

intestinal permeability is a critical factor in protection against gastrointestinal diseases and is impacted by nutrients that preserve or heal and repair the barrier and nurture anti-inflammatory effects.

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).

Role of the intestinal microbiota in contributing to weight disorders and associated comorbidities

SUMMARYThe gut microbiota is a major factor contributing to the regulation of energy homeostasis and has been linked to both excessive body weight and accumulation of fat mass (i.e., overweight, obesity) or body weight loss, weakness, muscle atrophy, and fat depletion (i.e., cachexia). These syndromes are characterized by multiple metabolic dysfunctions including abnormal regulation of food reward and intake, energy storage, and low-grade inflammation. Given the increasing worldwide prevalence of obesity, cachexia, and associated metabolic disorders, novel therapeutic strategies are needed. Among the different mechanisms explaining how the gut microbiota is capable of influencing host metabolism and energy balance, numerous studies have investigated the complex interactions existing between nutrition, gut microbes, and their metabolites. In this review, we discuss how gut microbes and different microbiota-derived metabolites regulate host metabolism. We describe the role of the gut barrier function in the onset of inflammation in this context. We explore the importance of the gut-to-brain axis in the regulation of energy homeostasis and glucose metabolism but also the key role played by the liver. Finally, we present specific key examples of how using targeted approaches such as prebiotics and probiotics might affect specific metabolites, their signaling pathways, and their interactions with the host and reflect on the challenges to move from bench to bedside.

An Overview of the Potential Role of Nutrition in Mental Disorders in the Light of Advances in Nutripsychiatry

PURPOSE OF REVIEW

As research on the potential impact of nutrition on mental disorders, a significant component of global disability continues to grow the concepts of "nutritional psychiatry, psycho-dietetics/nutripsychiatry" have taken their place in the literature. This review is a comprehensive examination of the literature on the the potential mechanisms between common mental disorders and nutrition and evaluates the effectiveness of dietary interventions.

RECENT FINDINGS

Inflammation, oxidative stress, intestinal microbiota, mitochondrial dysfunction, and neural plasticity are shown as potential mechanisms in the relationship between mental disorders and nutrition. As a matter of fact, neurotrophic factors, which make important contributions to repair mechanisms throughout life, and neuronal plasticity, which plays a role in mental disorders, are affected by nutritional factors. In metabolism, the antioxidant defense system works with nutritional cofactors and phytochemicals. A balanced, planned diet that provides these components is more likely to provide nutrients that increase resilience against the pathogenesis of mental disorders. Nutrition can be considered a risk factor for mental disorders. Therefore, developing public health strategies focused on improving diet may help reduce the global burden of mental disorders and other related diseases.

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.

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.

Microbial-Based Bioactive Compounds to Alleviate Inflammation in Obesity

The increased prevalence of obesity with several other metabolic disorders, including diabetes and non-alcoholic fatty liver disease, has reached global pandemic proportions. Lifestyle changes may result in a persistent positive energy balance, hastening the onset of these age-related disorders and consequently leading to a diminished lifespan. Although suggestions have been raised on the possible link between obesity and the gut microbiota, progress has been hampered due to the extensive diversity and complexities of the gut microbiota. Being recognized as a potential biomarker owing to its pivotal role in metabolic activities, the dysregulation of the gut microbiota can give rise to a persistent low-grade inflammatory state associated with chronic diseases during aging. This chronic inflammatory state, also known as inflammaging, induced by the chronic activation of the innate immune system via the macrophage, is controlled by the gut microbiota, which links nutrition, metabolism, and the innate immune response. Here, we present the functional roles of prebiotics, probiotics, synbiotics, and postbiotics as bioactive compounds by underscoring their putative contributions to (1) the reduction in gut hyperpermeability due to lipopolysaccharide (LPS) inactivation, (2) increased intestinal barrier function as a consequence of the upregulation of tight junction proteins, and (3) inhibition of proinflammatory pathways, overall leading to the alleviation of chronic inflammation in the management of obesity.

Fructan-type prebiotic dietary fibers: Clinical studies reporting health impacts and recent advances in their technological application in bakery, dairy, meat products and beverages

Fructooligosaccharides (FOS) and inulin are the most used fructans in food manufacturing, including bakery, dairy, meat products and beverages. In this context, this review investigated the recent findings concerning health claims associated with a diet supplemented with fructans according to human trial results. Fructans have been applied in different food classes due to their proven benefits to human health. Human clinical trials have revealed several effects of fructans supplementation on health such as improved glycemic control, growth of beneficial gut bacteria, weight management, positive influence on immune function, and others. These dietary fibers have a wide range of compounds with different molecular sizes, implying a great variety of technological properties depending on the food application of interest. Inulin has been mainly applied as a fat substitute and prebiotic ingredient. In general, inulin reduces the energy content and improves the structure, viscosity, emulsion, and water retention parameters of food products. Meanwhile, FOS have been more successful when used as a sucrose substitute and prebiotic ingredient. However, overall, FOS and inulin are promising alternatives for the development of structured systems dedicated to increase the functionality of foods and beverages besides reducing fat in bakery, dairy, and meat products.

Immunomodulatory effects of inulin and its intestinal metabolites

"Dietary fiber" (DF) refers to a type of carbohydrate that cannot be digested fully. DF is not an essential nutrient, but it plays an important part in enhancing digestive capacity and maintaining intestinal health. Therefore, DF supplementation in the daily diet is highly recommended. Inulin is a soluble DF, and commonly added to foods. Recently, several studies have found that dietary supplementation of inulin can improve metabolic function and regulate intestinal immunity. Inulin is fermented in the colon by the gut microbiota and a series of metabolites is generated. Among these metabolites, short-chain fatty acids provide energy to intestinal epithelial cells and participate in regulating the differentiation of immune cells. Inulin and its intestinal metabolites contribute to host immunity. This review summarizes the effect of inulin and its metabolites on intestinal immunity, and the underlying mechanisms of inulin in preventing diseases such as type 2 diabetes mellitus, inflammatory bowel disease, chronic kidney disease, and certain cancer types.

Prebiotics for depression: how does the gut microbiota play a role?

Depression, a mood disorder characterized by persistent feelings of sadness and aversion to activity that can interfere with daily life, is a condition of great concern. Prebiotics, which are non-digestible substances selectively utilized by host microorganisms for health benefits, have gained attention for their potential to improve overall wellness and alleviate various disorders including depression. This study aims to review clinical trials utilizing carbohydrate-type prebiotics such as inulin-type fructans, galactooligosaccharides (GOS), human milk oligosaccharides, resistant starch, prebiotic phytochemicals including epigallocatechin gallate (EGCG), chlorogenic acids, resveratrol, and prebiotic lipids (n-3 polysaturated fatty acids) to determine their effects on depression. Our findings suggest that GOS at a daily dosage of 5 g and eicosapentaenoic acid at or less than 1 g can effectively mitigate depressive symptoms. While EGCG exhibits potential antidepressant properties, a higher dosage of 3 g/d may be necessary to elicit significant effects. The plausible mechanisms underlying the impact of prebiotics on depression include the synthesis of neurotransmitters, production of short-chain fatty acids, and regulation of inflammation.