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High-fiber diet ameliorates gut microbiota, serum metabolism and emotional mood in type 2 diabetes patients.
Chen, L, Liu, B, Ren, L, Du, H, Fei, C, Qian, C, Li, B, Zhang, R, Liu, H, Li, Z, et al
Frontiers in cellular and infection microbiology. 2023;13:1069954
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Accumulating studies have demonstrated that there are strong correlations between type 2 diabetes mellitus (T2DM) and gut microbiota. A nutritious diet composed of an adequate level of dietary fibres could provide enough carbohydrates for the gut microbiota to ferment, and the microbial metabolites could provide energy supply and regulate the immune function of the host. The aim of this study was to analyse the changes in gut microbiota, serum metabolism and emotional mood of patients with T2DM after consumption of a high-fibre diet. This study was a randomised, open-label, parallel-group clinical trial in T2DM patients with a 4-week treatment period. Seventeen patients clinically diagnosed with T2DM enrolled in the clinical trial and were randomly assigned into two groups: the control group (n = 8) or the intervention group (n = 9). Results showed that the high-fibre diet (compared to the control group): - improved glucose homeostasis and lipid metabolism of participants with T2DM; - decreased serum levels of inflammatory chemokines in participants with T2DM; - alleviated depression and anxiety symptoms, particularly by the uptake of more diverse carbohydrates in the diet in participants with T2DM; - enhanced the diversity of gut microbiota in the treatment group. Authors conclude that the dietary source of fibre demonstrated protective impacts on the gut ecosystem, and the alteration of the gut microbiota composition improved the glucose homeostasis in patients with T2DM.
Abstract
Previous studies have demonstrated that patients with type 2 diabetes mellitus (T2DM) often had the problems of fecal microbiota dysbiosis, and were usually accompanied with psychiatric comorbidities (such as depression and anxiety). Here, we conducted a randomized clinical study to analyze the changes in gut microbiota, serum metabolism and emotional mood of patients with T2DM after consumption of a high-fiber diet. The glucose homeostasis of participants with T2DM was improved by the high-fiber diet, and the serum metabolome, systemic inflammation and psychiatric comorbidities were also altered. The increased abundances of Lactobacillus, Bifidobacterium and Akkermansias revealed that the proportions of beneficial gut microbes were enriched by the high-fiber diet, while the abundances of Desulfovibrio, Klebsiella and other opportunistic pathogens were decreased. Therefore, the current study demonstrated that the intestinal microbiota alterations which were influenced by the high-fiber diet could improve the serum metabolism and emotional mood of patients with T2DM.
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A Low-FODMAP Diet Provides Benefits for Functional Gastrointestinal Symptoms but Not for Improving Stool Consistency and Mucosal Inflammation in IBD: A Systematic Review and Meta-Analysis.
Peng, Z, Yi, J, Liu, X
Nutrients. 2022;14(10)
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The low-FODMAP diet eliminates carbohydrates that cannot be easily digested in order to reduce functional gastrointestinal symptoms associated with irritable bowel disease (IBD). The symptoms of irritable bowel disease include abdominal pain and bloating. This systematic review and meta-analysis aimed to evaluate whether a low-FODMAP diet can alleviate functional gastrointestinal symptoms in individuals with inflammatory bowel disease. In comparison with a regular diet, a low-FODMAP diet significantly reduced symptoms of bloating, wind, flatulence, abdominal pain, fatigue, and lethargy in patients with IBD. In addition, patients with Crohn's disease have achieved remission or reduced symptoms after following a low-FODMAP diet. Healthcare professionals can use this study to understand better the effects of a low-FODMAP diet on patients with IBD who have functional gastrointestinal symptoms. Further robust studies are, however, required to evaluate the evidence's robustness and identify the mechanism behind the improvement of symptoms.
Expert Review
Conflicts of interest:
None
Take Home Message:
- LFD use in IBD improved symptoms of bloating, wind or flatulence, borborygmi, abdominal pain, and fatigue or lethargy, but not nausea and vomiting.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction
This meta-analysis assesses the efficacy of a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) in inflammatory bowel disease [IBD: ulcerative colitis (UC) and Crohn’s disease (UC)] participants with functional gastrointestinal symptoms (FGSs).
Methods
A search was performed on PubMed, Web of Science, EMBASE, Cochrane Central Register of Controlled Trials, Chinese National Knowledge Infrastructure (CNKI), WanFang (Chinese) Database up to March 2022. Quality assessment of all included studies was performed.
Results
9 studies (4 randomised controlled trials, 5 non-randomised studies) with a total of 351 participants diagnosed with IBD were included, and compared LFD with a placebo diet or normal diet (ND), overall and individual
LFD Effects of FGS:
- Overall 9 studies: an improvement (0.47, 0.33–0.66, p = 0.0000)
- No difference in the subgroup classified by disease type
- CD and UC: no improvement
Individual improvement:
- Bloating (0.37, 0,24-0,57, p=0.0000); wind or flatulence (0.38, 0,28-0,51, p=0.0000); borborygmi (0.48, 0,26-0,89, p=0.0000), abdominal pain (0.5, 0,37-0,68, p=0.0000), fatigue/lethargy (0.71, 0,61-0,82, p=0.0000)
- No difference in nausea and vomiting (0.54, 0,22-1,32, p=018)
IBS Quality of Life Score:
- 2 studies: reduced Short IBD Questionnaire (SIBDQ) score (11.24, 6.61-15.87, p=0.0000)
Bristol Stool Form Chart:
- 2 studies: normal stool consistency (type 3-4); no difference (5.99, 0.17-216.51, p=0.33)
- 2 other studies: no difference (-0.17, 0.48 - 0.15, p=0.30)
Diseases activity (Harvey-Bradshaw index):
- 2 studies using the Mayo score: no difference (-32, -1,09-0.45, p=0.41)
- 3 studies using BHi score: reduction (-1.09, -1,77-0.42, p=0.002)
Faecal calprotectin:
- 2 studies: no change (-16.03, -36,78-4.73, p=0.13)
Limitations
- Comparison diets were not standardised, suggesting the potential of different dietary habits to bias results..
- Heterogeneity of included studies, and the relatively small sample size of the studies can reduce the reliability of the results.
Conclusion
While the study found inconsistent definition standards for FGS, all the nine studies showed that LFD was associated with an improvement in some symptoms.
Clinical practice applications:
- This study suggests that IBD patients with FGSs may benefit from LFD treatment with the assistance of a healthcare professional.
Considerations for future research:
- This study has shown that LFD can improve FGSs in IBD, but further research with a larger sample size and more comprehensive analysis is warranted to replicate the results.
- The description of the findings and Quality of Life data are a little unclear. The impact on Quality of Life warrants further investigation, as clinicians need to consider the impact of following a restrictive diet on Quality of Life.
Abstract
BACKGROUND A low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet (LFD) is claimed to improve functional gastrointestinal symptoms (FGSs). However, the role of LFD in inflammatory bowel disease (IBD) patients with FGSs remains unclear. OBJECTIVE To systematically assess the efficacy of LFD in IBD patients with FGSs. METHODS Six databases were searched from inception to 1 January 2022. Data were synthesized as the relative risk of symptoms improvement and normal stool consistency, mean difference of Bristol Stool Form Scale (BSFS), Short IBD Questionnaire (SIBDQ), IBS Quality of Life (IBS-QoL), Harvey-Bradshaw index (HBi), Mayo score, and fecal calprotectin (FC). Risk of bias was assessed based on study types. A funnel plot and Egger's test were used to analyze publication bias. RESULTS This review screened and included nine eligible studies, including four randomized controlled trials (RCTs) and five before-after studies, involving a total of 446 participants (351 patients with LFD vs. 95 controls). LFD alleviated overall FGSs (RR: 0.47, 95% CI: 0.33-0.66, p = 0.0000) and obtained higher SIBDQ scores (MD = 11.24, 95% CI 6.61 to 15.87, p = 0.0000) and lower HBi score of Crohn's disease (MD = -1.09, 95% CI -1.77 to -0.42, p = 0.002). However, there were no statistically significant differences in normal stool consistency, BSFS, IBS-QoL, Mayo score of ulcerative colitis, and FC. No publication bias was found. CONCLUSIONS LFD provides a benefit in FGSs and QoL but not for improving stool consistency and mucosal inflammation in IBD patients. Further well-designed RCTs are needed to develop the optimal LFD strategy for IBD.
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Role of the Intestinal Microbiome, Intestinal Barrier and Psychobiotics in Depression.
Trzeciak, P, Herbet, M
Nutrients. 2021;13(3)
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Major depressive disorder (MDD) is a disorder with feelings of depressed mood or loss of interest or pleasure alongside several other symptoms such as weight or appetite changes, difficulty sleeping and an inability to think or concentrate. The development of MDD is not fully understood and may involve several different factors such as the gut microbiome. The gut microbiome may be involved as it can communicate with the brain in a bidirectional fashion, known as the gut-brain axis. This review study aimed to summarise the data on the use of probiotics thought to confer benefits in the brain, known as psychobiotics. Depression is thought to involve aspects of imbalances in brain signalling molecules, stress hormones, and free radicals and inflammation. One of the newest ideas suggests that the gut microbiome may have a role. Individuals with depression have shown to have altered composition of gut microbiota, which may have an impact in several ways. Alterations in vitamin production, altered intestinal barrier function and poor diet during disease, may all contribute to the development of MDD. Psychobiotics may be of benefit to symptoms of depression shown in numerous animal and human studies. It was concluded that there are several ways that the microbiota may be involved in the development of depression. This study could be used by healthcare professionals to justify the introduction of psychobiotics as an adjuvant to standard therapy for MDD, to relieve symptoms.
Abstract
The intestinal microbiota plays an important role in the pathophysiology of depression. As determined, the microbiota influences the shaping and modulation of the functioning of the gut-brain axis. The intestinal microbiota has a significant impact on processes related to neurotransmitter synthesis, the myelination of neurons in the prefrontal cortex, and is also involved in the development of the amygdala and hippocampus. Intestinal bacteria are also a source of vitamins, the deficiency of which is believed to be related to the response to antidepressant therapy and may lead to exacerbation of depressive symptoms. Additionally, it is known that, in periods of excessive activation of stress reactions, the immune system also plays an important role, negatively affecting the tightness of the intestinal barrier and intestinal microflora. In this review, we have summarized the role of the gut microbiota, its metabolites, and diet in susceptibility to depression. We also describe abnormalities in the functioning of the intestinal barrier caused by increased activity of the immune system in response to stressors. Moreover, the presented study discusses the role of psychobiotics in the prevention and treatment of depression through their influence on the intestinal barrier, immune processes, and functioning of the nervous system.
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Exploring the Role and Potential of Probiotics in the Field of Mental Health: Major Depressive Disorder.
Johnson, D, Thurairajasingam, S, Letchumanan, V, Chan, KG, Lee, LH
Nutrients. 2021;13(5)
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A bi-directional communication between the brain and the microbiome of the gut may exist, known as the microbiome-gut-brain axis (MGBA). The role of this and the use of probiotics in relation to many psychiatric and neurological disorders is being increasingly researched. This review aimed to summarise the research on the use of probiotics for the treatment of mental health disorders and major depressive disorder (MDD). Probiotics and their use were summarised concluding that they have a diverse range of health benefits due to their anti-inflammatory, antipathogenic and antimicrobial actions. Imbalances in the four major phyla of gut bacteria; Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria may have a major role in the development of MDD. Probiotics may have several mechanisms through which they benefit MDD and decreased inflammation in the brain, increased production of chemicals involved in brain signalling and decreased stress hormones, were all implicated. It was concluded that probiotics have mental health benefits, however gaps in the evidence from studies needs to be addressed. This study could be used by healthcare professionals to understand the role of probiotics in the treatment of mental health disorders and in particular MDD.
Abstract
The field of probiotic has been exponentially expanding over the recent decades with a more therapeutic-centered research. Probiotics mediated microbiota modulation within the microbiota-gut-brain axis (MGBA) have been proven to be beneficial in various health domains through pre-clinical and clinical studies. In the context of mental health, although probiotic research is still in its infancy stage, the promising role and potential of probiotics in various mental disorders demonstrated via in-vivo and in-vitro studies have laid a strong foundation for translating preclinical models to humans. The exploration of the therapeutic role and potential of probiotics in major depressive disorder (MDD) is an extremely noteworthy field of research. The possible etio-pathological mechanisms of depression involving inflammation, neurotransmitters, the hypothalamic-pituitary-adrenal (HPA) axis and epigenetic mechanisms potentially benefit from probiotic intervention. Probiotics, both as an adjunct to antidepressants or a stand-alone intervention, have a beneficial role and potential in mitigating anti-depressive effects, and confers some advantages compared to conventional treatments of depression using anti-depressants.
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Gut Microbiota and Pathophysiology of Depressive Disorder.
Kunugi, H
Annals of nutrition & metabolism. 2021;77 Suppl 2:11-20
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Bidirectional communication between the brain and gastrointestinal tract has been established and evidence suggests the microbiota-gut-brain axis may play a role in many psychiatric diseases, including major depression disorder (MDD). Although there is currently no established biochemical marker used in the clinical setting, recent findings have identified four potential mechanisms underlying MDD. The aim of this review is to outline these mechanisms and summarise the current evidence related to the pathophysiology of MDD. The literature suggests the gut microbiota impacts each of the potential mechanisms in the pathophysiology of MDD, and recent clinical trials on probiotics indicate beneficial effects on depression symptoms. Based on these results, the author concludes that practices leading to a healthier gut microbiota may aid in the reduction of depression symptoms. Future research on the microbiota-gut-brain axis in MDD is a promising avenue for better understanding the pathophysiology of disease and developing improved treatments for MDD.
Abstract
BACKGROUND Accumulating evidence has suggested that the bi-directional communication pathway, the microbiota-gut-brain axis, plays an important role in the pathophysiology of many neuropsychiatric diseases including major depressive disorder (MDD). This review outlines current evidence and promising findings related to the pathophysiology and treatment of MDD. SUMMARY There are at least 4 key biological molecules/systems underlying the pathophysiology of MDD: central dopamine, stress responses by the hypothalamic-pituitary-adrenal axis and autonomic nervous system, inflammation, and brain-derived neurotrophic factor. Animal experiments in several depression models have clearly indicated that gut microbiota is closely related to these molecules/systems and administration of probiotics and prebitotics may have beneficial effects on them. Although the results of microbiota profile of MDD patients varied from a study to another, multiple studies reported that bacteria which produce short-chain fatty acids such as butyrate and those protective against metabolic diseases (e.g., Bacteroidetes) were reduced. Clinical trials of probiotics have emerged, and the majority of the studies have reported beneficial effects on depression symptoms and related biological markers. Key Messages: The accumulating evidence suggests that research on the microbiota-gut-brain axis in major depressive disorder (MDD) is promising to elucidate the pathophysiology and to develop novel treatment of MDD, although there is still a long distance yet to reach the goals.
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Early evidence of efficacy for orally administered SPM-enriched marine lipid fraction on quality of life and pain in a sample of adults with chronic pain.
Callan, N, Hanes, D, Bradley, R
Journal of translational medicine. 2020;18(1):401
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Alternatives for the management of chronic pain are needed due to the high side effect profiles, high incidence of developing tolerance, and high potential for addiction in the most common treatments which are currently used. Marine lipids (i.e. fish oil) are a well-known source of the long chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA can be metabolised in the body into potent anti-inflammatory and pro-resolving mediators, which are integral parts of a fatty acid metabolite class known as specialized pro-resolving mediators (SPMs). The aim of this study was to collect preliminary data on the effects of SPM-enriched marine lipid supplementation on quality of life, pain, mood, and inflammation in adults with a history of chronic pain. This study is a single-arm, open-label clinical trial. Forty-four adults with moderate pain intensity for at least 3 months were recruited. Results show improved quality of life in an adult population with chronic pain after supplementation. Furthermore, there were also reductions in measures of pain intensity, pain interference, depression, and anxiety, as well as an increase in physical function. Authors conclude that orally administered supplements containing resolving precursors may improve the quality of life, reduce pain intensity and interference, and improve mood within 4 weeks of supplementation.
Abstract
BACKGROUND Marine lipids contain omega-3 fatty acids that can be metabolized into anti-inflammatory and pro-resolving mediators-namely 17-HDHA and 18-HEPE-which can serve as modulators of the pain experience. The purpose of this study was to determine the impact of 4 weeks of oral supplementation with a fractionated marine lipid concentration, standardized to 17-HDHA and 18-HEPE, on health-related quality of life and inflammation in adults with chronic pain. METHODS This study was a prospective, non-randomized, open-label clinical trial. Forty-four adults with ≥ moderate pain intensity for at least 3 months were recruited. The primary outcome was change in health-related quality of life (QOL) using the Patient Reported Outcomes Measurement Information System-43 Profile (PROMIS-43) and the American Chronic Pain Association (ACPA) QOL scale. Exploratory outcomes assessed safety and tolerability, changes in anxiety and depression, levels of pain intensity and interference, patient satisfaction, and impression of change. Changes in blood biomarkers of inflammation (hs-CRP and ESR) were also explored. RESULTS Outcome measures were collected at Baseline, Week 2, and Week 4 (primary endpoint). At Week 4, PROMIS-43 QOL subdomains changed with significance from baseline (p < 0.05), with borderline changes in the ACPA Quality of Life scale (p < 0.052). Exploratory analyses revealed significant changes (p < 0.05) in all measures of pain intensity, pain interference, depression, and anxiety. There were no statistically significant changes in either hs-CRP or ESR, which stayed within normal limits. CONCLUSION We conclude that oral supplementation with a fractionated marine lipid concentration standardized to 17-HDHA and 18-HEPE may improve quality of life, reduce pain intensity and interference, and improve mood within 4 weeks in adults with chronic pain. The consistency and magnitude of these results support the need for placebo-controlled clinical trials of marine lipid concentrations standardized to 17-HDHA and 18-HEPE. Trial registration ClinicalTrials.gov: Influence of an Omega-3 SPM Supplement on Quality of Life, NCT02683850. Registered 17 February 2016-retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02683850 .
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PROFAST: A Randomized Trial Assessing the Effects of Intermittent Fasting and Lacticaseibacillus rhamnosus Probiotic among People with Prediabetes.
Tay, A, Pringle, H, Penning, E, Plank, LD, Murphy, R
Nutrients. 2020;12(11)
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The prevalence of diabetes is increasing worldwide, and with it, the risk of cardiovascular disease is also increasing. Intermittent fasting has been shown to reduce weight and improve glycaemic control. Weight control and glycaemic control were also improved with probiotic Lacticaseibacillus rhamnosus HN001 supplementation. This pilot, 12-week, double-blinded, two-armed, randomized 1:1 study aimed to investigate the combined effects of intermittent fasting with daily probiotic Lacticaseibacillus rhamnosus HN001 supplementation on glycaemic management in participants with prediabetes. For two days, participants restricted their calorie intake to 600-650 kcal, followed by five days of ad libitum consumption (5:2). Intermittent fasting for 12 weeks improved glycaemic control (reduced HbA1c) and reduced body weight by 5%. The supplementation with Lacticaseibacillus rhamnosus HN001 did not significantly improve these outcomes. Probiotic supplementation significantly improved mental health and social functioning in participants. There is a need for further large, robust studies to assess the effects of intermittent fasting alone and when it is combined with different exercise forms and different prebiotic and probiotic supplements on cardiometabolic markers and mental health. The findings of this study may be useful to healthcare professionals in understanding the effects of fasting on metabolism as well as the psychological benefits of Lacticaseibacillus rhamnosus HN001 supplementation.
Abstract
Both intermittent fasting and specific probiotics have shown promise in improving glucose tolerance with a potential for synergistic effects through alterations to gut microbiota. In this randomized, double-blinded, two-arm feasibility study, we investigated whether intermittent fasting, supplemented with Lacticaseibacillus rhamnosus HN001 probiotic, reduces HbA1c in individuals with prediabetes. All participants with HbA1c 40-50 mmol/mol commenced intermittent fasting (2 days per week of calorie restriction to 600-650 kcal/day) and were randomized 1:1 to either daily probiotic (Lacticaseibacillus rhamnosus HN001) or placebo for 12 weeks. The primary outcome was a change in HbA1c. Secondary outcomes included changes in anthropometry, body composition, glucoregulatory markers, lipids, hunger hormones, liver enzymes, inflammatory markers, gut hormones, calorie and macronutrient intake, quality of life, hunger, mood and eating behavior. Of 33 participants who commenced the trial, 26 participants (mean age 52 years, body mass index (BMI) 34.7 kg/m2) completed the intervention (n = 11 placebo, n = 15 probiotic). HbA1c decreased from 43 ± 2.7 mmol/mol to 41 ± 2.3 mmol/mol, p < 0.001, with average of 5% weight loss. No significant between-group differences were seen in primary or secondary outcomes except for social functioning (p = 0.050) and mental health (p = 0.007) scores as improvements were seen in the probiotic group, but not in the placebo group. This study shows additional psychological benefits of probiotic supplementation during intermittent fasting to achieve weight loss and glycemic improvement in prediabetes.
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Current Perspectives on Gut Microbiome Dysbiosis and Depression.
Capuco, A, Urits, I, Hasoon, J, Chun, R, Gerald, B, Wang, JK, Kassem, H, Ngo, AL, Abd-Elsayed, A, Simopoulos, T, et al
Advances in therapy. 2020;37(4):1328-1346
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The gut microbiome has been implicated in several neurological disorders; however exact mechanisms are still not fully understood. This review of recent studies, aimed to investigate the relationship between an imbalanced gut microbiome and depression. The authors first looked at the epidemiology of disease, concluding that significant burden needs to be assessed through improved preventative measures. This will depend upon the correct identification of risk factors, and the study focused on the role of the gut microbiome in this through animal and human studies. Imbalances in inflammation through altered gut microbiota, depleted biodiversity and stress induced microbiome changes were all implicated in the development of depression. It was concluded that studies on the role of microbiota in depression remain promising but are small and follow many different methodologies. This study could be used by healthcare professionals to better understand the role of gut microbiota in the development of depression and that ensuring a healthy gut may improve symptoms.
Abstract
The human gut microbiome partakes in a bidirectional communication pathway with the central nervous system (CNS), named the microbiota-gut-brain axis. The microbiota-gut-brain axis is believed to modulate various central processes through the vagus nerve as well as production of microbial metabolites and immune mediators which trigger changes in neurotransmission, neuroinflammation, and behavior. Little is understood about the utilization of microbiome manipulation to treat disease. Though studies exploring the role of the microbiome in various disease processes have shown promise, mechanisms remain unclear and evidence-based treatments for most illnesses have not yet been developed. The animal studies reviewed here offer an excellent array of basic science research that continues to clarify mechanisms by which the microbiome may affect mental health. More evidence is needed, particularly as it relates to translating this work to human subjects. The studies presented in this paper largely demonstrate encouraging results in the treatment of depression. Limitations include small sample sizes and heterogeneous methodology. The exact mechanism by which the gut microbiota causes or alters neuropsychiatric disease states is not fully understood. In this review, we focus on recent studies investigating the relationship between gut microbiome dysbiosis and the pathogenesis of depression. This article is based on previously conducted studies and does not contain any studies with human participants or animals performed by any of the authors.
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The Role of the Gut Microbiota in Dietary Interventions for Depression and Anxiety.
Bear, TLK, Dalziel, JE, Coad, J, Roy, NC, Butts, CA, Gopal, PK
Advances in nutrition (Bethesda, Md.). 2020;11(4):890-907
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A growing body of research suggests diet and mental health are closely connected through the microbiome-gut-brain axis (MGBA). This axis shows how the gut and brain are linked in a bidirectional relationship, and provides a model in which dietary interventions could help prevent, or be an alternative therapy, for depression and anxiety. While there is an increased understanding of the complex interplay between diet, gut microbiome and mental health, the literature has produced conflicting results. The aim of this review is to discuss possible reasons for the conflicting results on the link between diet and mental health and present the current findings. The authors explored the impact of various dietary components on the MGBA including macronutrient ratios, omega 3 fatty acids, prebiotic and probiotic foods, food additives, and whole diet approaches. The research shows mental health is likely to be influenced by the MGBA via changes in gut microbiota composition and function, but conflicting results and limited research elucidates the complexity in understand the extent of this bidirectional relationship. Based on the current findings, the authors suggest dietary patterns for positive mental health should be in support of a healthy gut microbiota. They conclude further research is needed into the mechanisms in which gut microbiota impacts mental health to pave the way for a holistic approach to preventing and treating anxiety and depression.
Abstract
There is emerging evidence that an unhealthy dietary pattern may increase the risk of developing depression or anxiety, whereas a healthy dietary pattern may decrease it. This nascent research suggests that dietary interventions could help prevent, or be an alternative or adjunct therapy for, depression and anxiety. The relation, however, is complex, affected by many confounding variables, and is also likely to be bidirectional, with dietary choices being affected by stress and depression. This complexity is reflected in the data, with sometimes conflicting results among studies. As the research evolves, all characteristics of the relation need to be considered to ensure that we obtain a full understanding, which can potentially be translated into clinical practice. A parallel and fast-growing body of research shows that the gut microbiota is linked with the brain in a bidirectional relation, commonly termed the microbiome-gut-brain axis. Preclinical evidence suggests that this axis plays a key role in the regulation of brain function and behavior. In this review we discuss possible reasons for the conflicting results in diet-mood research, and present examples of areas of the diet-mood relation in which the gut microbiota is likely to be involved, potentially explaining some of the conflicting results from diet and depression studies. We argue that because diet is one of the most significant factors that affects human gut microbiota structure and function, nutritional intervention studies need to consider the gut microbiota as an essential piece of the puzzle.
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Interleukin-6 Gene Expression Changes after a 4-Week Intake of a Multispecies Probiotic in Major Depressive Disorder-Preliminary Results of the PROVIT Study.
Reiter, A, Bengesser, SA, Hauschild, AC, Birkl-Töglhofer, AM, Fellendorf, FT, Platzer, M, Färber, T, Seidl, M, Mendel, LM, Unterweger, R, et al
Nutrients. 2020;12(9)
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Major depressive disorder (MDD) is a disease with multiple aetiology and symptoms that can end in death due to suicide. A biological imbalance in free radicals and inflammatory molecules have been associated with depression and diseases such as obesity which are often associated with MDD. Probiotics may potentially be able to redress this imbalance through several mechanisms. The aim of this randomised placebo-controlled trial was to assess the effect of probiotics on mood, brain function, gut microbiome and inflammation genes in 61 individuals with MDD over 4 weeks. The results showed that probiotic intake improved expression of some but not all of the assessed inflammatory genes and it was concluded that positive effects of probiotics on inflammation may mean that they are of benefit to those with MDD. This study could be used by healthcare professionals who are looking at additional, non-pharmacological ways of supporting patients with MDD.
Abstract
Major depressive disorder (MDD) is a prevalent disease, in which one third of sufferers do not respond to antidepressants. Probiotics have the potential to be well-tolerated and cost-efficient treatment options. However, the molecular pathways of their effects are not fully elucidated yet. Based on previous literature, we assume that probiotics can positively influence inflammatory mechanisms. We aimed at analyzing the effects of probiotics on gene expression of inflammation genes as part of the randomized, placebo-controlled, multispecies probiotics PROVIT study in Graz, Austria. Fasting blood of 61 inpatients with MDD was collected before and after four weeks of probiotic intake or placebo. We analyzed the effects on gene expression of tumor necrosis factor (TNF), nuclear factor kappa B subunit 1 (NFKB1) and interleukin-6 (IL-6). In IL-6 we found no significant main effects for group (F(1,44) = 1.33, p = ns) nor time (F(1,44) = 0.00, p = ns), but interaction was significant (F(1,44) = 5.67, p < 0.05). The intervention group showed decreasing IL-6 gene expression levels while the placebo group showed increasing gene expression levels of IL-6. Probiotics could be a useful additional treatment in MDD, due to their anti-inflammatory effects. Results of the current study are promising, but further studies are required to investigate the beneficial effects of probiotic interventions in depressed individuals.