-
1.
Effect of prebiotics, probiotics, synbiotics on depression: results from a meta-analysis.
Zhang, Q, Chen, B, Zhang, J, Dong, J, Ma, J, Zhang, Y, Jin, K, Lu, J
BMC psychiatry. 2023;23(1):477
-
-
-
Free full text
Plain language summary
Major depressive disorder (MDD) is a mood disorder that impairs psychosocial function and quality of life. Recent studies show that prebiotics, probiotics, and synbiotics reveal a novel way to treat psychiatric disorders such as depression through the microbiota-gut-brain axis. The aim of this study was to evaluate the effectiveness of prebiotics, probiotics and synbiotics in alleviating depressive symptoms. This study was a meta-analysis of thirteen studies with a total of 786 participants who were allocated to the intervention group (n=427) and the placebo group (n=359). Results showed that the overall effects of probiotics, prebiotics and synbiotics on depressive symptoms were significantly superior to those of placebo. Additionally, biological sex was a vital factor that influenced patients’ responses to the treatment. Authors concluded that agents that manipulate gut microbiota might become a novel approach to treat patients with mild-to-moderate depression.
Abstract
Accumulating studies have shown the effects of gut microbiota management tools in improving depression. We conducted a meta-analysis to evaluate the effects of prebiotics, probiotics, and synbiotics on patients with depression. We searched six databases up to July 2022. In total, 13 randomized controlled trials (RCTs) with 786 participants were included. The overall results demonstrated that patients who received prebiotics, probiotics or synbiotics had significantly improved symptoms of depression compared with those in the placebo group. However, subgroup analysis only confirmed the significant antidepressant effects of agents that contained probiotics. In addition, patients with mild or moderate depression could both benefit from the treatment. Studies with a lower proportion of females reported stronger effects for alleviating depressive symptoms. In conclusion, agents that manipulate gut microbiota might improve mild-to-moderate depression. It is necessary to further investigate the benefits of prebiotic, probiotic and synbiotic treatments relative to antidepressants and follow up with individuals over a longer time before these therapies are implemented in clinical practice.
-
2.
Effects of probiotics on neurocognitive outcomes in infants and young children: a meta-analysis.
Lin, FL, Chen, CM, Sun, CK, Cheng, YS, Tzang, RF, Chiu, HJ, Wang, MY, Cheng, YC, Hung, KC
Frontiers in public health. 2023;11:1323511
-
-
-
Free full text
Plain language summary
There have been increasing investigations into the use of probiotics for treating a variety of neurodevelopmental disorders and also for improvement of neurocognitive outcomes in preterm infants or children. The aim of this study was to provide updated evidence of the therapeutic effects of probiotics on enhancing different neurocognitive functions in infants and children as well as to identify important factors that may influence their treatment efficacies. This study was a meta-analysis of nine randomised controlled studies with 3,026 participants. Results did not show significantly better neurocognitive outcomes in those receiving probiotic treatments than those in the placebo group. However, significantly better neurocognitive development was noted in the probiotic group when focusing on studies that used probiotics for more than six months. Authors concluded that further investigations into the enhancement of therapeutic effects of probiotics on neurocognitive development is required since current evidence is still not strong enough to rule out the beneficial effects of probiotics on neurocognitive development.
Abstract
BACKGROUND Therapeutic efficacies of probiotics in improving neurocognitive functions in infants and young children remained unclear. This meta-analysis focused on different cognitive outcomes in this population. METHODS Major databases were searched electronically from inception to October 2023 to identify randomized controlled trials (RCTs) that investigated the therapeutic efficacy of probiotics in enhancing cognitive functions assessed by standardized tasks. The overall effect size was calculated as standardized mean difference (SMD) based on a random effects model. RESULTS Nine RCTs with 3,026 participants were identified. Both our primary and secondary results demonstrated no significant difference in neurocognitive outcomes between infants/children treated with probiotics and those receiving placebos. However, our subgroup analysis of studies that offered a probiotics treatment course of over six months demonstrated a significantly better neurocognitive outcome than placebos (SMD = 0.21, p = 0.03, two studies with 451 participants), but this finding was based on only two RCTs. CONCLUSION Despite lack of significant therapeutic effects of probiotics on neurocognitive outcomes, our finding of a positive impact of probiotics on neurocognitive development in those undergoing treatment for over six months may provide an important direction for further investigations into the enhancement of therapeutic effects of probiotics on neurocognitive development in infants and young children. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42023463412.
-
3.
Meta-Analysis Reveals Compositional and Functional Microbial Changes Associated with Osteoporosis.
Akinsuyi, OS, Roesch, LFW
Microbiology spectrum. 2023;11(3):e0032223
-
-
-
Free full text
Plain language summary
Osteoporosis (OP) is the most common metabolic bone disease associated with aging. Microbiome dysbiosis leading to impaired intestinal immune responses and subsequent production of osteoclastogenic cytokines has been proposed as the mechanism by which gut microbes are associated with osteoporosis. The aim of this study was to identify gut bacteria consistently associated with osteoporosis across different cohorts. This study was a meta-analysis of five studies. Results showed that gut microbial dysbiosis in osteoporosis patients is associated with functional changes, which result in significant changes in metabolites that play a key role in bone metabolism. Authors concluded that their findings set the stage for future studies to provide more comprehensive knowledge on how dysbiosis in the gut microbiome contributes to osteoporosis.
Abstract
Over the past decade, the role of the gut microbiota in many disease states has gained a great deal of attention. Mounting evidence from case-control and observational studies has linked changes in the gut microbiota to the pathophysiology of osteoporosis (OP). Nonetheless, the results of these studies contain discrepancies, leaving the literature without a consensus on osteoporosis-associated microbial signatures. Here, we conducted a comprehensive meta-analysis combining and reexamining five publicly available 16S rRNA partial sequence data sets to identify gut bacteria consistently associated with osteoporosis across different cohorts. After adjusting for the batch effect associated with technical variation and heterogeneity of studies, we observed a significant shift in the microbiota composition in the osteoporosis group. An increase in the relative abundance of opportunistic pathogens Clostridium sensu stricto, Bacteroides, and Intestinibacter was observed in the OP group. Moreover, short-chain-fatty-acid (SCFA) producers, including members of the genera Collinsella, Megasphaera, Agathobaculum, Mediterraneibacter, Clostridium XIV, and Dorea, were depleted in the OP group relative to the healthy control (HC) group. Lactic acid-producing bacteria, including Limosilactobacillus, were significantly increased in the OP group. The random forest algorithm further confirmed that these bacteria differentiate the two groups. Furthermore, functional prediction revealed depletion of the SCFA biosynthesis pathway (glycolysis, tricarboxylic acid [TCA] cycle, and Wood-Ljungdahl pathway) and amino acid biosynthesis pathway (methionine, histidine, and arginine) in the OP group relative to the HC group. This study uncovered OP-associated compositional and functional microbial alterations, providing robust insight into OP pathogenesis and aiding the possible development of a therapeutic intervention to manage the disease. IMPORTANCE Osteoporosis is the most common metabolic bone disease associated with aging. Mounting evidence has linked changes in the gut microbiota to the pathophysiology of osteoporosis. However, which microbes are associated with dysbiosis and their impact on bone density and inflammation remain largely unknown due to inconsistent results in the literature. Here, we present a meta-analysis with a standard workflow, robust statistical approaches, and machine learning algorithms to identify notable microbial compositional changes influencing osteoporosis.
-
4.
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)
-
-
-
-
Free full text
Plain language summary
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:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
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.
-
5.
Differential Health Effects on Inflammatory, Immunological and Stress Parameters in Professional Soccer Players and Sedentary Individuals after Consuming a Synbiotic. A Triple-Blinded, Randomized, Placebo-Controlled Pilot Study.
Quero, CD, Manonelles, P, Fernández, M, Abellán-Aynés, O, López-Plaza, D, Andreu-Caravaca, L, Hinchado, MD, Gálvez, I, Ortega, E
Nutrients. 2021;13(4)
-
-
-
Free full text
Plain language summary
Synbiotic, a mixture of prebiotics and probiotics, is known to improve neurotransmitter interactions, immune, inflammatory, and stress responses by modulating the gut microbial composition. It is also believed that physical activity plays an important role in the modulation of immune function and stress response. The purpose of this triple-blinded, randomized, placebo-controlled pilot study was to evaluate the health benefits of symbiotic intervention in fourteen sedentary students and thirteen soccer players, especially in terms of improving immunophysiological and metabolic parameters. The 300mg of symbiotic intervention contained Bifidobacterium lactis CBP-001010, Lactobacillus rhamnosus CNCM I-4036, Bifidobacterium longum ES1(109 colony-forming unit), and fructooligosaccharides (200 mg) plus 1.5 mg of zinc, 8.25 µg of selenium, 0.75 µg of vitamin, and maltodextrin. Following a one-month intervention with synbiotic formulation, soccer players showed improvements in anxiety, sleep quality and stress, a slight reduction in proinflammatory cytokine IL-1β, an exercise-induced significant increase in dopamine and a slight elevation of corticotropin-releasing hormone. For confirmation of results of this pilot study and to assess more significant effects of symbiotic intervention in athletes as well as in the general population, longer-term robust studies are required. The findings of this study can help healthcare professionals understand the extensive health benefits of synbiotic intervention and its relationship to physical activity.
Abstract
The main objective of this research was to carry out an experimental study, triple-blind, on the possible immunophysiological effects of a nutritional supplement (synbiotic, Gasteel Plus®, Heel España S.A.U.), containing a mixture of probiotic strains, such as Bifidobacterium lactis CBP-001010, Lactobacillus rhamnosus CNCM I-4036, and Bifidobacterium longum ES1, as well as the prebiotic fructooligosaccharides, on both professional athletes and sedentary people. The effects on some inflammatory/immune (IL-1β, IL-10, and immunoglobulin A) and stress (epinephrine, norepinephrine, dopamine, serotonin, corticotropin-releasing hormone (CRH), Adrenocorticotropic hormone (ACTH), and cortisol) biomarkers were evaluated, determined by flow cytometer and ELISA. The effects on metabolic profile and physical activity, as well as on various parameters that could affect physical and mental health, were also evaluated via the use of accelerometry and validated questionnaires. The participants were professional soccer players in the Second Division B of the Spanish League and sedentary students of the same sex and age range. Both study groups were randomly divided into two groups: a control group-administered with placebo, and an experimental group-administered with the synbiotic. Each participant was evaluated at baseline, as well as after the intervention, which lasted one month. Only in the athlete group did the synbiotic intervention clearly improve objective physical activity and sleep quality, as well as perceived general health, stress, and anxiety levels. Furthermore, the synbiotic induced an immunophysiological bioregulatory effect, depending on the basal situation of each experimental group, particularly in the systemic levels of IL-1β (increased significantly only in the sedentary group), CRH (decreased significantly only in the sedentary group), and dopamine (increased significantly only in the athlete group). There were no significant differences between groups in the levels of immunoglobulin A or in the metabolic profile as a result of the intervention. It is concluded that synbiotic nutritional supplements can improve anxiety, stress, and sleep quality, particularly in sportspeople, which appears to be linked to an improved immuno-neuroendocrine response in which IL-1β, CRH, and dopamine are clearly involved.
-
6.
Effects of Probiotics on Anxiety, Stress, Mood and Fitness of Badminton Players.
Salleh, RM, Kuan, G, Aziz, MNA, Rahim, MRA, Rahayu, T, Sulaiman, S, Kusuma, DWY, Adikari, AMGCP, Razam, MSM, Radhakrishnan, AK, et al
Nutrients. 2021;13(6)
-
-
-
Free full text
Plain language summary
Exercise has been shown to improve fitness, wellbeing, and health. However, strenuous exercise may be detrimental physiologically, as well as affecting psychological health. The aim of this study was to determine the effects of daily probiotic supplementation on anxiety, stress, mood and fitness levels among competitive badminton players. This study was a randomised, placebo-controlled study. Recruited participants (n=30) were randomly divided into the probiotic group and the control group. The participants were given treatments for six weeks without altering the training schedule of the athletes. Results showed that stress and anxiety in badminton players could be alleviated with the daily consumption of probiotics for six weeks. Additionally, probiotics supplementation increased aerobic capacity. Authors conclude that probiotic supplements could be beneficial for athletes to enhance their mental state and physical performance. Thus, probiotic supplementation that may influence the regulation of pathways (neuro-endocrine) and mechanism of action in response to physical and psychological stressors encountered by badminton players should further studied.
Abstract
BACKGROUND Reports of probiotic consumption on athletes' performance are debatable due to their equivocal results. There is a need for more evidence on the effects of probiotic intake on psychological state and fitness level. Thus, this study determined the effects of daily probiotic consumption on competitive anxiety, perceived stress and mood among university badminton players, besides their fitness like aerobic capacity, strength, speed, leg power and agility. METHODS Thirty university badminton players aged from 19 to 22 years old were randomly divided equally into two groups, where the probiotic group (PG; n = 15) received a drink that contained Lactobacillus casei Shirota (3 × 1010 CFU) and placebo group (CG; n = 15) a placebo drink for six weeks. Anxiety, stress and mood levels were determined using the CSAI-2R, PSS and BRUMS questionnaires, respectively. Fitness levels were measured using by subjecting the players to 20-m shuttle runs (aerobic capacity), handgrips (muscular strength), vertical jumps (leg power), 40-m dash (speed) and T-test (agility). The Student's t-test (p < 0.05) was used to determine the differences between PG and CG players. RESULTS After six weeks, the anxiety and stress levels of PG players significantly decreased by 16% (p < 0.001) and 20% (p < 0.001), respectively, but there were no significant changes detected in CG players. Supplementation of probiotics also improved aerobic capacity in PG players by 5.9% (p < 0.001) but did not influence the speed, strength, leg power and agility. CONCLUSIONS Probiotics supplementation showed improved aerobic capacity and relieve anxiety and stress. However, further studies need to be carried out to determine the mechanisms through which probiotic intake produces these effects.
-
7.
Evolution of the Human Diet and Its Impact on Gut Microbiota, Immune Responses, and Brain Health.
González Olmo, BM, Butler, MJ, Barrientos, RM
Nutrients. 2021;13(1)
-
-
-
Free full text
Plain language summary
One explanation for the increased prevalence in chronic disease and mental illness is from the evolutionary perspective. This suggests the rapid shift in diet towards processed foods in the past 200 years has not allowed for sufficient adaptation of the gut microbiome. The gut microbiome plays an important role in the digestive, immune and nervous systems via the gut-brain axis, and may be a key factor in modulating inflammation and disease. The aim of this review is to discuss how what we eat affects the immune system and impacts our brain health. The literature currently shows significant associations between the Western diet and its impact on the health of the gut microbiome and the brain. Increased intake of saturated fats, refined carbohydrates and sugar, coupled with a reduction in fiber, negatively impacts the digestive system and elicits an immune response. This response can lead to neuroinflammation, which is now found to be associated with deficits in learning and memory, as well as increased rates of neurodegenerative disease and depression. Based on the existing literature, the authors conclude the human gut microbiome has not had sufficient time to adapt to many modern foods, thus leading to inflammation and disease. The authors recommend that a diet composed of natural whole foods with minimal processing can help prevent and alleviate some of the burden caused by chronic disease, and suggest future studies focus on improving techniques to evaluate neuroinflammation in humans.
Abstract
The relatively rapid shift from consuming preagricultural wild foods for thousands of years, to consuming postindustrial semi-processed and ultra-processed foods endemic of the Western world less than 200 years ago did not allow for evolutionary adaptation of the commensal microbial species that inhabit the human gastrointestinal (GI) tract, and this has significantly impacted gut health. The human gut microbiota, the diverse and dynamic population of microbes, has been demonstrated to have extensive and important interactions with the digestive, immune, and nervous systems. Western diet-induced dysbiosis of the gut microbiota has been shown to negatively impact human digestive physiology, to have pathogenic effects on the immune system, and, in turn, cause exaggerated neuroinflammation. Given the tremendous amount of evidence linking neuroinflammation with neural dysfunction, it is no surprise that the Western diet has been implicated in the development of many diseases and disorders of the brain, including memory impairments, neurodegenerative disorders, and depression. In this review, we discuss each of these concepts to understand how what we eat can lead to cognitive and psychiatric diseases.
-
8.
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)
-
-
-
Free full text
Plain language summary
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.
-
9.
Gut Microbiota and Pathophysiology of Depressive Disorder.
Kunugi, H
Annals of nutrition & metabolism. 2021;77 Suppl 2:11-20
-
-
-
Free full text
-
Plain language summary
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.
-
10.
Food & mood: a review of supplementary prebiotic and probiotic interventions in the treatment of anxiety and depression in adults.
Noonan, S, Zaveri, M, Macaninch, E, Martyn, K
BMJ nutrition, prevention & health. 2020;3(2):351-362
-
-
-
Free full text
Plain language summary
The gut microbiome plays an important role in the bidirectional communication between the gastrointestinal tract and the brain. In this light, psychiatric disorders may be influenced by the gut microbiome, and pre/probiotics show potential as therapeutic agents in the clinical setting. The aim of this review is to investigate the efficacy of pre/probiotics in quantitatively reducing negative symptoms associated with anxiety and depression. This review included seven studies and found probiotic or combined pre/probiotic use demonstrated a significant quantitatively evident improvement in symptoms in depression. Prebiotics alone did not have a significant therapeutic impact. Based on these results, the authors suggest combined pre/probiotics, or probiotics alone, may be useful as an adjunct therapy when treating patients with depression, especially among patients with existing co-morbidities that impact gastrointestinal health. These results warrant further investigation to identify specific biochemical changes that accompany therapeutic outcomes.
Abstract
BACKGROUND A bidirectional relationship exists between the brain and the gastrointestinal tract. Foods containing bacteria that positively influence the gastrointestinal microbiome are termed, probiotics; compounds that promote the flourishing of these bacteria are termed, prebiotics. Whether microbiome influencing therapies could treat psychiatric conditions, including depression and anxiety, is an area of interest. Presently, no established consensus for such treatment exists. METHODS This systematic review analyses databases and grey literature sites to investigate pre and/or probiotics as treatments for depression and/or anxiety disorders. Articles included are from within 15 years. Pre-determined inclusion exclusion criteria were applied, and articles were appraised for their quality using a modified-CASP checklist. This review focuses specifically on quantitative measures from patients with clinical diagnoses of depression and/or anxiety disorders. RESULTS 7 studies were identified. All demonstrated significant improvements in one or more of the outcomes measuring the of effect taking pre/probiotics compared with no treatment/placebo, or when compared to baseline measurements. DISCUSSION Our review suggests utilising pre/probiotic may be a potentially useful adjunctive treatment. Furthermore, patients with certain co-morbidities, such as IBS, might experience greater benefits from such treatments, given that pre/probiotic are useful treatments for other conditions that were not the primary focus of this discourse. Our results are limited by several factors: sample sizes (adequate, though not robust); short study durations, long-term effects and propensity for remission undetermined. CONCLUSION Our results affirm that pre/probiotic therapy warrants further investigation. Efforts should aim to elucidate whether the perceived efficacy of pre/probiotic therapy in depression and/or anxiety disorders can be replicated in larger test populations, and whether such effects are maintained through continued treatment, or post cessation. Interventions should also be investigated in isolation, not combination, to ascertain where the observed effects are attributable to. Efforts to produce mechanistic explanations for such effect should be a priority.