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A Narrative Review of The Role of Foods as Dietary Sources of Vitamin D of Ethnic Minority Populations with Darker Skin: The Underestimated Challenge.
Guo, J, Lovegrove, JA, Givens, DI
Nutrients. 2019;11(1)
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Vitamin D is essential for healthy bones, and low vitamin D status is associated with an increased risk of chronic diseases such as cardiovascular disease and type 2 diabetes. Ethnic minority populations with darker skin are considered as a high-risk group for vitamin D deficiency, owing mainly to having less ability to synthesise vitamin D from sunlight due to the skin pigment melanin and/or reduced skin exposure due to clothing required by religious or cultural traditions. The aim of this literature review was to evaluate vitamin D intake and status of ethnic minority populations with darker skin. The authors examined previous observational studies and randomised controlled trials. Ethnic minority populations generally have a lower vitamin D status than white populations. Compared with Caucasians, there is evidence that Asians require approximately three times longer periods of sunlight exposure, and Africans six times the same exposure, to achieve the same blood levels of vitamin D. The main food sources for dietary vitamin D intake were different for ethnic minority populations and white populations. There is limited evidence on the impact of vitamin D supplementation on different ethnic groups. The authors concluded that food fortification could be explored to increase dietary vitamin D intake in ethnic minority populations who generally have lower levels of vitamin D.
Abstract
In recent years, vitamin D deficiency has attracted attention worldwide. Especially many ethnic minority populations are considered at high-risk of vitamin D deficiency, owing to a lesser ability to synthesis vitamin D from sunlight (ultraviolet B), due to the skin pigment melanin and/or reduced skin exposure due to coverage required by religious and cultural restrictions. Therefore, vitamin D intake from dietary sources has become increasingly important for many ethnic minority populations to achieve adequate vitamin D status compared with the majority of the population. The aim of the study was critically evaluate the vitamin D intake and vitamin D status of the ethnic minority populations with darker skin, and also vitamin D absorption from supplements and ultraviolet B. Pubmed, Embaase and Scopus were searched for articles published up to October 2018. The available evidence showed ethnic minority populations generally have a lower vitamin D status than the majority populations. The main contributory food sources for dietary vitamin D intake were different for ethnic minority populations and majority populations, due to vary dietary patterns. Future strategies to increase dietary vitamin D intake by food fortification or biofortification needs to be explored, not only for the majority population but more specifically for ethnic minority populations who are generally of lower vitamin D status.
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Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?
Burns-Whitmore, B, Froyen, E, Heskey, C, Parker, T, San Pablo, G
Nutrients. 2019;11(10)
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Fish and seafood are good sources of long-chain omega-3 fatty acids, like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A vegan diet does not include animal-sourced foods and is therefore void of EPA and DHA, unless algae-derived omega-3 supplements are consumed. Thus, vegans rely on the body's own production of long-chain fatty acids from plant-derived alpha-linolenic acid (ALA). However, adequate conversion can have several limitations. Vegan diets are generally rich in linoleic acid (LA), an omega-6 fatty acid, which in high levels can impede the conversion of ALA to EPA and DHA. Furthermore, the efficiency of conversion is influenced by gender, age or health conditions like obesity. This review sought to discuss whether vegans require special dietary recommendations for fatty acids and what these suggestions could be. Most studies assessing biological indicators of fatty acid status showed that vegans had lower levels of EPA and DHA compared to omnivores. Thus, the authors concluded that special consideration should be given to ALA and LA intake in vegan diets. In the absence of a set recommendation for a fatty acid ratio, a ratio of 4:1 (omega-6:omega-3) was proposed for vegans and omnivores. A reduction in LA and an increased intake of ALA of 2.2–4.4 g/day (or 1.1 g/day/1000 Kcals) was suggested to achieve such. This article is a useful guide when considering adequate fatty acid balance and omega-3 conversion for individuals following a vegan diet.
Abstract
Good sources of the long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) include cold-water fish and seafood; however, vegan diets (VGNs) do not include animal-origin foods. Typically, US omnivores obtain enough dietary EPA and DHA, but unless VGNs consume algal n-3 supplements, they rely on endogenous production of long-chain fatty acids. VGN diets have several possible concerns: (1) VGNs have high intakes of linoleic acid (LA) as compared to omnivore/non-vegetarian diets. (2) High intakes of LA competitively interfere with the endogenous conversion of alpha-linolenic acid (ALA) to EPA and DHA. (3) High somatic levels of LA/low ALA indicate a decreased ALA conversion to EPA and DHA. (4) Some, not all VGNs meet the Dietary Reference Intake Adequate Intake (DRI-AI) for dietary ALA and (5) VGN diets are high in fiber, which possibly interferes with fat absorption. Consequently, health professionals and Registered Dietitians/Registered Dietitian Nutritionists working with VGNs need specific essential fatty acid diet guidelines. The purpose of this review was: (1) to suggest that VGNs have a DRI-AI Special Consideration requirement for ALA and LA based on VGN dietary and biochemical indicators of status and (2) to provide suggestions to ensure that VGNs receive adequate intakes of LA and ALA.
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Nutrition Interventions in Rheumatoid Arthritis: The Potential Use of Plant-Based Diets. A Review.
Alwarith, J, Kahleova, H, Rembert, E, Yonas, W, Dort, S, Calcagno, M, Burgess, N, Crosby, L, Barnard, ND
Frontiers in nutrition. 2019;6:141
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Rheumatoid arthritis (RA) is a chronic autoimmune disease characterised by joint pain and inflammation with both genetic and modifiable risk factors. Research suggests a plant-based diet may play a role in management and remission. The aim of this review was to summarize the associations between plant-based diet patterns and RA symptoms. Current studies indicate an association between improvements in RA symptoms with weight loss and with plant-based diets. Based on these findings, the authors conclude excess weight and diets that include animal products may exacerbate symptoms associated with RA, whereas plant-based diets may help reduce pain and inflammation in these patients. The authors suggest further research is needed to test the effectiveness of plant-based diets on patients with RA.
Abstract
Rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease, affects roughly 1% of the world's population. RA pathogenesis remains unclear, but genetic factors account for 50-60% of the risk while the remainder might be linked to modifiable factors, such as infectious diseases, tobacco smoking, gut bacteria, and nutrition. Dietary triggers may play an inciting role in the autoimmune process, and a compromised intestinal barrier may allow food components or microorganisms to enter the blood stream, triggering inflammation. In addition, excessive body weight may affect pharmacotherapy response and the likelihood of disease remission, as well as the risk of disease mortality. Evidence suggests that changes in diet might play an important role in RA management and remission. Several studies have shown improvements in RA symptoms with diets excluding animal products. Studies have also shown that dietary fiber found in these plant-based foods can improve gut bacteria composition and increase bacterial diversity in RA patients, thus reducing their inflammation and joint pain. Although some of the trigger foods in RA patients are individualized, a vegan diet helps improve symptoms by eliminating many of these foods. This review examines the potential role of a plant-based diet in mediating RA symptoms. Further research is needed to test the effectiveness of plant-based diets on joint pain, inflammation, and quality of life in patients with RA.
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The Effects of Vegetarian and Vegan Diets on Gut Microbiota.
Tomova, A, Bukovsky, I, Rembert, E, Yonas, W, Alwarith, J, Barnard, ND, Kahleova, H
Frontiers in nutrition. 2019;6:47
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The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. This diversity appears to have an important association with BMI, obesity, and arterial compliance. This review highlights the effects of different diets, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health. The ratio between Bacteroidetes and Firmicutes is discussed and how different diets can change it. It explains how diet can affect the three main enterotypes: Prevotella, Bacteroides, and Ruminococcus. The food components proteins, carbohydrates, fats and polyphenols are discussed and how they influence gut microbiota. Up to date knowledge suggests that a plant-based diet may be an effective way to promote a diverse ecosystem of beneficial microbes that support overall health. However, due to the complexity and inter-individual differences, further research is required to fully characterize the interactions between diet, the microbiome, and health outcomes.
Abstract
The difference in gut microbiota composition between individuals following vegan or vegetarian diets and those following omnivorous diets is well documented. A plant-based diet appears to be beneficial for human health by promoting the development of more diverse and stable microbial systems. Additionally, vegans and vegetarians have significantly higher counts of certain Bacteroidetes-related operational taxonomic units compared to omnivores. Fibers (that is, non-digestible carbohydrates, found exclusively in plants) most consistently increase lactic acid bacteria, such as Ruminococcus, E. rectale, and Roseburia, and reduce Clostridium and Enterococcus species. Polyphenols, also abundant in plant foods, increase Bifidobacterium and Lactobacillus, which provide anti-pathogenic and anti-inflammatory effects and cardiovascular protection. High fiber intake also encourages the growth of species that ferment fiber into metabolites as short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate. The positive health effects of SCFAs are myriad, including improved immunity against pathogens, blood-brain barrier integrity, provision of energy substrates, and regulation of critical functions of the intestine. In conclusion, the available literature suggests that a vegetarian/vegan diet is effective in promoting a diverse ecosystem of beneficial bacteria to support both human gut microbiome and overall health. This review will focus on effects of different diets and nutrient contents, particularly plant-based diets, on the gut microbiota composition and production of microbial metabolites affecting the host health.
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Inflammatory Bowel Diseases and Food Additives: To Add Fuel on the Flames!
Marion-Letellier, R, Amamou, A, Savoye, G, Ghosh, S
Nutrients. 2019;11(5)
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Inflammatory Bowel Diseases (IBDs), such as Crohn’s disease (CD) and Ulcerative Colitis (UC) are becoming increasingly common. Diet is thought to play a role in the development of IBDs. The consumption of Ultra Processed Food (UPF) is increasing and has been associated with a higher risk of some chronic diseases. Food additives may be an aspect of UPF responsible for its harmful effects. This literature review examined the role of food additives in the development and severity of IBDs. The authors discuss how common food additives such as salt, emulsifiers, stabilisers, bulking agents, sweeteners, and food colouring may promote inflammation and disrupt gut bacteria. Metals and compounds found in food packaging such as aluminium and bisphenol A (BPA) may trigger intestinal permeability and increase inflammatory markers. Much of the evidence available is based on clinical trials on animals, whilst epidemiological studies on food additives and IBD risk are still limited. The authors concluded that the majority of food consumed by IBD patients should be home-cooked in order to reduce exposure to additives in the diet.
Abstract
Inflammatory bowel diseases (IBDs) develop in genetically predisposed individuals in response to environmental factors. IBDs are concomitant conditions of industrialized societies, and diet is a potential culprit. Consumption of ultra-processed food has increased over the last decade in industrialized countries, and epidemiological studies have found associations between ultra-processed food consumption and chronic diseases. Further studies are now required to identify the potential culprit in ultra-processed food, such as a poor nutritional composition or the presence of food additives. In our review, we will focus on food additives, i.e., substances from packaging in contact with food, and compounds formed during production, processing, and storage. A literature search using PubMed from inception to January 2019 was performed to identify relevant studies on diet and/or food additive and their role in IBDs. Manuscripts published in English from basic science, epidemiological studies, or clinical trials were selected and reviewed. We found numerous experimental studies highlighting the key role of food additives in IBD exacerbation but epidemiological studies on food additives on IBD risk are still limited. As diet is a modifiable environmental risk factor, this may offer a scientific rationale for providing dietary advice for IBD patients.
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The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients?
Butler, MI, Mörkl, S, Sandhu, KV, Cryan, JF, Dinan, TG
Canadian journal of psychiatry. Revue canadienne de psychiatrie. 2019;64(11):747-760
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The gut-brain axis is the bi-directional communication pathway and increasing evidence indicates its impact in neural health and disease. With the field of nutritional psychiatry actively developing, psychiatric patients have become increasingly aware of the therapeutic use of probiotics and mental health. This review aims to inform psychiatrists about the communication between the microbiome and brain and discuss its relevance to the management and treatment of psychiatric illness. In reviewing the common psychiatric illnesses, the current literature shows inconsistent results on specific microbiome compositions related to specific illnesses, yet shows promising effects for probiotic use in many disorders. These findings offer a novel paradigm for approaching mental illness through the lens of nutritional psychiatry. Authors conclude there is much work to be done translating laboratory findings into clinical practice, and highlight the necessity for clinicians to stay informed of the literature and make accurate recommendations to patients.
Abstract
The gut microbiome as a potential therapeutic target for mental illness is a hot topic in psychiatry. Trillions of bacteria reside in the human gut and have been shown to play a crucial role in gut-brain communication through an influence on neural, immune, and endocrine pathways. Patients with various psychiatric disorders including depression, bipolar disorder, schizophrenia, and autism spectrum disorder have been shown to have significant differences in the composition of their gut microbiome. Enhancing beneficial bacteria in the gut, for example, through the use of probiotics, prebiotics, or dietary change, has the potential to improve mood and reduce anxiety in both healthy people and patient groups. Much attention is being given to this subject in the general media, and patients are becoming increasingly interested in the potential to treat mental illness with microbiome-based therapies. It is imperative that those working with people with mental illness are aware of the rationale and current evidence base for such treatment strategies. In this review, we provide an overview of the gut microbiome, what it is, and what it does in relation to gut-brain communication and psychological function. We describe the fundamental principles and basic techniques used in microbiome-gut-brain axis research in an accessible way for a clinician audience. We summarize the current evidence in relation to microbiome-based strategies for various psychiatric disorders and provide some practical advice that can be given to patients seeking to try a probiotic for mental health benefit.
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Gut feeling: randomized controlled trials of probiotics for the treatment of clinical depression: Systematic review and meta-analysis.
Nikolova, V, Zaidi, SY, Young, AH, Cleare, AJ, Stone, JM
Therapeutic advances in psychopharmacology. 2019;9:2045125319859963
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Major depression is a common and complex illness that significantly diminishes quality of life. Currently, most pharmacological treatments target neurotransmitter activity in the brain and are known to have a delayed onset of effect as well as a range of side-effects. The aim of this study was to identify and synthesize all published data from randomized controlled trials (RCTs) on the efficacy of probiotics as treatment for depression in clinically depressed patients. This study is a systematic review of three studies. Within the three included RCTs, a total of 229 clinically depressed patients were randomized, with an average age of 36 years and a gender distribution of 76% female. Results indicate a non-significant difference in depressive symptoms between the probiotic and placebo groups post-intervention. Authors conclude that further larger studies in well-defined clinical populations are needed, both to determine the clinical utility of this novel treatment approach, and to investigate potential underlying mechanisms.
Abstract
BACKGROUND Recently the gut microbiota has attracted significant interest in psychiatric research due to the observed bidirectional gut-brain communication. A growing body of evidence from preclinical work has suggested that probiotics may be effective in reducing stress and anxiety and alleviating low mood. It is unclear to what extent these effects are seen in clinical populations. We aimed to identify all published evidence on the efficacy of probiotics as treatment for depression in clinically depressed populations. METHODS Randomized controlled trials of patients with depression where probiotics were used as supplementary or standalone treatment were considered eligible. A literature search with the terms (probiotic* OR bacteria OR Lactobacillus OR Bifidobacterium) AND depress* was performed in PubMed and Web of Science. Data on study population characteristics, treatment effectiveness, tolerability and risk of bias were extracted from eligible studies. A random effects model was used for meta-analyses. RESULTS Only three studies met inclusion criteria (229 individuals randomized), two of which administered probiotics as a supplementary treatment to antidepressants and one as a standalone treatment. Upon removal of the latter study from the meta-analysis due to clinical heterogeneity, there was an overall positive effect of probiotics on depressive symptoms (standardized mean difference = 1.371, 95% confidence interval 0.130-2.613). CONCLUSIONS There is limited evidence for the efficacy of probiotics in depression at present, although there may be a beneficial effect of probiotics on depressive symptoms when administered in addition to antidepressants. Further studies are required to investigate this and explore potential mechanisms.
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Gut microbial metabolites in depression: understanding the biochemical mechanisms.
Caspani, G, Kennedy, S, Foster, JA, Swann, J
Microbial cell (Graz, Austria). 2019;6(10):454-481
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Major depressive disorder is a leading cause of disability and is linked to shortened life expectancy and suicide. Despite its prevalence, for near to a third of patients, long-term treatment options are ineffective. In addition to the primary presentation of persistent low mood, other emotional and physiological symptoms, researchers have also identified alterations in metabolism, hormones and the immune system. Furthermore, increasing evidence suggests that depression and depressive behaviour is also influenced by divergences in gut health and gut bacteria composition. With insights from animal and human research, this review highlights how the gut and gut bacteria-derived metabolites can directly or indirectly influence mood. Described are the pathways of how the gut and its microorganism communicate with the brain, the essential role the immune system has as part of the gut-brain communication, and the impact of low-grade, chronic inflammation on neurofunction. Comprehensive summaries are dedicated to how several metabolites or by-products from gut bacteria can influence the nervous system and gene expression in relation to depression. These include substances like neurotransmitters, short-chain fatty acids, tryptophan metabolites, lactate, bile acids, choline metabolites and folate. This article yields a detailed overview of how gut health and microbiota can influence neurofunction and mental health. The authors promote the idea of the gut as a suitable target for the management of depressive disorders, whilst also eluding to the current limitations and need for further research.
Abstract
Gastrointestinal and central function are intrinsically connected by the gut microbiota, an ecosystem that has co-evolved with the host to expand its biotransformational capabilities and interact with host physiological processes by means of its metabolic products. Abnormalities in this microbiota-gut-brain axis have emerged as a key component in the pathophysiology of depression, leading to more research attempting to understand the neuroactive potential of the products of gut microbial metabolism. This review explores the potential for the gut microbiota to contribute to depression and focuses on the role that microbially-derived molecules - neurotransmitters, short-chain fatty acids, indoles, bile acids, choline metabolites, lactate and vitamins - play in the context of emotional behavior. The future of gut-brain axis research lies is moving away from association, towards the mechanisms underlying the relationship between the gut bacteria and depressive behavior. We propose that direct and indirect mechanisms exist through which gut microbial metabolites affect depressive behavior: these include (i) direct stimulation of central receptors, (ii) peripheral stimulation of neural, endocrine, and immune mediators, and (iii) epigenetic regulation of histone acetylation and DNA methylation. Elucidating these mechanisms is essential to expand our understanding of the etiology of depression, and to develop new strategies to harness the beneficial psychotropic effects of these molecules. Overall, the review highlights the potential for dietary interventions to represent such novel therapeutic strategies for major depressive disorder.
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Small talk: microbial metabolites involved in the signaling from microbiota to brain.
Caspani, G, Swann, J
Current opinion in pharmacology. 2019;48:99-106
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The gut-brain axis (GBA) is the communication network between the gastrointestinal tract and the central nervous system. An array of gut bacteria-derived metabolites mediates this interaction between the gastrointestinal system and the brain, influencing physiological and pathological processes in direct and indirect ways. Thus a variation in the gut microbiome can alter the functional capacity and output of the gut-brain-communication. In this review, the authors summarise key bacterial metabolites from the gut and their effect on the brain. Addressed are short-chain fatty acids, their impact on gut and brain barrier integrity, their role in appetite regulation, and their association with anxiety and depressive disorders amongst other aspects. Secondly, bile acids, which are processed by the microbiome, can activate several receptors. And thus divergence gut bacteria can alter the composition of bile acids and change their signalling capacity. Bile acids can also directly modify gut and blood-brain barrier function and may carry a signalling role in the brain. A few neurotransmitters are covered in this article, as several types of gut bacteria synthesize neurotransmitters, such as serotonin and dopamine. Though, it is uncertain whether all gut-derived neurotransmitters can reach the brain. However, certain GABA-producing bacteria have been shown to elicit higher GABA levels in the brain. The microbiota can also be involved with the conversion of neurotransmitters such as dopamine. The final section briefly capture the evidence of other brain health-relevant molecules derived from the intestinal microbiota, including Lipopolysaccharides, choline, lactate and B-Vitamins. This review yields a short and comprehensive summary highlighting the many ways the gut can influence brain function and health and could be of interest to those providing mental health support in light of gut function.
Abstract
The wealth of biotransformational capabilities encoded in the microbiome expose the host to an array of bioactive xenobiotic products. Several of these metabolites participate in the communication between the gastrointestinal tract and the central nervous system and have potential to modulate central physiological and pathological processes. This biochemical interplay can occur through various direct and indirect mechanisms. These include binding to host receptors in the brain, stimulation of the vagus nerve in the gut, alteration of central neurotransmission, and modulation of neuroinflammation. Here, the potential for short chain fatty acids, bile acids, neurotransmitters and other bioactive products of the microbiome to participate in the gut-brain axis will be reviewed.
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Current Understanding of Gut Microbiota in Mood Disorders: An Update of Human Studies.
Huang, TT, Lai, JB, Du, YL, Xu, Y, Ruan, LM, Hu, SH
Frontiers in genetics. 2019;10:98
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The bidirectional communication between the brain and gastrointestinal tract has been established, and evidence suggests the gut microbiota can influence brain function. While the underlying cause of mood disorders is multifactorial and complex, the gut microbiota may play a role in the pathogenesis of disease. The aim of this review is to summarize the human studies of gut microbiota in mood disorders and discuss the cause-effect relationship between microbiota composition and mood disorders. Twelve studies were included and showed the microbiome diversity and composition of those experiencing mood disorders were significantly different compared with healthy individuals. They found an increase in the abundance of Actinobacteria, Enterobacteriaceae and a decrease in Faecalibacterium, suggesting a pro-inflammatory state. Based on these results, the authors conclude the gut microbiota plays an important role in mood disorders through the brain-gut-microbiota axis, and suggests it to be a target for improved diagnosis and therapeutic interventions.
Abstract
Gut microbiota plays an important role in the bidirectional communication between the gut and the central nervous system. Mounting evidence suggests that gut microbiota can influence the brain function via neuroimmune and neuroendocrine pathways as well as the nervous system. Advances in gene sequencing techniques further facilitate investigating the underlying relationship between gut microbiota and psychiatric disorders. In recent years, researchers have preliminarily explored the gut microbiota in patients with mood disorders. The current review aims to summarize the published human studies of gut microbiota in mood disorders. The findings showed that microbial diversity and taxonomic compositions were significantly changed compared with healthy individuals. Most of these findings revealed that short-chain fatty acids-producing bacterial genera were decreased, while pro-inflammatory genera and those involved in lipid metabolism were increased in patients with depressive episodes. Interestingly, the abundance of Actinobacteria, Enterobacteriaceae was increased and Faecalibacterium was decreased consistently in patients with either bipolar disorder or major depressive disorder. Some studies further indicated that specific bacteria were associated with clinical characteristics, inflammatory profiles, metabolic markers, and pharmacological treatment. These studies present preliminary evidence of the important role of gut microbiota in mood disorders, through the brain-gut-microbiota axis, which emerges as a promising target for disease diagnosis and therapeutic interventions in the future.