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Does the microbiome and virome contribute to myalgic encephalomyelitis/chronic fatigue syndrome?
Newberry, F, Hsieh, SY, Wileman, T, Carding, SR
Clinical science (London, England : 1979). 2018;132(5):523-542
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Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) (ME/CFS) is a disabling and debilitating disease. Several studies have shown alterations in the gut microbiome (dysbiosis) in patients with ME/CFS. However, in focusing on the bacterial components of the microbiome, the viral component of the microbiome (known as the virome) has been neglected. Viruses can change the microbiome which can influence the health. This area is therefore important for research into ME/CFS. This article provides a comprehensive review of the current evidence supporting microbiome alterations in ME/CFS patients. Additionally, the challenges associated with microbiome studies are discussed. A literature search was done and 11 papers were found that had examined the microbiome ME/CFS patients, dating from 1998 to 2017. It was not possible to compare the studies statistically but from looking at each one individually there is sufficient evidence to support the claim of an altered intestinal microbiome in ME/CFS patients. ME/CFS is multifactorial and potential dysbiosis should be considered to be only part of the picture. Future studies are needed to adopt standardized techniques and analyses. As research increases, it is becoming clear that the virome can directly and indirectly affect host health, and may play a role in the pathogenesis of ME/CFS.
Abstract
Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) (ME/CFS) is a disabling and debilitating disease of unknown aetiology. It is a heterogeneous disease characterized by various inflammatory, immune, viral, neurological and endocrine symptoms. Several microbiome studies have described alterations in the bacterial component of the microbiome (dysbiosis) consistent with a possible role in disease development. However, in focusing on the bacterial components of the microbiome, these studies have neglected the viral constituent known as the virome. Viruses, particularly those infecting bacteria (bacteriophages), have the potential to alter the function and structure of the microbiome via gene transfer and host lysis. Viral-induced microbiome changes can directly and indirectly influence host health and disease. The contribution of viruses towards disease pathogenesis is therefore an important area for research in ME/CFS. Recent advancements in sequencing technology and bioinformatics now allow more comprehensive and inclusive investigations of human microbiomes. However, as the number of microbiome studies increases, the need for greater consistency in study design and analysis also increases. Comparisons between different ME/CFS microbiome studies are difficult because of differences in patient selection and diagnosis criteria, sample processing, genome sequencing and downstream bioinformatics analysis. It is therefore important that microbiome studies adopt robust, reproducible and consistent study design to enable more reliable and valid comparisons and conclusions to be made between studies. This article provides a comprehensive review of the current evidence supporting microbiome alterations in ME/CFS patients. Additionally, the pitfalls and challenges associated with microbiome studies are discussed.
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Food for Mood: Relevance of Nutritional Omega-3 Fatty Acids for Depression and Anxiety.
Larrieu, T, Layé, S
Frontiers in physiology. 2018;9:1047
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The human brain contains high levels of polyunsaturated fatty acids (PUFAs). Of these PUFAs, omega-3s have been widely studied in relation to many brain diseases, including anxiety and depression. This review focuses on the clinical and experimental data linking dietary intake of omega-3s with depression or anxiety. People diagnosed with anxiety and depressive disorders have lower omega-3s and a higher ratio of omega-6s to omega-3s in their blood and brains compared to healthy subjects. Experiments on omega-3 supplementation for depression and post-traumatic stress have had promising results. Numerous mechanisms have been proposed for the effects of omega-3s. These include direct effects on specific receptors in the brain, regulation of the endocannabinoid system, effects on the hypothalamic-pituitary-adrenal (HPA) axis, and reduction of inflammation in the brain. The authors conclude that more research is needed into the potential of omega-3s as treatment for mood-related diseases.
Abstract
The central nervous system (CNS) has the highest concentration of lipids in the organism after adipose tissue. Among these lipids, the brain is particularly enriched with polyunsaturated fatty acids (PUFAs) represented by the omega-6 (ω6) and omega-3 (ω3) series. These PUFAs include arachidonic acid (AA) and docosahexaenoic acid (DHA), respectively. PUFAs have received substantial attention as being relevant to many brain diseases, including anxiety and depression. This review addresses an important question in the area of nutritional neuroscience regarding the importance of ω3 PUFAs in the prevention and/or treatment of neuropsychiatric diseases, mainly depression and anxiety. In particular, it focuses on clinical and experimental data linking dietary intake of ω3 PUFAs and depression or anxiety. In particular, we will discuss recent experimental data highlighting how ω3 PUFAs can modulate neurobiological processes involved in the pathophysiology of anxiety and depression. Potential mechanisms involved in the neuroprotective and corrective activity of ω3 PUFAs in the brain are discussed, in particular the sensing activity of free fatty acid receptors and the activity of the PUFAs-derived endocannabinoid system and the hypothalamic-pituitary-adrenal axis.
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Impact of vegan diets on gut microbiota: An update on the clinical implications.
Wong, MW, Yi, CH, Liu, TT, Lei, WY, Hung, JS, Lin, CL, Lin, SZ, Chen, CL
Ci ji yi xue za zhi = Tzu-chi medical journal. 2018;30(4):200-203
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Gut microbiota is defined as microbes that collectively inhabit the gut ecosystem. Several factors, including diet, age, birth mode, breast-feeding or formula-feeding, geography, exercise, alcohol consumption, and exposure to antibiotics may influence gut microbiota. Previous conventional culturing together with recent culture-independent molecular studies show that vegan diets appear to affect gut microbiota. Furthermore, recent literature also indicates that vegan diets may have various health benefits, including amelioration of metabolic syndrome, cardiovascular disease and rheumatoid arthritis. Authors conclude that these findings have their limitations. Thus, further research may help to clarify the complex mechanisms and interrelationships between vegan diets and gut microbiota.
Abstract
Numerous studies indicate that microbiota plays an important role in human health. Diet is a factor related to microbiota which also influences human health. The relationships between diet, microbiota, and human health are complex. This review focuses on the current literature on vegan diets and their unique impact on gut microbiota. We also report on the health benefits of a vegan diet for metabolic syndrome, cardiovascular disease, and rheumatoid arthritis concerning relevant impacts from gut microbiota. Despite evidence supporting the clinical relevance of vegan gut microbiota to human health, the whole mechanism awaits further investigation.
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Cardiometabolic risk factors in vegans; A meta-analysis of observational studies.
Benatar, JR, Stewart, RAH
PloS one. 2018;13(12):e0209086
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Healthy, balanced, plant-based diets have been associated with better health outcomes, however the role of dairy and meat products on heart disease and death due to heart disease is not fully understood. Vegan diets are strictly plant-based and could provide an opportunity to investigate the effect of eliminating animal products on heart disease risk. This meta-analysis of 40 observational studies aimed to evaluate the effect of a vegan diet on heart disease risk factors. The results showed that vegans in most countries had improved heart disease risk factors such as a small waist circumference, lower body mass index (BMI) and balanced blood sugars compared to omnivores, however studies from Taiwan failed to show this trend. It was concluded that a vegan diet in most countries is associated with better health outcomes compared to an omnivorous diet. This study could be use by healthcare practitioners to recommend a vegan diet to those at a higher risk of heart disease.
Abstract
BACKGROUND There is increasing evidence that plant based diets are associated with lower cardiovascular risk. OBJECTIVE To evaluate effects of a vegan compared to an omnivorous diet on cardio-metabolic risk factors. METHODS Meta-analysis of observational studies published between 1960 and June 2018 that reported one or more cardio-metabolic risk factors in vegans and controls eating an omnivorous diet were undertaken. Macro-nutrient intake and cardio-metabolic risk factors were compared by dietary pattern. The Newcastle Ottawa Scale (NOS) was used to assess the quality of each study. The inverse-variance method was used to pool mean differences. Statistical analyses were performed using RevMan software version 5•2 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen. RESULTS 40 studies with 12 619 vegans and 179 630 omnivores were included. From food frequency questionnaires in 28 studies, vegans compared to omnivores consumed less energy (-11%, 95% confidence interval -14 to -8) and less saturated fat (- 51%, CI -57 to -45). Compared to controls vegans had a lower body mass index (-1.72 kg/m2, CI -2.30 to -1.16), waist circumference (-2.35 cm, CI -3.93 to -0.76), low density lipoprotein cholesterol (-0.49 mmol/L CI -0.62 to -0.36), triglycerides (-0.14 mmol/L, CI -0.24 to -0.05), fasting blood glucose (-0.23 mmol/, CI -0.35 to -0.10), and systolic (-2.56 mmHg, CI -4.66 to -0.45) and diastolic blood pressure (-1.33 mmHg, CI -2.67 to -0.02), p<0.0001 for all. Results were consistent for studies with < and ≥ 50 vegans, and published before and after 2010. However in several large studies from Taiwan a vegan diet was not associated with favourable cardio-metabolic risk factors compared to the control diets. CONCLUSION In most countries a vegan diet is associated with a more favourable cardio- metabolic profile compared to an omnivorous diet.
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The Western Diet-Microbiome-Host Interaction and Its Role in Metabolic Disease.
Zinöcker, MK, Lindseth, IA
Nutrients. 2018;10(3)
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The Western diet is characteristically high in ultra-processed foods, which may change the gut microbiome. As the gut microbiome is unique, any alterations may be associated with disease. This review study aimed to highlight how ultra-processing can affect the gut microbiome and its impact on the development of disease to better inform dietary guidelines. Associations between poor health outcomes and ultra-processed foods have been shown with processed meats, refined grains, and processed fish. Traditionally research has focussed on added salt, sugar and fat, however processed foods may contain or be processed in a way that promotes disease. Gut microbial changes can be driven by diet, which could be detrimental, permanent, and inheritable. Food processing such as heat treatment, and additives such as sweeteners and emulsifiers can all alter the gut microbiota, however these do not need to undergo microbiome testing before being approved for consumption. Effects of ultra-processed foods on the gut microbiome need to be extensively investigated in terms of health outcomes to better inform dietary guidelines. This study could be used by healthcare professionals to better understand how ultra-processed foods play a part in diseases beyond that of added salt, fat and sugar and that the microbiome has a pivotal role.
Abstract
The dietary pattern that characterizes the Western diet is strongly associated with obesity and related metabolic diseases, but biological mechanisms supporting these associations remain largely unknown. We argue that the Western diet promotes inflammation that arises from both structural and behavioral changes in the resident microbiome. The environment created in the gut by ultra-processed foods, a hallmark of the Western diet, is an evolutionarily unique selection ground for microbes that can promote diverse forms of inflammatory disease. Recognizing the importance of the microbiome in the development of diet-related disease has implications for future research, public dietary advice as well as food production practices. Research into food patterns suggests that whole foods are a common denominator of diets associated with a low level of diet-related disease. Hence, by studying how ultra-processing changes the properties of whole foods and how these foods affect the gut microbiome, more useful dietary guidelines can be made. Innovations in food production should be focusing on enabling health in the super-organism of man and microbe, and stronger regulation of potentially hazardous components of food products is warranted.
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Psoriasis and Microbiota: A Systematic Review.
Benhadou, F, Mintoff, D, Schnebert, B, Thio, HB
Diseases (Basel, Switzerland). 2018;6(2)
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Psoriasis is an autoimmune inflammatory skin disease that causes red, itchy, flaky and scaly skin. Skin integrity and function are critically dependent on the microbial population on it. Based on this systematic review, the immune system's interaction with microbes on the skin was examined and its relationship to psoriasis. T-cell mediated inflammation is characteristic of psoriasis where interaction between type IV collagen and α1β1 integrin, a collagen receptor, occurs. In psoriatic skin lesions, Firmicutes were predominant, while Actinobacteria were less prevalent. Psoriasis exacerbations are also associated with an exacerbated number of fungi, Malassezia species, in skin lesions. As therapeutic strategies for psoriasis, this systematic review suggests adhering to a gluten-free diet and incorporating prebiotics and probiotics such as Lactobacillus. However, further research is needed to develop specific therapeutic and skin modulation strategies. Health care professionals can benefit from this systematic review by understanding the pathophysiology behind psoriasis and possible therapeutic strategies to consider.
Abstract
BACKGROUND Recent advances have highlighted the crucial role of microbiota in the pathophysiology of chronic inflammatory diseases as well as its impact on the efficacy of therapeutic agents. Psoriasis is a chronic, multifactorial inflammatory skin disorder, which has a microbiota distinct from healthy, unaffected skin. AIM: Through an extensive review of the literature, we aim to discuss the skin and gut microbiota and redefine their role in the pathogenesis of psoriasis. CONCLUSIONS Unfortunately, the direct link between the skin microbiota and the pathogenesis of psoriasis remains to be clearly established. Apart from improving the course of psoriasis, selective modulation of the microbiota may increase the efficacy of medical treatments as well as attenuate their side effects.
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Dietary Considerations in Autism Spectrum Disorders: The Potential Role of Protein Digestion and Microbial Putrefaction in the Gut-Brain Axis.
Sanctuary, MR, Kain, JN, Angkustsiri, K, German, JB
Frontiers in nutrition. 2018;5:40
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Children with autism spectrum disorder (ASD) display high incidence of gastrointestinal (GI) co-morbidities. Growing evidence now shows an association between diet and ASD, demonstrating that impaired gut function may worsen both GI and behavioural symptoms associated with ASD. The aim of this review was to examine the existing literature to further understand the connection between gut structure and function and ASD. This review found children with ASD and gut co-morbidities exhibit poor protein digestion, impaired gut-barrier integrity and a compromised gut microbiome. A potential mechanistic explanation is that the elevated level of undigested proteins is negatively affecting the integrity of the gut. Based on these findings, the authors conclude it is urgent to perform more experimental and clinical research on the “fragile gut” in children with ASD in order to move towards advancements in individualised clinical practice.
Abstract
Children with autism spectrum disorders (ASD), characterized by a range of behavioral abnormalities and social deficits, display high incidence of gastrointestinal (GI) co-morbidities including chronic constipation and diarrhea. Research is now increasingly able to characterize the "fragile gut" in these children and understand the role that impairment of specific GI functions plays in the GI symptoms associated with ASD. This mechanistic understanding is extending to the interactions between diet and ASD, including food structure and protein digestive capacity in exacerbating autistic symptoms. Children with ASD and gut co-morbidities exhibit low digestive enzyme activity, impaired gut barrier integrity and the presence of antibodies specific for dietary proteins in the peripheral circulation. These findings support the hypothesis that entry of dietary peptides from the gut lumen into the vasculature are associated with an aberrant immune response. Furthermore, a subset of children with ASD exhibit high concentrations of metabolites originating from microbial activity on proteinaceous substrates. Taken together, the combination of specific protein intakes poor digestion, gut barrier integrity, microbiota composition and function all on a background of ASD represents a phenotypic pattern. A potential consequence of this pattern of conditions is that the fragile gut of some children with ASD is at risk for GI symptoms that may be amenable to improvement with specific dietary changes. There is growing evidence that shows an association between gut dysfunction and dysbiosis and ASD symptoms. It is therefore urgent to perform more experimental and clinical research on the "fragile gut" in children with ASD in order to move toward advancements in clinical practice. Identifying those factors that are of clinical value will provide an evidence-based path to individual management and targeted solutions; from real time sensing to the design of diets with personalized protein source/processing, all to improve GI function in children with ASD.
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Systematic review of palm oil consumption and the risk of cardiovascular disease.
Ismail, SR, Maarof, SK, Siedar Ali, S, Ali, A
PloS one. 2018;13(2):e0193533
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Palm oil, the most widely consumed vegetable oil in the world, derives from the palm tree fruit with a balanced ratio of unsaturated and saturated fatty acids. Studies have shown an association between high contents of saturated fats in palm oil with the detrimental atherogenic profile. The review aims at synthesising the available evidence reporting the association of palm oil consumption with cardiovascular disease risk and cardiovascular disease-specific mortality, including specifically Coronary Heart Disease (CHD) and stroke. The authors systematically searched three databases up to June 2017 without restriction on setting or language. Published interventional and observational studies that evaluated palm oil consumption with coronary heart disease or stroke in adults were searched. Separate searches were performed depending on the outcome. The study did not find a clear association between palm oil consumption and risk or mortality of cardiovascular disease, namely coronary heart disease and stroke. The health effects found between association of palm oil consumption and risk of coronary heart disease were not unique to just palm oil consumption as other food items were also included in the analysis. The review could not establish strong evidence for or against palm oil consumption relating to cardiovascular disease risk and cardiovascular disease-specific mortality. A healthy overall diet is suggested for good cardiometabolic health.
Abstract
BACKGROUND The high amount of saturated fatty acids (SFA) coupled with the rising availability and consumption of palm oil have lead to the assumption that palm oil contributes to the increased prevalence of cardiovascular diseases worldwide. We aimed at systematically synthesising the association of palm oil consumption with cardiovascular disease risk and cardiovascular disease-specific mortality. METHODS We systematically searched Central, Medline and Embase databases up to June 2017 without restriction on setting or language. We performed separate searches based on the outcomes: coronary heart disease and stroke, using keywords related to these outcomes and palm oil. We searched for published interventional and observational studies in adults (Age: >18 years old). Two investigators extracted data and a consensus was reached with involvement of a third. Only narrative synthesis was performed for all of the studies, as the data could not be pooled. RESULTS Our search retrieved 2,738 citations for stroke with one included study and 1,777 citations for coronary heart disease (CHD) with four included studies. Palmitic acid was reported to be associated with risk of myocardial infarction (MI) (OR 2.76; 95%CI = 1.39-5.47). Total SFA intake was reported to be not significant for risk of MI. Varying intake of fried foods, highest contributor to total SFA with 36% of households using palm oil for frying, showed no significant associations to risk of MI. Odds of developing first non-fatal acute MI was higher in palm oil compared to soybean oil with 5% trans-fat (OR = 1.33; 95%CI = 1.09-1.62) than palm oil compared to soybean oil with 22% trans-fat (OR = 1.16; 95%CI = 0.86-1.56). Nevertheless, these risk estimates were non-significant and imprecise. The trend amongst those taking staple pattern diet (characterised by higher palm oil, red meat and added sugar consumption) was inconsistent across the factor score quintiles. During the years of 1980 and 1997, for every additional kilogram of palm oil consumed per-capita annually, CHD mortality risk was 68 deaths per 100,000 (95% CI = 21-115) in developing countries and 17 deaths per 100,000 (95%CI = 5.3-29) in high-income countries, whereas stroke was associated with 19 deaths per 100,000 (95%CI = -12-49) and 5.1 deaths per 100,000 (95% CI: -1.2-11) respectively. The evidence for the outcomes of this review were all graded as very low. The findings of this review should be interpreted with some caution, owing to the lack of a pooled effect estimate of the association, significant bias in selection criteria and confounding factors, inclusion of other food items together with palm oil, and the possible out-dated trend in the ecological study. CONCLUSION In view of the abundance of palm oil in the market, quantifying its true association with CVD outcomes is challenging. The present review could not establish strong evidence for or against palm oil consumption relating to cardiovascular disease risk and cardiovascular disease-specific mortality. Further studies are needed to establish the association of palm oil with CVD. A healthy overall diet should still be prioritised for good cardiometabolic health.
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Magnesium and Human Health: Perspectives and Research Directions.
Al Alawi, AM, Majoni, SW, Falhammar, H
International journal of endocrinology. 2018;2018:9041694
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Magnesium is the fourth most abundant positively charged molecule in the human body and is involved as a co-factor in over 300 enzymatic reactions. Magnesium deficiency is commonly seen in clinic settings and intensive care units and is associated with an increased risk of mortality and length of hospital stay. Magnesium deficiency is also associated with a wide range of chronic diseases and is a known side-effect of some commonly used medications, such as proton pump inhibitors. This review study brings together the latest findings in the scientific literature on magnesium. The authors conclude from the literature that magnesium can play a therapeutic and preventative role in conditions such as diabetes mellitus, osteoporosis, asthma, migraine and cardiovascular disease.
Abstract
Magnesium is the fourth most abundant cation in the body. It has several functions in the human body including its role as a cofactor for more than 300 enzymatic reactions. Several studies have shown that hypomagnesemia is a common electrolyte derangement in clinical setting especially in patients admitted to intensive care unit where it has been found to be associated with increase mortality and hospital stay. Hypomagnesemia can be caused by a wide range of inherited and acquired diseases. It can also be a side effect of several medications. Many studies have reported that reduced levels of magnesium are associated with a wide range of chronic diseases. Magnesium can play important therapeutic and preventive role in several conditions such as diabetes, osteoporosis, bronchial asthma, preeclampsia, migraine, and cardiovascular diseases. This review is aimed at comprehensively collating the current available published evidence and clinical correlates of magnesium disorders.
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Microbiome-Gut-Brain Axis and Toll-Like Receptors in Parkinson's Disease.
Caputi, V, Giron, MC
International journal of molecular sciences. 2018;19(6)
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Parkinson’s disease (PD) is a progressively debilitating neurodegenerative disease and recently the role of the microbiota-gut-brain axis has gained attention in patients with PD. Research shows that an altered gut microbiota can activate Toll-like receptors (TLRs), receptors involved in the innate immune response, causing an inflammatory cascade in the gut and brain. Based on this knowledge, gut microbiota and TLRs may be potential therapeutic targets for PD. This review sheds light on the current knowledge regarding the association between the microbiota-gut-brain axis and innate immunity via TLR signalling in PD. Increased understanding of this relationship should lead to insights on the pathophysiology of PD, as well as improved dietary and pharmaceutical therapeutic approaches in PD patients. Based on the existing evidence, the authors conclude that through modulating the gut, thus balancing the immune response in PD patients, it may be possible to influence early phases of the neurodegenerative cascade.
Abstract
Parkinson’s disease (PD) is a progressively debilitating neurodegenerative disease characterized by α-synucleinopathy, which involves all districts of the brain-gut axis, including the central, autonomic and enteric nervous systems. The highly bidirectional communication between the brain and the gut is markedly influenced by the microbiome through integrated immunological, neuroendocrine and neurological processes. The gut microbiota and its relevant metabolites interact with the host via a series of biochemical and functional inputs, thereby affecting host homeostasis and health. Indeed, a dysregulated microbiota-gut-brain axis in PD might lie at the basis of gastrointestinal dysfunctions which predominantly emerge many years prior to the diagnosis, corroborating the theory that the pathological process is spread from the gut to the brain. Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing conserved motifs primarily found in microorganisms and a dysregulation in their signaling may be implicated in α-synucleinopathy, such as PD. An overstimulation of the innate immune system due to gut dysbiosis and/or small intestinal bacterial overgrowth, together with higher intestinal barrier permeability, may provoke local and systemic inflammation as well as enteric neuroglial activation, ultimately triggering the development of alpha-synuclein pathology. In this review, we provide the current knowledge regarding the relationship between the microbiota-gut⁻brain axis and TLRs in PD. A better understanding of the dialogue sustained by the microbiota-gut-brain axis and innate immunity via TLR signaling should bring interesting insights in the pathophysiology of PD and provide novel dietary and/or therapeutic measures aimed at shaping the gut microbiota composition, improving the intestinal epithelial barrier function and balancing the innate immune response in PD patients, in order to influence the early phases of the following neurodegenerative cascade.