Diet and the Microbiome

Psychological, behavioural and biological factors associated with gastrointestinal symptoms in autistic adults and adults with autistic traits

LAY ABSTRACT

Little is known about factors related to the increased risk for gastrointestinal symptoms in adults with an autism spectrum disorder (ASD), while the negative impact of gastrointestinal symptoms is evident. Especially, the relationship between gastrointestinal symptoms and psychological, behavioural, and biological risk factors in adults with ASD (traits) is unclear. Autistic peer support workers and autism-advocates also emphasised the importance of identifying risk factors, because of the high prevalence of gastrointestinal problems in people with ASD. Therefore, our study investigated which psychological, behavioural, and biological factors are associated with gastrointestinal symptoms in adults with ASD or with autistic traits. We analysed data from 31,185 adults in the Dutch Lifelines Study. Questionnaires were used to evaluate the presence of an autism spectrum disorder diagnosis, autistic traits, gastrointestinal symptoms, psychological and behavioural factors. Biological factors were examined with body measurements. We found that not only adults with ASD but also adults with higher levels of autistic traits were at increased risk for gastrointestinal symptoms. Adults with ASD who experienced psychological problems (psychiatric problems, worse perceived health, chronic stress) had a higher risk for gastrointestinal symptoms than adults with ASD without these psychological problems. Moreover, adults with higher levels of autistic traits were less physically active, which was also associated with gastrointestinal symptoms. In conclusion, our study highlights the relevance of identifying psychological problems and evaluating physical activity when trying to help adults with ASD or autistic traits and gastrointestinal symptoms. This suggests that healthcare professionals should be more aware of behavioural and psychological risk factors when evaluating gastrointestinal symptoms in adults with ASD (traits).

Questionnaire-based analysis of autism spectrum disorders and gastrointestinal symptoms in children and adolescents: a systematic review and meta-analysis

BACKGROUND

Gastrointestinal (GI) symptoms are frequently experienced by children with autism spectrum disorder (ASD), and these symptoms cause difficulties for these children and their families. However, studies of GI symptom prevalence differ significantly. This meta-analysis aimed to analyze the prevalence of GI symptoms in children with ASD.

METHODS AND FINDINGS

PubMed, Scopus, Web of Science, EMBASE were electronically searched to collect all literature on gastrointestinal symptoms of children with ASD collected through questionnaires or scales from January 2012 to May 2021. Four researchers independently scanned the literature and extracted information on general characteristics. First author name, year of publication, geographical location, type of study, sample sizes of ASD and control (if any) children, sex and average age, number of GI cases, number of GI symptoms, GI assessment tools (gastrointestinal symptoms scale), autism diagnosis methods, and other necessary data were collected and analyzed using Stata V16. The questionnaires included the Rome, 6-GSI, GIQ, GSRS, GSIQ, ADI-R, PedsQL-GI, parent-report, GI-related, and self-administered questionnaires. Compared with typically developing (TD) children, the odds ratio for In children with ASD with at least one GI symptom was 3.64, and the total prevalence was 55%. The cumulative prevalence rates of various symptoms were summarized, showing that 37% of children with ASD had constipation, 21% had abdominal pain, 19% had diarrhea, 8% had vomiting, and 23% had abdominal distension.

CONCLUSIONS

The results of this meta-analysis on GI symptoms in ASD show that patients with ASD are more likely to develop symptoms than TD children. The prevalence of GI symptoms in In children with ASD was 55%.

SYSTEMATIC REVIEW REGISTRATION

www.crd.york.ac.uk/PROSPERO, identifier, #CRD42017080579.

Effects of exercise and physical activity on gut microbiota composition and function in older adults: a systematic review

BACKGROUND

The characterization and research around the gut microbiome in older people emphasize microbial populations change considerably by losing the diversity of species. Then, this review aims to determine if there is any effect on the gut microbiota of adults older than 65 that starts an exercise intervention or improves physical activity level. Also, this review describes the changes in composition, diversity, and function of the gut microbiota of older subjects that had improved their physical activity level.

METHODS

The type of studies included in this review were studies describing human gut microbiota responses to any exercise stimulus; cross-sectional studies focused on comparing gut microbiota in older adults with different physical activity levels-from athletes to inactive individuals; studies containing older people (women and men), and studies written in English. This review's primary outcomes of interest were gut microbiota abundance and diversity.

RESULTS

Twelve cross-sectional studies and three randomized controlled trials were examined. Independently of the type of study, diversity metrics from Alpha and Beta diversity remained without changes in almost all the studies. Likewise, cross-sectional studies do not reflect significant changes in gut microbiota diversity; no significant differences were detected among diverse groups in the relative abundances of the major phyla or alpha diversity measures. Otherwise, relative abundance analysis showed a significant change in older adults who conducted an exercise program for five weeks or more at the genus level.

CONCLUSIONS

Here, we did not identify significant shifts in diversity metrics; only one study reported a significant difference in Alpha diversity from overweight people with higher physical activity levels. The abundance of some bacteria is higher in aged people, after an exercise program, or in comparison with control groups, especially at the genus and species levels. There needs to be more information related to function and metabolic pathways that can be crucial to understand the effect of exercise and physical activity in older adults.

TRIAL REGISTRATION

PROSPERO ID: CRD42022331551.

Altered serum bile acid profile in fibromyalgia is associated with specific gut microbiome changes and symptom severity

ABSTRACT

Alterations in the composition and function of the gut microbiome in women with fibromyalgia have recently been demonstrated, including changes in the relative abundance of certain bile acid-metabolizing bacteria. Bile acids can affect multiple physiological processes, including visceral pain, but have yet to be explored for association to the fibromyalgia gut microbiome. In this study, 16S rRNA sequencing and targeted metabolomic approaches were used to characterize the gut microbiome and circulating bile acids in a cohort of 42 women with fibromyalgia and 42 healthy controls. Alterations in the relative abundance of several bacterial species known to metabolize bile acids were observed in women with fibromyalgia, accompanied by significant alterations in the serum concentration of secondary bile acids, including a marked depletion of α-muricholic acid. Statistical learning algorithms could accurately detect individuals with fibromyalgia using the concentration of these serum bile acids. Serum α-muricholic acid was highly correlated with symptom severity, including pain intensity and fatigue. Taken together, these findings suggest serum bile acid alterations are implicated in nociplastic pain. The changes observed in the composition of the gut microbiota and the concentration of circulating secondary bile acids seem congruent with the phenotype of increased nociception and are quantitatively correlated with symptom severity. This is a first demonstration of circulating bile acid alteration in individuals with fibromyalgia, potentially secondary to upstream gut microbiome alterations. If corroborated in independent studies, these observations may allow for the development of molecular diagnostic aids for fibromyalgia as well as mechanistic insights into the syndrome.

Dietary Intake Is Unlikely to Explain Symptom Severity and Syndrome-Specific Microbiome Alterations in a Cohort of Women with Fibromyalgia

BACKGROUND

Significant alterations were recently identified in the composition and putative function of the gut microbiome in women with fibromyalgia. As diet can influence the composition of the gut microbiome, differences in nutritional intake could, in theory, account for some of these specific fibromyalgia microbiome alterations. The current study aims to compare the diet of women with fibromyalgia to that of controls in order to explore possible associations between the intake of certain nutrients, symptom severity and gut microbiome composition.

METHODS

The study population was comprised of 56 women with fibromyalgia and 68 controls. Dietary intake was assessed using the NIH Automated Self-Administered 24 h recall, following dietitian's instructions and the completion of a three-day dietary recall. The gut microbiome was assessed by 16S ribosomal RNA gene sequencing of stool samples.

RESULTS

Most demographic and anthropometric characteristics were comparable between groups. The average energy and macronutrient intake (total and relative) and overall diet quality score were not different between patients and controls, nor were the main vitamins, minerals, fatty acids, alcohol, caffeine, sugar or fiber intakes. The daily intake of micronutrients and normalized macronutrients in women with fibromyalgia was largely not correlated with disease-specific measures, including pain intensity, fatigue, cognitive symptoms and quality of sleep, or with the relative quantity of almost any of the gut microbiome bacterial taxa differentially abundant in fibromyalgia.

CONCLUSION

These data demonstrate that dietary intakes, as evaluated by self-reported questionnaires, probably cannot explain the syndrome-specific differences in gut microbiome or the clinical phenotype of fibromyalgia.

Gastrointestinal Issues and Autism Spectrum Disorder

Gastrointestinal disorders are one of the most common medical conditions that are comorbid with autism spectrum disorders. These comorbidities can cause greater severity in autism spectrum disorder symptoms, other associated clinical manifestations, and lower quality of life if left untreated. Clinicians need to understand how these gastrointestinal issues present and apply effective therapies. Effective treatment of gastrointestinal problems in autism spectrum disorder may result in marked improvements in autism spectrum disorder behavioral outcomes. This article discusses the gastrointestinal disorders commonly associated with autism spectrum disorders, how they present, and studied risk factors.

Gut Microbiome and Nonalcoholic Fatty Liver Disease (NAFLD): Implications for Nursing Care of Individuals Living With Chronic Metabolic Diseases

At present, the incidence of nonalcoholic fatty liver disease (NAFLD) in adults is increasing year by year and at a younger age. Evidence-based healthcare has confirmed that NAFLD is closely related to obesity, cardiovascular disease, type 2 diabetes, metabolic syndrome, and other chronic metabolic diseases. Despite the growing prevalence of NAFLD, little is known about symptoms for patients at risk of NAFLD progression, thus preventing healthcare providers from intervening at an early stage. In addition, these symptoms usually cause problems for patients to cope with other chronic metabolic diseases. Symptoms may have a biological basis; especially as the changes of gut microbes may affect the symptoms of metabolic diseases. This article aims to describe the new role of gut microbes in the development of NAFLD, focusing on the potential relationship between gut microbes and symptoms of NAFLD, as well as the mechanism of action of the "gut-liver-brain" axis. This information can be useful in developing precise nursing interventions for NAFLD patients, restoring the "health" of gut microbes, and alleviating the symptom burden of chronic metabolic disease in NAFLD.

The effect of different dietary structure on gastrointestinal dysfunction in children with cerebral palsy and epilepsy based on gut microbiota

BACKGROUND

Gastrointestinal (GI) difficulties are very common among children with cerebral palsy (CP) and comorbid epilepsy. GI function is influenced by dietary structure on gut microbiota. The aim of this study was to compare gut microbiota differences in two dietary groups of this population and examine whether such differences are related to GI dysfunction.

METHODS

Forty children with CP and epilepsy were recruited from a social welfare center, including 23 consuming a fluid diet (liquid diet group) and 17 consuming a normal diet (general diet group). Bacterial DNA was extracted from feces, the V3-V4 region of the 16S rRNA gene was amplified from the DNA, and high-throughput sequencing of the amplified sequences was performed. Microbe prevalence levels were compared on multiple phylogenic levels.

RESULTS

Gut microbial populations differed substantially between the liquid diet group and general diet group. The only two phyla that differed significantly between the two groups were Bacteroidetes (p = 0.034) and Actinobacteria (p = 0.013). Regarding representation of genera, Prevotella species were selectively predominant in the general diet group (25.849% vs. 3.612% in the liquid diet group, p < 0.001), while Bifidobacterium species were selectively predominant in the liquid diet group (24.929% vs. 12.947% in the general diet group, p = 0.013). The gut microbiota of children in the general diet group contained more butyric acid-producing microbiota which was also common in healthy people (e.g. Lachnoclostridium, Dorea, Ruminococcus, Faecalibacterium, Roseburia, and Coprococcus). The gut microbiota of children in liquid diet group however, were rich in symbiotic pathogenic bacteria (e.g. Collinsella, Alistipes, and Eggerthella).

CONCLUSION

The gut microbiota of children with CP and epilepsy consuming a liquid diet had elevated levels of symbiotic pathogens and diminished intestinal barrier protection bacteria, relative to a general diet group. These differences in bacterial microbiota were associated with GI dysfunction symptoms.

Gastrointestinal issues and Autism Spectrum Disorder

Gastrointestinal disorders are one of the most common medical conditions that are comorbid with autism spectrum disorders. These comorbidities can cause greater severity in autism spectrum disorder symptoms, other associated clinical manifestations, and lower quality of life if left untreated. Clinicians need to understand how these gastrointestinal issues present and apply effective therapies. Effective treatment of gastrointestinal problems in autism spectrum disorder may result in marked improvements in autism spectrum disorder behavioral outcomes. This article discusses the gastrointestinal disorders commonly associated with autism spectrum disorders, how they present, and studied risk factors.

Growth velocity in children with Environmental Enteric Dysfunction is associated with specific bacterial and viral taxa of the gastrointestinal tract in Malawian children

Environmental enteric dysfunction (EED) is characterized by diffuse villous atrophy of the small bowel. EED is strongly associated with stunting, a major public health problem linked to increased childhood morbidity and mortality. EED and subsequent stunting of linear growth are surmised to have microbial origins. To interrogate this relationship, we defined the comprehensive virome (eukaryotic virus and bacteriophage) and bacterial microbiome of a longitudinal cohort of rural Malawian children with extensive metadata and intestinal permeability testing at each time point. We found thirty bacterial taxa differentially associated with linear growth. We detected many eukaryotic viruses. Neither the total number of eukaryotic families nor a specific viral family was statistically associated with improved linear growth. We identified 3 differentially abundant bacteriophage among growth velocities. Interestingly, there was a positive correlation between bacteria and bacteriophage richness in children with subsequent adequate/moderate growth which children with subsequent poor growth lacked. This suggests that a disruption in the equilibrium between bacteria and bacteriophage communities might be associated with subsequent poor growth. Future studies of EED and stunting should include the evaluation of viral communities in addition to bacterial microbiota to understand the complete microbial ecology of these poorly understood entities.

Effects of Earthworms on the Microbiomes and Antibiotic Resistomes of Detritus Fauna and Phyllospheres

Our understanding of the influences of animals on microbial communities and antibiotic resistance genes (ARGs) throughout the food web is limited, particularly in the soil ecosystem. We performed a microcosm experiment using the combination of 16S rRNA gene high-throughput sequencing and high-throughput qPCR to study the effects of earthworms on the microbiomes and resistomes of the phyllospheres and soil detritus fauna. A full factorial design was employed in this study, including two earthworm treatments (control and earthworm addition) and two soil treatments (control and manure amendment). Earthworms changed the bacterial composition of the soil detritus fauna and the phyllosphere by modifying the shared habitat. Earthworms also reduced the number and abundance of ARGs in the soil fauna and phyllosphere microbiomes by changing their microbial communities, suggesting that earthworms may be able to provide a sustainable and natural solution to address the ARG crisis in the soil ecosystem. This study provides a new understanding on the effects of soil animals on microbial communities, driving shifts in the resistome of other animals and the phyllosphere, by altering the shared soil habitat.

Tea Compounds and the Gut Microbiome: Findings from Trials and Mechanistic Studies

In recent years, the gut microbiome has become a focal point of interest with growing recognition that a well-balanced gut microbiota composition is highly relevant to an individual’s health status and well-being. Its profile can be modulated by a number of dietary factors, although few publications have focused on the effects of what we drink. The present review performed a systematic review of trials and mechanistic studies examining the effects of tea consumption, its associated compounds and their effects on the gut microbiome. Registered articles were searched up to 10th September 2019, in the PubMed and Cochrane library databases along with references of original articles. Human trials were graded using the Jadad scale to assess quality. Altogether 24 publications were included in the main review—six were human trials and 18 mechanistic studies. Of these, the largest body of evidence related to green tea with up to 1000 mL daily (4–5 cups) reported to increase proportions of Bifidobacterium. Mechanistic studies also show promise suggesting that black, oolong, Pu-erh and Fuzhuan teas (microbially fermented ‘dark tea’) can modulate microbial diversity and the ratio of Firmicutes to Bacteroidetes. These findings appear to support the hypothesis that tea ingestion could favourably regulate the profile of the gut microbiome and help to offset dysbiosis triggered by obesity or high-fat diets. Further well-designed human trials are now required to build on provisional findings.

Unraveling the Molecular Mechanism of Traditional Chinese Medicine: Formulas Against Acute Airway Viral Infections as Examples

Herbal medicine, including traditional Chinese medicine (TCM), is widely used worldwide. Herbs and TCM formulas contain numerous active molecules. Basically, they are a kind of cocktail therapy. Herb-drug, herb-food, herb-herb, herb-microbiome, and herb-disease interactions are complex. There is potential for both benefit and harm, so only after understanding more of their mechanisms and clinical effects can herbal medicine and TCM be helpful to users. Many pharmacologic studies have been performed to unravel the molecular mechanisms; however, basic and clinical studies of good validity are still not enough to translate experimental results into clinical understanding and to provide tough evidence for better use of herbal medicines. There are still issues regarding the conflicting pharmacologic effects, pharmacokinetics, drug interactions, adverse and clinical effects of herbal medicine and TCM. Understanding study validation, pharmacologic effects, drug interactions, indications and clinical effects, adverse effects and limitations, can all help clinicians in providing adequate suggestions to patients. At present, it would be better to use herbs and TCM formulas according to their traditional indications matching the disease pathophysiology and their molecular mechanisms. To unravel the molecular mechanisms and understand the benefits and harms of herbal medicine and TCM, there is still much work to be done.

Trophic Transfer of Antibiotic Resistance Genes in a Soil Detritus Food Chain

The presence and spread of antibiotic resistance genes (ARGs) are causing substantial global public concern; however, the dispersal of ARGs in the food chain is poorly understood. Here, we experimented with a soil collembolan ( Folsomia candida)-predatory mite ( Hypoaspis aculeifer) model food chain to study trophic transfer of ARGs in a manure-contaminated soil ecosystem. Our results showed that manure amendment of soil could significantly increase ARGs in the soil collembolan microbiome. With the ARGs in the prey collembolan microbiome increasing, an increase in ARGs in the predatory mite microbiome was also observed, especially for three high abundant ARGs ( blaSHV, fosX and aph6ia). Three unique ARGs were transferred into the microbiome of the predatory mite from manure amended soil via the prey collembolan ( aac(6' )-lb(akaaacA4), yidY_mdtL and tolC). Manure amendment altered the composition and structure and reduced the diversity of the microbiomes of the prey collembolan and the predatory mite. We further reveal that bacterial communities and mobile genetic elements were two important drivers for the trophic transfer of ARGs, not just for ARGs distribution in the samples. These findings suggest that the importance of food chain transmission of ARGs for the dispersal of resistance genes in soil ecosystems may be underestimated.

The role of inflammation in temporal shifts in the inflammatory bowel disease mucosal microbiome

Studies of the human intestinal microbiome in patients with inflammatory bowel disease (IBD) consistently show that there are differences (an abnormal or unbalanced microbiome, "dysbiosis") when compared to healthy subjects. We sought to describe changes in the microbiome in individual patients over time, and determine the clinical factors that are associated with significant alteration. Forty-two mucosal biopsies were collected from 20 patients that were spaced an average of 2.4 years apart. These were analysed using bacterial 16S rRNA gene high-throughput sequencing methods. Presence of active inflammation was determined endoscopically and histologically. Inferred metagenomics analysis was conducted using the PICRUSt package. We found that the differences in the microbiome over time in individual patients were greatest in the presence of ongoing intestinal inflammation, as determined by the Yue and Clayton theta distance between sample pairs (adjusted p = 0.00031). Samples from patients with previous abdominal surgery had lower alpha (within sample) diversity compared with those with no prior operations (mean Shannon index 2.083, 2.510 respectively, p = 0.017). There were no changes in the inferred bacterial metagenomic profile. The microbiome in IBD undergoes considerable fluctuation over time. These changes are greatest when there is histologically confirmed inflammation at both time-points.

Dietary Polysaccharides in the Amelioration of Gut Microbiome Dysbiosis and Metabolic Diseases

The prevalence of metabolic diseases including obesity, diabetes, cardiovascular diseases, hypertension and cancer has evolved into a global epidemic over the last century. The rate of these disorders is continuously rising due to the lack of effective preventative and therapeutic strategies. This warrants for the development of novel strategies that could help in the prevention, treatment and/ or better management of such disorders. Although the complex pathophysiology of these metabolic diseases is one of the major hurdles in the development of preventive and/or therapeutic strategies, there are some factors that are or can speculated to be more effective to target than others. Recently, gut microbiome has emerged as one of the major contributing factors in metabolic diseases, and developing positive modulators of gut microbiota is being considered to be of significant interest. Natural non-digestible polysaccharides from plants and food sources are considered potent modulators of gut microbiome that can feed certain beneficial microbes in the gut. This has led to an increased interest in the isolation of novel bioactive polysaccharides from different plants and food sources and their application as functional components to modulate the gut microbiome composition to improve host's health including metabolism. Therefore, polysaccharides, as prebiotics components, are being speculated to confer positive effects in managing metabolic diseases like obesity and diabetes. In this review article, we summarize some of the most common polysaccharides from plants and food that impact metabolic health and discuss why and how these could be helpful in preventing or ameliorating metabolic diseases such as obesity, type 2 diabetes, hypertension and dyslipidemia.

Introduction to the special focus issue on the impact of diet on gut microbiota composition and function and future opportunities for nutritional modulation of the gut microbiome to improve human health

Over the past decade, application of culture-independent, next generation DNA sequencing has dramatically enhanced our understanding of the composition of the gut microbiome and its association with human states of health and disease. Host genetics, age, and environmental factors such as where and who you live with, use of pre-, pro- and antibiotics, exercise and diet influence the short- and long-term composition of the microbiome. Dietary intake is a key determinant of microbiome composition and diversity and studies to date have linked long-term dietary patterns as well as short-term dietary interventions to the composition and diversity of the gut microbiome. The goal of this special focus issue was to review the role of diet in regulating the composition and function of the gut microbiota across the lifespan, from pregnancy to old age. Overall dietary patterns, as well as perturbations such as undernutrition and obesity, as well as the effects of dietary fiber/prebiotics and fat composition are explored.