FOOD, MICROBES, AND THE MIND: INTERVENTIONS AND TECH-FOR-HEALTH IMPLICATIONS

Microbiota is the summation of all microorganisms living in the body. The alteration in microbiota can lead to chronic diseases, however; colonization with different commensal bacteria can correct these deficits. Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by inadequate communication skills and social withdrawal and its etiology is uncertain. Typical gastrointestinal (GI) disorders symptoms are associated with ASD, in a prevalence range from 23% to 70%. The method of communication between the brain and the gut microbiota is likely the microbiota-gut-brain axis. Therefore, intervention studies have been published based on the use of prebiotics, probiotics and fecal microbiota transplantation (FMT). In this review, the possible correlation between gut microbiota and ASD is demonstrated. Additionally, how probiotics and microbial fecal microbiota transplantation (FMT) could modulate the gut microbiota and might represent a potential therapy for patients with ASD. Nearly all the GI functions postulated to be affected in ASD are improved by probiotics in animal studies. (FMT) ensures the transfer of several hundred bacterial strains, as opposed to probiotic therapy where only certain bacterial strains are supplemented. For ASD patients with dysbiosis, FMT is an interesting new therapeutic choice that could be considered.

Autism spectrum disorder (ASD) is a severe brain development disorder that is characterized by deficits in social communication and restricted, repetitive and stereotyped behaviors. Accumulating evidence has suggested that gut microbiota disorders play important roles in gastrointestinal symptoms and neurodevelopmental dysfunction in ASD patients. Manipulation of the gut microbiota by fecal microbiota transplantation (FMT) was recently shown to be a promising therapy for the treatment of various diseases. Here, we performed a clinical trial to evaluate the effect of FMT on gastrointestinal (GI) and ASD symptoms and gut microbiota alterations in children with ASD. We found that there was a large difference in baseline characteristics of behavior, GI symptoms, and gut microbiota between children with ASD and typically developing (TD) control children. FMT could improve GI symptoms and ASD symptoms without inducing any severe complications. Similarly, FMT significantly changed the serum levels of neurotransmitters. We further observed that FMT could promote the colonization of donor microbes and shift the bacterial community of children with ASD toward that of TD controls. The abundance of Eubacterium coprostanoligenes pre-FMT was positively correlated with high GSRS scores, whereas a decrease in Eubacterium coprostanoligenes abundance induced by FMT was associated with the FMT response. Our data suggest that FMT might be a promising therapeutic strategy to improve the GI and behavioral symptoms of patients with ASD, possibly due to its ability to alter gut microbiota and highlight a specific microbiota intervention that targets Eubacterium coprostanoligenes that can enhance the FMT response. This trial was registered at the Chinese Clinical Trial Registry (www.chictr.org.cn) (trial registration number ChiCTR1800014745).

Background/Objectives: Autism Spectrum Disorder (ASD) is a neurodevelopmental condition often accompanied by gastrointestinal (GI) symptoms and gut microbiota imbalances. The microbiota–gut–brain (MGB) axis is a bidirectional communication network linking gut microbes, the GI system, and the central nervous system (CNS). This narrative review explores the role of the MGB axis in ASD pathophysiology, focusing on communication pathways, neurodevelopmental implications, gut microbiota alteration, GI dysfunction, and emerging therapeutics. Methods: A narrative review methodology was employed. We searched major scientific databases including PubMed, Scopus, and Google Scholar for research on MGB axis mechanisms, gut microbiota composition in ASD, dysbiosis, leaky gut, immune activation, GI disorders, and intervention (probiotics, prebiotics, fecal microbiota transplantation (FMT), antibiotics and diet). Key findings from recent human, animal and in vitro studies were synthesized thematically, emphasizing mechanistic insights and therapeutic outcomes. Original references from the initial manuscript draft were retained and supplemented for comprehensiveness and accuracy. Results: The MGB axis involves neuroanatomical, neuroendocrine, immunological, and metabolic pathways that enable microbes to influence brain development and function. Individuals with ASD commonly exhibit gut dysbiosis characterized by reduced microbial diversity (notably lower Bifidobacterium and Firmicutes) and overpresentation of potentially pathogenic taxa (e.g., Clostridia, Desulfovibrio, Enterobacteriaceae). Dysbiosis is associated with increased intestinal permeability (“leaky gut”) and newly activated and altered microbial metabolite profiles, such as short-chain fatty acids (SCFAs) and lipopolysaccharides (LPSs). Functional gastrointestinal disorders (FGIDs) are prevalent in ASD, linking gut–brain axis dysfunction to behavioral severity. Therapeutically, probiotics and prebiotics can restore eubiosis, fortify the gut barrier, and reduce neuroinflammation, showing modest improvements in GI and behavioral symptoms. FMT and Microbiota Transfer Therapy (MTT) have yielded promising results in open label trials, improving GI function and some ASD behaviors. Antibiotic interventions (e.g., vancomycin) have been found to temporarily alleviate ASD symptoms associated with Clostridiales overgrowth, while nutritional strategies (high-fiber, gluten-free, or ketogenic diets) may modulate the microbiome and influence outcomes. Conclusions: Accumulating evidence implicates the MGB axis in ASD pathogenesis. Gut microbiota dysbiosis and the related GI pathology may exacerbate neurodevelopmental and behavioral symptoms via immune, endocrine and neural routes. Interventions targeting the gut ecosystem, through diet modification, probiotics, symbiotics, or microbiota transplants, offer therapeutic promise. However, heterogeneity in findings underscores the need for rigorous, large-scale studies to clarify causal relationships and evaluate long-term efficacy and safety. Understanding MGB axis mechanisms in ASD could pave the way for novel adjunctive treatments to improve the quality of life for individuals with ASD.

Fecal Microbiota Transplantation for Ulcerative Colitis: Not Just Yet

This paper concludes that recent research on the interrelationship between gut microbiota and autism spectrum disorder (ASD) has gained significant attention. The study found that the composition of the gut microbiota in ASD patients is often markedly different from that of the general population, particularly in the species and abundance of beneficial bacteria, such as Bifidobacterium and Lactobacillus, which are frequently imbalanced. The imbalance in intestinal microorganisms not only affects gut health but also disrupts the neurological functions mediated by the gut-brain axis, exacerbating the behavioral and cognitive symptoms associated with ASD. In recent years, microbial interventions, including probiotics, prebiotics, and fecal microbiota transplantation (FMT), have shown some promise. The use of probiotics and prebiotics can increase the proportion of beneficial flora in the gut of patients with ASD, helping to produce anti-inflammatory short-chain fatty acids, thereby improving neurological symptoms. Additionally, FMT, which involves transplanting gut microbes from healthy individuals into ASD patients, has demonstrated significant improvements in both gut and behavioral symptoms in several studies. However, due to the high individual variability among ASD patients, a single microbial intervention is not consistently effective across all individuals. Some patients respond well to probiotics or FMT, whereas others show limited symptom improvement. This variability may be attributed to each patient's unique microbiota composition, immune status, and metabolic profile. Therefore, further research is needed to identify biomarkers that can predict the effectiveness of microbial interventions, thereby enabling more precise and individualised therapies. This review aims to provide guidance for future research and to offer a theoretical foundation and data support for exploring microbial modulation as a potential treatment for ASD.

BackgroundAlterations in both oral and gut microbiota have been identified in children with autism spectrum disorder (ASD), but the interaction between these microbiota and their potential to predict outcomes of fecal microbiota transplantation (FMT) remain poorly understood.MethodsThis study investigated the structure and function of the tongue-coating microbiota in children with ASD and explored its correlation with ASD symptoms and gut microbiota. Germ-free ASD mice, colonized with healthy gut microbiota, and children with ASD treated with washed microbiota transplantation (WMT) were assessed for changes in autism symptoms and microbiota composition. Predictive models were also developed based on pre-treatment tongue-coating microbiota and clinical features to forecast WMT outcomes.ResultsSignificant alterations were detected in the tongue-coating microbiota of children with ASD, with several bacterial species showing associations with ASD symptoms and gut microbiota composition. Following WMT, both mice and children exhibited substantial improvements in autism-related behaviors, alongside marked shifts in their gut and tongue-coating microbiota. A significant decrease in Haemophilus in the tongue-coating microbiota, which positively correlated with ASD severity, was observed. Additionally, a reduction in chemoheterotrophic and fermentation functions in the tongue-coating microbiota was identified. Predictive models utilizing pre-treatment tongue-coating microbiota and clinical data demonstrated comparable accuracy to those based on gut microbiota for forecasting WMT outcomes.ConclusionsThese findings highlight a significant interaction between gut and tongue-coating microbiota in ASD, which may play a pivotal role in treatment outcomes. Predictive models integrating pre-treatment microbiota and clinical features could improve precision treatment strategies for children with ASD undergoing WMT.Graphical abstractSupplementary InformationThe online version contains supplementary material available at 10.1186/s12967-025-06846-z.

Autism spectrum disorder (ASD) is a group of heterogeneous neurodevelopmental disorders that is characterized by core features in social communication impairment and restricted, repetitive sensory-motor behaviors. This study aimed to further investigate the utilization of fecal microbiota transplantation (FMT) in children with ASD, both with and without gastrointestinal (GI) symptoms, evaluate the effect of FMT and analyze the alterations in bacterial and fungal composition within the gut microbiota. A total of 38 children diagnosed with ASD participated in the study and underwent oral lyophilized FMT treatment. The dosage of the FMT treatment was determined based on a ratio of 1 g of donor stool per 1 kg of recipient body weight, with a frequency of once every 4 weeks for a total of 12 weeks. In addition, 30 healthy controls (HC) were included in the analysis. The clinical efficacy of FMT was evaluated, while the composition of fecal bacteria and fungi was determined using 16S rRNA and ITS gene sequencing methods. Median age of the 38 children with ASD was 7 years. Among these children, 84.2% (32 of 38) were boys and 81.6% (31 of 38) exhibited GI symptoms, with indigestion, constipation and diarrhea being the most common symptoms. Sample collections and assessments were conducted at baseline (week 0), post-treatment (week 12) and follow-up (week 20). At the end of the follow-up phase after FMT treatment, the autism behavior checklist (ABC) scores decreased by 23% from baseline, and there was a 10% reduction in scores on the childhood autism rating scale (CARS), a 6% reduction in scores on the social responsiveness scale (SRS) and a 10% reduction in scores on the sleep disturbance scale for children (SDSC). In addition, short-term adverse events observed included vomiting and fever in 2 participants, which were self-limiting and resolved within 24 h, and no long-term adverse events were observed. Although there was no significant difference in alpha and beta diversity in children with ASD before and after FMT therapy, the FMT treatment resulted in alterations in the relative abundances of various bacterial and fungal genera in the samples of ASD patients. Comparisons between children with ASD and healthy controls (HC) revealed statistically significant differences in microbial abundance before and after FMT. Blautia, Sellimonas, Saccharomycopsis and Cystobasidium were more abundant in children with ASD than in HC, while Dorea were less abundant. After FMT treatment, levels of Blautia, Sellimonas, Saccharomycopsis and Cystobasidium decreased, while levels of Dorea increased. Moreover, the increased abundances of Fusicatenibacter, Erysipelotrichaceae_UCG-003, Saccharomyces, Rhodotorula, Cutaneotrichosporon and Zygosaccharomyces were negatively correlated with the scores of ASD core symptoms. Oral lyophilized FMT could improve GI and ASD related symptoms, as well as sleep disturbances, and alter the gut bacterial and fungal microbiota composition in children with ASD. Chinese Clinical Trial Registry, ChiCTR2200055943. Registered 28 January 2022, www.chictr.org.cn.

Background: Autism spectrum disorders (ASD) is a complex neurodevelopmental disorder that lacks an ideal animal model to recapitulate the disease state of ASD. Previous studies have reported that transplanting gut microbiota of ASD patients into pregnant mice is sufficient to promote the changes of autism-like behavior in offspring. This study aims to explore whether fecal microbiota transplantation (FMT) can be used as a new method to establish the ASD animal model.Methods: We transplanted the fecal sample extract of ASD children into pregnant rats (rFMT) repeatedly to establish an ASD rat model (oFMT) and compare it with the classical valproic acid (VPA) model (oVPA).Results: First, we reveal that oFMT shows hypoevolutism and typical behavioral characteristics of ASD, consistent with the previous study. Second, the gut microbiota of oFMT mainly consists of Firmicutes and Bacteroidetes, recapitulating the abnormal gut microbiota of ASD. In oFMT, the abundance of Lactobacillus and Collinsella increased (Lactobacillus: oFMT 60.16%, oVPA 64.13%, oCON 40.11%; Collinsella: oFMT 3.73%, oVPA 1.39%, oCON 1.28%), compared with oVPA, gut microbiota also showed high consistency. Third, the expression of 5-hydroxytryptamine (5-HT) in oFMT serum increased, γ-aminobutyric acid (GABA) and norepinephrine (NE) in oFMT serum decreased. Fourth, the gut microbiota of oFMT also has some ASD characteristic gut microbiota not found in oVPA. Fifth, pregnant rat with VPA showed significant immune activation, while those with FMT showed relatively minor immune activation.Limitations: Although the mechanism of establishing FMT autism rat model (oFMT) has not clearly defined, the data show that the model has high structural validity, and FMT model is likely to be a new and reliable potential animal model of ASD, and will have potential value in studying gut microbiota of ASD.Conclusions: The FMT autism rat model has high structural validity, and the FMT model is likely to be a new and reliable potential animal model of ASD.

Targeting the Gut Microbiota in Coronavirus Disease 2019: Hype or Hope?

IntroductionGut microbiota dysbiosis is implicated in autism spectrum disorder (ASD), yet scalable therapeutic interventions remain limited. This study investigated gut dysbiosis profiles in children with ASD and evaluated the clinical efficacy of a simplified fecal microbiota transplantation (FMT) protocol using pediatric donors.MethodsIn a cross-sectional phase, 48 children with ASD and 51 age-/sex-matched healthy controls underwent gut microbiota analysis. Subsequently, 25 ASD participants received FMT via a streamlined protocol: 3-day bowel preparation followed by 6-day transcolonoscopic microbiota infusion from pediatric donors. Clinical outcomes and microbiota shifts were assessed at 3-month follow-up.Results(1) Baseline Dysbiosis: ASD subjects exhibited reduced microbial diversity, with decreased Faecalibacterium and Bifidobacterium but elevated Megamonas and Akkermansia vs. controls. (2) Clinical Efficacy: Post-FMT, significant improvements occurred in core ASD symptoms and gastrointestinal comorbidities. (3) Microbiota Shifts: FMT recipients showed increased beneficial genera (Prevotella, Faecalibacterium, Agathobacter, Dorea) and reduced Escherichia-Shigella.DiscussionA simplified pediatric donor FMT protocol effectively modulates gut microbiota composition and alleviates both behavioral and gastrointestinal symptoms in children with ASD. This strategy demonstrates feasibility for clinical translation, highlighting microbiota-targeted therapy as a promising intervention for ASD.

Effects of gut microbial-based treatments on gut microbiota, behavioral symptoms, and gastrointestinal symptoms in children with autism spectrum disorder: A systematic review

The emerging role of a microbiota-gut-brain axis in autism spectrum disorder (ASD) suggests that modulating gut microbial composition may offer a tractable approach to addressing the lifelong challenges of ASD. The aim of this systematic review was to provide an overview and critically evaluate the current evidence on the efficacy and safety of probiotic, prebiotic, synbiotic, and fecal microbiota transplantation therapies for core and co-occurring behavioral symptoms in individuals with ASD. Comprehensive searches of MEDLINE, EMBASE, Scopus, Web of Science Core Collection, Cochrane Library, and Google Scholar were performed from inception to March 5, 2020, and two update searches were completed on October 25, 2020, and April 22, 2021, respectively. A total of 4306 publications were identified, of which 14 articles met the inclusion criteria. Data were extracted independently by two reviewers using a preconstructed form. Results of probiotic studies do not confirm the supposed beneficial effect of probiotics on ASD, whereas prebiotics and synbiotic combinations appear to be efficacious in selective behavioral symptoms. Evidence of the efficacy of fecal microbiota transplantation in ASD is still scarce but supports further research. Overall, the current evidence base to suggest beneficial effects of these modalities in ASD is limited and inconclusive. More clinical trials are currently looking at the use of microbial-based therapies in ASD. With a robust double-blind randomized controlled protocol to investigate the efficacy, these trials should provide significant and definitive results. LAY SUMMARY: There is a link between altered gut bacteria and autism spectrum disorder. Some people believe that modulating bacterial composition in the gut may help reduce autism symptoms, but evidence from human studies suggesting beneficial effects of probiotic, prebiotic, and combination thereof as well as fecal transplants in autism spectrum disorder is limited and inconclusive. Current data should not encourage use of these modalities. Further clinical studies are needed.

Autism spectrum disorder (ASD) is a complex behavioral disorder diagnosed by social interaction difficulties, restricted verbal communication, and repetitive behaviors. Fecal microbiota transplantation (FMT) is a safe and efficient strategy to adjust gut microbiota dysbiosis and improve ASD-related behavioral symptoms, but its regulatory mechanism is unknown. The impact of the microbiota and its functions on ASD development is urgently being investigated to develop new therapeutic strategies for ASD. We reconstituted the gut microbiota of a valproic acid (VPA)-induced autism mouse model through FMT and found that ASD is in part driven by specific gut dysbiosis and metabolite changes that are involved in the signaling of serotonergic synapse and glutamatergic synapse pathways, which might be associated with behavioral changes. Further analysis of the microbiota showed a profound decrease in the genera Bacteroides and Odoribacter, both of which likely contributed to the regulation of serotonergic and glutamatergic synapse metabolism in mice. The engraftment of Turicibacter and Alistipes was also positively correlated with the improvement in behavior after FMT. Our results suggested that successful transfer of the gut microbiota from healthy donors to ASD mice was sufficient to improve ASD-related behaviors. Modulation of gut dysbiosis by FMT could be an effective approach to improve ASD-related behaviors in patients.

Targeted fecal microbiota transplantation ameliorates autism-like behaviors via gut-brain axis and excitatory/inhibitory balance restoration in a propionic acid mouse model.

Fecal microbiota transplantation (FMT) is the administration of fecal bacteria from a healthy donor into the intestinal tract of a recipient in order to directly change the recipient's gut microbial composition and confer a health benefit. The relationship between the gut microbiome and the central nervous system, termed the gut-brain axis, has been a frequent topic of gut microbiome studies. Commensal gut bacteria communicate with the central nervous system through various hormones, cytokines, and neural pathways. Therefore, influencing the gut microbiome via FMT may have the potential in treating symptoms of neurodegenerative conditions. This study aims to identify current uses of FMT in treating neurodegenerative diseases and highlight areas of future investigation. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, a literature search was conducted of peer-reviewed sources on September 27, 2022, from Embase, MEDLINE, Web of Science, and Cochrane Central. Search terms were utilized that were related to the application of FMT and neurodegenerative disorders and limited those human studies, those that were published in English, and those that were published between 2017 and 2022. The initial search yielded 450 unique articles, and after the assessment of the title and abstract for inclusion and exclusion criteria, six articles were identified for full-text review. Studies that focused on either Parkinson's disease (PD) or multiple sclerosis (MS) demonstrated improvements in both motor symptoms and non-motor symptoms. FMT was also shown to provide significant relief of constipation and general gastrointestinal (GI) symptoms in all conditions studied. The studies related to MS showed the most mixed results with regard to symptomatic improvement. The data on the use of FMT as a treatment for neurodegenerative disorders is limited; however, studies have shown not only improvement in GI symptoms but also improvement in the cognitive symptoms of PD and dementia. The data on FMT as a treatment to improve the motor symptoms of PD is both more complete and more compelling than the data on the motor symptoms of MS. The studies that were reviewed showed no major adverse effects of FMT and generally promising results. There is a strong case to be made for larger, more well-controlled studies to be done on FMT and its potential use as a treatment not only for GI symptoms but for the motor and cognitive symptoms of neurodegenerative diseases.