4 Bacteria Strains Plus FOS Normalize Microbiome, GI Function, Neurotransmitters & Behaviors in Children
A new study1 confirms differences in gut microbiome composition between autistic children and typically developing children, and has reported improvement in autism symptomatology with a probiotic/prebiotic treatment. Improvements were seen in gut microbiome diversity, metabolites and function, as well as autism behaviors and neurotransmitters.
The microbiome and brain have ongoing bidirectional communications, and each affects the other’s health and function. Many individuals with autism spectrum disorder (ASD) have dysbiosis2, or a persistent imbalance of the gut’s microbial community, with resulting leaky gut and alterations in metabolites such as short chain fatty acids (SCFAs) that impact brain function and behavior. Probiotics and prebiotics may help to normalize gut microbiota and act via the gut-brain axis to influence neurotransmission and psychological conditions.
Probiotics3 are live organisms, usually bacteria, that confer health benefits, particularly to the gut. Prebiotics4 are specialized plant fibers that stimulate the growth of healthy bacteria in the gut. This study utilized a mixture of four probiotic strains – Bifidobacterium infantis Bi-26, Lactobacillus rhamnosus HN001, Bifidobacterium lactis BL-04, and Lactobacillus paracasei LPC-37 – at a dose of 1010 CFUs per day. Fructo-oligosaccharides (FOS), a prebiotic5, was added to the probiotics to stimulate their growth in the colon.
Method
The study was conducted in two phases. Phase 1 enrolled 26 children with ASD and 24 typically-developing children in the control group, all ages 3-9. It compared the gut microbiota profiles, SCFAs and neurotransmitters between the autism and control groups. To control for dietary effects on the microbiome, both groups ate the same food for the duration of the study.
In the second phase, the 26 autistic children from phase 1 were randomized into two groups: the probiotic + FOS group (n = 16) and a placebo group (n = 10) given inactive capsules. This stage compared the two groups on autism behaviors using the Autism Treatment Evaluation Checklist (ATEC), a gastrointestinal function questionnaire (6-GI Severity Index for constipation, diarrhea, average stool consistency, odor, flatulence and abdominal pain), and gut microbiota compositions, SCFAs and neurotransmitters using stool and blood samples. The children were followed up to 108 days after the start of treatment. Several children dropped out of the study over the 180 day period.
Results
Microbiome Composition. The study found that, prior to taking the probiotic/prebiotic, the microbiota of children with autism were significantly distinct from that of the typical children in the control group. As seen in Figure 1, beneficial bacteria such as Bifidobacteriaceae and B. longum were decreased. Potentially pathogenic bacteria such as Clostridium and Ruminococcus, some linked to autism symptomatology, were increased. These observations are consistent with previously published work on gut microbiota in children with ASD.
After getting the treatment, the profile of the gut bacteria in the autistic group became more like that of the typical children, with beneficial strains increased and harmful strains decreased.
Figure 1. Autism Profiles Compared to Typical Children
| Measure | Increased in ASD | Decreased in ASD | No Difference between ASD & Typical Children |
| Bacteria | Rikenellaceae, Ruminococcus, Osillospira, Odoribacter, Cetobacterium, Victivallales, Clostridium | Actinobacteria, Bifidobacterium, Bifidobacteriales, Bifidobacteriaceae, Veillonellaceae, B. adolescentis, B. longum | |
| SCFAs | acetic, butyric and propionic acid | isobutyric acid, valeric acid, isovaleric acid and caproic acid | |
| Neurotransmitters | 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid, L-glutamine, L-arginine, L-histidine and L-histamine | kynurenine and HVA | L-tyrosine, L-dopa, vanillylmandelic acid, L- glutamic acid, acetylcholine, and GABA |
SCFAs. Metabolites produced by gut microbiota which are altered in autism include the SCFAs butyrate, propionate and acetate. Butyrate is involved in energy production, is an anti-inflammatory, and regulates blood-brain barrier (BBB) and gut permeability. In an autism animal model, injections of propionic acid resulted in autistic-like behaviors such as repetitive behavior and object preference. Acetate, and to a lesser extent butyrate and propionate, increase blood flow in the colon, helping with muscle contraction, tissue oxygenation and nutrient supply. SCFAs can reduce the pH of the gut, increasing growth of beneficial bacteria and suppressing the growth of pathogens.
SCFAs cross the BBB and influence early brain development by modulating production of the neurotransmitters serotonin and dopamine. Almost all serotonin (90%) is produced in the gastrointestinal tract.
Prior to treatment, autistic children in the study harbored different levels of SCFAs compared with children in the control group (see Figure 1). The levels of acetic, butyric and propionic acid were significantly lower in the ASD group compared with that in the control group. No significant differences were found in the levels of isobutyric acid, valeric acid, isovaleric acid and caproic acid.
With the probiotic/prebiotic treatment, the levels of acetic, butyric and propionic acid approached those of the control group.
Neurotransmitters. The levels of some neurotransmitters or their metabolites in the plasma of children with ASD differed from those of the typical group prior to treatment (see Figure 1), consistent with other research on autism and indicative of a hyperserotonergic state and lowered dopaminergic activity. Beneficial bacteria have been found to produce a range of major neurotransmitters.
With the probiotic/prebiotic treatment, the concentration levels of L-tryptophan, kynurenine, L-tyrosine, homovanillic acid and vanillylmandelic acid significantly increased in the children with ASD, while there was a significant reduction of 5-hydroxyindoleacetic acid and serotonin (5-HT) levels with the treatment. Values approached those observed in the typical control group.
The treatment failed to modulate other neurotransmitters and metabolites, including glutamic acid, glutamine, acetylcholine, GABA, arginine, histidine and histamine.
Behaviors. Probiotic + FOS intervention improved the symptoms in children with ASD compared to the ASD group which did not receive the treatment, based on ATEC scores. It took several months of treatment for the changes to be significant. Specific improvement was seen in the speech/language/communication and sociability categories of the ATEC.
GI Symptoms and Leaky Gut. Zonulin6 is a protein released by the gut mucosa that regulates the gut and blood-brain barriers, and is a biomarker of human intestinal barrier permeability. Certain bacteria and gluten can trigger release of zonulin.7 The zonulin level was significantly higher in the ASD group than the control group before probiotics + FOS intervention, suggesting increased intestinal and BBB permeability in the ASD group.
After probiotics + FOS intervention, the plasma zonulin levels decreased in the ASD group and approached levels similar to the control group suggesting a positive effect on ameliorating leaky gut. There was significant improvement observed in the gastrointestinal symptoms of constipation, diarrhea and stool smell after the probiotic/FOS treatment.
Improvements Increase with Time. Interestingly, the improvement effects were more significant the longer the treatment was given. Changes at 108 days follow up were greater than at 60 or 30 days of treatment. Children with ASD in the placebo group did not exhibit improvement over time on any of the measures.
No adverse effects were reported in this study.
Helpful Resources
Want to learn more about the microbiome? A podcast from Technology Networks gives the basics to get you started.
Want to learn more about FOS? This website has helpful information, including a summary of the side effects of FOS which should be considered before trying, as well as discussing any treatment with a healthcare provider.
References
1 Ying Wang, Ning Li, Jun-Jie Yang, Dong-Mei Zhao, Bin Chen, Guo-Qing Zhang, Shuo Chen, Rui-Fang Cao, Han Yu, Chang-Ying Zhao, Lu Zhao, Yong-Sheng Ge, Yi Liu, Le-Hai Zhang, Wei Hu, Lei Zhang, Zhong-Tao Gai. Probiotics and fructo-oligosaccharide intervention modulate the microbiota-gut brain axis to improve autism spectrum reducing also the hyper-serotonergic state and the dopamine metabolism disorder. Pharmacological Research. Available online 17 April 2020, 104784.
2 Belizário JE, Faintuch J. Microbiome and Gut Dysbiosis. Exp Suppl. 2018;109:459–476. doi:10.1007/978-3-319-74932-7_13
3 National Institutes of Health Office of Dietary Supplements. Probiotics Fact Sheet for Health Professionals.
4 mayoclinic.org/prebiotics-probiotics-and-your-health/art-20390058
5 Sabater-Molina M, Larqué E, Torrella F, Zamora S. Dietary fructooligosaccharides and potential benefits on health. J Physiol Biochem. 2009;65(3):315‐328. doi:10.1007/BF03180584.
6 Rahman MT, Ghosh C, Hossain M, et al. IFN-γ, IL-17A, or zonulin rapidly increase the permeability of the blood-brain and small intestinal epithelial barriers: Relevance for neuro-inflammatory diseases. Biochem Biophys Res Commun. 2018;507(1-4):274–279.
7 Fasano A. Intestinal permeability and its regulation by zonulin: diagnostic and therapeutic implications. Clin Gastroenterol Hepatol. 2012;10(10):1096–1100. doi:10.1016/j.cgh.2012.08.012.
