Psychobiotics in pediatric autism spectrum disorder: A systematic review of efficacy, mechanisms, and clinical translation

Table 9 Synbiotic strains, prebiotic components, dose, treatment duration, and reported outcomes in autism spectrum disorder studies

Ref.	Probiotic strain(s)	Prebiotic component	Dose	Treatment duration	Microbiome outcomes	Clinical outcomes
Sanctuary et al[21]	Bifidobacterium longum subsp. infantis	Bovine colostrum product containing oligosaccharides	0.15 g/Lb body weight/day + FOS	5 weeks synbiotic phase (within 12-week crossover design)	Changes in gut microbial composition; modulation of immune markers, including decreased IL-13 and TNF-α	Reduction in gastrointestinal symptoms and modest improvements in aberrant behavior scores in some participants. Symbiotics
Wang et al[20]	Multi-strain probiotic mixture (including Bifidobacterium longum)	FOS	1010 CFU/pack/day	30, 60, 108 days	Increased abundance of beneficial bacteria (Bifidobacterium longum); increased SCFAs	Significant reduction in autism severity scores and gastrointestinal symptoms; normalization of serotonin and dopamine metabolites. Symbiotics
Schmitt et al[29]	Limosilactobacillus reuteri (SB-121 formulation)	Dextran microparticles with maltose carrier	2 × 1010 CFU of Limosilactobacillus reuteri, + 200 mg Sephadex, + 74 mmol/L of maltose in a final volume of 10.8 mL	28-day treatment periods (crossover design)	Designed to enhance bacterial adherence and colonization	Significant improvement in Vineland-3 Adaptive Behavior Composite score; improved social preference trends; treatment well tolerated
Phan et al[42]	Multi-strain probiotic formulation	Precision synbiotic formulation (specific prebiotic composition not specified)	Personalized	3 months	Increased microbial diversity; restoration of beneficial taxa such as Faecalibacterium and Prevotella; reduction of pathogenic taxa including Shigella and Klebsiella	Improvements in gastrointestinal discomfort and ASD-related symptoms including language, cognition, and communication
Mitchell et al[44]	Multi-strain probiotic blend	Prebiotic component included within the synbiotic formulation	5 g of PHGG and a probiotic mixture	12 weeks	Increased abundance of beneficial taxa including Bifidobacterium animalis and Dialister	Significant reductions in gastrointestinal symptom scores; improvements in anxiety and irritability when combined with hypnotherapy
Wong et al[43]	Synbiotic formulation SCM06, including probiotic strains	Prebiotic component included in SCM06	Maltodextrin + galactooligosaccharide + 5 × 109 CFU of 4 probiotic species: Bifidobacterium bifidum, Bifidobacterium longum, Lactobacillus plantarum, and Streptococcus thermophilus	12 weeks	Increased abundance of Bifidobacterium pseudocatenulatum and increased SCFAs (butyrate and valeric acid)	Improvements in anxiety, sensory hyperresponsiveness, and abdominal pain in children with ASD

ASD: Autism spectrum disorder; CFU: Colony-forming units; FOS: Fructo-oligosaccharides; IL-13: Interleukin-13; PHGG: Partially hydrolyzed guar gum; SB-121: Investigational synbiotic formulation SB-121; SCFAs: Short-chain fatty acids; TNF-α: Tumor necrosis factor alpha.