Key studies, characteristics, and finding detailed of results in this review

Study designKey studies, characteristics, study population, intervention, effect of microbiotaFindings Reference
Meta-analysisIncreased beneficial bacteria, reduced harmful bacteria
Type 2 diabetes patients
Various probiotic strains		Probiotics improve glycemic control and modulate gut microbiotaTao et al. (2020) [41]
Randomized controlled trialIncreased production of SCFAs
Healthy adults Lactobacillus and Bifidobacterium strains		Probiotics enhance the production of beneficial SCFAs in the gutMarkowiak-Kopeć et al. (2020) [42]
Consensus statementGeneral improvement in gut microbiota balance
N/A
Various probiotic strains		Standardized definition and guidelines for probiotic useHill et al. (2014) [43]
Randomized controlled trialReduced diarrhea incidence, increased beneficial bacteria Malnourished children
Lactobacillus rhamnosus GG		Probiotics reduce diarrhea incidence in malnourished childrenAmadi et al. (2020) [44]
Animal studyImproved gut microbiota composition, enhanced growth
Infant mice
Lactobacillus rhamnosus GG		Early-life probiotics improve gut health and growth in miceSindhu et al. (2020) [45]
Systematic review & Meta-analysisImproved gut microbiota diversity, reduced depressive symptoms
Depression patients
Lactobacillus and Bifidobacterium strains		Probiotics may alleviate depressive symptoms by modulating gut microbiotaXiao et al. (2021) [46]
Animal studyModulated gut microbiota composition, improved metabolic health
Mice on high-fat diet
Lactobacillus and Bifidobacterium strains		Probiotics counteract high-fat diet-induced gut microbiota changesTomas et al. (2020) [47]
Randomized controlled trialImproved gut microbiota diversity, enhanced immune response
Rheumatoid arthritis patients
Lactobacillus casei		Probiotics improve immune response and gut health in rheumatoid arthritisFerro et al. (2021) [48]

Self-elaboration with adapted data from [40]. SCFAs: short-chain fatty acids; N/A: not available