METABOLITES | SOURCE | FUNCTION |
GABA | Lactobacillus, Bifidobacterium | Inhibitory neurotransmitters, prevents anxiety & depression [82] |
Serotonin | Streptococcus, Escherichia, enterococci, Enterococcus, Lactococcus, Lactobacillus | Neurotransmitter, control emotion [83] [84] |
Norepinephrine | Bacillus | Neurotransmitters, central nervous and endocrine regulation [83] [85] |
Acetylcholine | Lactobacillus, Bacillus | Act on neurotransmitters, involved in learning & memory [86] [87] |
Histamine | Lactobacillus, Lactococcus, Streptococcus, Enterococcus | Regulating neurotransmitter, associated to sleep & cognitive function [88] [89] |
IPA | Clostridium, C. sporogenes | Antioxidant, safeguard neurons [90] [91] |
SCFA (Short chain fatty acid) | Bacteroides, Bifidobacterium, Propionibacterium, Eubacterium, Lactobacillus, Clostridium, Roseburia, Prevotella | Provide energy, regulate endothelial cell function, aids in synthesis & secretion of neurotransmitters & hormones, reduce inflammation [92] |
BMAA | Cyanobacteria | Related to neurotoxicity, neuronal damage & misfolded proteins [93] |
Endotoxin | Gram-negative bacteria | Induce inflammation, release abundant cytokines [94] [95] |
Dopamine | Escherichia, Bacillus, Lactococcus, Lactobacillus, Streptococcus | System-wide target, associated with PD, AD, depression [83] [84] [85] |