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]