In the follow-up and treatment of autism and ADHD, maintaining the balance of intracranial signaling molecules is critically important. The gut microbiota plays a key role in maintaining this balance. This is because the signaling molecules, which are very important for autism, are synthesized by the gut microbiota. After synthesis, they reach the brain through the bloodstream. The amount of neurotransmitters in the blood is related to the amounts in the brain, reflecting each other at high and low points.

For example, 90% of the serotonin present in the human body is synthesized by enterochromaffin cells in the gut and bacteria that are part of the microbiota. The balance of gut microbiota (in terms of bacterial species diversity and bacterial species numbers) should be established first. Maintaining gut microbiota balance will undoubtedly contribute to maintaining the balance of signaling molecules in the brain.

For instance, the following neurotransmitters are produced (synthesized) by the bacteria provided in the gut:

Gamma-Aminobutyric Acid (GABA) Synthesizing Microbiota:

• Bifidobacterium adolescentis
• Bifidobacterium dentium
• Lactobacillus brevis
• Lactobacillus plantarum
• Lactobacillus paracasei

Acetylcholine (ACH) Synthesizing Microbiota:

• Lactobacillus spp.
• Bacillus spp.

Serotonin Synthesizing Microbiota:

• Streptococcus spp.
• Enterococcus spp.
• Akkermansia muciniphila
• Lactobacillus plantarum