Children with Autism Have Altered Gut Bacteria

Most gut bacteria are beneficial, aiding food digestion, producing vitamins, and protecting against harmful bacteria. If left unchecked, however, harmful bacteria can excrete dangerous metabolites or disturb a balance in metabolites that can affect the gut and the rest of the body, including the brain.

Increasing evidence suggests that children with Autism Spectrum Disorders (ASD) have altered gut bacteria. In order to identify possible microbial metabolites associated with ASD researchers looked for and compared the compounds in fecal samples from children with and without ASD. They found that children with ASD had significantly different concentrations of seven of the 50 compounds they identified.

Most of the seven metabolites play a role in the brain, working as neurotransmitters or controlling neurotransmitter biosynthesis. They suspect that gut microbes may alter levels of neurotransmitter-related metabolites affecting gut-to-brain communication and/or altering brain function."

Of particular interest was the significantly higher glutamine/glutamate ratio in children with ASD. Glutamine and glutamate are further metabolized to gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter. An imbalance between glutamate and GABA transmission has been associated with ASD-like behaviors such as hyper-excitation.

Children with ASD also harbored distinct and less diverse gut bacterial composition. The study was presented in May at the American Society for Microbiology.