Scientists have identified a link between the microbiome and chemical processes in the brain

The ability of intestinal bacteria to produce and break down biologically active compounds is related to the levels of important neurotransmitters in certain areas of the human brain. This was reported in the journal Molecular Psychiatry.

The study involved 61 healthy women aged 17 to 25 years. The researchers measured levels of gamma-aminobutyric acid, or GABA, and glutamate in three brain regions using proton magnetic resonance spectroscopy.

GABA predominantly suppresses the activity of nerve cells, while glutamate promotes their excitation. The ratio of these neurotransmitters plays an important role in neuroplasticity, cognitive processes, and mental health maintenance.

Samples of the intestinal microbiome of the participants were examined by full-genome metagenomic sequencing. This allowed us to determine which genes are present in bacteria and which processes related to GABA, glutamate, short-chain fatty acids and other compounds they are potentially capable of performing.

The connections varied depending on the area of the brain. The largest number of associations was found in the inferior occipital gyrus, involved in visual information processing. They related to bacterial pathways of GABA metabolism, glutamate cleavage, production of short-chain fatty acids, inositol and paracresol.

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In the anterior cingulate cortex, associated with attention, cognitive control, and emotion processing, neurotransmitter levels correlated with microbial pathways of glutamate and propionate metabolism. A more selective association with potential GABA production by bacteria was found in the dorsolateral prefrontal cortex.

Some microbial pathways have also been correlated with self-reported anxiety, symptoms of depression, and sleep quality. However, the researchers emphasized that these results do not mean that specific bacteria cause anxiety or directly alter neurotransmitter levels.

The work was simultaneous, so it is impossible to establish the direction of communication. In addition, scientists assessed the genetic potential of microorganisms, but did not measure the substances they actually produced. All participants were young women, which also limits the ability to transfer the results to other population groups.

Belousov said on August 19 that apples, when consumed regularly, can have a positive effect on cholesterol levels, but they are not a substitute for drug treatment. This effect is primarily due to the high content of soluble fiber, especially pectin. Once in the intestine, it binds part of the bile acids, which the body uses cholesterol to synthesize. Because of this, the liver spends more cholesterol on the formation of new bile acids, which can lead to a moderate decrease in the level of low-density lipoproteins.