An unhealthy diet can trigger changes in the brain that affect neurotransmitters and gray matter volume and are associated with the onset of depression and anxiety.
A new study involving experts from King's College London examined the links between diet quality, neurochemistry and the structure of the frontal cortex and common mental disorders. The results can be read in the journal Nutritional Neuroscience.
Diet of 30 adults examined
A total of 30 participants were assigned by the researchers to different groups with high or low nutritional quality (Mediterranean diet). The team carried out measurements to determine the concentrations of metabolic products in the medial prefrontal cortex. The volume of gray matter in the brain was also measured.
Lower volume of grey matter
The studies showed that participants who ate an unhealthy diet showed changes in neurotransmitters and gray matter volume compared to people who ate a Mediterranean, i.e. healthy, diet.
An unhealthy diet is associated with a decrease in gamma-aminobutyric acid and an increase in glutamate, both so-called neurotransmitters. In addition, the volume of gray matter in the frontal area of the brain decreases, the researchers explain.
This could be an explanation for the connection between diet and emotional life, the research team continued.
Dangers of sugar and saturated fats
“Ultimately, we see that people who eat an unhealthy diet – high in sugar and saturated fat – have an imbalance between excitatory and inhibitory neurotransmission and a lower volume of gray matter in the front part of the brain,” study author Dr. Piril Hepsomali of the University of Reading reports in a press release.
This part of the brain is a region involved in mental health problems such as depression and anxiety.
Although the exact causes of the connection between diet and changes in the brain remain unclear, researchers are already looking at various mechanisms.
According to them, dietary habits high in saturated fats cause changes in glutamate and GABA metabolism and neurotransmission, which are probably due to the intestinal flora.
A diet high in saturated fats is associated with significant changes in the intestinal flora, which affect the cellular machinery that drives the production of glutamate and GABA.
According to the researchers, it has already been proven that a diet high in saturated fatty acids and sugar reduces the number of parvalbumin interneurons, which are known to bring GABA to where it is needed.
Influence on blood sugar and insulin
The unhealthy diet also leads to an increase in insulin and blood sugar levels, which results in an increase in glutamate in the brain and blood plasma and a reduced production and release of GABA.
A diet high in fat and cholesterol may also trigger changes in cell membranes that alter the release of neurotransmitters, the team says. This, in turn, may trigger the changes in gray matter volume in the brain observed in the current study, the team reports.
Effects on appetite
“I would like to note that GABA and glutamate are also closely linked to appetite and food intake. Reduced GABA levels and/or increased glutamate levels could also be a driving factor in choosing unhealthy foods,” adds Dr. Hepsomali.
According to the doctor, this suggests that there may be a cycle between a healthy diet, a healthier brain, better mental well-being and better food choices. However, the exact reason why diet affects the brain in this way still needs further investigation. (as)