This research provides new insights into the connection between what we eat and our mental well-being.

While the authors did not find a direct association between brain changes and anxiety or depression, they did see an increase in rumination, a common risk factor of the two.

What the Study Found

The study is the first to examine the relationship between diet quality and brain neurochemistry in humans. Thirty adults were divided into two groups based on whether they followed a high- or low-quality diet. Participants in both groups were similar in age, gender, education, income, and caloric and macronutrient intake.

The quality of the diet was defined by adherence to the Mediterranean diet. Participants reported how frequently they ate 130 different food items, their consumption frequency, and food intake habits. Screening questionnaires were administered to assess current depression, anxiety, and rumination levels. Whole brain MRI scans measured prefrontal cortex metabolite concentrations and gray matter volume.

The study found that participants in the low-quality diet group had lower levels of GABA, higher levels of glutamate, and reduced gray matter volume in the brain—markers commonly seen in depression and anxiety. Those in the high-quality diet group had balanced levels of GABA and glutamate and a larger volume of gray matter in the brain.

GABA and glutamate are neurotransmitters. Neurotransmitters are chemical messengers that transmit signals between nerve cells and regulate various processes in the brain and body, such as mood, sleep, and cognition. Gray matter in the brain is involved in memory and emotions.

The researchers noted a trending relationship between increased rumination and decreased frontal gray matter volume. The researchers also observed a correlation between increased glutamate concentrations and increased rumination. Rumination is a major risk factor for anxiety and depression.