Eating a poor quality diet might lead to brain changes that are associated with depression and anxiety, according to a first-of-its-kind study into the brain chemistry, structure, and diet quality of 30 volunteers.
Brain scans show changes in neurotransmitters and grey matter volume in people who have a poor diet, versus those who adhere to a Mediterranean style diet, which is considered very healthy. The researchers also found that these changes are associated with rumination, a part of the diagnostic criteria for conditions affecting mental health, such as depression and anxiety.
The research, carried out by the University of Reading, Roehampton University, FrieslandCampina (Netherlands), and Kings College London, is published in Nutritional Neuroscience. It reveals that when someone eats a poor quality diet, there is reduced gamma aminobutyric acid (GABA) and elevated glutamate – both neurotransmitters, along with reduced grey matter volume – in the frontal area of their brain. This could explain the association between what we eat and how we feel.
Diet Quality Impacts Brain Chemistry and Mental Health
Dr Piril Hepsomali, from the University of Reading, said: “We can eat ourselves well! Ultimately, we see that people who have an unhealthy diet – high in sugar and saturated fat – have imbalanced excitatory and inhibitory neurotransmission, as well as reduced volume of grey matter in the frontal part of the brain. This part of the brain is involved in mental health issues such as depression and anxiety.”
The exact reason that diet affects the brain in this way is still under investigation. It’s possible that obesity and dietary patterns that are high in saturated fats cause changes in glutamate and GABA metabolism and neurotransmission, as has been shown in animal studies. Distinct alterations of the gut microbiome, due to dietary patterns that are high in saturated fats, is thought to have an impact on cell machinery that drives both GABA and glutamate production.
Unhealthy Diets Alter Brain Structure and Function
A high saturated fat, high sugar diet has also been shown to reduce the number of parvalbumin interneurons, which perform the role of delivering GABA to where it is needed. Unhealthy diets also have an impact on glucose, making blood glucose and insulin higher. This increases glutamate in the brain and plasma, thus reducing GABA production and release. Having a diet high in fat and cholesterol can cause changes in cell membranes that alter the release of neurotransmitters, too.
These changes in brain chemistry might lead to changes in the brain grey matter volume, as observed in this study. Dr Hepsomali added: “I would like to note that GABA and glutamate are intimately involved in appetite and food intake, too. Reduced GABA and/or increased glutamate might also be a driving factor in making unhealthy food choices. So, there may be a circular relationship between eating well, having a healthier brain and better mental wellbeing, and making better food choices to eat well.”
This groundbreaking study sheds light on the complex interplay between diet, brain chemistry, and mental health. As researchers continue to unravel the mechanisms behind these associations, it becomes increasingly clear that what we eat not only affects our physical health but also our cognitive function and emotional well-being. The findings underscore the importance of promoting healthy eating habits as a potential strategy for preventing and managing mental health disorders.
