What foods can worsen your mood and increase your risk of depression?

The study, conducted by the Center for Biomedical Research Network, suggests that consuming ultra-processed foods could be associated with depressive symptoms and affect the volume of gray matter in the amygdala and frontal regions of the brain. The article, published in the Journal of Affective Disorders, also explores the effects of obesity and inflammation levels.

The study directly links ultra-processed foods to depression, gray matter volume in the mesocorticolimbic brain circuit, and inflammation parameters.

The study aims to shed light on the potential adverse effects that consuming ultra-processed foods (which include snacks, sugary drinks, convenience foods, processed pastries, processed meats, cookies, sugary dairy products, refined cereals, pizzas, and nuggets) can have on mental health and the brain.

Most of these foods have a low nutrient density and a higher energy concentration than unprocessed foods. They are high in saturated and trans fatty acids, added sugars, and salt, and low in protein, dietary fiber, and micronutrients.

Furthermore, these types of products often contain additives to enhance their sensory qualities and mimic the appearance of minimally processed foods, making them edible, tasty, highly appealing, and potentially addictive.

Currently, depressive disorders are among the most common psychiatric conditions worldwide, severely limiting psychosocial functioning and significantly diminishing the quality of life of those who suffer from them. According to data from the World Health Organization (WHO), approximately 280 million people live with depression.

Now, the lead researchers of this study, Oren Contreras-Rodríguez and José Manuel Fernández-Real, explain that their objective was to determine the relationship between ultra-processed food consumption and depressive symptoms, as well as to provide new data on the association between these products' consumption and brain gray matter volumes in 152 adults.

They also proposed exploring the interaction effects with obesity, as well as assessing whether inflammatory biomarkers mediate these prior associations. “As a working hypothesis, we expected that higher consumption of ultra-processed foods would be associated with a higher risk of depressive symptoms and lower gray matter volume in the amygdala and frontal regions, especially in participants with obesity, as they tend to have higher consumption of ultra-processed foods,” says Contreras-Rodríguez. And indeed, “the results confirmed our hypothesis,” notes Fernández-Real.

For this cross-sectional study, 233 individuals were recruited, resulting in a final sample of 152 participants. Focusing on the consumption of ultra-processed foods, information on these individuals' diets over the past year was collected using validated food frequency questionnaires.

In turn, the NOVA food classification system was used to identify foods and beverages based on their degree of processing. Finally, the percentage of ultra-processed food consumption in the overall diet was also calculated.

Depressive symptoms were also assessed, and structural magnetic resonance imaging was performed. Finally, several metabolic parameters and inflammatory biomarkers were measured, such as white blood cell count, lipopolysaccharide-binding protein, and C-reactive protein.

One of the main results is the association between higher consumption of ultra-processed foods and a greater presence of depressive symptoms, as well as a smaller volume in brain regions involved in processing reward and monitoring conflict, essential aspects of decision-making, including dietary decisions.

The mediation of white blood cell counts in the association between ultra-processed food consumption and depressive symptoms is also highlighted.

Indeed, the association between consumption of these products and depressive symptoms was especially notable in the obese group (58.6% of participants), who initially had a higher presence of depressive symptoms compared to the non-obese group.

In conclusion, the research supports previous evidence and provides new data linking dietary habits with changes in the structure of specific brain networks. Furthermore, it shows that these associations may be dependent on the presence of obesity and levels of peripheral inflammation.

The research was led by two departments of CIBER, CIBERSAM (Mental Health) and CIBEROBN (Pathophysiology of Obesity and Nutrition). Researchers from the Barcelona Public Health Agency and the Sant Pau Research Institute also collaborated.