Consumption of foods containing flavorings, colorings, and sweeteners is associated with a higher risk of developing depression. The study also found that the greater the estimated amount of these components in a person’s diet, the higher the risk. The findings were published in the European Journal of Nutrition.
Researchers from Justus Liebig University Giessen analyzed dietary data from 171,818 participants in the UK Biobank who completed food questionnaires. During the average follow-up period of 10.7 years, 5,424 participants were diagnosed with depression for the first time.
The scientists assessed the dietary intake of 10 categories of markers of ultra-processed foods and 39 individual substances. These markers included flavorings, colorings, and sweeteners, as well as certain types of sugars, modified oils, starches, and isolated proteins.
A clear dose-dependent association with depression risk was identified for three categories. When foods presumed to contain flavorings accounted for up to 40% of the total diet, the risk of developing depression was 46% higher compared with the level of consumption associated with the lowest estimated risk. For colorings, increasing the proportion of such foods to 20% was associated with a 49% higher risk, while for sweeteners, the increase was 45%.
No significant association with an increased risk of depression was found for the other components examined.
The researchers emphasize that the study demonstrates a statistical association and does not prove that flavorings, colorings, or sweeteners directly cause depression. One possible explanation is that these substances may affect brain function and communication between neurons. An indirect effect through obesity, metabolic disorders, and changes in the gut microbiome cannot be ruled out either.
The researchers also identified a dose-dependent association between fructose consumption and the risk of developing depression. However, the mechanism underlying this relationship remains unclear.
The authors point to several limitations of the study. Participants’ diets were assessed using self-reported data, while the composition of individual products was not determined directly from ingredient lists. As a result, the presence of specific additives was estimated based on the likelihood that they were used in particular types of products.
In addition, reverse causation cannot be completely ruled out: people with emerging depression may be more likely to choose ready-made foods because reduced activity levels can make it more difficult for them to prepare meals themselves.
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