Flavorings, Colors, and Sweeteners in UPFs Linked to Higher Depression Risk: Study

Could the ingredients that make ultra-processed foods more colourful, flavourful and sweet also be linked to depression risk?

A new study published in the European Journal of Nutrition has found that higher estimated dietary exposure to foods likely containing flavouring agents, colouring agents and sweeteners was associated with a dose-dependent increase in the risk of developing depression.

Researchers from Justus-Liebig University of Giessen, Germany, analysed dietary data from 171,818 UK Biobank participants who completed at least one 24-hour dietary recall. Over an average follow-up of 10.7 years, 5,424 participants developed depression.

Rather than relying solely on the NOVA classification of ultra-processed foods (UPFs), researchers assessed 10 categories and 39 specific markers used to identify foods likely containing UPF-related ingredients.

Among the categories studied, flavouring agents showed the strongest associations. Compared with a modeled intake level representing 5% of total food intake, having 40% of intake represented by foods likely containing flavouring agents was associated with a 46% higher risk of incident depression.

Similarly, foods likely containing colouring agents at 20% of intake, compared with 3%, were associated with a 49% higher risk. For sweeteners, 20% versus 0% was associated with a 45% higher risk.

The associations remained significant in sensitivity analyses. Fructose was also identified as a specific UPF marker showing a dose-dependent association with depression risk.

Researchers suggest several possible explanations, including effects on brain function and neurotransmitter signalling, as well as indirect pathways involving obesity, metabolic dysfunction and gut microbiota changes.

However, the findings do not prove that these additives cause depression. Dietary intake was self-reported, ingredient lists were not directly captured, and exposure was estimated based on the likelihood that foods contained specific markers. Reverse causation and residual confounding also remain possible.

The authors say future human and animal studies are needed to establish whether these associations reflect causal relationships.

REFERENCE: Blumenthal, A.K., Eichner, G., Fasshauer, M. et al. Relationship between 39 dietary markers of ultra-processed food and incident depression: evidence from the prospective UK Biobank cohort study. Eur J Nutr 65, 238 (2026). DOI: 10.1007/s00394-026-04084-7,