Diets that are higher in ultraprocessed foods (UPFs) are associated with worse depressive symptoms in Korean adults, according to a study published in Psychiatry Research. However, the link between degree of food processing and mood was modest—and not a direct linear connection.Why It’s Relevant
The global food supply has changed rapidly in recent decades, with UPFs—which are defined as foods that have been industrially formulated—becoming a staple in many cultures, sometimes replacing minimally processed foods (MPFs), defined as foods that have undergone minimal processing without the addition of other substances. While the mental health field increasingly has been researching the connection between UPFs and depression, most studies have focused on Western populations.
By the Numbers
- Researchers assessed health and nutrition surveys completed annually among 18,213 adults in Korea (average age of 47) that assessed depressive symptoms using the Patient Health Questionnaire-9.
- When analyzed along a continuous scale, higher MPF intake (either by food weight or calories) was associated with lower depressive symptoms, while higher UPF intake was associated with greater symptoms.
- However, further analysis dividing participants into discrete groups suggested that the relationship between MPF intake and depressive symptoms may be U-shaped, in that diets both very low and very high in MPFs were associated with greater depressive symptoms.
- For UPFs, depressive symptoms remained relatively low at both minimal and moderate intake levels but increased with diets high in UPFs.
What’s More
At the symptom level, MPFs were associated with participants being less likely to report feeling bad about themselves or that they had trouble sleeping. In contrast, UPF intake was associated with participants being more likely to report feeling bad about themselves, feeling depressed, and experiencing suicidal ideation.
The Other Side
The findings should not be construed as causal, as reverse causation—with depressive symptoms influencing dietary choices—may be at play. Further, respondents self-reported their diets for one 24-hour period only, which may not reflect their typical diets.
Takeaway Message
Taken together with previous research, the researchers wrote, “these patterns suggest that reducing UPF intake may represent a plausible dietary target for individuals with cognitive symptoms such as anhedonia or poor concentration, warranting further confirmation in future studies.”
Related Information
Source
Lita Kim, et. al. Associations between food processing levels and depressive symptoms: a cross-sectional study using the Korea national health and nutrition examination survey (KNHANES) 2014-2020. Psychiatry Research. Published July 22, 2026. doi:10.1016/j.psychres.2026.117336
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