Cutting Ultraprocessed Foods in Depression: Pilot Shows Feasibility

Significantly reducing ultraprocessed foods (UPF) from the diets of patients with major depressive disorder (MDD) was feasible and acceptable in a small pilot crossover trial published in JAMA Psychiatry. Depression and anxiety scores were also lower during the low-UPF period, although the investigators characterized those exploratory findings as hypothesis generating at best.

The investigators noted that epidemiological and observational studies have associated greater UPF consumption with an increased risk of developing depression in a dose-response manner, but no direct mechanistic link has been established. The pilot was designed to establish whether trials manipulating UPF intake in MDD are viable.

Investigators led by the University of California, San Francisco compared usual diet with a low-UPF diet in an open-label, order-randomized crossover trial conducted from June 2024 through June 2025. Of 20 enrolled adults with a primary diagnosis of depression, high UPF consumption, and at least 1 self-reported metabolic abnormality, 19 completed the study. Mean UPF screening-questionnaire scores fell from 10.10 at baseline to 1.42 after the intervention (P < .001), and mean ease and utility ratings were 5.74 and 8.42, respectively.

In exploratory analyses, MADRS scores averaged 8.05 during the low-UPF period vs 18.9 during the regular-diet period (treatment difference, −10.78; 95% CI, −13.90 to −7.66). Patient Health Questionnaire–9 and GAD-7 scores were also lower during the low-UPF period. No adverse events occurred.

The authors noted that mood outcomes were not primary end points in this small, nonblinded study, that the specific aspect of UPF linked to depressive symptoms is unknown, and that UPF intake relied on self-report. They also said modest ease scores highlight the challenge of this dietary change and called for larger, blinded studies using objective UPF measures and assessing mechanisms.

Source: Chagwedera DN, Kim E, Chiu DT, et al. Reducing ultraprocessed foods from the diets of patients with depression: a pilot crossover trial. JAMA Psychiatry. Published online September 23, 2026. doi:10.1001/jamapsychiatry.2026.2320