A recent study from the University of California, San Francisco, examined whether reducing ultra-processed foods (UPFs) could influence symptoms of depression. This pilot study, published in JAMA Psychiatry, involved 20 adults with depression, 19 of whom completed the trial. Participants had an average age of 44, with 14 being women, and all had overweight or obesity, with some also having conditions such as high blood pressure, diabetes, or elevated cholesterol.
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Ultra-processed foods are industrially manufactured products containing ingredients often not found in home cooking. They typically have high levels of refined sugars, salt, and unhealthy fats while being low in beneficial nutrients. Popular examples include packaged biscuits, chips, and ready meals.
During the study, each participant followed two diets for four weeks each: their usual diet and a low-UPF diet. They were responsible for purchasing and preparing their food, while keeping their medication, therapy, exercise, and sleep routines consistent.
Results showed that participants successfully reduced their UPF intake, with their average consumption score decreasing from 10.1 before the intervention to 1.42 afterward. Additionally, participants reported lower scores for depression and anxiety during the low-UPF phase compared to their usual diet.
Despite these promising findings, the study does not definitively prove that a decrease in UPFs directly improves depression symptoms. Limitations include the small sample size and the knowledge of participants about which diet they were following. Andrew Krystal, the senior author, emphasized the study's success in demonstrating the feasibility of larger trials, with plans for future research involving a bigger group expected to begin by 2028.