WASHINGTON (dpa-AFX) - A diet containing fewer ultra-processed foods may help reduce symptoms of depression, according to a small pilot study published in JAMA Psychiatry.
The study, led by Nyasha Chagwedera, a psychiatry researcher at the University of California, included 20 adults who regularly consumed large amounts of ultra-processed foods. Participants were around 44 years old on average and had been living with depression for nearly 13 years.
The researchers used four weeks for each diet to compare how the participants responded to different eating patterns. They were randomly divided into two groups. One group continued eating as usual for four weeks, while the other reduced its intake of ultra-processed foods. After this period, the groups switched diets.
Participants purchased their own groceries with guidance from the research team. They were also asked to maintain their existing medication, therapy, exercise and sleep routines throughout the trial so that these factors would remain unchanged.
Researchers used three different assessments to measure depression symptoms. On the nine-question Patient Health Questionnaire (PHQ-9), the average depression score was 8.68 when participants followed their regular diet. This fell to 5.53 during the low-ultra-processed-food diet.
A second assessment, known as the Montgomery-Åsberg Depression Rating Scale (MADRS), also showed a reduction in symptoms. The average score was 18.9 during the usual diet, compared with 8.05 during the dietary intervention. The third depression assessment and a questionnaire measuring anxiety symptoms also recorded lower scores when participants reduced their intake of ultra-processed foods.
The researchers concluded that the dietary approach was practical and acceptable to participants. However, the findings do not establish exactly why reducing ultra-processed foods was associated with lower depression scores. Changing food choices can also affect sugar, fat and calorie consumption. Other possible explanations include differences in food additives or contaminants linked to processing.
The researchers also observed that depression scores had improved during the usual-diet period compared with the beginning of the study. Average PHQ-9 scores fell from 12.8 at baseline to 8.68 during this period, suggesting that factors other than the dietary intervention may also have influenced the results.
The team has called for larger studies with stronger research methods, including blinded assessments and objective ways to measure ultra-processed food consumption. Further research is also needed to understand how dietary changes might affect depression symptoms.
Copyright(c) 2026 RTTNews.com. All Rights Reserved
Copyright RTT News/dpa-AFX
© 2026 AFX News
