Research on Ultra-Processed Foods and Depression
Grab a packet of snacks, a sugary drink, or a meal that’s ready in minutes. Ultra-processed foods certainly make life in the kitchen simpler. But researchers are now looking into whether cutting back on these foods might also have an impact on depression symptoms.
In a pilot trial, individuals diagnosed with depression showed lower symptom scores when following a diet that was low in ultra-processed foods compared to their typical eating habits.
The study lasted four weeks for each dietary period, which allowed researchers to effectively compare two different eating patterns in the same participants.
Led by Nyasha Chagwedera from the University of California, San Francisco (UCSF), the research involved 20 adults who consumed a significant amount of ultra-processed foods. Their average age was around 44, and these individuals had been living with depression for nearly 13 years on average.
Participants were randomly assigned to begin with one of two diets: one group continued their usual diet for four weeks, while the other reduced their intake of ultra-processed foods. After that, they switched diets.
Participants purchased their own food with guidance but were instructed to maintain their medications, therapy, exercise, and sleep schedules unchanged throughout the trial.
Nineteen individuals completed the study. The average score on a questionnaire measuring highly processed food consumption fell from 10.10 at the beginning to 1.42 after the intervention.
Three separate assessments on depression indicated improved scores during the low-ultra-processed-foods period compared to the usual diet.
During a nine-question assessment known as the PHQ-9, average scores were 8.68 with the usual diet and dropped to 5.53 during the dietary intervention. Analysis that considered initial symptoms, order of diets, and study phases estimated a difference of about three points between the two dietary patterns.
Another depression assessment, the MADRS, revealed average scores of 18.9 during the usual diet, compared to 8.05 when on the low-ultra-processed-food diet.
Additionally, the third assessment for depression and an anxiety questionnaire showed lower scores during the dietary intervention.
Previous observational studies have found a link between high consumption of ultra-processed foods and depression. This research explored the effects of changing eating habits on individuals already living with depression.
Changing these routines isn’t easy. Packaged snacks and some ready-made meals provide convenient options, especially when time and energy are running low, though it’s worth noting that not all processed foods fall into the ultra-processed category.
Chagwedera noted that cutting down on ultra-processed foods can be tough because they are often tasty, affordable, and convenient.
Participants rated the ease of making dietary changes at 5.74 on average, while its usefulness was rated at 8.42, with no adverse events reported.
The research team determined that the intervention was both practical and acceptable, laying the groundwork for more extensive trials in the future.
Reducing ultra-processed foods might also alter sugar, fat, or caloric intake, with processing-related contaminants or additives being other potential influencing factors. However, this study didn’t pinpoint which specific aspects of the dietary changes were impactful.
Interestingly, symptoms were also lower during the usual diet period compared to baseline levels. For reference, average PHQ-9 scores were 12.8 at the start of the study and fell to 8.68 during the usual diet.
Therefore, the reported dietary effects primarily concern the differences between the two dietary periods rather than attributing full improvement from baseline solely to reduced ultra-processed food intake.
This trial was relatively small and unblinded, meaning participants were aware of which diet they were following, and their expectations could have influenced the results. Additionally, food consumption was self-reported, lacking an objective measure of ultra-processed food intake.
All participants had high body weight and reported at least one metabolic abnormality, so these findings may not apply equally to all individuals with depression.
The main goals were to assess feasibility and acceptance, while depression and anxiety outcomes were more exploratory. The authors describe the findings as generating hypotheses.
The researchers advocated for larger, blinded studies that utilize objective measures of ultra-processed food intake and explore the mechanisms behind the outcomes.
The research has been published in JAMA Psychiatry.
