Reducing Ultra-Processed Food Intake for Mental Health Improvement

A recent study highlights the mental health benefits of reducing ultra-processed food consumption. Conducted by researchers at the University of California San Francisco, the study found that cutting back on these foods could significantly ease depression and even modestly reduce anxiety. The research appeared in JAMA Psychiatry on September 23.

Understanding Ultra-Processed Foods

Ultra-processed foods contain ingredients not commonly found in home kitchens, as well as chemical preservatives, emulsifiers, sweeteners like high fructose corn syrup, and artificial colors and flavors. Common examples include sodas, prepackaged snacks like chips and cookies, boxed macaroni and cheese, frozen meals, lunch meats, and hot dogs.

Study Highlights

The study involved 20 participants and is potentially the first to compare symptoms in individuals with depression before and after switching from a diet high in ultra-processed foods to healthier options.

Dr. Andrew Krystal, the study’s senior author, stated that previous studies showed a correlation between ultra-processed food consumption and increased depression risk. This study sought to explore the effects of reducing intake. Krystal said that it was a preliminary study with a small sample size, but he and his team are eager to expand the research.

Experts like Dr. Uma Naidoo from Massachusetts General Hospital noted the study’s encouraging results. She believes further studies are warranted given these initial findings.

Findings in Detail

Participants who cut their ultra-processed food consumption by 85% experienced significant mental health improvements. Depression scores on the Montgomery-Asberg Depression Rating Scale (MADRS) decreased by 63%. On the Patient Health Questionnaire-9 (PHQ-9) and Quick Inventory of Depressive Symptomatology (QIDS), reductions were around 60%.

Dr. Nicole Avena suggested that the study supports the link between ultra-processed food intake and poor mental health. Although it’s an association rather than causation, similar patterns emerged in various studies, making it difficult to ignore.

Possible Effects on Mental Health

Dr. Krystal mentioned several potential factors for why ultra-processed foods might affect mental health. These include high sugar and fat content, calorie density, and additives that could impact the brain. Dr. Avena added that her lab’s research at Princeton shows sugar’s effects on the brain’s reward system resemble those from addictive drugs.

Blood sugar spikes and crashes, along with chronic low-grade inflammation and gut microbiome disruption, might also contribute to mood changes. Dr. Naidoo emphasized that these are possible mechanisms derived from observational studies, not proven causal links.

Tackling Ultra-Processed Food Consumption

According to Dr. Avena, individuals don’t need to eliminate ultra-processed foods entirely. Small, consistent changes can be beneficial. She suggested cooking more at home, choosing minimally processed foods, and reducing sugary drinks as achievable steps.

Alyssa Moran from the Center for Food and Nutrition Policy noted the difficulties of preparing home-cooked meals, especially for those with depression. Supporting loved ones by helping to cook can be beneficial.

Changing dietary patterns requires more than improving the availability or affordability of healthy foods, Moran suggested. Measures like taxing ultra-processed foods, subsidizing fresh produce, and clear front-of-package labeling could provide more effective solutions.

Dr. Naidoo emphasized that many Americans consume a Western diet high in processed foods. There is a need for better public education on dietary guidelines and reducing ultra-processed food consumption.

Chagwedera DN, Kim E, Chiu DT, et al. (2026) Reducing Ultraprocessed Foods From the Diets of Patients With Depression: A Pilot Crossover Trial. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2026.2320