Eliminating processed foods, snacks, and fast food led to a significant reduction in symptoms of depression and anxiety. This conclusion was drawn from the results of the first clinical experiment focused on changing dietary habits.

Study Progress

In a four-week study conducted by specialists from the University of California, San Francisco, volunteers aged 18 to 80 with a confirmed diagnosis of major depressive disorder participated. On average, participants had been living with depression for about 13 years, regularly consumed large amounts of processed foods, and had accompanying metabolic disorders such as high body mass index, elevated cholesterol, hypertension, and diabetes.

During the experiment, participants were not allowed to change their medication dosages, visit new psychotherapists, or alter their usual physical activity and sleep patterns. The study results were published in the scientific journal JAMA Psychiatry.

Methodology and Results

The experiment followed a crossover design: for one period, volunteers maintained their usual diet high in processed foods, and for another month, under researchers’ supervision, they reduced their intake of such foods by more than 85%. Analysis showed that changing dietary habits led to a noticeable improvement in emotional well-being.

According to the Montgomery clinical scale, the severity of depressive symptoms decreased from 21.6 to 8.05 points. On the PHQ-9 questionnaire, depression levels dropped from 12.8 to 5.53 points. Anxiety levels, measured by the GAD-7 scale, also decreased—from 9.35 to 4.63 points.

Possible Mechanisms

One key mechanism by which diet may affect mental health is damage to the intestinal barrier. Preservatives, emulsifiers, artificial colorings, and excess sugar destroy the protective mucous lining of the gut, causing chronic low-grade systemic inflammation, which directly impacts the central nervous system.

Future Plans

A second phase of trials with a larger group of participants is planned, with the study scheduled for 2028.