Study Suggests Reducing Ultra-Processed Foods May Alleviate Depression Symptoms

The pilot study involved 20 participants, and according to senior author Andrew Krystal, MD, of UCSF's departments of Psychiatry and Behavioral Sciences and Neurology, it demonstrated the feasibility of conducting a larger study.

Participants decreased their ultra-processed food consumption by over 85%, resulting in moderate to significant improvements in three measures of depression. Additionally, there were modest improvements in anxiety scores.

Ultra-processed foods are defined as packaged snacks, fast food, sugary drinks, and other industrially manufactured items that often contain preservatives, artificial colors, flavor enhancers, and emulsifiers. Nyasha Chagwedera, MD, Ph.D., the study's corresponding author, noted that cutting back on these foods can be difficult due to their appealing taste, low cost, and convenience.

"Ultra-processed food triggers dopamine, the pleasure hormone, which promotes cravings. Food companies collaborate with scientists to determine the optimal levels of sugar, salt, and fat that compel consumption," Chagwedera explained.

The study participants, averaging 44 years of age and 70% female, included individuals with depression and anxiety. All had a high body mass index and at least one metabolic disorder, such as hypertension or diabetes.

Participants were divided into two groups: one maintained their usual diet while the other adopted a low ultra-processed diet for four weeks, shopping and preparing their meals with guidance from researchers. After four weeks, the groups swapped diets.

Chagwedera suggested that the connection between ultra-processed foods and depression could be linked to damage to the gut's protective lining, often referred to as a "leaky gut." This damage can lead to chronic inflammation, which may either directly cause depression or heighten vulnerability to it.

The researchers plan to begin enrollment for the second phase of the study in 2028.