Scientists have pointed to the role of ultraprocessed foods in depression
Reducing the proportion of ultra-processed foods in the diet by more than 85% was associated with a marked reduction in symptoms of depression in participants in a small study. The scientists also recorded a more moderate improvement in anxiety indicators and suggested that one of the possible mechanisms could be the effect of diet on the intestines and chronic inflammation. About how a change in diet turned out to be related to a mental state, see the Izvestia article.
Minus 85% — and the symptoms have become weaker
A study by specialists from the University of California at San Francisco involved 20 people with depression. The average age of the participants was 44 years, 70% of them were women. In addition to depression, anxiety was also observed in 14 people.
The work was published in the journal JAMA Psychiatry. The researchers studied what would happen to depression symptoms if participants significantly reduced the amount of ultra-processed foods in their diets.
The authors referred to ultra-processed foods, in particular, packaged snacks, fast food, sugary drinks and other industrially manufactured foods.
After switching to such a diet, the participants reduced their consumption of ultra-processed foods by more than 85%. On three different scales of assessment of depression, scientists have recorded improvements from moderate to significant. Anxiety indicators also decreased slightly.
Four weeks — then the participants switched places
To compare different eating patterns, the researchers divided the participants into two groups. During the first four weeks, one group maintained their usual diet, while the other switched to a diet low in ultra-processed foods.
Nyasha Chagvedera, founder of the Program on Metabolism and Mental health at the University of California, San Francisco and co-author of the study
Ultra-processed foods stimulate the production of dopamine, the pleasure hormone that causes food cravings. Food companies work with scientists to find the optimal amount of sugar, salt, and fat that makes you want to eat more.
The participants independently selected and bought food, receiving recommendations from the research team. After four weeks, the groups switched their eating patterns: those who initially followed the usual diet switched to a less ultra-processed diet, while the rest returned to their original diet.
This approach made it possible to compare the changes in the same people under different nutritional conditions. The researchers call the work a pilot and note that it showed the possibility of conducting a larger-scale study.
Depression has changed more noticeably than anxiety
The main result concerned specifically the symptoms of depression. After a significant reduction in ultraprocessed food, improvements were noted in three different indicators at once. At the same time, the changes in anxiety turned out to be more moderate. Scientists do not claim that avoiding certain foods cures depression by itself: we are talking about the results of a small preliminary study that observed a link between dietary changes and the condition of participants.
At the time of the study, all participants also had a high body mass index and at least one metabolic disorder, such as high blood pressure, diabetes, or high levels of low-density lipoprotein cholesterol. Therefore, the results obtained cannot be automatically extended to people with other health characteristics.
The intestine is a possible link between food and the brain
Scientists associate one of the possible explanations with the "gut—brain" axis. According to the researchers' hypothesis, a large amount of ultraprocessed food can damage the protective lining of the intestine.
This, in turn, has the potential to support chronic low-grade inflammation in the body. The authors suggest that such a condition may directly affect the symptoms of depression or increase susceptibility to them.
Nyasha Chagvedera
Intestinal damage can cause sluggish chronic inflammation throughout the body, which either directly leads to depression or makes people more susceptible to it. In other words, poor-quality food processing can harm your intestines, which will affect your brain.
However, this explanation remains a hypothesis: the study did not establish that it was intestinal damage that caused the changes in mental state.
A small sample is the main issue
The authors emphasize that the results cannot yet be considered final. Only 20 people participated in the study, so the patterns obtained need to be tested on a much larger group. Senior author Andrew Krystal noted that the study showed the possibility of conducting a larger experiment.
Thus, the work so far indicates a possible link between a significant reduction in ultraprocessed foods and a reduction in symptoms of depression, but does not prove a cause-and-effect relationship. Additional studies should show how stable this effect will be and what biological processes can explain it.
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