Study reveals which foods are behind depression symptoms

Researchers from the University of São Paulo (USP) who have been monitoring the eating patterns of the Brazilian population since 2020 reveal that the high consumption of ultra-processed foods is related to the manifestation of depressive symptoms. Analyzes indicate an increased risk of 42% for depression within the group in which these products make up almost two-fifths of the diet.

André Werneck, the person mainly responsible for the work, was already researching the relationship between physical activity and mental health when he joined the Center for Epidemiological Research in Nutrition and Health (Nupens) at USP to begin his doctorate. It was there that he saw an opportunity to expand the scope of his research and also look into nutritional aspects. He didn’t expect the job would change his own relationship with food. “Today, I try my best to avoid ultra-processed foods,” he says.

Experts evaluated data from almost 16,000 adults who were not diagnosed with depression at the start of the study. Volunteers reported, through online questionnaires applied every six months, the main foods consumed the previous day and their health status. With this information in hand, Werneck and the Nupens team were able to assess the role of ultra-processed foods in these people’s diets.

According to Nupens, on average, highly processed foods represent 20% of the total energy consumed daily by Brazilians. In the group with the healthiest diet, this average percentage is 7%, while it reaches almost 40% in the group that consumes these products the most.

Ultra-processed foods are generally made from cheap ingredients extracted from fresh foods, to which preservatives, flavorings and flavorings are added. They are cheaper, more durable, convenient for consumption and pleasant to the taste. Therefore, the group most susceptible to these products is those with lower income and education.

Highly processed foods are known for their low nutritional value. They are generally rich in added sugars, sodium and fats, which is one of the reasons behind the emergence of mental health problems. However, scientists suspected there was something more.

Therefore, Werneck conducted other statistical analyzes to verify whether the relationship between depressive symptoms also exists for people who consume both fruits, vegetables and large amounts of ultra-processed foods. “There was a significant reduction in the association [nos resultados]but it remained beyond the nutritional profile”, explains the specialist.

Evidence shows that the causes of psychiatric problems may also lie in chemical additives. According to the study authors, this relationship may be related to changes in the intestinal microbiota promoted by these substances, which, in turn, cause an imbalance in the absorption of nutrients.

The solution for those who want to take care of their health is to reduce the consumption of these products as much as possible. This is also the recommendation of the Ministry of Health. In the food classification system of the Food Guide for the Brazilian Population, ultra-processed foods occupy the fourth category, after natural or minimally processed foods, processed ingredients and only processed foods.

In addition to the cohort data, Nupens researchers also carried out a meta-analysis that included five other large similar studies. Combining Brazilian data with studies conducted in Europe and the United States, the risk of ultra-processed foods for the emergence of depressive symptoms was 32% higher between the lowest and highest risk groups. Werneck emphasizes that this step is important to confirm the observations made and reinforce that the results are not mere coincidences.