Reacción a "A small pilot study examines the reduction in the consumption of ultra-processed foods among patients with depression"

This is a small-scale exploratory study that examines whether a reduction in the consumption of ultra-processed foods improves indicators of depression. The study takes the form of a ‘letter to the editor’, which means it does not carry the same weight as an original article. In this case, only the results of the depression tests for the two study groups are presented, which does not allow for an exploration of physiological explanations.

The significance of the study lies in the fact that this is the first time a clinical trial has been conducted for this purpose. Furthermore, whilst there is a wealth of scientific literature on the potential harmful effects of ultra-processed foods, the vast majority of studies are observational in nature, which do not allow for the establishment of cause-and-effect relationships. Numerous researchers have highlighted the need to carry out randomised controlled trials, such as this one, in order to determine such causality.

The study design is a crossover study, meaning that all participants consumed both proposed diets: their usual diet, high in ultra-processed foods, and the intervention diet, low in ultra-processed foods. However, the article does not mention the duration of the intervention or the system used for classifying foods and defining ultra-processed foods, which is usually the NOVA framework. Furthermore, the sample size is very small (only 19 participants completed the trial).

These limitations, along with others stated by the authors themselves in the article, mean that the study cannot be regarded as more than an exploratory piece of research, despite the fact that the results clearly show that reducing the consumption of ultra-processed foods significantly lowers the scores on the depression tests administered.

In light of these results, the appropriate course of action is to repeat the clinical trial, increasing the sample size and improving the experimental design, so that the results are more robust. In any case, although to a lesser extent, it contributes to the scientific evidence regarding the adverse health effects of consuming ultra-processed foods.