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

The study published in JAMA Psychiatry by Chagwedera et al. as a Research Letter is a crossover trial conducted on 20 people diagnosed with depression (Patient Health Questionnaire-9 >=5), who had a high intake of ultra-processed foods (UPFs) and at least one metabolic problem (excess weight, dyslipidaemia, insulin resistance or hypertension), and in which the intervention consisted of removing UPFs from the patients’ diets. The results show that 19 participants completed the intervention, reducing their UPF intake on average, whilst also experiencing a reduction in symptoms of depression and anxiety. Another interesting finding from the study was the modest ease with which UPFs could be removed from the diet, and, consequently, the inherent difficulty of following a UPF-free diet today.

This is a small-scale study, in which the reduced symptoms of depression and anxiety were secondary analyses of the trial; the primary outcome was to assess the feasibility of the intervention, the duration of which is not specified in the main paper. Furthermore, given the outcomes studied, and despite the cross-over methodology, it cannot be entirely ruled out that part of the observed protective effect is due to a care bias, whereby participants’ levels of depression and anxiety might improve simply because they felt cared for and listened to. Nevertheless, the results are consistent with previous findings from longitudinal studies linking a higher risk of depression to higher consumption of UFP, including those from a Spanish cohort: the SUN Project (Gómez-Donoso C, et al. Eur J Nutr 2020).

For all these reasons, the suggestive findings of this study raise new questions regarding the possible mechanism linking high consumption of these products to mental health, and highlight the need to carry out further prospective studies and randomised trials to gain a better understanding of this relationship and implement appropriate preventive measures.