Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Change in Ultra-Processed Food Consumption Moderates Clinical Trial Outcomes in Depression: A Secondary Analysis of the SMILES Randomised Controlled Trial

Melissa M Lane
ORCID logo ,
Mojtaba Lotfaliany
,
Priscila Machado
ORCID logo ,
Felice N Jacka
,
Mohammadreza Mohebbi
,
Adrienne O’Neil
,
André O Werneck
ORCID logo ,
Carlos Monteiro
,
Amy Loughman
,
Tetyana Rocks
,
Nikolaj Travica
,
Michael Berk
,
Rachelle S Opie
* ,
Wolfgang Marx
* ORCID logo
Version 1 : Received: 15 August 2023 / Approved: 15 August 2023 / Online: 15 August 2023 (09:38:10 CEST)

How to cite: Lane, M.M.; Lotfaliany, M.; Machado, P.; Jacka, F.N.; Mohebbi, M.; O’Neil, A.; Werneck, A.O.; Monteiro, C.; Loughman, A.; Rocks, T.; Travica, N.; Berk, M.; Opie, R.S.; Marx, W. Change in Ultra-Processed Food Consumption Moderates Clinical Trial Outcomes in Depression: A Secondary Analysis of the SMILES Randomised Controlled Trial. Preprints 2023, 2023081110. https://doi.org/10.20944/preprints202308.1110.v1 Lane, M.M.; Lotfaliany, M.; Machado, P.; Jacka, F.N.; Mohebbi, M.; O’Neil, A.; Werneck, A.O.; Monteiro, C.; Loughman, A.; Rocks, T.; Travica, N.; Berk, M.; Opie, R.S.; Marx, W. Change in Ultra-Processed Food Consumption Moderates Clinical Trial Outcomes in Depression: A Secondary Analysis of the SMILES Randomised Controlled Trial. Preprints 2023, 2023081110. https://doi.org/10.20944/preprints202308.1110.v1

Abstract

Background: In this secondary analysis of the Supporting the Modification of Lifestyle In Lowered Emotional States (SMILES) randomised controlled trial, we investigated if the beneficial effects of a dietary intervention on clinical depression were driven, in part, by reducing the consumption of foods classified as ultra-processed.Methods: The SMILES trial enrolled 67 adults with major depressive disorder, randomly assigning them to either a 12-week modified Mediterranean dietary intervention or a social support control. Our analysis included 44 participants with non-missing dietary data and at least one valid Montgomery–Åsberg Depression Rating Scale (MADRS) assessment at 12 weeks of follow-up. The Nova food classification system was used to estimate the proportion of ultra-processed foods in the overall diet (percentage of grams) based on data from seven-day food diaries. We fitted linear regression models under blinded conditions to determine whether ultra-processed food intake-change from baseline to 12 weeks moderated the dietary intervention effects on depressive symptoms. We estimated mean differences in depressive symptoms along with ninety-five per cent confidence intervals (95%CIs).Results: For participants in the dietary intervention, there was an additional 2.5-point improvement in MADRS scores for each 10% reduction in the dietary share of ultra-processed foods compared to participants in the control group (between-group mean differences in depressive symptoms: −2.46, 95%CIs −4.71 to −0.20, p=0.039, η p 2 of 0.10).Conclusions: These preliminary findings suggest that the therapeutic benefit of a dietary intervention for depression may stem, at least in part, from reductions in the dietary share of ultra-processed foods.

Keywords

ultra-processed food; Nova food classification system; major depressive disorder; nutritional psychiatry; secondary analysis; randomised controlled trial

Subject

Medicine and Pharmacology, Psychiatry and Mental Health

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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