The Association Between Adherence to the Mediterranean Diet and Depression and Anxiety Symptoms in University Students: The Mediating Role of Lean Mass and the Muscle Strength Index

Background/objectives: recent studies have suggested that components typical of the Mediterranean diet (MedDiet) are associated with depression and anxiety prevention. In this sense, the main objective of this study was to analyse the associations between adherence to the MedDiet and depression and anxiety symptoms and to examine whether this relationship is mediated by lean mass and the muscle strength index (MSI). Methods: a cross-sectional study (based on data obtained from the Nuts4Brain-Z study) was conducted from 2023-2024, involving 428 university students, aged 18-30 years, from a Spanish public university. Depression was assessed using the Beck Depression Inventory (BDI-II), and anxiety was assessed via the General Anxiety Disorder-7 (GAD-7) tool. Adherence to the MedDiet was assessed using the MEDAS questionnaire. Lean mass was assessed via bioimpedance, and MSI was measured via a dynamometer. ANCOVA models were used to test the mean differences in depression and anxiety scores using MEDAS categories (low adherence < 9 points vs high adherence >= 9 points). Serial multiple mediation models, adjusted for the main confounders, were used to explore the role of lean mass and MSI in the relationships between adherence to the MedDiet and depression and anxiety symptoms. Results: university students with high adherence to the MedDiet exhibited lower scores for depression and anxiety symptoms (p < 0.05) than did students with low adherence to the MedDiet. The mediation analysis preliminarily revealed that both lean mass and MSI acted as mediators of the relationships between adherence to the MedDiet and depression and anxiety. Conclusion: adherence to the MedDiet in university students per se does not appear to have a direct effect on depression and anxiety symptoms because these associations are partially (for depression) or entirely (for anxiety) explained by lean mass and MSI.