Evaluating the impact of Mediterranean dietary adherence on psychological distress and Wellbeing: The MoodFood pilot study

Psychological distress is a growing public health concern, and there is increasing interest in the role of diet as a modifiable factor for improving mental wellbeing. There is limited evidence on the real-world (i.e., naturalistic, non-clinical) impacts of dietary interventions outside clinical settings. This study evaluated the impact of a 6- to 12-week online Mediterranean-style dietary pilot intervention on psychological distress and wellbeing in an adult sample. Participants ( N = 122) completed the Mediterranean Diet Adherence Screener (MDAS), Kessler Psychological Distress Scale (K10), and WHO-5 Wellbeing Index before and after the pilot intervention. Results showed significant improvements in dietary adherence, z = -4.78, p < .001, with scores increasing from 7.35 + 2.17 to 8.89 + 3.06. Psychological distress significantly decreased, z = -7.51, p < .001, from 19.31 + 5.80 to 15.66 + 4.78. Wellbeing also improved, t (121) = -11.69, p < .001, increasing from 12.50 + 4.25 to 16.62 + 3.36. No significant correlations or predictive relationships were found between dietary change and psychological outcomes, suggesting that improvements in mental health may not be directly attributable to dietary adherence alone in this pilot study. The absence of demographic data lack of a control group, and reliance on self-report measures limit generalisability, causal inference and objectivity. Additionally, item level data were unavailable, preventing reliability testing within the present sample. Despite these methodological limitations, the study contributes valuable real-world evidence to the growing field of nutritional psychiatry by demonstrating the potential of scalable, food-based interventions delivered outside clinical settings to support mental wellbeing in a non-clinical adult population. • First real-world evaluation of an online Mediterranean-style dietary intervention in adults. • Participants (N = 122) completed a 6 to12-week self-guided program promoting Mediterranean dietary adherence. • Significant improvements observed in diet adherence, reduced psychological distress, and increased wellbeing. • No direct correlations between dietary adherence and psychological outcomes, suggesting other behavioural or psychosocial mechanisms may underlie mood improvements. • Provides foundational evidence for scalable, food-based interventions supporting mental wellbeing outside clinical settings.