Short-term effects of a Mediterranean-style dietary pattern on cognition and mental wellbeing: A systematic review of clinical trials

Background: Although the long-term effects of a Mediterranean-style dietary pattern (MDP) on cognition and overall mental wellbeing have been consistently described, the short-term effects of the MDP on cognitive performance, mood and anxiety have not been as widely reviewed. Objectives: The aims of this systematic review were to synthesise the evidence from randomised controlled trials (RCT) to examine whether a MDP can alter cognition and overall mental wellbeing in the short-term (up to 10 days). This will also be used to identify research gaps and to inform the design of future acute RCTs in the area. Methods: Ovid EMBASE, Ovid MEDLINE and Web of Science Core Collection were searched from inception to 8/12/2020. The data was synthesised narratively with no quantitative synthesis. The detailed protocol is available on PROSPERO, with the registration number CRD42021221085. Results: A total of 3002 studies were initially identified. After the deduplication and screening stages, 4 studies (3 articles and 1 conference proceeding) were eligible to be included. Despite the very limited data obtained, the literature suggests that a MDP can improve cognition and mood in the short-term. Specifically, improvements in attention, alertness and contentment were consistently reported. Conclusion: A MDP appears a promising strategy to improve short-term cognitive and mental health. A limitation of this review is the small number of studies identified, therefore, future studies are required to confirm these initial novel findings, and to provide granularity as to which domains are most responsive and in which population subgroups.