Abstract
Background/Objectives: Alzheimer's disease (AD) remains a leading cause of mortality with millions suffering worldwide. The number of annual cases is sharply increasing primarily due to growing older adult populations. To date, there is neither an effective prevention nor cure for AD. Recently, AD was specified using biomarkers, facilitating research into primary and secondary prevention strategies, including dietary interventions. This systematic narrative review maps the literature on dietary prevention of AD by synthesizing the evidence on diet and AD biomarkers in cognitively normal adults. Additionally, it explores limitations in the current evidence base and identifies areas for future research. Methods: Search terms and inclusion/exclusion criteria were set, and PubMed and EBSCOhost were searched for articles up through September 2025. Out of 331 results, 14 articles passed the inclusion/exclusion criteria and were included in this review. Results: Most studies were cross-sectional (n = 8), followed by cohort (n = 4), with one study including both cross-sectional and longitudinal analyses (n = 1). Only one intervention study was published. Various dietary exposures were tested, with most studies (n = 5) supporting a protective relationship between the Mediterranean diet and prevention of the neuropathological hallmarks of AD. However, the evidence base varies in methodology. Future research would benefit from greater consensus in methodology and should prioritize prospective cohort and randomized trial designs. Conclusions: Evidence from this review suggests existence of a potential role for dietary interventions, especially the Mediterranean diet, in AD prevention. However, further research is needed to address existing gaps. (248 words).