Exploring the Preventive Effects of Omega-3 Polyunsaturated Fatty Acids Supplementation on Global Cognition: A Systematic Review and Meta-Analysis of Cognitively Unimpaired Older Adults

Dementia prevention is a global public health priority, and lifestyle interventions, including nutrition, have gained interest for their potential to maintain cognitive health. Among nutritional interventions, omega-3 polyunsaturated fatty acids (n-3 FA), particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been widely studied for their potential to support cognitive health. This systematic review evaluated whether n-3 FA supplementation improves global cognition in cognitively unimpaired older adults. Nineteen randomized controlled trials (RCTs) met inclusion criteria, of which five reported significant improvements in global cognition. A random-effects meta-analysis of 11 placebo-controlled RCTs showed no significant effect (SMD = −0.02, 95% CI: −0.07 to 0.04). Heterogeneity in supplement type, dosage, duration, and outcome measures may have contributed to inconsistent findings and limited comparability. Furthermore, methodological quality of the trials was generally low. While current evidence does not demonstrate a significant effect of n-3 FA supplementation on global cognition, future research should prioritize well-powered, longer-duration RCTs that incorporate biomarker monitoring and more appropriate doses. Clarifying the role of n-3 FA in cognitive aging remains essential for informing nutrition-based dementia prevention strategies.