Background/Objectives: As global aging accelerates, prevalence of mild cognitive impairment (MCI) continues to rise, challenging healthcare systems and diminishing older adults’ quality of life. There is great interest in better understanding the neuroprotective/anti-inflammatory properties of omega-3 polyunsaturated fatty acids but the results from many published studies in humans come to different conclusions. This review aims to clarify the efficacy of n-3 fatty acids as a preventive or therapeutic strategy for cognitive health and to inform future clinical recommendations within aging populations. Methods: Following PRISMA guidelines and a registered PROSPERO protocol, we reviewed systematic reviews (SRs) from 2014 to 2024 assessing exclusive n-3 fatty acid supplementation and cognitive outcomes via MMSE. Data were extracted on intervention details and cognitive scores. Meta-analyses used fixed and random-effects models, with Hedges’ estimating overall impact. Quality was assessed using AMSTAR-2, and statistical analyses were performed (SPSS 28). Results: A total of nine SRs incorporating 14 RCTs were included, representing 26,881 participants aged 40 years or older. The pooled random-effects meta-analysis showed a statistically significant but modest improvement in MMSE scores (effect size: 0.16; 95% CI: 0.01–0.32). Heterogeneity was moderate (I2 = 42.8%), and no publication bias was detected. Further analyses revealed no significant associations between treatment duration or dosage and cognitive outcomes, suggesting a threshold effect rather than a dose–response relationship. Conclusions: These findings support n3-PUFA supplementation as a complementary approach to lifestyle-based strategies for cognitive health, including diet, physical activity, sleep optimization, and cognitive training. While benefits appear modest, consistent effects across studies warrant further high-quality research and well-designed studies to strengthen clinical recommendations.
Barros et al. (2025) studied this question.