Fish intake, n-3 fatty acid body status, and risk of cognitive decline: a systematic review and a dose–response meta-analysis of observational and experimental studies
2021/09/08 by Rena I. Kosti, Rena I Kosti, Maria‐Iosifina Kasdagli +7 · 26 citations
Medicine · Nursing · #Biology #Cognitive decline #Confidence interval #Dementia #Diet and metabolism studies #Disease #Docosahexaenoic acid #Eicosapentaenoic acid #Fatty Acid Research and Health #Fatty acid #Gerontology #Internal medicine #Lower risk #Medicine #Meta-analysis #Nutritional Studies and Diet #Observational study #Physiology #Polyunsaturated fatty acid #Randomized controlled trial
paper · doi:10.1093/nutrit/nuab078
openalex publication_date 2021/09/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/26
Abstract
CONTEXT: Randomized controlled trials (RCTs) testing supplementation with eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids have failed to provide evidence supporting a suggested inverse association between fish intake and dementia risk. OBJECTIVE: Dose-response analyses were conducted to evaluate associations between fish intake, all-cause dementia or Alzheimer's Disease (AD), and the effect of EPA/DHA supplementation on cognitive performance. DATA SOURCES: PubMed, Scopus and Web of Science databases were searched for original research evaluating either associations between fish intake and dementia or AD, or the impact of EPA and/or DHA supplementation on the risk of cognitive decline. DATA EXTRACTION: Data were collected on study characteristics and methods; number of cases/deaths (for observational studies); categories of exposure; model covariates; risk estimates from the most-adjusted model; type and dosage of supplementation (from RCTs); fatty acid levels in blood; and differences in cognition test results before and after supplementation. Risk of bias was assessed through the ROBINS-E and RoB2.0 tools for observational and experimental studies, respectively. DATA ANALYSIS: Weighted mixed-effects models were applied, allowing for the inclusion of studies with 2 levels of exposure. Based on findings with low/moderate risk of bias, fish intake of up to 2 portions (250 g) per week was associated with a 10% reduction (95% confidence interval [CI]: 0.79, 1.02, Ν = 5) in all-cause dementia and a 30% reduction (95% CI: 0.54, 0.89, Ν = 3) in AD risk. Changes in EPA and DHA body status had a positive impact on participants' executive functions, but not on their overall cognitive performance. CONCLUSION: The protection offered by fish intake against cognitive decline levels off at intakes higher than 2 portions/week and likely relates to the impact of EPA and DHA on the individual's executive functions, although there remain questions about the mechanisms linking the short- and long-term effects. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42019139528.
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