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

source extracted confidence: high 2026-04-09
#alzheimer-disease #animals #cognitive-dysfunction #dietary-supplements #docosahexaenoic-acids

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

Kosti et al., 2022 | Nutr Rev | Meta Analysis

Citation

Kosti Rena I, Kasdagli Maria I, ... Naska Androniki. 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. Nutr Rev. 2022-May-09;80(6):1445-1458. doi:10.1093/nutrit/nuab078

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.

Key Findings

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.

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition cognitive

MeSH Terms

  • Alzheimer Disease
  • Animals
  • Cognitive Dysfunction
  • Dietary Supplements
  • Docosahexaenoic Acids
  • Eicosapentaenoic Acid
  • Fatty Acids, Omega-3
  • Humans

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Systematic Review
  • Vertical: omega-3

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09