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Omega-3 (DHA and EPA) and global cognition: grade N

No benefit shown evidence. Direction: No effect.

N No benefit shown

Educational guidance, not medical advice

Why this grade

Rubric condition met: Adequate human RCTs (several meta-analyses, including a Cochrane review, and large RCTs) found no meaningful effect

Meta-analyses of RCTs in healthy and non-demented adults find no effect on global cognition (Alex 2020 g = 0.02; Brainard 2020, 38 RCTs, little or no effect; Cochrane 2012, no benefit in cognitively healthy older people; Suh 2024, 24 RCTs in adults aged 40 and over without dementia, no association with global cognition), and large RCTs in young, mid-life and older healthy adults were null. One BASF-funded RCT in 310 healthy adults found better global accuracy and speed with EPA-rich oil, the main conflicting result. Shahinfar 2025 (58 RCTs) reported a dose-related gain in global cognition at low GRADE certainty, but pooled healthy and clinical populations, had significant publication bias, and found no statistically significant difference in its healthy subgroup. Most participants were older adults, so N for younger adults rests on fewer trials.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)20102015202020252030Meta-analysisSystematic reviewRCTBrainard 2020, 2020: meta-analysis, n = 49,757, result not recordedSuh 2024, 2024: meta-analysis, n = 9,660, result not recordedSydenham 2012, 2012: systematic review, n = 4,080, result not recordedDanthiir 2018, 2018: RCT, n = 390, result not recordedPatan 2021, 2021: RCT, n = 310, result not recordedMaltais 2022, 2022: RCT, n = 193, result not recordedJackson 2012, 2012: RCT, n = 159, result not recordedShahinfar 2025, 2025: meta-analysis, n not recorded, result not recordedCooper 2015, 2015: meta-analysis, n not recorded, result not recordedAlex 2020, 2020: meta-analysis, n not recorded, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Jackson 20122012RCT159result not recorded
Sydenham 20122012systematic review4080result not recorded
Cooper 20152015meta-analysisnot recordedresult not recorded
Danthiir 20182018RCT390result not recorded
Alex 20202020meta-analysisnot recordedresult not recorded
Brainard 20202020meta-analysis49757result not recorded
Patan 20212021RCT310result not recorded
Maltais 20222022RCT193result not recorded
Suh 20242024meta-analysis9660result not recorded
Shahinfar 20252025meta-analysisnot recordedresult not recorded

A systematic review and dose response meta analysis of Omega 3 supplementation on cognitive function.

Shahinfar H, Yazdian Z, Avini NA. A systematic review and dose response meta analysis of Omega 3 supplementation on cognitive function Sci Rep, 2025. PMID 40836005

Result not recorded
Design
Systematic review and dose-response meta-analysis of 58 RCTs (GRADE assessed)
Population
Adults: healthy people and people with cognitive impairment, dementia or Alzheimer's disease (mixed populations)
Funding
Funding: not stated in the PubMed or Crossref record; full text not read.

The influence of n-3 polyunsaturated fatty acids on cognitive function in individuals without dementia: a systematic review and dose-response meta-analysis.

Suh SW, Lim E, Burm SY. The influence of n-3 polyunsaturated fatty acids on cognitive function in individuals without dementia: a systematic review and dose-response meta-analysis BMC Med, 2024. PMID 38468309

Result not recorded
Design
Systematic review and dose-response meta-analysis of 24 RCTs (follow-up 3 to 36 months)
Sample
n = 9,660
Population
Adults aged 40 and over without dementia, including some trials in people with mild cognitive impairment
Funding
Ottogi Ham Taiho Foundation (Research and Publication Projects); Korea Dementia Research Project (KDRC, HU20C0015); Korean Health Technology R&D Project (A092077) (full text and Crossref funder)

Supplementation with oil rich in eicosapentaenoic acid, but not in docosahexaenoic acid, improves global cognitive function in healthy, young adults: results from randomized controlled trials.

Patan MJ, Kennedy DO, Husberg C. Supplementation with oil rich in eicosapentaenoic acid, but not in docosahexaenoic acid, improves global cognitive function in healthy, young adults: results from randomized controlled trials Am J Clin Nutr, 2021. PMID 34113957

Result not recorded
Design
Randomized controlled trial (26 weeks), three arms
Sample
n = 310
Population
Healthy adults aged 25-49
Funding
BASF (Crossref and Europe PMC funder)

Long-chain Omega-3 fatty acids supplementation and cognitive performance throughout adulthood: A 6-month randomized controlled trial.

Maltais M, Lorrain D, Léveillé P. Long-chain Omega-3 fatty acids supplementation and cognitive performance throughout adulthood: A 6-month randomized controlled trial Prostaglandins Leukot Essent Fatty Acids, 2022. PMID 35338847

Result not recorded
Design
Randomized double-blind controlled trial (6 months)
Sample
n = 193
Population
Healthy adults aged 20 to 80
Funding
CIHR MOP119454

No effect of 12 weeks' supplementation with 1 g DHA-rich or EPA-rich fish oil on cognitive function or mood in healthy young adults aged 18-35 years.

Jackson PA, Deary ME, Reay JL. No effect of 12 weeks' supplementation with 1 g DHA-rich or EPA-rich fish oil on cognitive function or mood in healthy young adults aged 18-35 years Br J Nutr, 2012. PMID 21864417

Result not recorded
Design
Randomized placebo-controlled trial (12 weeks)
Sample
n = 159
Population
Healthy young adults aged 18-35
Funding
not stated

An 18-mo randomized, double-blind, placebo-controlled trial of DHA-rich fish oil to prevent age-related cognitive decline in cognitively normal older adults.

Danthiir V, Hosking DE, Nettelbeck T. An 18-mo randomized, double-blind, placebo-controlled trial of DHA-rich fish oil to prevent age-related cognitive decline in cognitively normal older adults Am J Clin Nutr, 2018. PMID 29722833

Result not recorded
Design
Randomized, double-blind, placebo-controlled trial (18 months)
Sample
n = 390
Population
Cognitively healthy community-dwelling adults aged 65-90 (Australia)
Funding
not stated

Omega-3 polyunsaturated fatty acid supplementation and cognition: A systematic review and meta-analysis.

Cooper RE, Tye C, Kuntsi J. Omega-3 polyunsaturated fatty acid supplementation and cognition: A systematic review and meta-analysis J Psychopharmacol, 2015. PMID 26040902

Result not recorded
Design
Systematic review and meta-analysis of 24 RCTs
Population
Healthy adults and school-aged children, plus children with ADHD and related disorders
Funding
not stated

Long-chain omega-3 polyunsaturated fatty acids and cognitive decline in non-demented adults: a systematic review and meta-analysis.

Alex A, Abbott KA, McEvoy M. Long-chain omega-3 polyunsaturated fatty acids and cognitive decline in non-demented adults: a systematic review and meta-analysis Nutr Rev, 2020. PMID 31841161

Result not recorded
Design
Systematic review and meta-analysis of 25 RCTs (PROSPERO CRD42017078664)
Population
Non-demented adults, including people with mild cognitive impairment
Funding
International Postgraduate Research Scholarship (Crossref funder)

Omega 3 fatty acid for the prevention of cognitive decline and dementia.

Sydenham E, Dangour AD, Lim WS. Omega 3 fatty acid for the prevention of cognitive decline and dementia Cochrane Database Syst Rev, 2012. PMID 22696350

Result not recorded
Design
Cochrane systematic review of 3 RCTs (minimum 6 months)
Sample
n = 4,080
Population
Cognitively healthy adults aged 60 and over
Funding
Medical Research Council MC_U122785832

Omega-3, Omega-6, and Polyunsaturated Fat for Cognition: Systematic Review and Meta-analysis of Randomized Trials.

Brainard JS, Jimoh OF, Deane KHO. Omega-3, Omega-6, and Polyunsaturated Fat for Cognition: Systematic Review and Meta-analysis of Randomized Trials J Am Med Dir Assoc, 2020. PMID 32305302

Result not recorded
Design
Systematic review and meta-analysis of 38 RCTs (41 comparisons), duration at least 24 weeks
Sample
n = 49,757
Population
Adults (mostly older adults)
Funding
World Health Organization (Crossref funder)

Search and history

Search (): (omega-3[ti] OR "n-3"[ti] OR docosahexaenoic[ti] OR DHA[ti] OR "fish oil"[ti]) AND (cognition[tiab] OR cognitive[tiab]) AND (healthy[tiab] OR non-demented[tiab] OR cognitively healthy[tiab]) AND (meta-analysis[pt] OR systematic review[pt])

  • Graded N (proposed): Proposed in the monograph draft
  • N to N (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page