Protocol
Omega-3 DHA 1–2 g/day
DHA is concentrated in the brain, but supplementing it has not improved measured cognition in older adults in the larger and longer trials.
Grade D, tested: a human randomized trial looked for a benefit on the endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded and did not find one. How to read a grade →
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How this letter has changedLatest: October 2026 · Added.
Liao et al. (J Prev Alzheimers Dis, 2026; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 42000571) reported faster cognitive decline among older adults in the ADNI cohort who took omega-3 supplements, and Dyall and Plourde (J Prev Alzheimers Dis, 2026; PMID 42612546) replied that confounding and method limits may explain it. Supplement type and dose were not recorded, so this is not a test of the DHA dose the protocol names. Both are now cited on the DHA cognition protocol, whose B was already under review for resting on a single trial. The letter does not move on observational data.PMID 42000571 PMID 42612546
The DHA 1 to 2 g/day protocol held a B on one trial, MIDAS (Yurko-Mauro et al., Alzheimers Dement 2010; PMID 20434961), which gave 900 mg/day, improved one memory test of several and was led by an employee of the company that made the DHA tested. The larger and longer trials are null: EPOCH (Danthiir et al., Am J Clin Nutr 2018; PMID 29722833) at 1,720 mg/day for 18 months, MAPT (Andrieu et al., Lancet Neurol 2017; PMID 28359749) over 3 years, and the DHA-specific meta-analysis A study that pools the numbers from several trials into one combined estimate. (Balachandar et al., Eur J Clin Pharmacol 2020; PMID 32060571). A Cochrane review of cardiovascular prevention that the record cited for cognition has been removed. Tested, no benefit: D on Route 2. Editor adjudication, October 2026.PMID 20434961 PMID 29722833 PMID 28359749 PMID 32060571
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This protocol is the fish oil DHA at 1 to 2 grams a day for the aging brain. In older adults, studies at or near this dose found no gain in memory or thinking, including one that lasted 3 years. A review of DHA studies found no benefit in any area of thinking. The one positive study used a lower dose than this protocol.
DHA is concentrated in the brain, but supplementing it has not improved measured cognition in older adults in the larger and longer trials. The one positive trial, MIDAS, gave 900 mg/day for 24 weeks and improved one memory test of several; its first author was employed by the company that made the DHA tested. Trials inside this protocol's dose range were null.
Why this gradeGrade D, tested, no benefit. The reasoning, and what the grade does not cover.
Grade D, Route 2: tested in older adults and no benefit found. The trials at or near this protocol's 1 to 2 g/day dose were null (EPOCH at 1,720 mg/day for 18 months; MAPT at 800 mg/day for 3 years), and the DHA-specific meta-analysis was null on every domain. The only positive trial (MIDAS) used 900 mg/day, below the protocol's dose, was positive on one test of several, and was led by an employee of the maker of the DHA it tested. Moved from B in October 2026 by editor adjudication: the B rested on MIDAS alone, and the Cochrane review previously cited (PMID 32114706) studied cardiovascular disease, not cognition, and has been removed from this record.
WHAT THIS GRADE DOES NOT COVERDHA in infants and children, which is a different population; mild cognitive impairment, where small trials are mixed and the pooled analyses combine DHA with EPA; and EPA or mixed fish oil for cardiovascular outcomes, which is graded on the omega-3 record.
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The evidence, in fullSeven papers, each linked to its PubMed record.
Yurko-Mauro et al. (Alzheimers Dement, 2010; PMID 20434961): MIDAS, 485 adults aged 55 and over, algal DHA 900 mg/day for 24 weeks; better on one paired-associate learning test, null on working memory and executive function. The first author was employed by the company that made the DHA tested. Danthiir et al. (Am J Clin Nutr, 2018; PMID 29722833): EPOCH, 390 cognitively healthy adults aged 65 to 90, 1,720 mg/day DHA for 18 months; no benefit on any cognitive domain and slightly slower psychomotor speed. Andrieu et al. (Lancet Neurol, 2017; PMID 28359749): MAPT, 1,680 adults aged 70 and over, 800 mg/day DHA with 225 mg EPA for 3 years; no effect on a blinded cognitive composite. Balachandar et al. (Eur J Clin Pharmacol, 2020; PMID 32060571): meta-analysis of DHA in age-related cognitive decline, 10 studies, 2,327 participants; no significant effect on memory, attention, working memory or executive function. Mazereeuw et al. (Neurobiol Aging, 2012; PMID 22305186): meta-analysis of omega-3 trials; no effect on composite memory in healthy or Alzheimer's subjects, small domain effects only in cognitive impairment without dementia. Liao et al. (J Prev Alzheimers Dis, 2026; PMID 42000571): in the Alzheimer's Disease Neuroimaging Initiative cohort, older adults reporting omega-3 supplement use declined faster on MMSE, ADAS-Cog13 and CDR-SB than non-users. Observational, with supplement type and dose unrecorded, and a published reply by Dyall and Plourde (J Prev Alzheimers Dis, 2026; PMID 42612546) argues that confounding and method limits may explain the association. It carries no grade and is listed as context beside the randomized trials above.
For cognitive applications, track MoCA or ADAS-Cog at baseline and 6 months. The Omega-3 Index The share of EPA and DHA among the fatty acids in red blood cell membranes, reported as a percentage. at baseline and 4 months: DHA specifically targets neuronal membrane composition and the index reflects tissue uptake. If tracking for depression, use the PHQ-9 at baseline and 8 weeks; benefit appears most pronounced in those with low baseline omega-3 status.
Evidence notes: randomized trial, meta-analysis
Endpoint graded: Cognitive function in older adults (functional)
Last reviewed: July 2026
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These statements have not been evaluated by the Food and Drug Administration. Any grade on this page describes the strength of published human trial evidence in the populations studied. It is not a recommendation for any individual and is not medical advice. Starting, stopping or changing any supplement or medication is a decision for your physician.
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(docosahexaenoic[tiab] OR DHA[tiab]) AND (cognit*[tiab] OR memory[tiab]) AND (older[tiab] OR elderly[tiab] OR aged[mh]) AND randomized controlled trial[pt]Grades move when new trials publish. A free monthly email lists every grade EBL moved, with the reason and the trial behind it: the sign-up is on the Evidence Log →