08/05/2026
Omega-3 supplements have been promoted for brain health, but several randomized clinical trials have found little or no cognitive benefit from omega-3 supplementation in older adults and in people with Alzheimer’s disease.
A 2026 observational study reported an association between omega-3 supplement use and faster cognitive decline, potentially related to reduced brain glucose metabolism.
In short, after nearly two decades of studies, omega-3 supplements have not demonstrated consistent cognitive benefits for preventing cognitive decline or treating Alzheimer’s disease.
If you want to keep your brain healthy, pay attention to physical activity, sleep, cardiovascular health, social connection, and dietary patterns rich in whole plant foods. 🧠
References:
Freund-Levi Y, Eriksdotter-Jönhagen M, Cederholm T, et al. Omega-3 fatty acid treatment in 174 patients with mild to moderate Alzheimer disease: OmegAD study: a randomized double-blind trial. Arch Neurol. 2006;63(10):1402-1408. doi:10.1001/archneur.63.10.1402
https://pubmed.ncbi.nlm.nih.gov/17030655/
van de Rest O, Geleijnse JM, Kok FJ, et al. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial. Neurology. 2008;71(6):430-438. doi:10.1212/01.wnl.0000324268.45138.86
https://pubmed.ncbi.nlm.nih.gov/18678826/
Quinn JF, Raman R, Thomas RG, et al. Docosahexaenoic acid supplementation and cognitive decline in Alzheimer disease: a randomized trial. JAMA. 2010;304(17):1903-1911. doi:10.1001/jama.2010.1510
https://pubmed.ncbi.nlm.nih.gov/21045096/
Sydenham E, Dangour AD, Lim WS. Omega 3 fatty acid for the prevention of cognitive decline and dementia. Cochrane Database Syst Rev. 2012;2012(6):CD005379. Published 2012 Jun 13. doi:10.1002/14651858.CD005379.pub3
https://pubmed.ncbi.nlm.nih.gov/22696350/
Liao ZB, Hu ZC, Zeng GH, et al. The association between omega-3 supplementation and cognitive decline in older adults. J Prev Alzheimers Dis. 2026;13(6):100569. doi:10.1016/j.tjpad.2026.100569
https://pubmed.ncbi.nlm.nih.gov/42000571/
“Results: Omega-3 supplementation was associated with significantly accelerated cognitive decline.”