[A version of this item appears in: Dementia: the Latest Evidence Newsletter (RWHT), Volume 3 Issue 1, August 2012].
Diets high in omega-3 long-chain polyunsaturated fatty acids (PUFA) had recently been suggested in some quarters to help protect people from cognitive decline and dementia. This Cochrane systematic review re-assessed the effects of omega-3 PUFA supplementation for the prevention of dementia and cognitive decline in cognitively healthy older people.
The authors examined randomised controlled trials about omega-3 PUFA interventions lasting a minimum of six months, given to people aged 60 years and over and without any obvious signs of dementia or cognitive impairment at the beginning of the studies. Data on incident dementia, cognitive function, the safety of these supplements and adherence were reviewed regarding the 4080 participants in three such trials.
Participants aged 60 and over had been assigned to consume either an omega-3 supplement (in the form of a pill or margarine spread) or a dummy “placebo” food supplement in the same format. Researchers used various types of tests to assess the participants’ cognitive performance and then tracked these individuals for a period of 6, 12 and 40 months.
The results showed that participants taking omega-3 fish oil supplements scored no better in memory and mental performance tests at the end of the trials than those given dummy treatments. The main reported side-effect of omega-3 PUFA supplementation was mild gastrointestinal problems. The authors found no direct evidence for the effect of omega-3 PUFA on incident dementia and no benefit of omega-3 PUFA supplementation on cognitive function in cognitively healthy older people.
Further studies of longer duration would be required to identify any possible slight effects of omega-3 PUFA supplementation in preventing cognitive decline in older people.
Sydenham, E. Dangour, AD. [and] Lim, WS. [et al] (2012). Omega 3 fatty acid for the prevention of cognitive decline and dementia. Cochrane Database of Systematic Reviews, 2012, Issue 6, No. CD005379. (Click here to view the PubMed abstract).
Fish oil capsules ‘may not slow mental decline’. London: NHS Choices, June 13th 2012. (Behind the headlines assessment).
An evidence update relating to CVDs from the Agency for Healthcare Research and Quality (AHRQ):
John M. Eisenberg Center for Clinical Decisions and Communications Science (2019). Omega-3 fatty acids and cardiovascular disease: current state of the evidence. Comparative effectiveness review summary guides for clinicians. [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US), 2017-.