The Cochrane Collaboration performed the review and published their findings in the Cochrane Database of Systematic Reviews. After looking at all of the studies of omega-3 fats and changes in thinking (cognitive) ability, the researchers found three high-quality trials to review. These trials together included 4,080 healthy people over age 60 who were given supplements providing 400 to 1,800 mg of the omega-3 fats, DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), per day or placebo. They were monitored for cognitive change for 6 to 24 months.
The authors summarized: “Omega-3 PUFAs [polyunsaturated fatty acids] were shown to provide no benefit to cognitive function among cognitively healthy older people who took a variety of cognitive tests at baseline and final follow-up, including the Mini-Mental State Examination and tests of memory and executive function.” They also noted that longer trials might yet reveal a benefit from supplementing with omega-3 fats, and encouraged the use of omega-3 fats for their other health benefits.
Cochrane reviews are considered one of the highest standards for evidence-based practice. They analyze studies with a strict set of criteria, looking for high-quality study methods as well as any potential bias on the part of the researchers. However, the conclusions they reach are very specific: in this case, the finding is that there is not enough evidence at this time to suggest that healthy seniors using omega-3 supplements are protected from cognitive decline.
Whether different amounts of omega-3s might show different effects, whether omega-3 fats prevent dementia over longer periods of time, or whether they may benefit people who already have age-related cognitive decline or dementia still needs to be explored.
Although omega-3 fats may not prevent cognitive decline in healthy older people, research has shown that there are several other solid reasons to eat cold-water fish or take omega-3 fatty acid supplements:
(Cochrane Database Syst Rev 2012;6:CD005379)