Epidemiology cohorts reveal associations between levels or intake of omega-3 polyunsaturated fatty acids (n-3 PUFA) and a lower risk of Alzheimer’s disease (AD). However, the results of randomized clinical trials have been inconsistent.
Objective:
A systematic review was performed to understand the effects of n-3 PUFA supplementation on cognition in adults. The objective was to present suggestions for new study designs to translate epidemiological findings into effective clinical trials.
Methods:
A database search was conducted on PubMed (MEDLINE) and Web of Science to retrieve articles published between 2000 and 2023 that evaluated the effects of n-3 PUFA supplementation on cognitive function. Subsequently, the search results were filtered to collect randomized controlled trials with 100 or more participants, n-3 PUFA supplementation was one of the interventions, cognition was an outcome of interest, and participants were at least 18 years of age.
Results:
A total of 24 articles met the inclusion criteria. In 5 of the 24 studies reviewed, supplementation with n-3 PUFAs improved cognition. All four trials in persons with AD reported null outcomes. Most of the n-3 PUFA studies in cognitively normal individuals or participants with mild cognitive impairment were null, not powered to detect small effect sizes, or selected participants without dementia risk factors.
Conclusions:
We recommend that newer n-3 PUFA supplement trials targeting AD prevention be personalized. For the general population, the null hypothesis appears to be correct, and future interventions are needed to identify and test dietary patterns that include PUFA-rich food rather than supplements.
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