Abstract

BACKGROUNDMarine long‐chain omega‐3 (n‐3) fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been associated with lower risk of cognitive decline. N‐3 fatty acids may help to maintain neuronal tissue integrity1 and enhance synaptic plasticity;2 may have direct neuroprotective effects, antioxidant and anti‐inflammatory properties,3 and may reduce amyloid beta accumulation,4 important in Alzheimer's disease pathology. Marine n‐3 fats may reduce the incidence of hypertension, or dyslipidemia,5 which in turn are associated with cognitive decline.6,7 A meta‐analysis of 21 prospective observational studies reported that greater fish and marine n‐3 intakes were associated with lower cognitive impairment risk.8RESEARCH IN CONTEXTSystematic Review: The authors conducted a PubMed search to review the literature and have cited the relevant works, including meta‐analyses of randomized clinical trials of marine n‐3 fatty acids and cognitive function. Previous clinical trials have been small, of short duration, and few were in general community‐dwelling healthy older adults.Interpretation: Our null findings for marine n‐3 fats and cognition in the VITAL trial cognitive ancillary study contribute to the existing literature in that it was a large randomized clinical trial of n‐3 fatty acids of 2 to 3 years duration among 4218 relatively healthy community‐dwelling older adults, including close