Fish Oil Supplements Have No Beneficial Effect on Cognitive Function in Healthy Older Adults
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In the largest study of its kind to date, fish oil supplements were found to have no effect on cognitive function in cognitively healthy older people.
The randomized, double-blind trial included 867 patients 70 to 79 years of age recruited from 20 general practices in England and Wales. All participants consumed two vanilla-flavored gelatin capsules daily for 24 months. In the treatment arm, the capsules contained a total of 200 mg eicosapentaenoic acid (EPA) plus 500 mg docosahexaenoic acid (DHA); in the placebo arm, the capsules contained olive oil. Trained research nurses administered a battery of cognitive tests—including the primary outcome, the California Verbal Learning Test (CVLT)—at baseline and 24 months.
At 24 months, mean (± SD) serum EPA and DHA concentrations were significantly higher in the active arm (49.9 ± 2.7 mg EPA/L; 95.6 ± 3.1 mg DHA/L) than in the placebo arm (39.1 ± 3.1 mg EPA/L; 70.7 ± 2.9 mg DHA/L). However, there was no change in cognitive function scores from baseline to 24 months, and intention-to-treat analysis showed no significant differences between trial arms at 24 months in the CVLT or any secondary cognitive outcome.
The authors speculated that the lack of decline in the control arm and the relatively short intervention period may have limited the ability to detect any potential beneficial effect of fish oil on cognitive function in this study.
Am J Clin Nutr. 2010;91(6):1725-32.