Low Doses of Long-chain Polyunsaturated Fatty Acids Affect Cognitive Function in Elderly Japanese Men: A Randomized Controlled Trial

Several studies have reported that the supplementation of long-chain polyunsaturated fatty acids (LCPUFA), such as docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) improve cognitive function in the elderly. However, the doses used in these studies were higher than general dietary LCPUFA intake levels. This randomized, double-blind, placebo-controlled trial evaluated the effects of low doses of LCPUFA supplementation corresponding to general dietary intake on cognitive function in non-demented elderly Japanese participants. Japanese men aged 55-64 years were enrolled and randomly allocated to the placebo or LCPUFA group. Participants received 4 weeks of supplementation with LCPUFA-containing oil (DHA, 300 mg/day; EPA, 100 mg/day; and ARA, 120 mg/day) or purified olive oil as placebo. Event-related potential P300, reflecting cognitive processes, was measured before and after supplementation. A total of 113 participants completed the supplementation period, and the per-protocol analysis included 69 participants. Changes in P300 latency were significantly different between the placebo group (+13.6 msec) and the LCPUFA group (-1.8 msec) after supplementation. Significant increases in DHA (+0.9%) and ARA (+0.6%) contents in plasma phospholipids were observed in the LCPUFA group; no changes were observed in the placebo group. Dietary DHA, EPA, and ARA intake were in the normal range for Japan participants and remained unchanged during the study. These results suggest that low doses of LCPUFA supplementation have the potential to improve cognitive function in elderly Japanese men.