Omega-3 Fatty Acids for Cognitive Function

Research suggests that omega-3 fatty acids — particularly DHA and EPA derived from marine sources — may offer some benefit for cognitive health, especially in the earlier stages of cognitive decline, though the evidence is notably inconsistent across different populations and study designs. A 2019 systematic review of 14 randomized controlled trials found that ten reported improvements in at least one area of cognitive function in older adults, and multiple reviews and meta-analyses indicate that omega-3 intake may be associated with lower rates of mild cognitive impairment, with DHA supplementation appearing more promising for those in early decline than for those with established Alzheimer's disease. However, a large well-designed clinical trial in healthy older adults found no significant cognitive benefit after three years of supplementation, a 2020 meta-analysis concluded that omega-3s did not consistently improve cognition in Alzheimer's patients, and a 2024 clinical review similarly listed omega-3 fatty acids among interventions found to be ineffective for Alzheimer's disease. Taken together, the body of evidence — spanning randomized controlled trials, meta-analyses, systematic reviews, and mechanistic reviews — presents a mixed picture in which factors such as the stage of cognitive decline, individual genetics, trial duration, and dosage may all influence outcomes, and researchers consistently call for more rigorous, long-term studies before firm conclusions can be drawn.