Daily supplements with the omega-3 fatty acid docosahexaenoic acid (DHA) may improve both memory function and heart health in healthy older adults.
In a randomized controlled trial in 485 healthy people with memory complaints, individuals who took algal DHA capsules (900mg/day) for six months had almost double the reduction in errors on a test that measures learning and memory performance versus those who took a placebo (1). The benefit was roughly equivalent to having the learning and memory skills of someone three years younger.
Cognitive decline occurs naturally as we age, and precedes diseases such as Alzheimer's. However, according to another randomized controlled trial involving 402 people, the omega-3 fatty acid supplements (2 g/day for 18 months) did not benefit people already suffering from Alzheimer’s disease (2).
Researchers commented that these two studies raise the possibility that interventions for Alzheimer's must be given very early in the disease for them to be truly effective.