A two-year clinical trial has shown that high-dose omega-3 fish oil supplements do not improve memory or slow brain changes linked to Alzheimer's disease. The research involved 365 older adults at elevated risk for the condition. Results challenge widespread claims about the supplements' protective effects.
Researchers at Keck Medicine of USC conducted a placebo-controlled trial with participants aged 55 to 80 who rarely ate fish. Nearly half carried the APOE4 gene, a major genetic risk factor for late-onset Alzheimer's. Each day, half received 2,000 milligrams of DHA, an omega-3 fatty acid, while the others took a placebo.
DHA levels in cerebrospinal fluid rose by 17 percent after six months, confirming the supplement reached the brain. Yet cognitive tests and brain scans after two years showed no differences between groups in memory performance or shrinkage of the hippocampus.
Hussein Naji Yassine, the lead investigator, stated that fish oil supplements do not appear to protect brain health. He noted that omega-3s may work better as part of a Mediterranean-style diet rather than in pill form.
The study, published in eBioMedicine, reinforces that regular exercise, quality sleep and balanced eating remain key for reducing Alzheimer's risk.
