Two-year trial finds no brain benefits from fish oil supplements

Researchers at Keck Medicine of USC ran a two-year trial with 365 adults aged 55–80 at elevated Alzheimer's risk. Daily 2,000 mg DHA raised cerebrospinal fluid levels by 17% but produced no gains in memory or protection against hippocampal shrinkage.

• 365 participants aged 55–80; 47% carried the APOE4 variant
• Daily dose of 2,000 mg DHA in a double-blind, placebo-controlled trial
• DHA in cerebrospinal fluid rose 17% after six months
• No cognitive benefit or protection against hippocampus shrinkage