Americans spend over $1 billion annually on fish oil supplements, hoping to boost brain health. But a new study from Keck Medicine of USC suggests this might be a costly placebo. The research, published in eBioMedicine, found that high-dose omega-3 supplements successfully reached the brain but did not improve memory, cognitive performance, or reduce brain cell loss in 365 older adults at increased risk for Alzheimer's disease.

Over a two-year, placebo-controlled trial, participants aged 55 - 80 who rarely ate fish took daily supplements containing 2,000 mg of DHA. While DHA levels in cerebrospinal fluid increased by 17%, cognitive test scores and hippocampal shrinkage showed no benefit. Lead investigator Dr. Hussein Naji Yassine noted, "We all wish there was a silver bullet for preventing Alzheimer's, but our findings showed that fish oil supplements do not appear to protect brain health."

The researchers now suspect that omega-3s may work better as part of a Mediterranean diet rather than as standalone pills. They're exploring how factors like genetics, diet, and health affect omega-3 absorption. Meanwhile, Dr. Yassine advises that maintaining overall health - exercise, sleep, balanced diet - is the brain's equivalent of regular car maintenance. In other words, skip the supplement aisle and head to the produce section.