Fish oil supplements are a popular choice for those looking to protect their memory as they age. But a new two-year study suggests the capsules may not deliver the brain benefits that many consumers expect. Even when omega-3 fatty acids reached the brain, researchers found they did not enhance memory or prevent Alzheimer’s disease -related changes.

The clinical trial, led by researchers at the University of Southern California and published in eBioMedicine , involved 365 adults aged 55 to 80 years old. They rarely ate fish and had at least one risk factor for dementia. Researchers randomly assigned them to take either 2,000 milligrams of DHA daily, an omega-3 fatty acid found in fish oil, or a placebo.

The researchers saw no major differences in cognitive performance between the groups after two years.…