Eating foods rich in flavanols, like dark chocolate or berries, might help older people remember details better by boosting a specific part of the brain that separates similar memories—but it doesn’t help them remember things after a delay, which uses a different brain area.

The study found that eating cocoa with lots of flavanols helped older adults remember details better by improving a specific part of the brain called the dentate gyrus, but didn’t test whether it helped with other kinds of memory — so it supports the idea that the benefit is focused on just one brain area.