Fat, suggests a new study, may be the secret to remembering important things—like where you put your keys or how to navigate one-way streets to a favorite restaurant.
The link between eating fat and retaining memories was once a survival tool: when our ancestors found a source of nourishing food, it was helpful to remember how to get back for more. Research published in a May 2009 issue of the Proceedings of the National Academy of Sciences hints at the science behind the connection. When digesting fats that contain oleic acid—a “good” monounsaturated fatty acid found in olive oil, fish, nuts and soybeans—the small intestine produces a molecule called oleoylethanolamide (OEA). OEA binds to a receptor in the gut, which sends signals to the brain.
One of these signals ends up in a part of the brain called the hypothalamus, where it conveys a satisfying sense of fullness. A second message, according to the study, winds up in the amygdala, the almond-shaped center of the brain where emotionally charged memories are cemented into long-term memories (think: your wedding or where you were on September 11, 2001).
Daniele Piomelli, Ph.D., Pharm.D., and his colleagues at the University of California, Irvine, injected rats with OEA just after the animals had learned to master two challenges—one spatial, one emotional. The rodents had to find a submerged platform in cloudy water and then avoid a room where they were shocked. They were twice as likely to remember both solutions 48 hours after receiving OEA.