By Emily Sohn, September/October 2009
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.
“A foraging animal needs to remember not just that it’s eating a nice avocado in the forest,” says Piomelli. “It needs to remember to make a right or left turn at the third branch, not the fourth,” to find it again.
Piomelli’s preliminary results suggest that OEA might help people form these same sorts of memories, but more research is needed to say for sure. The relationship is complex, and OEA is far from the only piece of the puzzle, says Eleftheria Maratos-Flier, M.D., an endocrinologist at Harvard Medical School. “[OEA] probably plays a role, but it’s small.”
Still, with a newly clarified picture of how OEA works, scientists hope to develop drugs that might improve memory and treat brain disorders, such as Alzheimer’s.
In the meantime, it can’t hurt to eat nuts, salmon, vegetable oils and other sources of healthy fats. They’re good for you and they might help you to remember, especially if you eat them right before an experience you don’t want to forget. Fat starts being absorbed—and OEA is at its peak—10 to 20 minutes after a meal. It’s then, says Piomelli, that your gut and brain are primed to strengthen memories.