Fernando Gomez-Pinilla suggests foods rich in omega-3 fatty acids -- such as salmon, walnuts and kiwi fruit -- can have additional nutrients not found in omega-3 supplements.

Gomez-Pinilla says scientists are learning which omega-3 fatty acids seem to be especially important.

One fatty acid -- docosahexaenoic acid, or DHA -- reduces oxidative stress and enhances synaptic plasticity and learning and memory. DHA is the most abundant omega-3 fatty acid in cell membranes in the brain.

"The brain and the body are deficient in the machinery to make DHA; it has to come through our diet," Gomez-Pinilla says in a statement. "Dietary deficiency of omega-3 fatty acids in humans has been associated with increased risk of several mental disorders, including attention-deficit disorder, dyslexia, dementia, depression, bipolar disorder and schizophrenia."

Gomez-Pinilla, who studies the effects of food, exercise and sleep on the brain, says omega-3 fatty acids are essential and he eats salmon three times a week.