​“It is well known that those with diabetes are at higher risk for cognitive impairment and Alzheimer’s disease. Some go so far as to call Alzheimer’s disease type 3 diabetes,” says Dan Nadeau, MD, program director at the Mary & Dick Allen Diabetes Center and Kris V. Iyer Endowed Chair in Diabetes Care.

In a study published in JAMA Internal Medicine, Dr. Emilio Ros and his colleagues from the Hospital Clinic in Barcelona, Spain conducted a study of 447 men and women aged 55 to 80 years to see whether changing their diet could affect their performance on cognitive tests. The study confirmed what we’ve known for a while: A diet rich in fruits, vegetables, olive oil, legumes, whole grains and fish is good for the brain. Those eating more nuts showed improvements in executive function skills. Those on a low fat diet did not perform as well. In a separate review published in the journal Epidemiology, researchers examined 12 studies and concluded that strong adherence to a Mediterranean-style diet was associated with better cognitive function, lower decline in brain activity, and a reduced risk of Alzheimer’s disease.

“The brain is 60 to 70% fat, and that fat comes from foods people eat,” says Nadeau. One of the more common fats in the brain is an unsaturated fat found in nuts, olive oil, sunflower seeds and avocados. Omega-3 fatty acids are also important for brain health, and found in canola oil, walnuts and soy foods. Longer chain omega-3 fatty acids such as DHA is found in fish and plays a role in fighting depression.

"Healthy fats can improve brain structure, health and memory," Nadeau says. Furthermore, he adds: "Dangerous unhealthy fats like trans fats found in processed foods, and saturated fats in red meat and high fat cheese accelerated cognitive decline, poor memory, and are linked with an increased risk of dementia."

Typically, those following a Mediterranean diet limit their intake of red meat and high-sugar foods, and focus instead on fresh fruits and vegetables, and healthy fats, like olive oil, fish, and eggs.

“It’s never too late to change your dietary patterns to improve your health,” says Ros. “The results, are especially encouraging since a Mediterranean diet can also lower cardiovascular risk,” adds Nadeau “If you intervene with a healthy dietary pattern in people who are at risk of cognitive failure, even in people who still haven’t had any memory complaints or loss of cognitive function, you can prevent cognitive deterioration,” Ros says.