October 16, 2015
Can eating healthier help stave off Alzheimer’s in old age? A rigorous new study suggests it might. Older men and women who ate a traditional Mediterranean-style diet, rich in fresh fruits, vegetables, fish, and whole grains, and supplemented with nuts or heart-healthy fats like olive oil, were less likely to suffer from the memory and thinking declines of advancing age.
“Our results suggest that in an older population, a Mediterranean diet supplemented with olive oil or nuts may counteract age-related cognitive decline,” the researchers note. “The lack of effective treatments for cognitive decline and dementia points to the need of preventive strategies to delay the onset or minimize the effects of these devastating conditions.”
For the study, conducted in Spain, researchers studied 447 older men and women whose average age was 67. All were at high risk for heart disease, but all had normal memory and thinking skills at the start of the study.
They divided them into three groups, who each followed a different diet for four to five years. One group ate a Mediterranean diet, and was told to add at least five tablespoons of extra-virgin olive oil a day. A second group also ate a Mediterranean diet but added 30 grams of mixed nuts daily – about two tablespoons of walnuts, almonds or hazelnuts. The third group was instructed to eat a low-fat diet.
Participants were given memory tests at the start of the study, and again at the end. The researchers found that those eating the Mediterranean diet – supplemented with either nuts or more olive oil – scored higher on tests of memory and thinking skills than those who ate the low-fat diet.
In those following the Mediterranean diet, improvements occurred in various areas of cognition, including the ability to memorize names or pay attention. They also did better on tests that require speed of thought and executive function, or the ability to plan and organize tasks. Executive function is among the first areas affected by Alzheimer’s disease, and is critical for everyday tasks like getting dressed or preparing a meal.
In contrast, those who adhered to a low-fat diet did worse on memory tests at the end of the study period.
During the course of the study, some of the volunteers developed mild cognitive impairment, a form of memory loss that can be a harbinger of Alzheimer’s disease or other forms of dementia. But none of the study participants developed full-blown dementia.
The results can’t prove that eating a Mediterranean style diet will prevent Alzheimer’s; the researchers stress that more research is needed to define the role of diet in dementia. But the findings do suggest that what you eat is important for long-term brain health.
“It’s never too late to change your diet,” said the study leader, Dr. Emilio Ros, of the Institut d’Investigacions Biomediques August Pi Sunyer, Hospital Clinic, in Barcelona. “Change your lifestyle before you become ill.”
Scientists aren’t sure why a Mediterranean style diet may be good for the brain. But the fresh fruits and vegetables and other foods that form the core of such a diet are high in antioxidants, which may help to counteract the effects of inflammation. Increasingly, doctors have tied inflammation to heart disease and diseases like Alzheimer’s.
Earlier research, relying on dietary questionnaires, has suggested that men and women who ate a Mediterranean diet were less likely to develop Alzheimer’s disease. Other studies have shown that the heart-healthy diet may help prevent those with mild cognitive impairment from progressing to full-blown Alzheimer’s. People who follow a Mediterranean diet are also at lower risk of developing diabetes, which has also been linked to an increased risk of Alzheimer’s.
This study was more rigorous than many past studies, randomly assigning participants to one of three diets. The results provide stronger evidence that consuming lots of fruits, vegetables and fish – along with nuts and olive oil — is good for the brain.
The main elements of the Mediterranean diet include:
*An abundance of plant foods, such as fruits, vegetables, cereals, nuts and beans.
*Using “good” fats, such as olive oil, rather than butter or lard.
*Moderate consumption of dairy products like cheese and yogurt.
*Eating moderate amounts of fish and poultry, rather than red meat.
*Finally, drinking a glass or two of red wine a day.
Many other factors besides diet, including the genes you inherit and advancing age, play an important role in who ultimately develops Alzheimer’s. Still, the findings add to a growing body of evidence that a heart-healthy lifestyle, with plenty of exercise, a sound diet, not smoking, and keeping weight down, may help keep the brain sharp.
Source: Cinta Valls-Pedret, MSc; Aleix Sala-Vila, DPharm PhD; Merce Serra-Mir, RD, et al: “Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial.” JAMA Internal Medicine, May 11, 2015