(CNN) -Following a plant based, Mediterranean diet has been linked to a lower risk of heart disease, but does this type of diet also help preserve memory?
A new study suggests eating a Mediterranean diet supplemented with extra virgin olive oil or nuts is associated with better memory.
A busy market in the heart of Barcelona; fruits and vegetables are plentiful. Shoppers line up to buy fresh fish, olives and nuts…all of these are key foods in a Mediterranean diet. Following this type of diet has been linked to a reduced risk of heart disease.
"We are surprised at the tremendous power of food and nutrients in foods to influence health," said Dr. Emilio Ros.
Recent evidence suggests a relationship between diet and cognitive function. In order to better understand the potential benefits of a Mediterranean diet on memory, Dr. Ros and co-authors randomly assigned 447 patients to three different types of diets. All patients were at high risk of developing heart disease and were an average of 67 years old. Two groups were asked to follow the Mediterranean diet and either add olive oil or nuts.
"They had to consume at least five tablespoons full per day," Dr. Ros said.
The second group was given a handful of walnuts, almonds and hazelnuts to eat daily. The third, a control group, was just told to reduce the amount of fat in their diet. Patients were followed for an average of four years and periodically tested on various memory skills.
"The group with nuts did better compared to the control group in memory tests, memorizing names or words, while the olive oil group did better on tests that require speed of thought, your frontal function, your executive function," Dr. Ros said.
The study appeared in the journal JAMA Internal Medicine.
"They improved over baseline, not only counteracted age related cognitive decline, but it improved cognition," Dr. Ros said.
Memory function in the control group declined over time, consistent with what is seen with normal aging.
"It's never too late to change your diet toward a good diet. You should change your lifestyle before you are ill. It's like you have a tremendous health capsule, which is your daily food," Dr. Ros said.
This is among the first large clinical trials assessing how diet can affect memory.
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