Eating two to three servings of vegetables every day might help keep the mind sharp in old age, a study suggests.

The new findings add to the scientific evidence suggesting that a diet packed with vegetables might shore up the memory and protect against Alzheimer’s.

Martha Clare Morris of the Rush University Medical Center and her colleagues studied 3,718 Chicago residents ages 65 and older.  Each senior filled out a diet questionnaire and took at least two memory tests during a six year period.

Test scores usually worsen slightly as time goes on, but seniors who said they ate 2.8 servings of vegetables a day saw their rate of cognitive change slowed by 40% during the study.  A serving in the study was defined as a half-cup.

“People who ate more vegetables could think faster and had better memories,” Morris says.  Green leafy vegetables such as spinach, kale, or romaine lettuce provided the most benefit, she says.

The oldest people in this study, those at highest risk for Alzheimer’s, showed the most memory protection when they reported eating a vegetable-laden diet.  The study appears in Neurology.

At the same time, the study found fruit consumption was not associated with a brain benefit.  Other researchers have found fruit to be associated with protection, so experts still recommend fruit.

“Don’t throw out your oranges – just step up your vegetable intake,” says Elizabeth Edgerly of the Alzheimer’s Association.  Foods that reduce the risk of heart disease might protect the brain, she says.  That heart-healthy diet includes whole grains, fish such as salmon and a wide variety of fruits and vegetables, particularly the dark skinned ones that are thought to contain high levels of brain-protective substances called antioxidants, she says.