The 1,946 participants in the 6-year study filled out questionnaires about their eating habits and had three mental function tests during the period. The researchers measured short-term and delayed memory by reading them stories and then asking them to recall parts of what had just been read to them. They also gave them a flashcard-like exercises involving symbols and numbers.
The participants' scores generally went down over time; however, those who consumed more than two servings of vegetables a day did about 40 percent better on the tests than did participants who didn't eat vegetables at all or didn't eat them very often.
Green leafy vegetables, like spinach, kale and collards, seemed to be particularly effective in preventing cognitive decline. The researchers think this might be due to the high amount of vitamin E such vegetables contain. Eating them with healthy fats like salad oil may increase the beneficial effect because oils aid the body in absorbing antioxidants, says lead author Martha Clare Morris, a researcher at the Rush Institute for Healthy Aging at Rush University Medical Center in Chicago.
The researchers also discovered that vegetable-eaters tended to be more physically active, adding to evidence that "what's good to your heart is good for your brain," neuroscientist Maria Carillo tells the AP.
Fruit did not show the same benefits for preventing cognitive decline, perhaps because they don't contain as much vitamin E as vegetables do.
The study was published in this week's issue of the journal Neurology.
Dr. Meir Stampfer of Harvard's School of Public Health says, "This is a sound paper and contributes to our understanding of cognitive decline.
"The findings specific for vegetables and not fruit add further credibility that this is not simply a marker of a more healthy lifestyle."
