Researchers evaluated the eating habits and mental ability of more than 950 older adults for an average of five years.
Those who consumed one or two servings of foods such as spinach, kale, mustard greens and/or collards daily experienced slower mental deterioration than those who ate no leafy greens at all, the study found.
The brain benefits associated with dark leafy greens likely stem from several key nutrients, particularly vitamin K, said study lead author Martha Clare Morris of Rush University Medical Center in Chicago.
The researchers “observed a protective benefit from just one serving per day of green leafy vegetables,” which are known to be rich in vitamin K, added Morris, a nutritional epidemiologist at the Rush Alzheimer’s Disease Center.
Morris was scheduled to present her team’s findings Monday at the annual meeting of the American Society for Nutrition in Boston. Research presented at meetings is usually considered preliminary until published in a peer-reviewed medical journal.
The study cannot actually prove that leafy greens preserve clarity of thinking.
But another expert, Dr. Yvette Sheline, said the finding is both “interesting and in some ways surprising.”
“It makes sense that leafy green vegetables would have an effect on mental health,” said Sheline, a professor of psychiatry and neurology at the University of Pennsylvania Perelman School of Medicine.
“We know generally that what you eat, or don’t eat, can affect your risk for high blood pressure and vascular disease, which can both then worsen the course of dementia,” she said.
But exactly how leafy greens may alter dementia risk remains a mystery, Sheline said.