Eating kale may help older adults slow the decline in cognitive skills

But at what cost?

Swapping out a salad for French fries is obviously a smart choice for keeping your weight down, but it also seems to be good for your brain. A recent study found that consumption of green leafy vegetables may help slow the decline in cognitive abilities—or brain function—in older adults.

The study by researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts found that those who ate about one-and-a-half servings of green leafy vegetables per day had the cognitive functioning of people roughly eleven years younger than those who ate little or no leafy greens.

The finding is striking given that dementia, a decline in memory and other brain functions, affects between four and five million older Americans, and with the growing number of aging Americans, this number is expected to increase three-fold by 2050.

Tufts researchers, working in collaboration with scientists at Rush University, followed 960 adults between the ages of fifty-eight and ninety-nine, as part of the Rush Memory and Aging Project. Each year, participants took tests that assessed different aspects of brain function, including memory and learning. Researchers also looked at the consumption of green leafy vegetables—especially cooked spinach, kale, and collard greens and raw lettuce—at the time participants enrolled in the study and approximately five years later. The study was recently published in the journal Neurology.

“The benefit to brain health was obtained simply by meeting dietary recommendations,” said senior author Sarah Booth, senior scientist and lab director of the Vitamin K Laboratory and director of the HNRCA. “This emphasizes not only the importance, but feasibility, of incorporating leafy greens into the diet.”

Researchers found that it wasn’t just overall intake of leafy greens that mattered. “We were able to tease out certain nutrients in leafy green vegetables that are suggested to have a role in brain health,” said Booth. Nutrients such as folate, vitamin K, and lutein, which are all abundant in leafy greens, were also suggested to slow cognitive decline.

The findings from this study open up many questions surrounding how green leafy vegetables, and the nutrients in them, protect the brain. Booth said that additional research is already in progress, involving analyses of brain sections of deceased participants who agreed to donate their tissues to the study.

Though the exact mechanisms at work are still unclear, the message is clear, Booth said: eating green leafy vegetables is good for your brain as you age. As dietary recommendations already state, aim for at least one to two servings—equivalent to one to two cups—per day of those leafy greens.