Data from the long-running Rush Memory and Aging Project, involving 960 participants who completed a food frequency questionnaire from 2004 to 2013, found that those who ate one daily serving of green, leafy vegetables had a slower rate of cognitive decline than people who rarely or never ate them. Those who ate at least one serving of leafy green vegetables showed an equivalent of being 11 years younger cognitively.

Participants had an average age of 81 at the beginning of the study. Analysis took into account such factors as seafood and alcohol consumption, smoking, high blood pressure, obesity, education level and amount of physical and cognitive activities.