According to a new study conducted by Chicago's Rush University Medical Center, just one serving of leafy green vegetables per day could help preserve memory and thinking skills as we get older. In fact, following such a diet may slow brain aging by up to 11 years.

The study involved 960 participants, who were followed over an average of 4.7 years. Their average age was 81 when the study began, and none of them were experiencing dementia. They got their thinking and memory skills tested every year, plus they completed food frequency questionnaires – these assessed how often they ate one or more half-cup servings of greens such as spinach, kale, lettuce or collard greens.

Although all of the participants' test scores decreased somewhat over the years, the rate of decline for the people who ate the most leafy vegetables (1.3 servings per day) was 0.05 standardized units slower than that of the people who ate the least vegetables (0.1 servings per day). While that might not sound like much, over the course of the study it added up to the equivalent of their being 11 years younger than their veg-shunning counterparts.

The study did account for factors such as alcohol consumption, smoking, high blood pressure, obesity, education level and amount of physical and cognitive activities. That said, the researchers do admit that the majority of the participants were older and white, so their findings may not apply to those who are younger or of other races.

"Adding a daily serving of green leafy vegetables to your diet may be a simple way to help promote brain health," says study author Martha Clare Morris. "There continue to be sharp increases in the percentage of people with dementia as the oldest age groups continue to grow in number. Effective strategies to prevent dementia are critically needed."