Want to keep your brain sharp? Eat a lot of greens, researchers suggest.
As if veggies didn't have enough benefits to boast, they also prevent the decline of cognitive abilities.
Study author Martha Clare Morris, a professor of nutrition science at Rush Medical College in Chicago and her colleagues, recruited 960 participants of the Memory and Aging Project, aged 58-99 years (average age 81), not suffering from any type of dementia.
They completed a food frequency questionnaire and based on the results, they were split into five groups.
"My goal every day is to have a big salad," says Candace Bishop, one of the study participants who ranked highly on the veggie eating scale. "I get those bags of dark, leafy salad mixes."
The top 20% reported eating an average of 1.3 servings of leafy greens a day, while the bottom fifth ate little or no greens at all. Researchers then proceeded to follow these people for a period of five years, monitoring any potential cognitive decline.
They found that the more greens people ate, the better they were able to maintain their cognitive functions and stay sharp. The correlation carried out for all groups.
Of course, this study established only a correlation, and no causation has been determined. In other words, it might not be the greens themselves that help the brain, but some other, unforeseen element. Researchers adjusted for other factors that might play a role, such as lifestyle, education, and overall health, but there may yet be an unforeseen factor causing the effect. Still, this is consistent with what previous studies reported.
For instance, a 2017 study found that lutein, a carotenoid commonly found in leafy greens and vegetables protects the brain against decay and diseases such as Alzheimer's. Another study that exclusively included women published in 2006 also reports similar conclusions, and a previous effort from the same team suggested that vitamin K plays a key role.
"Our study identified some very novel associations," said Morris in 2015, before the work was peer-reviewed. "No other studies have looked at vitamin K in relation to change in cognitive abilities over time, and only a limited number of studies have found some association with lutein." Other studies have linked folate and beta-carotene intake with slower cognitive decline.
Vitamin E and K, lutein, beta-carotene, and folate have all been proposed as the underlying reason for these benefits. However, it may be not one, but rather the whole cocktail of nutrients that does the magic. Morris says more work is needed to establish this.
While the exact mechanism remains an area of active research, it's becoming increasingly clear that veggies and leafy greens are good for you in a variety of ways.
The study, Nutrients and bioactives in green leafy vegetables and cognitive decline: Prospective study, was published in Neurology. doi: 10.1212/WNL.0000000000004815