Spinach, kale, and collards
These plants contain beneficial bioactive compounds
A series of studies by researchers at the Rush University Medical Center in Chicago found links between diet and cognitive decline and Alzheimer’s disease (AD). Participants included about 900 Chicago-area residents free of dementia at baseline with an average age of about 80 years. Follow-up lasted 5-6 years on average. An initial study found that higher adherence to the brain-healthy MIND diet predicted slower rate of cognitive decline. This diet is a hybrid between the DASH diet (designed to reduce hypertension) and the widely recommended Mediterranean diet.
Next, the researchers tested the relative associations of the MIND diet, the DASH diet, and the Mediterranean diet with respect to the risk of developing AD. Compared to the lowest one-third of MIND diet scores (that is, less adherence to the diet), participants in the highest one-third of MIND diet scores had a 53 percent lower risk of developing AD after adjusting for age, sex, education and participation in cognitively stimulating activities. Participants in the top one-third of DASH and Mediterranean diet adherence had 35 and 54 percent lower risks of AD, respectively. The MIND diet specifies only two vegetable servings per day and two berry servings and one fish serving per week, among other things. Thus, small improvements in diet quality may substantially reduce risk of AD in older people.
Another Rush study investigated the links between leafy green vegetable consumption, bioactive chemicals in leafy green vegetables, and cognitive decline. Participants with the highest quintile of leafy green vegetable intake had significantly a slower rate of cognitive decline compared to participants in the lowest quintile. This difference equated to being 11 years younger. Similarly, participants with the highest quintile of the bioactive compounds phylloquinone, folate, lutein, beta-carotene, alpha-tocopherol, nitrate, and kaempferol had significantly slower rate of cognitive decline compared to participants with the lowest quintile of intake. Notably, the average leafy green vegetable intake for the highest quintile was only 1.29 servings per day. Thus, a single serving of leafy green vegetables, such as spinach, kale, or collards, may reduce the risk of cognitive decline in older people.
A final study investigated flavonoids, a class of more than 5,000 bioactive compounds found in fruits and vegetables. Several groups of flavonoids, including flavonols, exhibit antioxidant and anti-inflammatory properties. Kale, tomatoes, tea, spinach, broccoli, apples, oranges, and pears contain lots of flavonols. Previous research suggested that diets rich in flavonols protect against AD and cognitive decline. The Rush study confirmed that higher intake of flavonols predicted lower risk of incident AD. Compared to participants in the lowest quintile of flavonol intake, those in the highest quintile had a 48 percent lower risk of developing AD. This result was independent of numerous factors, such as age, education, and physical activity, known to be associated with AD. These studies provides further evidence that eating more leafy green veggies and fruits may reduce your risk of mental deterioration in old age.