[www.ncbi.nlm.nih.gov]

In this prospective study of an older US community population, the consumption of green leafy vegetables was linearly associated with slower cognitive decline. The rate of decline among those who consumed 1–2 servings per day was the equivalent of being 11 years younger compared with those who rarely or never consumed green leafy vegetables.

Many prospective studies report protective relations against dementia with dietary intakes of folate12,–16 and ß-carotene,17,–20 although the evidence is by no means consistent for either folate21,–24 or ß-carotene.17,25,–27 One randomized trial of 3-year supplementation with folic acid in individuals with biochemical evidence of marginal folate status found significantly slower cognitive decline compared with placebo.28 The effect of ß-carotene supplementation on cognitive decline was also tested in randomized trials,29,30 with protective benefit demonstrated only after 18 years of supplementation.29

These nutrients for which green leafy vegetables are a rich source may have independent mechanisms of action that synergistically protect the brain. Serum carotenoid levels were associated with less severe periventricular white matter lesions, particularly in older smokers.35 In addition, lutein has been shown to reduce phospholipid peroxidation in human erythrocytes,36 and to attenuate oxidative stress and mitochondrial dysfunction37 and neuroinflammation.38 Folate was reported to inhibit tau phosphorylation and APP, PS1, and Aß protein levels that underlie Alzheimer disease pathogenesis, and to increase methylation potential and DNA methyltransferase activity.39

Consumption of green leafy vegetables may help to slow decline in cognitive abilities with older age, perhaps due to the neuroprotective actions of lutein, folate, ß-carotene, and phylloquinone. The addition of a daily serving of green leafy vegetables to one's diet may be a simple way to contribute to brain health.