To increase understanding of the biological mechanisms underlying the association, the researchers at Rush investigated the individual relations to cognitive decline of the primary nutrients and bioactives in green leafy vegetables, including vitamin K1 (phylloquinone), lutein, β-carotene, nitrate, folate, kaempferol, and α-tocopherol.
The study involved the 960 participants of the Memory and Aging Project, ages 58-99 years, who completed a food frequency questionnaire and had ≥2 cognitive assessments over a mean 4.7 years. The data was adjusted for age, sex, education, participation in cognitive activities, physical activities, smoking, and seafood and alcohol consumption. After controlling for these factors, consumption of green leafy vegetables was associated with slower cognitive decline; the decline rate for those in the highest quintile of intake (median 1.3 servings/d) was slower by the equivalent of being 11 years younger in age. Higher intakes of each of the nutrients and bioactives except β-carotene were individually associated with slower cognitive decline.
The conclusion was very clear, consumption of approximately 1 serving per day of green leafy vegetables and foods rich in phylloquinone, lutein, nitrate, folate, α-tocopherol, and kaempferol help to slow cognitive decline with aging.