Nutrients and bioactives in green leafy vegetables and cognitive decline: Prospective study.
Level 3 - non-randomized controlled study
Prospective longitudinal cohort study with repeated cognitive assessments.
PubMed 29263222 · doi:10.1212/WNL.0000000000004815
What was done
A prospective cohort study evaluated 960 participants of the Memory and Aging Project (ages 58–99 years) who completed a food frequency questionnaire and underwent two or more cognitive assessments over a mean follow-up of 4.7 years. Linear mixed models assessed the relationship between cognitive decline and intakes of green leafy vegetables as well as specific bioactives (phylloquinone, lutein, β-carotene, nitrate, folate, kaempferol, and α-tocopherol), controlling for age, sex, education, cognitive activities, physical activities, smoking, and seafood and alcohol consumption.
What was found
Participants in the highest quintile of green leafy vegetable intake (median 1.3 servings/day) had a slower rate of cognitive decline compared to the lowest quintile (β = 0.05 standardized units, p = 0.0001), equivalent to being 11 years younger. Slower decline was individually associated with highest versus lowest quintiles of phylloquinone (β = 0.02, p = 0.002), lutein (β = 0.04, p = 0.002), folate (β = 0.05, p < 0.001), α-tocopherol (β = 0.03, p = 0.02), nitrate (β = 0.04, p = 0.002), and kaempferol (β = 0.04, p = 0.003). Intake of β-carotene was not significantly associated with slower decline (β = 0.02, p = 0.08).
Why it matters
This study links specific dietary bioactives found in leafy greens with preservation of cognitive function, supporting dietary recommendations of approximately one serving daily to slow cognitive decline in aging.
Limits
The observational cohort design cannot establish causality and is vulnerable to residual confounding. Dietary intake relied on self-reported food frequency questionnaires, and the study population was restricted to older adults in the Memory and Aging Project, limiting generalizability.
Cited by
- supports Research from Rush University showed that people who consume a serving of dark leafy greens daily have brains that test up to 11 years younger cognitively.