Intake of dark green vegetables may benefit specific cognitive domains in US men and women aged 60 years or older

Authors: BIGMAN, GALYA - Veterans Affairs Medical Center - Maryland; SHEA, KYLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; RUSU, MARIUS EMIL - University Of Medicine And Pharmacy; RYAN, ALICE - University Of Maryland School Of Medicine

Submitted to: Journal of Nutrition Health and Aging
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2023
Publication Date: 5/26/2023
Citation: Bigman, G., Shea, K., Rusu, M., Ryan, A.S. 2023. Intake of dark green vegetables may benefit specific cognitive domains in US men and women aged 60 years or older. Journal of Nutrition Health and Aging. https://doi.org/10.3233/NHA-220193.
DOI: https://doi.org/10.3233/NHA-220193

Interpretive Summary: Higher intakes of dark green vegetables (DGV) appear to be an important dietary component for maintaining cognitive function and reducing the risk of age-related cognitive decline in older age. Previous studies also suggest certain dietary components may have protective effects in specific cognitive domains. However, the association of DGV intake with domain-specific cognitive function has not been well-studied. We evaluated the association between DGV intake and overall cognitive function as well as learning, memory, executive function, and problem-solving, in adults 60 years and older using data from the National Health and Nutrition Examination Survey (NHANES 2011-2014). Cognitive function was assessed using four different tests. Dietary intakes were assessed by asking participants to recall what they ate over the previous 24 hours on two separate occasions. We found over 60% of adults 60+ years old reported consuming no DGV on either occasion. Those that reported consuming DGV had better overall cognitive function and better memory and learning ability. We also explored associations between phylloquinone, beta-carotene, and alpha-tocopherol intake (three micronutrients that are found in DGV) with cognitive function and found higher intakes of all three micronutrients were generally associated with better cognitive performance. Our findings suggest DGV intake may benefit certain domains of cognition such as learning and memory in adults 60 years and older. Due to the correlative design of our study, replication in longitudinal studies is needed to help clarify the temporal relationship between DGV intake and cognitive function.

Technical Abstract: BACKGROUND: The prevalence and relationship between dark green vegetables (DGV) and specific cognitive domains in the aging US population are not well-established for men and women. OBJECTIVE: To explore the associations between DGV, its bioactive nutrients, and cognitive function, including its specific domains, and whether they differ by sex. METHODS: The study analyzed a cross-sectional sample of 2,793 US adults aged 60 or older from the 2011-2014 NHANES. DGV was dichotomized, and bioactive nutrients were divided into quartiles. Weighted linear regressions were used to analyze the association between DGV, bioactive nutrients, and standardized cognitive function scores, including specific domains (CERAD, DWR, AFT, DSST), while controlling for covariates. The study also tested for sex-based effect modification. RESULTS: Overall, 61.7% of participants reported no DGV intake, and men reported no DGV intake more frequently than women (67.8 vs 56.5%, p < 0.001). DGV was associated with overall cognitive function (beta= 0.10, p = 0.024) and by its specific domains: memory-related i.e., learning and remembering (CERAD beta = 0.10, p = 0.015; DWR: beta = 0.10, p = 0.010), marginally associated with executive function (AFT: beta = 0.10, p = 0.075), but not with problem-solving (DSST: beta = 0.03, p = 0.587). Although the associations between bioactive nutrients and specific cognitive domains were mixed, a higher intake of these nutrients was still linked to higher overall cognitive function. Only beta-carotene and its associations with overall cognitive and AFT were modified by sex. CONCLUSION: The majority of US older adults (> 60%) lack DGV in their diet. Intake of DGV, which is rich in phylloquinone, beta-carotene, and alpha-tocopherol, may benefit certain domains of cognition in men and women, such as learning and memory.