Association of Zinc, Iron, Copper, and Selenium Intakes with Low Cognitive Performance in Older Adults: A Cross-Sectional Study from National Health and Nutrition Examination Survey (NHANES)

Background: The association of zinc, iron, copper, and selenium intakes with cognitive function is poorly understood so far. Objective: To examine the associations of dietary and total zinc, iron, copper, and selenium intakes with low cognitive performance. Methods: Cross-sectional study data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 was used. Zinc, iron, copper, and selenium intakes from foods and supplements were estimated from two non-consecutive 24-hour diet recalls. Cognitive function was measured by the Consortium to Establish a Registry for Alzheimer's disease (CERAD) Word Learning sub-test, Animal Fluency test, and Digit Symbol Substitution test (DSST). For each cognitive measurement, people whose score were lower than the age group stratified lowest quartile were defined as low cognitive performance. Logistic regression and restricted cubic spline models were applied to examine the associations of dietary and total zinc, iron, copper, and selenium intakes with different measures of low cognitive performance. Results: A total of 2,332 adults aged 60 years or older were included. The association between zinc, iron, copper, and selenium intake and low cognitive performance was significant in different test. Compared with the lowest quartile of total copper intake, the weighted multivariate adjusted ORs (95% CI) of the highest quartile were 0.34 (0.16-0.75) for low cognitive performance in DSST. L-shaped associations between total copper or selenium and low cognitive performance in DSST and animal fluency were found. Conclusion: Dietary and total zinc, copper, and selenium intakes might be inversely associated with the prevalence of low cognitive performance.