With the global population aging rapidly, cognitive disorders such as mild cognitive impairment and Alzheimer’s disease are becoming increasingly prevalent and present a growing public health challenge. As the number of dementia cases is expected to exceed 150 million by 2050, it is essential to identify strategies that promote brain health. Recent research studies suggest that micronutrients may be protective factors, particularly among the elderly. Copper is one of them, and it is an essential trace element important in brain metabolism and antioxidant protection.
The copper can be detrimental in sufficient quantities, causing neurotoxicity despite its necessity. A recent study of National Health and Nutrition Examination Survey (NHANES) data examined the relationship between dietary copper intake and cognitive performance among U.S. adults aged 60 and older.
The researchers conducted a cross-sectional analysis of 2,420 U.S. adults using structured interviews and 24-hour dietary recalls to estimate daily copper intake. Cognitive performance was assessed using the CERAD Word Learning Test, animal fluency test (AFT), and digit symbol substitution test (DSST). A composite Z-score was calculated to reflect overall cognitive ability. Participants were classified into four quartiles (Q1-Q4) based on the level of copper intake: Q1 (<0.76 mg/day) to Q4 (≥1.44 mg/day). Associations were evaluated using multivariable linear regression (four models) after adjustment for demographics, health behaviours, and nutrients. The statistical tools employed were ANOVA, Chi-square, trend tests, and generalized additive models. The two-piecewise regression was used to test a threshold effect. All analyses were conducted using Free Statistics software v2.0, with p < 0.05 considered statistically significant.
An increased consumption of copper was associated with higher cognitive function, along with better cognitive scores. In adjusted models, individuals in Q4 had significantly higher scores in DSST(β = 3.80, 95 % CI: 1.90-5.70), AFT(β = 1.23, 95 % CI: 0.48-1.99), Z score (β = 0.20, 95 % CI:0.10-0.29; p < 0.001).
The non-linear relationship was observed, which led to an inverse L-shape. The cognitive improvements flattened at levels: 1.63 mg/day (DSST), 1.42 mg/day (AFT), and 1.22 mg/day (Z score). Under these points, the following outcomes improved significantly: DSST (β = 4.16, 95% CI: 1.92-6.40), AFT (β = 1.19, 95% CI: 0.15-2.24), and Z score (β = 0.16, 95% CI: 0.01-0.36). The higher the inflection, the greater the reduction in gains (p > 0.05).
Stroke survivors showed the highest improvement in subgroup analysis (β=0.55, 95% CI: 0.24-0.86; p = 0.009), and Q4 had a greater Z-score. There were no other meaningful interactions identified with age, gender, or health status.
In the current study, a strong direct positive association was noted between copper intake and cognitive performance in the U.S. older adults, particularly among those with a history of stroke. The cognitive benefits are maximized at certain intake levels near 1.22 mg/day. Beyond these levels, no additional advantage was observed. Copper can assist neurotransmitter activity, inflammation regulation, and neural repair in mechanisms such as Wnt signaling. But its action can be affected by diet and nutrient interactions. Although the analysis contained various assessments and subgroup data, the cross-sectional methodology does not allow causal interpretation.
In conclusion, higher copper intake in the diet could improve cognitive performance in older adults, specifically in individuals with a history of stroke, in the U.S. The maximum benefits were noticed at approximately 1.22 mg/day. Future longitudinal and interventional studies are needed to confirm these findings and clarify the long-term relationship between copper intake and cognitive health.
References: Jia W, Zhu K, Shi J, et al. Association between dietary copper intake and cognitive function in American older adults: NHANES 2011–2014. Sci Rep. 2025;15:24334. doi:10.1038/s41598-025-09280-9
