- As the population ages, disorders affecting the nervous system, including cognitive decline and dementia, are the leading cause of overall disease burden worldwide.
- Diet and lifestyle can affect a person’s risk of developing cognitive decline as they age.
- Vitamins and minerals, such as vitamins B and C, calcium, magnesium, and zinc, are essential in maintaining cognitive function.
- A new study suggests that dietary copper intake may also be important, with too little or too much negatively affecting cognitive function.
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To help maintain cognitive function, people should ensure that their diet contains correct levels of vitamins and minerals. Although these micronutrients are needed in only tiny amounts, deficiencies can affect cognitive performance as well as physical health.
A new study suggests that one particular micronutrient, copper, may be important in maintaining cognitive function as we get older.
The study, which is published in
“The study suggests that moderate dietary copper intake (approximately 1.2–1.6 mg/day) is associated with better cognitive function in older adults, particularly in processing speed and executive function. The observed reverse L-shaped curve indicates benefits up to a threshold, beyond which no additional cognitive advantage is observed. This aligns with copper’s role in neurotransmission and antioxidant defence.”
— Steven Allder, consultant neurologist at Re:Cognition Health, who was not involved in the study.
The study used data from the National Health and Nutrition Examination Survey (NHANES), between 2011 and 2014.
Researchers analyzed 2,420 participants, determining their dietary copper intake by averaging two 24-hour dietary recalls. From this, they divided them into quartiles, from greatest to least copper intake. They then assessed their cognitive function using 4 standard tests:
- The Digit Symbol Substitution Test (DSST) — a paper-and-pencil cognitive test on a single sheet of paper that requires a subject to match symbols to numbers according to a key at the top of the page.
- The Animal Fluency Test (AFT) — naming as many animals as possible in a short period of time (usually 1 minute).
- A Consortium to Establish a Registry for Alzheimer’s disease (CERAD) subtest — a range of tests used to assess Alzheimer’s disease.
- Global cognition Z score — a standardized measure that summarizes an individual’s overall cognitive function across a battery of cognitive tests.
Thomas M. Holland, MD, MS, physician-scientist and assistant professor at the RUSH Institute for Healthy Aging, RUSH University, College of Health Sciences, not involved in the study, explained how copper is used in the brain:
“Copper plays a vital role in the brain’s health by supporting several biological systems, most notably energy metabolism, neurotransmitter synthesis, and antioxidant defenses. It acts as a cofactor for enzymes that help generate cellular energy and protect neurons from oxidative stress, which is a key contributor to aging and cognitive decline. One enzyme in particular, superoxide dismutase (SOD1), relies on copper to neutralize harmful free radicals-that can harm normal brain tissue,” he told Medical News Today.
In this cross-sectional observational study, the researchers found that people in the top quartile for copper intake scored higher on the cognitive function tests. However, they observed that cognitive function scores peaked at a certain level of copper intake then did not increase further.
The optimum levels for each test were 1.63 mg/day for DSST, 1.42 mg/day for AFT and 1.22 mg/day for the Z score.
“This study highlights that cognitive benefits of copper appear most pronounced at moderate dietary levels, around 1.2 to 1.6 mg/day. Above that threshold, the gains taper off, which aligns with our understanding that both deficiency and excess can disrupt brain health. Too little copper may impair synaptic function and energy production, while too much can promote oxidative damage and inflammation, essentially flipping copper’s role from protector to stressor.”
— Thomas M. Holland, MD
Allder also emphasized that balance is key:
“Excessive copper can generate free radicals, overwhelm antioxidant systems, and disrupt mineral homeostasis, potentially accelerating neurodegenerative changes such as amyloid-beta accumulation and tau tangles seen in Alzheimer’s disease.”
Our experts advised that eating a diverse, whole-food diet will ensure adequate, but not excess copper, and supplements should be taken only on medical advice.
Elena Rolt, registered nutritional therapist and functional medicine practitioner at health.miro, explained how you can get the right amount of copper.
“Shellfish such as oysters, crabs and lobsters are among the richest natural sources, providing high concentrations of this mineral. Organ meats, particularly liver, are also exceptional sources of copper and have long been valued for their nutrient profile.”
Sources of copper in diet“For those following plant-based diets, mushrooms, especially shiitake, nuts and seeds, including cashews, sunflower seeds and sesame seeds, offer an excellent alternative. Whole grains, such as quinoa and oats, are other significant contributors, alongside legumes like lentils and chickpeas, which provide both copper and plant-based protein. […] leafy greens such as spinach and kale contain moderate amounts of copper, further supporting overall intake when incorporated into daily meals.”
— Elena Rolt, registered nutritional therapist
There’s good news for chocolate lovers, too. Both Rolt and Holland advocated dark chocolate, provided it is more than 70% cocoa, as a rich source of dietary copper.
As a cross-sectional study, this research cannot determine whether copper causes improved cognitive function.
“The methodological approach, leveraging NHANES data and validated cognitive assessments, gives the findings strong credibility, and the fact that the results held up even after adjusting for a range of sociodemographic and lifestyle factors adds to their weight,” Holland said.
“To really move the science forward, I’d love to see prospective studies that follow people over time to determine whether copper intake actually slows cognitive decline. Even better would be randomized trials that test copper supplementation, specifically in individuals at risk of cognitive impairment,” he told MNT.
“This study really highlights how our brains are influenced by the foods we eat, even at the micronutrient level. It reinforces my belief that lifestyle and nutrition aren’t just about preventing chronic diseases like dementia, diabetes, or heart disease, but also about preserving the very essence of who we are, our memory, our ability to think clearly, connect with others, and maintain independence as we age.”
— Thomas M. Holland, MD
