Copper is an essential trace mineral that plays a vital role in maintaining overall health. Naturally found in a variety of foods and available as a dietary supplement, copper is a crucial cofactor for numerous enzymes, known as cuproenzymes. These enzymes are involved in critical bodily functions such as energy production, iron metabolism, and the synthesis of connective tissues and neurotransmitters [1-3]. One of the most abundant cuproenzymes, ceruloplasmin (CP), is instrumental in iron metabolism and carries the majority of copper in our blood plasma [4]. Beyond these core functions, copper is also involved in angiogenesis, hormone balance, gene regulation, brain development, pigmentation, and immune system function [1]. Furthermore, copper-dependent superoxide dismutases are key defenders against oxidative damage in the body [5,6].
A diverse range of both plant and animal foods are sources of copper, ensuring that a typical human diet provides a substantial amount of this mineral. On average, men consume around 1,400 mcg/day and women around 1,100 mcg/day through their diets, with absorption primarily occurring in the upper small intestine [1,2,7-9]. Interestingly, the skeleton and muscles house nearly two-thirds of the body’s total copper content [1,3].
The body’s copper storage is relatively small, with an average adult holding between 50–120 mg in total [1,2]. The primary route of copper excretion is through bile, with a minor amount excreted in urine. Daily fecal copper losses, originating from bile and unabsorbed dietary copper, amount to approximately 1 mg [1,2]. The body maintains a delicate balance of copper levels through intestinal absorption and liver release into bile, protecting against both deficiency and toxicity [3].
Assessing copper status in clinical settings is not routine due to the lack of reliable biomarkers [2]. While studies often measure copper levels and cuproenzyme activity in plasma and blood cells, these measurements can be influenced by factors other than copper status, such as estrogen levels, pregnancy, inflammation, and certain illnesses [2]. Normal serum copper concentrations range from 10–25 mcmol/L (63.5–158.9 mcg/dL), and ceruloplasmin levels are typically between 180–400 mg/L [10].
Recommended Daily Copper Intake
Dietary Reference Intakes (DRIs) for copper and other essential nutrients are established by the Food and Nutrition Board (FNB) at the National Academies of Sciences, Engineering, and Medicine [3]. DRIs serve as guidelines for planning and evaluating nutrient intake for healthy individuals, varying by age and sex. Key DRI values include:
- Recommended Dietary Allowance (RDA): The average daily intake level sufficient to meet the nutrient needs of nearly all (97%–98%) healthy individuals, often used for dietary planning for individuals.
- Adequate Intake (AI): Established when evidence is insufficient to set an RDA, this level is assumed to ensure nutritional adequacy.
- Estimated Average Requirement (EAR): The average daily intake level estimated to meet the needs of 50% of healthy individuals, used to assess and plan diets for groups and can also be used for individuals.
- Tolerable Upper Intake Level (UL): The maximum daily intake unlikely to cause adverse health effects.
Table 1 outlines the current RDAs for copper [3]. For infants up to 12 months, an AI is set based on the average copper intake of healthy, breastfed infants.
Table 1: Recommended Dietary Allowances (RDAs) for Copper [3]
| Age | Male | Female | Pregnancy | Lactation |
|---|---|---|---|---|
| Birth to 6 months* | 200 mcg | 200 mcg | ||
| 7–12 months* | 220 mcg | 220 mcg | ||
| 1–3 years | 340 mcg | 340 mcg | ||
| 4–8 years | 440 mcg | 440 mcg | ||
| 9–13 years | 700 mcg | 700 mcg | ||
| 14–18 years | 890 mcg | 890 mcg | 1,000 mcg | 1,300 mcg |
| 19+ years | 900 mcg | 900 mcg | 1,000 mcg | 1,300 mcg |
*Adequate Intake (AI)
Top Copper Foods to Include in Your Diet
Food Sources of Copper
The best food sources of copper are diverse and readily available, making it easy to incorporate them into your diet. Shellfish, including oysters and crab, are exceptionally rich in copper. Seeds and nuts like cashews and sunflower seeds are also excellent sources. Organ meats, particularly liver, are among the most concentrated dietary sources of copper. Whole-grain products, wheat-bran cereals, and even chocolate contribute significantly to copper intake [1,2]. Interestingly, the body’s absorption rate of copper is influenced by dietary intake levels. Bioavailability can range from a high of 75% when copper intake is low (around 400 mcg/day) to as low as 12% when intake is high (around 7.5 mg/day) [3].
Tap water and various beverages can also provide copper, although the amount varies depending on the water source, ranging from trace amounts to 1 mg/L [2,11].
Table 2 highlights a selection of copper-rich foods to help you increase your dietary intake.
Table 2: Copper Content of Selected Foods [12]
| Food | Micrograms (mcg) per serving | Percent DV* |
|---|---|---|
| Beef Liver, pan fried (3 ounces) | 12,400 | 1,378 |
| Oysters, eastern, wild, cooked, 3 ounces | 4,850 | 539 |
| Baking Chocolate, unsweetened, 1 ounce | 938 | 104 |
| Potatoes, cooked, flesh and skin, 1 medium | 675 | 75 |
| Mushrooms, shiitake, cooked, ½ cup pieces | 650 | 72 |
| Cashew Nuts, dry roasted, 1 ounce | 629 | 70 |
| Crab, Dungeness, cooked, 3 ounces | 624 | 69 |
| Sunflower Seed Kernels, toasted, ¼ cup | 615 | 68 |
| Turkey Giblets, simmered, 3 ounces | 588 | 65 |
| Chocolate, dark, 70%–85% cacao, 1 ounce | 501 | 56 |
| Tofu, raw, firm, ½ cup | 476 | 53 |
| Chickpeas, mature seeds, ½ cup | 289 | 32 |
| Millet, cooked, 1 cup | 280 | 31 |
| Salmon, Atlantic, wild, cooked, 3 ounces | 273 | 30 |
| Pasta, whole wheat, cooked, 1 cup (not packed) | 263 | 29 |
| Avocado, raw, ½ cup | 219 | 24 |
| Figs, dried, ½ cup | 214 | 24 |
| Spinach, boiled, drained, ½ cup | 157 | 17 |
| Asparagus, cooked, drained, ½ cup | 149 | 17 |
| Sesame Seeds, ¼ cup | 147 | 16 |
| Turkey, ground, cooked, 3 ounces | 128 | 14 |
| Cereal, Cream of Wheat, cooked, 1 cup | 104 | 12 |
| Tomatoes, raw, chopped, ½ cup | 53 | 6 |
| Yogurt, Greek, plain, low fat, 7-ounce | 42 | 5 |
| Milk, nonfat, 1 cup | 27 | 3 |
| Apples, raw, with skin, ½ cup slices | 17 | 2 |
*DV = Daily Value. The U.S. Food and Drug Administration (FDA) Daily Value for copper is 0.9 mg (900 mcg) for adults and children age 4 years and older [13]. Foods providing 20% or more of the DV are considered high sources of a nutrient.
For a comprehensive list of nutrient content in various foods, refer to the U.S. Department of Agriculture’s (USDA’s) FoodData Central [12].
Copper Supplements
Copper is also available in dietary supplements, either as a standalone supplement, combined with other minerals, or in multivitamin/mineral formulations [14]. These supplements come in various forms, including cupric oxide, cupric sulfate, copper amino acid chelates, and copper gluconate. Currently, research has not established differences in bioavailability among these forms [15]. Copper content in supplements can vary widely, ranging from a few micrograms to 15 mg, significantly exceeding the Daily Value [14].
Copper Intake and Nutritional Status
Generally, dietary copper intake in the United States is sufficient, meeting or exceeding the RDA. Average dietary copper intake from food ranges from 800 to 1,000 mcg daily for children aged 2–19 [9]. For adults over 20, the average daily intake is around 1,400 mcg for men and 1,100 mcg for women. Considering both food and supplements, total daily copper intake ranges from 900 to 1,100 mcg for children and 1,400 to 1,700 mcg for adults over 20.
However, data from the 2009–2012 National Health and Nutrition Survey (NHANES) indicates that between 6% and 15% of adults over 19 who do not take copper supplements have intakes below the EAR [16]. This percentage decreases to 2.2% to 7.2% among supplement users.
Copper Deficiency: When You Don’t Get Enough Copper Foods
Copper deficiency is relatively rare in humans [2]. However, inadequate copper intake can lead to various health issues, including anemia, hypopigmentation, elevated cholesterol, connective tissue problems, bone defects like osteoporosis, abnormal lipid metabolism, coordination issues (ataxia), and increased susceptibility to infections [1,17,18].
Groups at Higher Risk of Copper Deficiency
Certain populations are more susceptible to copper inadequacy.
Individuals with Celiac Disease
Celiac disease, an autoimmune disorder triggered by gluten, can lead to intestinal malabsorption, increasing the risk of copper deficiency. A study involving adults and children with celiac disease revealed that 15% suffered from copper deficiency, even with a majority adhering to a gluten-free diet [19]. The American College of Gastroenterology guidelines acknowledge the increased risk of copper deficiency in celiac disease patients, noting that copper levels typically normalize with supplementation and a gluten-free diet [20].
People with Menkes Disease
Menkes disease is a rare genetic disorder affecting copper metabolism. Caused by mutations in the ATP7A gene, it impairs intestinal copper absorption, leading to severe copper deficiency [1]. Symptoms include low serum copper and ceruloplasmin levels, failure to thrive, cognitive impairment, seizures, aortic aneurysms, and distinctive kinky hair [1,21,22]. Without treatment, most individuals with Menkes disease do not survive beyond age 3. Early copper injections can improve outcomes [23].
High Zinc Supplement Users
Excessive zinc intake can hinder copper absorption, potentially leading to copper deficiency. Even moderately high zinc intakes (around 60 mg/day) over several weeks have been shown to reduce erythrocyte copper-zinc superoxide dismutase levels, a marker of copper status [3]. Regularly consuming high doses of zinc supplements or using zinc-containing denture creams can induce copper deficiency. This interaction is a key reason why the FNB has set a UL for zinc at 40 mg/day for adults [1,3].
Copper’s Role in Health and Disease
Copper’s involvement in various physiological processes suggests potential roles in disease prevention and management. This section explores copper’s relationship with cardiovascular disease (CVD) and Alzheimer’s disease.
Cardiovascular Health
Copper deficiency has been linked to alterations in blood lipid levels, a known risk factor for atherosclerotic CVD [1]. Animal studies have demonstrated that copper deficiency can lead to cardiac abnormalities, possibly due to reduced activity of cardiac cuproenzymes [1,2].
However, research on copper and CVD in humans has yielded mixed results. An Italian cohort study found that higher self-reported copper intakes were associated with lower diastolic blood pressure and cholesterol levels in asymptomatic adults [24]. Conversely, a NHANES analysis indicated a higher risk of death from coronary heart disease in individuals with higher serum copper concentrations [25]. Similarly, a German study in acute coronary syndrome patients found increased hazard ratios for CVD-related death with higher serum copper and ceruloplasmin levels [26].
Small supplementation studies in healthy adults have shown limited impact of copper on CVD risk factors. While copper supplementation can increase cuproenzyme activity, it has not consistently affected markers like CRP, homocysteine, or cholesterol [27,28]. Notably, no clinical trials have investigated copper supplementation in individuals at high CVD risk.
Currently, the evidence is inconclusive regarding the association between copper levels and CVD risk, or the effectiveness of copper supplementation for CVD prevention or management.
Alzheimer’s Disease and Copper Foods
Some researchers propose that copper deficiency might contribute to Alzheimer’s disease, citing reports of low copper levels and reduced activity of copper-dependent enzymes in the brains of Alzheimer’s patients [7,29]. Some limited evidence suggests that higher copper levels may be associated with a reduced risk of Alzheimer’s [30]. However, paradoxically, elevated copper levels have also been observed in the brains of individuals with Alzheimer’s, leading some to suggest that excessive copper intake may be involved in the disease’s development [31]. It’s important to note that copper accumulation in damaged brain areas might not accurately reflect overall body copper status [32].
Observational studies examining the link between dietary copper and Alzheimer’s disease have produced inconsistent findings. One study found no overall association between copper intake and cognitive decline, but in a subgroup with higher saturated and trans fat intake, higher copper intake was linked to faster cognitive decline [33]. In contrast, another study found no difference in serum copper or ceruloplasmin levels between Alzheimer’s patients and healthy controls, although it did observe a decline in non-ceruloplasmin bound copper in patients with mild cognitive impairment or Alzheimer’s [32].
Meta-analyses have indicated that Alzheimer’s patients tend to have higher serum copper levels compared to healthy individuals [34,35].
Clinical trials investigating copper supplementation in Alzheimer’s patients are scarce. One trial showed no significant cognitive benefits from copper supplementation in mild Alzheimer’s patients [36].
Some experts suggest that individuals at increased risk of Alzheimer’s may want to choose multivitamin/mineral supplements without copper (or iron) due to concerns that excessive intake of these minerals could potentially contribute to cognitive issues [37]. However, further research is necessary to clarify the role of copper levels in Alzheimer’s disease and the potential impact of copper supplements.
Health Risks of Excessive Copper Intake
Excessive chronic copper exposure can lead to adverse health effects, including liver damage and gastrointestinal issues like abdominal pain, nausea, diarrhea, and vomiting [10,38]. Copper toxicity is uncommon in healthy individuals without underlying copper metabolism disorders. However, it can occur from consuming water with high copper levels due to copper pipes or plumbing leaching copper into the water supply [10,38]. The Environmental Protection Agency (EPA) has set a maximum contaminant level for copper in public water systems at 1.3 mg/L [38,39].
Individuals with Wilson’s disease, a genetic condition causing impaired copper excretion, are at high risk of copper toxicity. This condition leads to copper accumulation in tissues, potentially causing liver and neurological damage [40]. Lifelong copper chelation therapy or high-dose zinc can help manage Wilson’s disease.
The FNB has established Tolerable Upper Intake Levels (ULs) for copper to prevent liver damage in healthy individuals [10]. These ULs do not apply to individuals under medical supervision for copper supplementation.
Table 3: Tolerable Upper Intake Levels (ULs) for Copper [10]
| Age | Male | Female | Pregnancy | Lactation |
|---|---|---|---|---|
| Birth to 6 months | Not established* | Not established* | ||
| 7–12 months | Not established* | Not established* | ||
| 1–3 years | 1,000 mcg | 1,000 mcg | ||
| 4–8 years | 3,000 mcg | 3,000 mcg | ||
| 9–13 years | 5,000 mcg | 5,000 mcg | ||
| 14–18 years | 8,000 mcg | 8,000 mcg | 8,000 mcg | 8,000 mcg |
| 19+ years | 10,000 mcg | 10,000 mcg | 10,000 mcg | 10,000 mcg |
* Breast milk, formula, and food should be the sole sources of copper for infants.
Copper Interactions
Currently, no clinically significant interactions between copper and medications are known.
Incorporating Copper Foods into a Healthful Diet
The 2020–2025 Dietary Guidelines for Americans emphasizes obtaining nutrients primarily from food sources. Fortified foods and dietary supplements can be useful in specific situations, such as pregnancy, when dietary needs are difficult to meet through food alone.
For guidance on building a healthy dietary pattern, consult the Dietary Guidelines for Americans and USDA’s MyPlate. resources.
A healthy dietary pattern, as outlined by the Dietary Guidelines, includes:
- A variety of vegetables, fruits, grains (at least half whole grains), fat-free or low-fat dairy, and oils. Many of these food groups provide copper.
- Diverse protein sources, including lean meats, poultry, eggs, seafood, beans, peas, lentils, nuts, seeds, and soy products. Organ meats, seafood, nuts, and seeds are particularly good copper sources.
- Limiting foods and beverages high in added sugars, saturated fat, and sodium.
- Limiting alcohol consumption.
- Staying within daily calorie needs.
References
Disclaimer
This information is for educational purposes and should not be considered medical advice. Consult with a healthcare professional for personalized dietary guidance and health concerns.
Updated: October 18, 2022
