Copper is a trace mineral required by humans. We need copper as a cofactor for enzymes that play a huge role in the function of our brain and immune system. Alarmingly, many Americans are not consuming enough copper in their diet (1)!
Here I was to describe for you some of the most important roles of copper in the human body and share some of the best sources of copper in the diet.
Why we need copper
Copper is important for several enzymes in our body to function. Most of these enzymes, like superoxide dismutase, require copper as a redox cofactor. Here are a few of the important copper-containing proteins and enzymes in the human body.
- Copper-zinc superoxide dismutase (SOD)
- Dopamine monooxygenase
- Cytochrome C oxidase
Biological functions dependent on copper
Copper deficiency most notably causes problems in the immune system and the visible signs of hypopigmentation of hair and skin. Although these are signs of severe copper deficiency, we must maintain adequate levels of copper for many other biological processes described below.
Ceruloplasmin is the main copper transport protein. It shuttles copper through the blood to other tissues. Ceruloplasmin also responds to inflammation and has been shown to make immune cells more effective at dealing with pathogens and foreign objects through enhancing the process called “phagocytosis”. Ceruloplasmin also reacts with iron, oxidizing it into a form more available to use.
Copper-zinc SOD is an antioxidant that we produce in our own bodies…we don’t obtain this through the diet. However, it requires copper to function. SOD reduces the very reactive superoxide molecule into oxygen and hydrogen peroxide. SOD enzymes are critical for preventing cellular damage from oxidative stress.
Dopamine monooxygenase converts dopamine into norepinephrine and is, therefore, very important in brain function. This is one of the many examples showing that what we eat can affect how our brains function and therefore our mood, thought processes, and susceptibility to neurodegenerative diseases later in life.
Copper is very important for the immune system, particularly in the ability of immune cells to “phagocytose” (meaning swallow and destroy) pathogens and foreign material (2). One notable feature of copper deficiency is a decrease in circulating immune cells, particularly neutrophils. Besides supporting phagocytosis, copper is known to accumulate in mature immune cells and may be important in how immune cells use reactive oxygen species to defend against infections.
Another reason that copper is important for brain health is that it supports myelination. The myelin sheath is what protects nerve fibers from damage and allows normal communication between neurons. Myelin is rich in phospholipids, which require the copper-containing enzyme cytochrome C oxidase for their synthesis (3).
Can you consume too much copper?
Copper excess clinically manifests as “Wilson’s disease”. This is usually caused by a genetic abnormality in copper excretion (ATP7B) rather than actually consuming too much copper. Therefore, the vast majority of people don’t have to worry about high copper intake from foods (1).
Sources of dietary copper
The absolute best sources of dietary copper are organ meats and shellfish. It has been postulated that vegetarians may be more susceptible to copper deficiency because they do not consume these foods. However, cocoa and some fruits and vegetables also contain some copper and one human study showed that consuming a vegetarian diet for 8 weeks did not lower copper status (4).
Vegetarian and vegan diets likely contain a higher volume of foods containing a modest amount of copper like potatoes, legumes, and mushrooms which could compensate for not consuming organs and shellfish.
However, the ratio of copper to zinc in your meal is well known to impact copper absorption. Zinc stimulates metallothionein production which can prevent proper utilization of ingested copper. In fact, even 10 months of high-dose zinc supplementation was enough to cause copper deficiency according to a case study in 1998 (at least 10X the RDA of copper was given)(5).
Finally, I chose a copper pot as the featured image of this essay for a reason. We can actually absorb some copper from copper cookware, especially when the contents being cooked are acidic. While this is interesting, it’s unlikely that copper intake from cookware is biologically significant unless you are doing A LOT of cooking in copper pots!
America has a copper problem
It is probably because A) Americans don’t frequently eat the richest sources of copper (organ meat and shellfish) and B) Americans consume too many ultra-processed foods instead of real food. Unfortunately, processed grain and vegetable oil products are not great sources of copper.
How can you improve your copper intake?
As I just mentioned, eating real foods is going to be one of the easiest ways to get more copper in your diet. What does this look like in practice? Try cooking liver once every month. Even eating liver once every few weeks is still going to be nutritionally beneficial. If you are not so into organs yet, even making a simple switch from a box of mac-and-cheese to a baked potato could improve your copper intake.
- Copper is important for immunity, brain function, and utilization of iron
- Many Americans do not consume enough copper due to consuming a diet rich in highly processed foods
- Organ meats and shellfish are the best sources of dietary copper. Potatoes and legumes are also fairly good copper sources
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