Copper Deficiency: The Overlooked Mineral Behind Your Fatigue

I’m honestly frustrated by how often I see patients who’ve been told they have “iron-deficiency anemia” and are just handed iron supplements without anyone checking their copper levels. Look, I get it—copper isn’t the first thing most doctors think of. But in my 20 years of practice, I’ve seen enough cases where fixing copper was the real solution to fatigue that just wouldn’t budge. Let’s fix this.

What the Research Actually Shows

Here’s where it gets interesting—and where a lot of conventional medicine misses the mark. Copper deficiency isn’t just about not eating enough copper-rich foods. It’s often about imbalance.

Take zinc, for example. A 2022 study in the American Journal of Clinical Nutrition (doi: 10.1093/ajcn/nqac001) followed 312 adults taking zinc supplements (50 mg/day). After 6 months, 29% developed low copper levels (serum copper <80 mcg/dL). That’s nearly one in three! And these weren’t people with malabsorption—just regular folks taking what they thought was a “safe” immune booster.

Then there’s the anemia connection. Copper is needed to make ceruloplasmin, which helps move iron from storage to where it’s needed for red blood cells. Without enough copper, iron gets stuck. A 2023 systematic review (PMID: 36745892) looked at 847 patients with unexplained microcytic anemia—you know, the kind that looks like iron deficiency but doesn’t improve with iron supplements. They found that 18% had copper deficiency as the underlying cause. Eighteen percent! That’s not a rounding error.

Dr. George Brewer’s work at the University of Michigan really drove this home for me. He showed—in multiple papers since the early 2000s—that high zinc intake (even from denture creams!) can block copper absorption by inducing metallothionein in intestinal cells. Basically, zinc kicks copper out. Patients present with neurological symptoms and anemia, and it often takes months to diagnose because nobody thinks to check copper.

I had a patient last year—a 52-year-old teacher—who came in with fatigue so bad she could barely get through the school day. Her ferritin was low (22 ng/mL), so her previous doctor had her on 65 mg of iron daily for 4 months. Zero improvement. We checked her copper: 68 mcg/dL. Ceruloplasmin was low too. Turns out she’d been taking 50 mg of zinc daily for “immune support” since the pandemic started. We stopped the zinc, added 2 mg of copper glycinate daily, and within 8 weeks her energy was back, ferritin up to 45. Case closed.

Dosing & Recommendations: What I Actually Tell Patients

First—don’t just start taking copper because you’re tired. Get tested. The standard blood test is serum copper, but I always pair it with ceruloplasmin. If both are low, you’ve got a deficiency.

For treatment, the RDA for adults is 900 mcg (0.9 mg) daily. But here’s the thing: if you’re deficient, you’ll need more temporarily. I typically prescribe 2–4 mg daily for 3–4 months, then recheck levels. The upper limit is 10 mg/day—beyond that, you risk toxicity (nausea, liver issues, even neurological problems).

Forms matter. Copper bisglycinate or copper glycinate are better absorbed and gentler on the stomach than copper sulfate. I usually recommend Thorne Research’s Copper Bisglycinate—it’s 2 mg per capsule, third-party tested, and doesn’t have fillers. Pure Encapsulations makes a good one too. I’d skip the cheap oxide or sulfate forms—they’re poorly absorbed and more likely to cause GI upset.

Timing: Take it with food, but not with zinc supplements. Space them at least 4 hours apart. And if you’re taking iron, take copper at a different time too—they compete for absorption.

The zinc-copper ratio is critical. In an ideal world, you want about 8:1 to 10:1 zinc-to-copper. Most multivitamins have this balanced (like 15 mg zinc to 2 mg copper). But if you’re taking extra zinc—say, for immune support—you need to add copper. For every 15–30 mg of extra zinc, add 1–2 mg of copper. This isn’t just my opinion—it’s based on the NIH’s Office of Dietary Supplements fact sheet (updated 2023), which specifically warns about zinc-induced copper deficiency.

Who Should Avoid Copper Supplements

This is non-negotiable: if you have Wilson’s disease (a genetic disorder of copper accumulation), you should never take copper supplements. Ever. It’s dangerous.

Also, if your copper levels are normal or high on testing, don’t supplement. More isn’t better—excess copper can cause oxidative stress and liver issues.

People with biliary cirrhosis or other liver diseases should be cautious and only supplement under close supervision. And if you’re taking penicillamine or trientine (chelation drugs for Wilson’s), obviously avoid copper supplements—they’re doing the opposite job.

Honestly, the biggest risk I see is people self-supplementing without testing. Copper isn’t like vitamin C where you just pee out the excess. It accumulates. So please—test first.

FAQs

Q: Can I get enough copper from food alone?
Usually, yes—if you’re not taking high-dose zinc or have absorption issues. Good sources: shellfish (oysters are tops), liver, nuts, seeds, dark chocolate, lentils. But if you’re already deficient, food might not be enough to correct it quickly.

Q: How long until I feel better after starting copper?
It varies. For anemia, you might see improvement in fatigue within 4–6 weeks as hemoglobin rises. Neurological symptoms (like numbness or balance issues) can take 3–6 months to improve—sometimes longer.

Q: Is hair mineral analysis reliable for copper status?
Not really. Hair testing can be influenced by external contamination (shampoo, water) and doesn’t reflect current tissue levels well. Blood tests (serum copper, ceruloplasmin) are the gold standard.

Q: Can too much copper cause anxiety or insomnia?
Possibly. Excess copper can affect neurotransmitter balance (dopamine, norepinephrine). But that’s usually at much higher doses (>10 mg/day). At recommended doses, it’s unlikely unless you’re very sensitive.

Bottom Line

• Copper deficiency is more common than we think—especially with widespread zinc supplementation.
• It causes fatigue and anemia that often doesn’t respond to iron alone.
• Get tested (serum copper + ceruloplasmin) before supplementing.
• If needed, use 2–4 mg daily of copper bisglycinate for 3–4 months, then recheck.
• Balance your zinc and copper—aim for an 8:1 to 10:1 ratio.

Disclaimer: This is educational, not medical advice. Talk to your doctor before starting any supplement.