If I take 30 milligrams (mg) of zinc every other day, how much copper will I absorb?

Copper Absorption with Every-Other-Day 30mg Zinc Supplementation

Taking 30mg of zinc every other day will still significantly reduce your copper absorption—by approximately 40-50%—because zinc induces intestinal metallothionein that persists for 2-6 days, meaning the copper-blocking effect continues even on days you don't take zinc. 1

The Metallothionein Problem

The critical issue is not just about taking zinc and copper at the same time—it's about zinc's lasting biological effect:

• Zinc induces synthesis of metallothionein in your intestinal cells, a protein that preferentially binds copper and prevents its absorption into your bloodstream 2, 1
• This metallothionein remains active for approximately 2-6 days as long as zinc intake continues, even intermittently 1
• Once copper binds to this metallothionein, it stays trapped in intestinal cells and is lost when these cells naturally turn over every 2-6 days 1

Why Every-Other-Day Dosing Doesn't Solve the Problem

Your alternating schedule creates a continuous metallothionein presence:

• The metallothionein induced by Monday's zinc dose is still active on Tuesday when you might take copper 1
• Even without taking zinc daily, the 2-6 day persistence means you maintain ongoing copper blockade 1
• The elimination of excess zinc is slow, and until such elimination occurs, intestinal copper absorption remains blocked 3

Quantifying Your Copper Absorption

Based on the mechanism and your 30mg zinc dose:

• At 30mg zinc (double the standard 15mg supplementation dose), you can expect approximately 40-50% reduction in copper absorption even with every-other-day dosing 1
• This means if you're taking 2mg copper, you may only absorb 1-1.2mg effectively 1
• Your zinc-to-copper ratio at 30mg zinc to 2mg copper is 15:1, which is at the upper limit of the recommended 8:1 to 15:1 ratio 2

Critical Risk: Copper Deficiency

The clinical consequences of this interference are serious:

• High zinc intake relative to copper causes copper deficiency presenting as anemia, leukopenia, thrombocytopenia, and neuromuscular abnormalities including myeloneuropathy 2
• Copper deficiency from zinc supplementation manifests as hypochromic-microcytic anemia and neutropenia that doesn't respond to iron therapy 3
• Even at 150mg daily zinc for 6 weeks, some studies showed no change in plasma copper, but case reports demonstrate severe deficiency can occur with chronic use at lower doses 3, 4

Practical Solutions

To maximize copper absorption while taking 30mg zinc every other day:

• Separate zinc and copper by at least 5-6 hours—take zinc 30 minutes before breakfast and copper with dinner or before bed 1
• Consider increasing your copper supplementation to 3-4mg daily (rather than 2mg) to compensate for the reduced absorption 2
• Monitor both zinc and copper levels every 6-12 months to ensure the ratio remains appropriate and you're not developing copper deficiency 1

Common Pitfall to Avoid

Do not assume that taking zinc with food will prevent copper interference—while food reduces zinc absorption by 30-40%, it does not eliminate the metallothionein induction and copper-blocking effect 1