Zinc
Trace element for immune function, wound healing, and hormone synthesis
Also known as
Definition
Zinc is an essential trace element and cofactor for more than 300 enzymes. It regulates immune defense, wound healing, protein synthesis, DNA replication, and sex hormone production. Zinc is a potent aromatase inhibitor and supports testosterone synthesis. Dietary sources are primarily meat, seafood (especially oysters), and nuts. Phytates in plant foods inhibit zinc absorption.
| Parameter | Value |
|---|---|
| Unit | µmol/l (µg/dl) |
| Reference Range | 11.5–18.5 µmol/l (75–120 µg/dl) |
Agree on your personal target range with your doctor.
Conversion: 1 µmol/l = 6.54 µg/dl. US labs report in µg/dl (normal: 70–120 µg/dl).
↓ What a low value means
Zinc deficiency occurs with vegan diets, chronic alcoholism, kidney disease, malabsorption (celiac disease, IBD), or after bariatric surgery. Symptoms: increased susceptibility to infections, impaired wound healing, hair loss, hypogonadism, taste and smell disturbances, acne.
↑ What a high value means
Zinc excess (> 20 µmol/l) from excessive supplementation can cause copper deficiency (competitive absorption), impair immune function, cause nausea, and raise LDL. The tolerable upper intake level for zinc was set in 2002 by the EU Scientific Committee on Food (SCF), EFSA's predecessor, to protect copper status. EFSA carries it forward in its overview (EFSA overview of tolerable upper intake levels, version 11, August 2025). It is a safety limit, not an intake recommendation.
✓ What can influence this value
The zinc value is influenced by intake from food (oysters have the highest content, followed by beef, poultry, pumpkin seeds, almonds, legumes), by phytates in plant foods, which inhibit absorption, by vegan diets, chronic alcohol consumption, kidney disease, malabsorption, and bariatric surgery. A high intake from supplements can impair copper absorption. The assessment is made by the treating doctor.
When to test
With frequent infections, hair loss, impaired wound healing, fertility problems, acne, or vegan diet. Plasma zinc is measured in the morning while fasting (circadian variation). Serum zinc reflects short-term status; no long-term marker available.
Frequently asked questions
What is the relationship between zinc and testosterone? +
A link appears mainly when zinc deficiency is present. Zinc is a cofactor for testosterone synthesis and inhibits aromatase, which converts testosterone to estrogen. Multiple studies show testosterone increases in zinc-deficient men with supplementation. With already adequate status, the effect is minimal.
What is the relationship between zinc and colds? +
Zinc inhibits rhinovirus replication and modulates inflammatory responses. Meta-analyses show that zinc lozenges can shorten the duration of a cold when started soon after symptoms begin.
Do zinc compounds differ in how well they are absorbed? +
Zinc gluconate and citrate have better bioavailability than zinc oxide or sulfate; zinc picolinate is also well absorbed. Zinc oxide has the lowest bioavailability. Your doctor decides whether any supplement is appropriate, and which.
Can too much zinc be harmful? +
Yes. A chronically high zinc intake causes copper depletion, as zinc and copper compete for the same transporter. Copper deficiency causes anemia and neurological disorders.
Zinc
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.