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 is 25 mg/day (EFSA).
✓ 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. Measure plasma zinc in the morning fasting (circadian variation). Serum zinc reflects short-term status; no long-term marker available.
Frequently asked questions
Can zinc raise testosterone levels? +
Yes, but only 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.
Why does zinc reduce the duration of colds? +
Zinc inhibits rhinovirus replication and modulates inflammatory responses. Meta-analyses show that zinc lozenges (at least 75 mg/day elemental zinc) can reduce cold duration by ~33% when started within 24 hours of symptom onset.
How do zinc forms differ in quality? +
Zinc gluconate and citrate have better bioavailability than zinc oxide or sulfate. Zinc picolinate is well absorbed but more expensive. Zinc oxide (common in cheaper products) has the poorest bioavailability. Organic forms are preferred for therapeutic purposes.
Can too much zinc be harmful? +
Yes. Chronic high-dose zinc (> 40 mg/day) causes copper depletion, as zinc and copper compete for the same transporter. Copper deficiency causes anemia and neurological disorders. Always co-supplement copper with long-term zinc use (10:1 zinc-to-copper ratio).
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.