Clear evidence. Transparent sources. Practical guidance. Our evidence policyContact
Food Health Lab
Home › Supplements › Zinc

Zinc — The Complete Supplement Guide

Immune mineral and enzyme workhorse: which form, how much, the honest evidence for colds, and why too much zinc quietly causes copper deficiency.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsMineralsZinc

Widely supplemented — sometimes to excess, which can quietly trigger a copper deficiency. Dose and timing matter more than most people realise. For the short dietary version, see the Minerals page.

Read first. Long-term high-dose zinc (>40 mg/day) quietly causes copper deficiency (anaemia, nerve damage). Lozenge "cold" doses are short-term only. Information, not a prescription — check with a professional for ongoing use, in pregnancy, or with medication.

Key takeaways

  • Well-absorbed as picolinate/citrate; long-term high doses can cause a copper deficiency.
  • Adults need men 9–11 mg / women 7–8 mg/day.
  • Upper limit 25 mg (EFSA) / 40 mg (US).

Function

Zinc is structural and catalytic in more than 300 enzymes:

  • Immune function: needed for the development and activity of immune cells — deficiency clearly weakens defence.
  • Wound healing & skin: essential for tissue repair and healthy skin.
  • DNA & protein synthesis and normal cell division — hence its role in growth.
  • Growth & development: critical in childhood, pregnancy and puberty.
  • Taste & smell: required for normal sensory function.
  • Reproduction: involved in testosterone metabolism and sperm production.
  • Antioxidant defence: part of copper–zinc superoxide dismutase (SOD).

Different forms — and which to choose

Picolinate / citrateWell-absorbed everyday forms.
Gluconate / acetateThe lozenge forms studied for colds; acetate may release ionic zinc best.
BisglycinateChelated, gentle on the stomach.
Sulfate / oxideCheap; sulfate can upset the stomach, oxide is poorly absorbed.

Absorption in the body

How muchRoughly 20–40%, regulated by need. There is no large store, so regular intake matters.
HindersPhytates in whole grains/legumes markedly reduce absorption — vegetarians may need ~50% more. High-dose iron or calcium taken together also compete.
HelpsTaken away from high-phytate meals; animal protein aids absorption.

Deficiency symptoms

SymptomsFrequent infections and slow wound healing, loss of taste/smell, hair loss, skin rashes (especially around mouth), poor appetite, and in children impaired growth and delayed puberty.
Who's at riskVegetarians/vegans, people with GI disease or after bariatric surgery, heavy drinkers, older adults, and pregnancy/lactation.

Recommended intake

Men 9–11 mg · Women 7–8 mg/day

Reference intakes (higher for vegetarians and in pregnancy/lactation):

  • Men: ~9–11 mg/day · Women: ~7–8 mg/day
  • Vegetarians: up to ~50% more (phytates lower absorption)

Best sources: oysters and shellfish (richest), red meat, poultry, seeds (pumpkin), nuts, legumes, cheese.12

Therapeutic use

Common coldsZinc acetate/gluconate lozenges started within 24 h may modestly shorten a cold (short-term high ionic-zinc doses); not for ongoing use.
Deficiency & skinCorrecting deficiency; acrodermatitis enteropathica; some role in acne and slow-healing wounds when low.
Eye (AMD)Part of the AREDS formula for age-related macular degeneration (with copper to offset).

Therapeutic doses

Everyday: 8–15 mg · Cold lozenges: short-term only
MaintenanceA multivitamin-level 8–15 mg/day covers most needs.
Cold lozengesStudied at higher short-term doses over a few days — not to be continued.
Pair with copperIf taking >25–40 mg/day for more than a couple of weeks, add copper (about 1 mg per 15 mg zinc).

Toxicity & upper limit

UL: 25 mg/day (EFSA) · 40 mg (US)
Upper limit25 mg/day (EFSA) or 40 mg/day (US) from all sources.12
Copper deficiencyThe key long-term risk: sustained high zinc blocks copper absorption → anaemia and potentially irreversible nerve damage.
Acute excessNausea and stomach pain; very high intakes impair immunity.
InteractionsReduces absorption of some antibiotics and vice-versa — separate doses.

Bottom line: get zinc from shellfish, meat, seeds and legumes. A modest 8–15 mg supplement is reasonable if intake is low or you're vegetarian; zinc lozenges may slightly shorten colds if started early. Don't take high doses long-term without added copper.

← All supplementsShort dietary version

References

Reference and upper-limit values are general adult figures from official bodies; individual needs vary. Therapeutic doses describe clinical/research use, not prescriptions.

  1. US NIH Office of Dietary Supplements. Zinc — Health Professional Fact Sheet. ods.od.nih.gov
  2. EFSA Panel (NDA). Dietary Reference Values for zinc. EFSA Journal 2014;12(10):3844. efsa.onlinelibrary.wiley.com

This article summarizes nutrition science from official health authorities and peer-reviewed sources for education. It is not a substitute for individual medical advice, and the doses given are not prescriptions — always consult a professional before therapeutic supplement use, in pregnancy, in kidney disease, or alongside medication.

✓
Bodil Isaksson, Licensed Biomedical Scientist (Sweden)

At Food Health Lab we explain what the science says in plain language, and we cite our sources so you can check for yourself.

Read next

Mineral
Iodine
Mineral
Selenium
Mineral
Copper