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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Zinc

Zinc is part of hundreds of enzymes and of the proteins that read DNA; it is key for growth, wound healing and fighting infection.

Updated 2026-11-01

## Key facts

- Cofactor of more than 300 enzymes: carbonic anhydrase, alcohol dehydrogenase, alkaline phosphatase, cytosolic superoxide dismutase (Cu/Zn), ALA dehydratase.
- Forms the 'zinc fingers' of many transcription factors and nuclear receptors (steroid and thyroid hormones, vitamins A and D).
- Deficiency: poor growth, dermatitis around body openings and on the limbs, alopecia, diarrhoea, impaired taste and smell, hypogonadism, infections.
- Excess zinc induces metallothionein in the gut, which traps copper: it can cause copper deficiency (and is used in Wilson disease).

## In detail

- Sources: red meat, shellfish (oysters), poultry, legumes, seeds, whole grains. Phytates in cereals and legumes reduce its absorption.
- Absorption: in the duodenum and jejunum through the ZIP4 transporter (SLC39A4 gene); it leaves the enterocyte through ZnT1. In blood it travels bound to albumin.
- Roles: structural (zinc fingers, insulin stored as hexamers), catalytic (activates water in carbonic anhydrase) and regulatory (immune signalling, T-cell division).
- Causes of deficiency: a diet low in meat and high in phytates, chronic diarrhoea, malabsorption (Crohn, coeliac disease), alcoholism, cirrhosis, kidney disease, zinc-free parenteral nutrition, acrodermatitis enteropathica (ZIP4 failure).
- Excess: acute nausea and vomiting; chronically, copper deficiency with anaemia, neutropenia and myelopathy.
- Lab: plasma zinc (falls with inflammation, low albumin and after meals: drawn fasting, in the morning); low alkaline phosphatase as an indirect clue.

**Also called**
Zn

## Clinical notes

- In children with acute diarrhoea, WHO advises zinc together with oral rehydration salts: it shortens the episode.
- Zinc deficiency is common in low- and middle-income countries, where it contributes to child stunting.
- Zinc acetate is a maintenance treatment in Wilson disease because it blocks gut copper absorption.

## Related conditions

- [Zinc deficiency (acrodermatitis enteropathica)](https://durgical.com/en/conditions/zinc-deficiency/)
- [Acute (viral) gastroenteritis](https://durgical.com/en/conditions/acute-gastroenteritis/)
- [Wilson disease](https://durgical.com/en/conditions/wilson-disease/)

## Related

- [Copper](https://durgical.com/en/biochemistry/topics/copper/)
- [Vitamin A (retinol)](https://durgical.com/en/biochemistry/molecules/vitamin-a/)
- [Iron](https://durgical.com/en/biochemistry/topics/iron/)

## Test yourself

Think of the answer, then tap the question to see it.

## What are zinc fingers?

Protein domains in which a zinc atom holds a loop that binds DNA; many transcription factors and nuclear receptors have them.

## Why can excess zinc cause copper deficiency?

Zinc induces metallothionein in enterocytes, which traps copper; it is lost when the cell is shed.

## Which transporter fails in acrodermatitis enteropathica?

ZIP4 (SLC39A4 gene), which carries zinc from the gut lumen into the enterocyte.

## Why is zinc given to children with acute diarrhoea?

It replaces losses, helps mucosal repair and immunity, and shortens the length and severity of the episode.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Zinc in diet: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002416.htm) (MedlinePlus, US National Library of Medicine, 2026); [SLC39A4: Zinc transporter ZIP4 (human)](https://www.uniprot.org/uniprotkb/Q6P5W5/entry) (UniProt, 2026); [Fact sheets - Malnutrition](https://www.who.int/news-room/fact-sheets/detail/malnutrition) (World Health Organization, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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