DNA synthesis — how zinc
contributes to the genetic material

What is meant by DNA synthesis?

DNA synthesis describes the biological process by which deoxyribonucleic acid (DNA) is duplicated or repaired within a cell. This process is fundamental to every cell division and thus to the growth, renewal and repair of tissues throughout the organism.

In what is called replication, the DNA double strand is unwound and each single strand serves as a template for a new complementary strand. The enzymes involved — among them DNA polymerases, helicases and primases — need various cofactors in order to carry out their tasks precisely.

One particular mineral has a health claim in connection with normal DNA synthesis that has been assessed by the European Food Safety Authority (EFSA) and authorised by the EU Commission: zinc.

Why DNA synthesis matters to the organism

Every cell division requires a complete and error-free duplication of the DNA. The human body produces billions of new cells daily — in the skin, in the blood, in the gut and in many other tissues. The following aspects illustrate the scale of this process:

• Cell renewal: Skin cells, mucous membrane cells and blood cells are continuously replaced. Every new cell needs an exact copy of the genetic material.
• Tissue repair: After injuries, damaged cells have to be replaced by new ones, which presupposes error-free DNA replication.
• Immune response: Immune cells multiply rapidly when needed. Fast and correct DNA synthesis is the precondition for a functioning immune response.
• DNA repair: Thousands of DNA lesions occur daily in every cell and are fixed by specific repair mechanisms.

For these processes the body needs, among other things, zinc as a component of the enzymes involved. The EU-authorised claim reads:

“Zinc contributes to normal DNA synthesis” — pursuant to Regulation (EU) No 432/2012

The molecular level: replication and repair

At the molecular level, DNA replication begins at so-called origins of replication. Helicases unwind the double strand, while single-strand binding proteins stabilise the separated strands. DNA polymerase reads the template strand and synthesises the new complementary strand in the 5’–3’ direction.

DNA repair comprises various mechanisms such as base excision repair (BER), nucleotide excision repair (NER) and mismatch repair. Many of the enzymes involved — among them endonucleases and ligases — are zinc-dependent.

Zinc in context: more than a trace element

Zinc is an essential trace element that the body cannot produce itself and has to take in through food. Under EU Regulation 1169/2011 the reference value for daily zinc intake is 10 mg. In connection with DNA synthesis, zinc is involved in the following areas:

• DNA polymerases: Zinc ions are a structural component of several DNA polymerases and contribute to correct base pairing.
• Zinc finger proteins: Hundreds of transcription factors need zinc for their three-dimensional structure and for binding to the DNA.
• Tumour suppressor protein p53: This protein, important for DNA repair and cell cycle control, contains zinc as a structural element.

Foods such as oysters, pumpkin seeds, beef, lentils and oats are among the natural sources of zinc.