The role of zinc in antiviral
defence

Zinc, a trace element essential to many physiological roles

Zinc is involved in the activity of more than 300 metalloproteins and metalloenzymes where it acts as a metallic cofactor. This means that these specific proteins and enzymes can only function if zinc plays a structural or regulatory role.

Zinc is essential then to multiple biological reactions (immunity, growth, insulin synthesis, etc.) and plays a major role in the body in all major metabolic processes and physiological mechanisms.

Zinc and immunity

A cause and effect relationship has been recognised and accepted by EFSA¹ between dietary intake of zinc and normal immune system function. In fact, zinc plays a dominant role in the body’s natural defences, from maintaining the skin barrier to immune cell activity.

Zinc is involved in the function of thymulin, a hormone which stimulates the development and maturation of T lymphocytes in the thymus. These cells play a major role in the immune response, as they recognise and fight against foreign bodies, pathogens and cells infected with the virus.

In addition, scientific studies have shown numerous mechanisms by which zinc is involved in the viral replication cycle². Replication is the phenomenon by which the virus, once it has infected a cell, multiplies and produces new viruses, thus spreading the infection to other cells.

The role of zinc in the antiviral response can be summarised in 2 actions therefore:

• Improvement of the immune response (activation of T lymphocytes)
• Inhibition of viral replication and of multiplication of the virus in the body

Zinc requirements and risk of deficiency

In the general population, the recommended dietary allowance for zinc varies between 8 mg for women and 11 mg for men. It is also about 11 mg daily for pregnant women. It is still advisable not to exceed a dose of 15 mg zinc per day, from all sources (7 mg for children aged from 10 to 18 years, 3 mg for children aged less than 10 years).

Although serious cases are rare, mild to moderate deficiencies are common and may affect up to one third of the world’s population⁴. Our bodies have no significant reserves of zinc so it is important to ensure a regular supply through the diet.

In major zinc deficiencies, one of the most commonly observed signs is the loss of smell and taste⁵ because zinc is involved in the synthesis of gustin, a protein vital to the perception of taste in the taste buds.

Skin problems, wound healing difficulties, hair loss, reproductive disorders and increased sensitivity to infection have also been observed.

POPULATIONS SENSITIVE TO ZINC DEFICIENCY

Some people are particularly vulnerable to the risk of zinc deficiency:

• Older people: It has been demonstrated that 50 % of older people living in institutions have zinc deficiency⁶.
• People with diabetes: Zinc deficiency is more common in people with type 2 diabetes⁷.

Pregnant women: Because of increased requirements, pregnant women also represent a population potentially more susceptible to zinc deficiency.

Zinc and food

Zinc is found in many foods such as fish or red meat. Vegan diets are very often deficient in zinc, however.

To ensure efficient absorption, it is important to avoid combining it with too many cereals or legumes rich in phytates and to avoid consuming too many preserves because preservatives are mineral traps.

Phytates are actually compounds found in vegetables (maize, rice, cereals, legumes) which bind to certain metals including zinc and prevent their efficient intestinal absorption.