Zinc Deficiency

See also: Zinc Excess and Zinc Toxicity, and Zinc Supplements.

Zinc is an essential mineral that is important for immune function, wound healing, normal taste and smell, and is needed for DNA synthesis. Zinc also supports normal growth and development during pregnancy, childhood, and adolescence.

• Zinc is a co-factor in DNA and protein synthesis and cell division. It is believed to be important in wound healing.
• The UK recommended ranges are 5.5-9.5 mg/day for males and 4.0-7.0 mg/day for females.¹
• The body contains 2 to 3 g of zinc (Zn), found mainly in bones, teeth, hair, skin, liver, muscle, leukocytes, and testes.
• One third of the of zinc found in plasma is attached loosely to albumin, and about two thirds is firmly bound to globulins.
• Absorption of zinc salts from food is approximately 20-40%. Absorption of zinc is higher from fish and meat but lower from whole-grain bread and cereals, where phytate content impairs absorption. Zinc is mainly lost from body in faeces.²
• Meat, liver, peas, beans, eggs, and seafood (especially oysters) are good sources of zinc.

Although a confirmed diagnosis of zinc deficiency is rare, relative zinc deficiency caused by poor diet, malabsorption, or following burns and trauma is probably common.

Risk factors

• Excessive loss of zinc can occur in trauma, burns and protein-losing conditions.
• Liver disease
• Inadequate diet or malabsorption
• Prolonged parenteral nutrition (total parenteral nutrition usually includes trace amounts of zinc).

Presentation will depend on the severity of zinc deficiency. Mild deficiency may cause no obvious symptoms, whereas severe deficiency may cause most or even all of the following features.

• Anorexia, lethargy, diarrhoea
• Growth retardation, delayed sexual maturation, hypogonadism and hypospermia
• Alopecia, dermatitis, paronychia
• Mental retardation, impaired nerve conduction and nerve damage
• Hepatomegaly
• Immune disorders and susceptibility to infections
• Iron deficiency anaemia
• Macular degeneration, night blindness
• Impaired taste and smell
• Impaired wound healing
• Maternal zinc deficiency may cause anencephaly in the fetus.

Diagnosis may be difficult to confirm, particularly with mild levels of deficiency.

• Decreased levels of plasma zinc (less than 10.7 μmol/L). Plasma levels are an unreliable indicator of zinc deficiency because the plasma level may be lowered, e.g. in acute infection and after trauma. Hypoproteinaemia spuriously lowers plasma-zinc concentration
• Reduced alkaline phosphatase and plasma testosterone
• Impaired T-lymphocyte function
• Decreased collagen synthesis (resulting in poor wound healing), and decreased RNA polymerase activity in several tissues.

Management is based on both treatment of any underlying cause and zinc supplementation.

• Dietary advice and zinc supplementation if necessary.
• Zinc supplementation has a positive effect on growth in premature infants.³
• There is weak evidence that zinc supplementation may help to heal leg ulcers in patients with low serum zinc.^4,5

Rare autosomal recessive disorder caused by failure to generate a transport protein that enables zinc to be absorbed in the intestine.^6,7

• Symptoms usually begin after an infant is weaned from breast milk.
• Presents with psoriasiform dermatitis (characteristic pustular rash over the mucocutaneous junctions, particularly the mouth, the genital areas and pressure areas), hair loss, paronychia, failure to thrive and severe diarrhoea. Also leads to secondary bacterial and fungal infections.
  In older children, failure to thrive, anorexia, alopecia, nail dystrophy, and repeated infections are more common.
  Similar clinical manifestations are seen in children or adults with zinc deficiency from any cause.
• Oral zinc sulphate supplements: if treated early, most of the symptoms are reversible and usually leave no sequelae. Therapy is lifelong and total compliance is essential.