Zinc deficiency in humans results from reduced dietary intake, inadequate absorption, increased loss or increased use. The most common cause is reduced dietary intake; as much as 25% of the world’s population is at risk. Zinc deficiency affects about 2.2 billion people around the world.
Zinc plays an essential role in numerous biochemical pathways. Zinc deficiency affects many organ systems, including the skin, gastro-intestinal tract, central nervous system & immune, skeletal & reproductive systems. A lack of zinc has numerous manifestations, the most common of which are an increased rates of diarrhœa, pneumonia and malaria.
Zinc deficiency can be classified as acute, as may occur during prolonged inappropriate zinc-free total parenteral nutrition or chronic, as may occur in dietary deficiency or inadequate absorption.
Zinc deficiency can also be considered as mild as typically accompanies dietary deficiency or severe, as typically accompanies defective absorption.
Mouth. Zinc deficiency can manifest as non-specific oral ulceration, stomatitis (painful mouth) or white tongue coating. Rarely, it can cause angular cheilitis (sores at the corners of the mouth) and burning mouth syndrome (mouth or tongue soreness).
Smell and taste. Severe zinc deficiency may disturb the sense of smell and taste.
Immune system. Impaired immune function in people with zinc deficiency can lead to the development of respiratory, gastro-intestinal or other infections. During inflammation, there is an increased cellular demand for zinc and impaired zinc homeostasis from zinc deficiency is associated with chronic inflammation.
Dietary Sources of Zinc
- Oysters, crab, lobster and other shellfish (oysters contain more zinc per serving than any other food)
- Red meat and poultry (these are the main sources of zinc for many)
- Pulses, nuts and legumes
- Wholegrain cereals
- Fortified breakfast cereals
- Dairy products such as cheese
- Inadequate diet
- Gastro-intestinal diseases including ulcerative colitis, Crohn’s disease, short bowel syndrome and chronic diarrhœa
- Chronic liver disease
- Chronic kidney disease
- Alcoholism (decreases zinc absorption and increases urinary zinc excretion)
- Sickle cell disease
- Pregnancy and breast-feeding
- Vegetarian diet
- People taking large amounts of iron supplementation (iron can interfere with zinc absorption)
A diet which is high in phytate-containing whole grains, high in foods grown in zinc deficient soil or high in processed foods containing little or no zinc can result in zinc deficiency.