Zinc Deficiency

Basics

Description

  • Nutritional condition whose manifestations may involve growth retardation, decreased bone mineralization, hypogonadism, cell-mediated immune dysfunction, poor wound healing, poor appetite, hair loss, lethargy, increased infections, anorexia, diarrhea, and eye and skin lesions
  • Zinc is a mineral and integral component of >300 enzymes and 3,000 transcription factors and plays structural role in cell membranes and proteins. Zinc is essential for wound healing and anabolic processes (1,2,3).
  • System(s) affected: endocrine/metabolic, nervous, skin/exocrine, hematologic/oncologic, gastroenterologic, musculoskeletal

Geriatric Considerations

  • 30–40% of ambulatory elderly may have zinc-deficient diets; elderly may also have decreased absorption (1,2).
  • Zinc deficiency may cause delayed wound healing, chronic ulcers, and impaired recovery from infections. Poor night vision may contribute to increased falls/accidents; loss of taste, which may contribute to worsening nutrition (4)
  • Reactive oxygen species leading to inflammation are involved in many chronic diseases attributed to aging: atherosclerosis, Alzheimer disease, neurodegenerative disorders, diabetes mellitus type 2, and cancer (1).
  • Increased depression and poor cognitive function in the elderly are associated with low zinc levels.
  • Supplementation in one study with elderly subjects decreased the incidence of infection (1)[B].

Pediatric Considerations

  • Zinc deficiency may cause failure to thrive and may impair growth and development of secondary sexual characteristics (1).
  • Peak requirement during pubertal growth spurt (ages 10 to 15 years old) (2)
  • Supplementing deficient children decreases mortality from diarrhea (5)[A] and pneumonia in certain populations (2,5)[B].

Pregnancy Considerations

  • Requirements increase; deficiency may cause spontaneous abortion, preterm labor.
  • Supplementation in deficient individuals reduces preterm labor but does not improve birth weight (6)[A].
  • Severe deficiency is associated with congenital malformations and increased maternal morbidity.

Epidemiology

Prevalence

  • Uncommon in the United States; estimated prevalence is 1–3% (3,7).
  • Globally: Estimated prevalence is 20%; worse in developing countries (4,7)
  • Predominant age: all ages
  • Predominant sex: male = female

Etiology and Pathophysiology

  • Insufficient dietary intake
    • Diet lacking in animal proteins (dairy, eggs, meat, seafood)
    • Parenteral nutrition without zinc supplementation
    • Breastfeeding (infants)
    • Alcoholism
    • Restricted eating/eating disorder
  • Increased requirements
    • Pregnancy
    • Lactation
    • Preterm infants
    • Rapid growth phases in childhood
    • Burns
    • Major trauma
    • Systemic illness resulting in oxidative stress
  • Increased losses
    • Diabetes
    • Cirrhosis, alcoholism
    • Renal disease, dialysis
    • Steatorrhea, enterostomy, fistula
    • Sickle cell disease
    • Diuretics: thiazides, chlorthalidone, ACEI, ARB
  • Decreased absorption
    • Diet high in: phytates (plant fiber), cadmium, copper, iron
    • Acrodermatitis enteropathica: autosomal recessive deficiency in the enzyme required for intestinal absorption of zinc
    • Parasitism
    • Liver or pancreas dysfunction
    • Inflammatory bowel disease
    • After bariatric surgery
    • Medications: chelating agents, penicillamine, tetracyclines, quinolones, bisphosphonates, valproate

Genetics

  • Usually an acquired deficiency
  • Rarely caused by acrodermatitis enteropathica
  • Associated with sickle cell anemia

Risk Factors

  • Medications: diuretics, penicillamine, valproate, iron chelators, ACEI/ARB, cisplatin
  • Low socioeconomic status
  • Living in developing nations
  • Strict vegetarian diet
  • Malabsorption syndromes
  • Thermal burns
  • Alcoholism
  • Chronic renal failure

General Prevention

  • Diverse and adequate diet
  • Supplementation when indicated (see “Medication”)

Commonly Associated Conditions

  • Acrodermatitis enteropathica
  • Sickle cell anemia
  • Malabsorption
  • Advanced age
  • Diarrheal illness, especially in children

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