Trace elements

Summary

Essential trace elements are dietary elements including iron, copper, zinc, iodine, selenium, and sulfur that the body requires in minute amounts for proper physiological function and development. While most essential trace elements primarily function as cofactors for a variety of reactions, some also function as constituents of essential molecules (e.g., iron in hemoglobin and myoglobin), transcription factors (e.g., zinc finger), and amino acids (e.g., sulfur in methionine and cysteine). Excess and deficiency of essential trace elements can cause symptoms and diseases, the most important of which are discussed below.

Overview

  • Definition: In biochemistry, trace elements are dietary elements that the body requires in minute amounts for proper function and development.
Trace element Main function Deficiency Excess
Iron
Copper
Zinc
Iodine
  • Integral part of 3-iodotyrosine (T3) and thyroxine (T4)
Selenium
Sulfur

Iron

General

Iron absorption and transport

Iron storage, recycling, and loss

References:[1][2][3]

Function

Deficiency

For more details regarding the clinical features, diagnosis, and etiology of iron deficiency, see the learning card on iron deficiency anemia.

Excess

Copper

General

Function

Deficiency

Excess

Zinc

General

  • Source: poultry, oysters, fish, meat, zinc-fortified food products (e.g., cereals), nuts
  • Metabolism

Function

Deficiency

Excess

  • Causes
    • Rare, but can develop due to excess zinc intake
  • Clinical features

References:[4]

Iodine

General

Function

Iodine deficiency

Iodine excess

Selenium

General

Function

Selenium plays an important role in neutralizing oxidant stress as part of the glutathione peroxidase.

Deficiency

Excess

Sulfur

General

  • Source: meat, eggs, nuts, salmon, leafy green vegetables (e.g., kale, spinach), legumes

Function

Deficiency

  • Causes
    • Deficiency is very rare.
    • Diet based on products grown in sulfur-depleted soils
    • Low-protein diets
  • Clinical features

Excess

  • Causes: Excess consumption of sulfur-rich foods
  • Clinical features
  • 1. Kumar V, Abbas AK, Aster JC. Robbins & Cotran Pathologic Basis of Disease. Philadelphia, PA: Elsevier Saunders; 2014.
  • 2. Soe-Lin S, Apte SS, Andriopoulos B Jr. Nramp1 promotes efficient macrophage recycling of iron following erythrophagocytosis in vivo. Proc Natl Acad Sci U S A. 2009; 106(14): pp. 5960–5965. doi: 10.1073/pnas.0900808106.
  • 3. University of Washington. Iron Absorption. https://courses.washington.edu/conj/bess/iron/iron.htm. Updated February 28, 2017. Accessed February 28, 2017.
  • 4. Dela Rosa KM. Acrodermatitis Enteropathica. In: James WD. Acrodermatitis Enteropathica. New York, NY: WebMD. https://emedicine.medscape.com/article/1102575. Updated November 12, 2018. Accessed December 29, 2018.
  • 5. Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2013; 10(3): pp. 136–142. doi: 10.1038/nrendo.2013.251.
  • 6. Markou K, Georgopoulos N, Kyriazopoulou V, Vagenakis AG. Iodine-Induced Hypothyroidism. Thyroid. 2001; 11(5): pp. 501–510. doi: 10.1089/105072501300176462.
last updated 03/13/2020
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