Trace elements

Last updated: July 6, 2023

Summarytoggle arrow icon

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.

Overviewtoggle arrow icon

In biochemistry, trace elements are dietary elements that the body requires in minute amounts for proper function and development.

Overview of the most important trace elements
Trace element Main function Deficiency Excess


  • Component of chromium-containing glucose tolerance factors


Irontoggle arrow icon


Iron absorption and transport [1]

Iron storage, recycling, and loss [3][4]


Iron deficiency

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

Iron excess

Coppertoggle arrow icon



Copper deficiency

Copper excess

Zinctoggle arrow icon


  • RDA: 8–11 mg/d
  • Sources: poultry, oysters, fish, meat, zinc-fortified food products (e.g., cereals), nuts
  • Metabolism


Zinc deficiency

Zinc excess

Iodinetoggle arrow icon



Iodine deficiency

Iodine excess

Seleniumtoggle arrow icon


  • RDA: 55 μg/d
  • Sources: meat, seafood, grains and seeds (e.g., brazil nut)
  • Metabolism


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

Selenium deficiency

Selenium excess

Sulfurtoggle arrow icon


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


Sulfur deficiency

Sulfur excess

Chromiumtoggle arrow icon

Chromium is not considered an essential element, even though it is often erroneously listed as such. The question of whether chromium can improve insulin sensitivity remains controversial. [9]


  • Sources: meat (e.g., beef), seafood, vegetables (e.g., broccoli, green beans, potatoes), fruits (e.g., apples, bananas), whole grains


Chromium deficiency

Chromium excess

See also “Chromium toxicity.”

Fluoridetoggle arrow icon

General [10]

  • Sources: fluoridated water, fluoridated toothpaste, shellfish, tea (e.g., black tea, green tea),

Function [11]

Fluoride deficiency

Fluoride excess

  • Causes
    • Excessive use of fluoride toothpaste (only causes dental fluorosis)
    • Excessive consumption of fluoride, typically due to very high levels in drinking water, or supplements
  • Clinical features: fluorosis
    • Dental fluorosis: porous, mottling, and opaque, white staining enamel (due to hypomineralization during the formation of permanent teeth during the first 6 years of life)
    • Skeletal fluorosis (due to mineralization of ligaments, cartilage, and periarticular muscles and demineralization of the bone)

Referencestoggle arrow icon

  1. Iron Absorption. Updated: February 28, 2017. Accessed: February 28, 2017.
  2. Duck KA, Connor JR. Iron uptake and transport across physiological barriers. BioMetals. 2016; 29 (4): p.573-591.doi: 10.1007/s10534-016-9952-2 . | Open in Read by QxMD
  3. Kumar V, Abbas AK, Aster JC. Robbins & Cotran Pathologic Basis of Disease. Elsevier Saunders ; 2014
  4. 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): p.5960-5965.doi: 10.1073/pnas.0900808106 . | Open in Read by QxMD
  5. FINCH CA, HEGSTED M, KINNEY TD, et al. IRON METABOLISM. Blood. 1950; 5 (11): p.983-1008.doi: 10.1182/blood.v5.11.983.983 . | Open in Read by QxMD
  6. Saito H. Metabolism of iron stores. Nagoya J Med Sci. 2014; 76 (3-4): p.235-254.
  7. Leung AM, Braverman LE. Consequences of excess iodine. Nat Rev Endocrinol. 2013; 10 (3): p.136-142.doi: 10.1038/nrendo.2013.251 . | Open in Read by QxMD
  8. Markou K, Georgopoulos N, Kyriazopoulou V, Vagenakis AG. Iodine-Induced Hypothyroidism. Thyroid. 2001; 11 (5): p.501-510.doi: 10.1089/105072501300176462 . | Open in Read by QxMD
  9. Vincent JB. New Evidence against Chromium as an Essential Trace Element. The journal of nutrition. 2017; 147 (12): p.2212-2219.doi: 10.3945/jn.117.255901 . | Open in Read by QxMD
  10. Kanduti D, Sterbenk P, Artnik and. Fluoride: a Review of Use and Effects on Health. Materia Socio Medica. 2016; 28 (2): p.133.doi: 10.5455/msm.2016.28.133-137 . | Open in Read by QxMD
  11. Poundarik AA, Boskey A, Gundberg C, Vashishth D. Biomolecular regulation, composition and nanoarchitecture of bone mineral. Scientific Reports. 2018; 8 (1).doi: 10.1038/s41598-018-19253-w . | Open in Read by QxMD

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