What Are the Elements in the Human Body?

Review the Elemental Composition of a Human Being

human body composition
The most abundant element by mass is oxygen, from water. Youst / Getty Images

There are several ways to consider the composition of the human body, including its elements, molecule types, and cell types. Most of the body is made up of water (H2O) with bone cells comprised of 31% water and the lungs 83%. Therefore, it isn't surprising that most of the human body's mass is oxygen. Carbon, the basic unit for organic molecules, comes in second in terms of mass. Additionally, 96.2% of the human body's mass is made of only four elements: oxygen, carbon, hydrogen, and nitrogen.

  1. Oxygen (O) - 65% - Oxygen and hydrogen form water—the primary solvent in the body—which regulates temperature and osmotic pressure. Oxygen is found in many key organic compounds.
  2. Carbon (C) - 18.5% - Carbon has four bonding sites for other atoms, which makes it the key atom for organic chemistry. Carbon chains build carbohydrates, fats, nucleic acids, and proteins. Breaking bonds with carbon is an energy source.
  3. Hydrogen (H) - 9.5% - Hydrogen is found in water and all organic molecules.
  4. Nitrogen (N) - 3.2% - Nitrogen is found in proteins and nucleic acids that make up the genetic code.
  5. Calcium (Ca) - 1.5% - Calcium is the most abundant mineral in the body. It's a structural material in bones essential for protein regulation and muscle contraction.
  6. Phosphorus (P) - 1.0% - Phosphorus is found in the molecule ATP, which is the primary energy carrier in cells. It's also found in bone.
  7. Potassium (K) - 0.4% - Potassium is an important electrolyte. It's used to transmit nerve impulses and regulate heartbeat.
  8. Sodium (Na) - 0.2% - Sodium is an important electrolyte. Like potassium, it's used for nerve signaling. Sodium is one of the electrolytes that helps regulate the amount of water in the body.
  9. Chlorine (Cl) - 0.2% - Chlorine is an important negatively charged ion (anion) that maintains fluid balance.
  10. Magnesium (Mg) - 0.1% - Magnesium is involved in more than 300 metabolic reactions. It's used to build the structure of muscles and bones and is an important cofactor in enzymatic reactions.
  11. Sulfur (S) - 0.04% - Two amino acids are made of sulfur. The bonds that sulfur forms help give proteins the shape needed to perform their functions.

Many other elements may be found in extremely small quantities (less than 0.01%). For example, the human body often contains trace amounts of thorium, uranium, samarium, tungsten, beryllium, and radium. Essential trace elements in humans include zinc, selenium, nickel, chromium, manganese, cobalt, and lead.

Not all the elements found within the body are essential for life. Some are considered contaminants that appear not to harm but serve no known function. Examples include cesium and titanium. Others are actively toxic, including mercury, cadmium, and radioactive elements. Arsenic is considered toxic to humans but serves a function in other mammals (goats, rats, hamsters) in trace amounts. Aluminum is interesting because it's the third most common element in the Earth's crust, but its role in the human body is unknown. Fluorine is used by plants to produce protective toxins and has an "apparent beneficial intake" in humans.

Additional References

  • Chang, Raymond (2007). Chemistry, 9th Edition. McGraw-Hill. ISBN 0-07-110595-6.
  • Emsley, John (2011). Nature's Building Blocks: An A-Z Guide to the Elements. OUP Oxford. p. 83. ISBN 978-0-19-960563-7.
  • Frausto Da Silva, J. J. R; Williams, R. J. P (2001-08-16). The Biological Chemistry of the Elements: The Inorganic Chemistry of Life. ISBN 9780198508489.
  • H. A., V. W. Rodwell; P. A. Mayes, Review of Physiological Chemistry, 16th ed., Lange Medical Publications, Los Altos, California 1977.
  • Zumdahl, Steven S. and Susan A. (2000). Chemistry, 5th Edition. Houghton Mifflin Company. p. 894. ISBN 0-395-98581-1.
View Article Sources
  1. "The Water in You: Water and the Human Body." U.S. Geological Survey.

  2. "What Elements Are Found in the Human Body?" Ask a Biologist. Arizona State University.

Format
mla apa chicago
Your Citation
Helmenstine, Anne Marie, Ph.D. "What Are the Elements in the Human Body?" ThoughtCo, Sep. 4, 2024, thoughtco.com/elements-in-the-human-body-p2-602188. Helmenstine, Anne Marie, Ph.D. (2024, September 4). What Are the Elements in the Human Body? Retrieved from https://www.thoughtco.com/elements-in-the-human-body-p2-602188 Helmenstine, Anne Marie, Ph.D. "What Are the Elements in the Human Body?" ThoughtCo. https://www.thoughtco.com/elements-in-the-human-body-p2-602188 (accessed January 8, 2025).