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Major Minerals

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    505
  • The approximate elemental composition of a healthy 70.0 kg (154 lb) adult human is listed in Table \(\PageIndex{1}\). Note that most living matter consists primarily of the so-called bulk elements: oxygen, carbon, hydrogen, and nitrogen—the building blocks of the compounds that constitute our organs and muscles. These four elements also constitute the bulk of our diet; tens of grams per day are required for humans. Seven other elements— sulfur sodium, magnesium, potassium, calcium, chlorine, and phosphorus—are often referred to as macrominerals because they provide essential ions in body fluids and form the major structural components of the body. In addition, phosphorus is a key constituent of both DNA and RNA: the genetic building blocks of living organisms.

    Table \(\PageIndex{1}\): Approximate Elemental Composition of a Typical 70 kg Human
    Bulk Elements (kg) Major Minerals (g)
    oxygen 44 sulfur 0.1
    carbon 12.6 calcium 1700
    hydrogen 6.6 phosphorus 680
    nitrogen 1.8 potassium 250
        chlorine 115
        sodium 70
        magnesium 42

    • 8.3A: Calcium
      Calcium is an essential trace element in living organisms. It is the most abundant metal by mass in many animals, and it is an important constituent of bone, teeth, and shells. In cell biology, the movement of the calcium ion into and out of the cytoplasm functions as a signal for many cellular processes. Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organization's List of Essential Medicines.
    • 8.3B: Chlorine
      The chloride anion is an essential nutrient for metabolism. Chlorine is needed for the production of hydrochloric acid in the stomach and in cellular pump functions. The main dietary source is table salt, or sodium chloride. Overly low or high concentrations of chloride in the blood are examples of electrolyte disturbances. Hypochloremia (having too little chloride) rarely occurs in the absence of other abnormalities.
    • 8.3C: Magnesium
      Manganese is an important element for human health, essential for development, metabolism, and the antioxidant system. Nevertheless, excessive exposure or intake may lead to a condition known as manganism, a neurodegenerative disorder that causes dopaminergic neuronal death and symptoms similar to Parkinson's disease. The classes of enzymes that have manganese cofactors is large and includes oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, lectins, and integrins.
    • 8.3D: Phosphorus
      Inorganic phosphorus in the form of the phosphate \(PO_4^{3−}\) is required for all known forms of life. Phosphorus plays a major role in the structural framework of DNA and RNA. Living cells use phosphate to transport cellular energy with adenosine triphosphate (ATP), necessary for every cellular process that uses energy. ATP is also important for phosphorylation, a key regulatory event in cells. Phospholipids are the main structural components of all cellular membranes. Calcium phosphate salts
    • 8.3E: Potassium
      Potassium is the eighth or ninth most common element by mass (0.2%) in the human body, so that a 60 kg adult contains a total of about 120 g of potassium. The body has about as much potassium as sulfur and chlorine, and only calcium and phosphorus are more abundant (with the exception of the ubiquitous organic elements). Potassium ions are present in a wide variety of proteins and enzymes.
    • 8.3F: Sodium
      Calcium is an important component of a healthy diet and a mineral necessary for life. The National Osteoporosis Foundation states, "Calcium plays an important role in building stronger, denser bones early in life and keeping bones strong and healthy later in life." Approximately 99 percent of the calcium in the human body is in the bones and teeth. Intracellular calcium overload can cause oxidative stress and apoptosis in some cells, sometimes leading to several diseases.
    • 8.3G: Sulfur
      Sulfur is an essential component of all living cells. It is the seventh or eighth most abundant element in the human body by weight, about equal in abundance to potassium, and slightly greater than sodium and chlorine. A 70 kg human body contains about 140 grams of sulfur. In plants and animals, the amino acids cysteine and methionine contain most of the sulfur, and the element is present in all polypeptides, proteins, and enzymes that contain these amino acids.

    Thumbnail: Table salt shaker. Image used with permission (CC BY-SA 4.0; Lexlex)