Background
Minerals are elements that originate in the Earth and cannot be made by living
systems. Plants obtain minerals from the soil, and most of the minerals in our
diets come directly from plants or indirectly from animal sources. Minerals may
also be present in the water we drink, but this varies with geographic locale.Minerals from plant sources may also vary from place to place, because soil mineral content varies geographically.
In the body, minerals play a number of vital roles. Several mineral elements are necessary to maintain the structural integrity of bones and teeth, while others are required for enzyme activity and numerous essential biological processes.
|
Calcium
Chromium
Flouride
Iodide
Iron
Magnesium
Manganese
Phosphorus
Potassium
Selenium
Zinc
| |
Top
|
Calcium
| |
|---|---|
| Facts
- Calcium is the most common mineral in the human body. About 99% of the calcium in the body is found in bones and teeth, while the other 1% is found in the blood and soft tissue. Calcium levels in the blood and fluid surrounding the cells (extracellular fluid) must be maintained within a very narrow concentration range for normal physiological functioning (1). The physiological functions of calcium are so vital to survival that the body will demineralize bone to maintain normal blood calcium levels, when calcium intake is inadequate. Thus, adequate dietary calcium is a critical factor in maintaining a healthy skeleton.
|
Top
|
Chromium
| |
|---|---|
| Facts
- Although trivalent chromium is recognized as a nutritionally essential mineral, scientists are not yet certain exactly how it functions in the body. The two most common forms of chromium are trivalent chromium (III) and hexavalent chromium (VI). Chromium (III) is the principal form in foods, as well as the form utilized by the body. Chromium (VI) is derived from chromium (III) by heating at alkaline pH and is used as a source of chromium for industrial purposes. It is a strong irritant and is recognized as a carcinogen when inhaled (see Safety). At low levels, chromium (VI) is readily reduced to chromium (III) by reducing substances in foods and the acidic environment of the stomach, which serve to prevent the ingestion of chromium (VI) (1-3).
|
Top
|
Flouride
| |
|---|---|
| Facts
- Fluorine occurs naturally in the Earth's crust, water, and food as the negatively charged ion, fluoride (F-). Fluoride is considered a trace element because only small amounts are present in the body (about 2.6 grams in adults), and because the daily requirement for maintaining dental health is only a few milligrams a day (see The RDA). About 95% of the total body fluoride is found in bones and teeth (1). Although its role in the prevention of dental caries (tooth decay) is well established, fluoride is not generally considered an essential mineral element because humans do not require it for growth or to sustain life (2). However, if one considers the prevention of chronic disease (dental caries), an important criterion in determining essentiality, then fluoride might well be considered an essential trace element (3).
|
Top
|
Iodide
| |
|---|---|
| Facts
- Iodine, a non-metallic trace element, is required by humans for the synthesis of thyroid hormones. Iodine deficiency is an important health problem throughout much of the world. Most of the Earth's iodine is found in its oceans. In general, the older an exposed soil surface, the more likely the iodine has been leached away by erosion. Mountainous regions, such as the Himalayas, the Andes, and the Alps, and flooded river valleys, such as the Ganges, are among the most severely iodine deficient areas in the world (1).
|
Top
|
Iron
| |
|---|---|
| Facts
- Oxygen transport and storage: Heme is an iron-containing compound found in a number of biologically important molecules. Hemoglobin and myoglobin are heme-containing proteins that are involved in the transport and storage of oxygen. Hemoglobin is the primary protein found in red blood cells and represents about two thirds of the body's iron. The vital role of hemoglobin in transporting oxygen from the lungs to the rest of the body is derived from its unique ability to acquire oxygen rapidly during the short time it spends in contact with the lungs and to release oxygen as needed during its circulation through the tissues. Myoglobin functions in the transport and short-term storage of oxygen in muscle cells, helping to match the supply of oxygen to the demand of working muscles (3,4).
|
Top
|
Magnesium
| |
|---|---|
| Facts
- Energy production: The metabolism of carbohydrates and fats to produce energy requires numerous magnesium-dependent chemical reactions. Magnesium is required by the adenosine triphosphate (ATP) synthesizing protein in mitochondria. ATP, the molecule that provides energy for almost all metabolic processes, exists primarily as a complex with magnesium (MgATP).Synthesis of essential molecules: Magnesium is required at a number of steps during the synthesis of nucleic acids (DNA and RNA) and proteins. A number of enzymes participating in the synthesis of carbohydrates and lipids require magnesium for their activity. Glutathione, an important antioxidant, requires magnesium for its synthesis.
|
Top
|
Manganese
| |
|---|---|
| Facts
- Manganese (Mn) plays an important role in a number of physiologic processes as a constituent of some enzymes and an activator of other enzymes (2).
Antioxidant function: Manganese superoxide dismutase (MnSOD) is the principal antioxidant enzyme of mitochondria. Because mitochondria consume over 90% of the oxygen used by cells, they are especially vulnerable to oxidative stress. The superoxide radical is one of the reactive oxygen species produced in mitochondria during ATP synthesis. MnSOD catalyzes the conversion of superoxide radicals to hydrogen peroxide, which can be reduced to water by other antioxidant enzymes (3).
Metabolism: A number of manganese-activated enzymes play important roles in the metabolism of carbohydrates, amino acids, and cholesterol (4). Pyruvate carboxylase, a manganese-containing enzyme, and phosphoenolpyruvate carboxykinase (PEPCK), a manganese-activated enzyme, play critical roles in gluconeogenesis the production of glucose from non-carbohydrate precursors. Arginase, another manganese-containing enzyme, is required by the liver for the urea cycle, a process that detoxifies ammonia generated during amino acid metabolism (3).
|
Top
|
Phosphorus
| |
|---|---|
| Facts
- Phosphorus is a major structural component of bone in the form of a calcium phosphate salt called hydroxyapatite. Phospholipids (e.g., phosphatidylcholine) are major structural components of cell membranes. All energy production and storage are dependent on phosphorylated compounds, such as adenosine triphosphate (ATP) and creatine phosphate. Nucleic acids (DNA and RNA), responsible for the storage and transmission of genetic information, are long chains of phosphate-containing molecules. A number of enzymes, hormones, and cell signaling molecules depend on phosphorylation for their activation. Phosphorus also helps to maintain normal acid-base balance (pH) in its role as one of the body's most important buffers. The phosphorus-containing molecule 2,3-diphosphoglycerate (2,3-DPG) binds to hemoglobin in red blood cells and affects oxygen delivery to the tissues of the body (1).
|
Top
|
Potassium
| |
|---|---|
| Facts
- Maintenance of membrane potential: Potassium is the principal positively charged ion (cation) in the fluid inside of cells, while sodium is the principal cation in the fluid outside of cells. Potassium concentrations are about 30 times higher inside than outside cells, while sodium concentrations are more than 10 times lower inside than outside cells. The concentration differences between potassium and sodium across cell membranes create an electrochemical gradient known as the membrane potential. A cell's membrane potential is maintained by ion pumps in the cell membrane, especially the sodium, potassium-ATPase pumps. These pumps use ATP (energy) to pump sodium out of the cell in exchange for potassium. Their activity has been estimated to account for 20%-40% of the resting energy expenditure in a typical adult. The large proportion of energy dedicated to maintaining sodium/potassium concentration gradients emphasizes the importance of this function in sustaining life. Tight control of cell membrane potential is critical for nerve impulse transmission, muscle contraction, and heart function (2,3).
|
Top
|
Selenium
| |
|---|---|
| Facts
- Selenium is a trace element that is essential in small amounts, but can be toxic in larger amounts. Humans and animals require selenium for the function of a number of selenium-dependent enzymes, also known as selenoproteins. During selenoprotein synthesis, selenocysteine is incorporated into a very specific location in the amino acid sequence in order to form a functional protein. Unlike animals, plants do not appear to require selenium for survival. However, when selenium is present in the soil, plants incorporate it non-specifically into compounds that usually contain sulfur (1, 2).
|
Top
|
Zinc
| |
|---|---|
| Facts
- Numerous aspects of cellular metabolism are zinc-dependent. Zinc plays important roles in growth and development, the immune response, neurological function, and reproduction. On the cellular level, the function of zinc can be divided into three categories: 1) catalytic, 2) structural, and 3) regulatory (3).
Catalytic: Nearly 100 different enzymes depend on zinc for their ability to catalyze vital chemical reactions. Zinc-dependent enzymes can be found in all known classes of enzymes (4).
Structural: Zinc plays an important role in the structure of proteins and cell membranes. A finger-like structure, known as a zinc finger motif, stabilizes the structure of a number of proteins. For example, copper provides the catalytic activity for the antioxidant enzyme copper-zinc superoxide dismutase (CuZnSOD), while zinc plays a critical structural role (4,5). The structure and function of cell membranes are also affected by zinc. Loss of zinc from biological membranes increases their susceptibility to oxidative damage and impairs their function (6).
Regulatory: Zinc finger proteins have been found to regulate gene expression by acting as transcription factors (binding to DNA and influencing the transcription of specific genes). Zinc also plays a role in cell signaling and has been found to influence hormone release and nerve impulse transmission. Recently zinc has been found to play a role in apoptosis (gene-directed cell death), a critical cellular regulatory process with implications for growth and development, as well as a number of chronic diseases (7)
|
|
