Microminerals in General

Microminerals in General
A precise definition for the essential microminerals (or trace minerals) has not been established. Some define essential microminerals as one that comprises less than one hundredth of one percent of total body weight. Others define it as a nutrient the body needs in concentrations of one part per million or less. These minerals initially gained the nomenclature of trace because their concentrations in tissue were not easily quantified by early analytical method.

Iron appears to be mineral that divides the macrominerals from microminerals; consequently, some define an essential trace mineral as one that is needed by the body in a concentration equal to or lower than iron.

Although fourteen microminerals are designated as essential, questions currently exist about essential of three of trace minerals, i.e., chromium, fluorine and vanadium. Their essentiality is questioned because they fail to meet all the proposed criteria for an essential trace mineral:

• It is present in all healthy tissue of living things.
• Its concentration from one animal to the next is fairly constant.
• Its withdrawal from the body induces reproducibly the same physiological and structural abnormalities, regardless of species studied.
• The abnormalities induced by deficiencies are always accompanied by specific biochemical changes.
• These biochemical changes can be prevented or cured when the deficiency is prevented or cured.
  

Microminerals in General

Magnesium Function in Human Body

Magnesium Function in Human Body
Of the total magnesium, about 0.5 gm/kg fat-free tissue, roughly 60% is located in bone. The function of magnesium in hard tissues is not known; one third of it is in combination with phosphate, and the remainder appears to be adsorbed loosely on the surface of the mineral structure.

A small amount of magnesium is dissolved in the extracellular fluid and is easily exchanged with that adsorbed at the bone surface. Only 1 – 3 mg/100ml is present in serum; of this about 35% is bound to protein or complexed with other substances and is not available for exchange.

Within the cells of soft tissue the concentration of magnesium is greater than any other mineral except potassium. Loss of magnesium from the body therefore is usually associated with tissue breakdown and cell destruction.

Magnesium is required for cellular respiration, specifically in oxidative phosphorylation leading to formation of ATP. In fact magnesium is necessary for all phosphate transferring system and in certain tissues, such a heart, a major fraction of the Magnesium present is complexed with ATP, ADP and AMP.

Chronic deficiency produces alopecia, skin lesions and swollen gums. High calcium intakes tend to aggravate symptoms of magnesium deficiency. Personality changes, muscles tremor, lack of coordination and gastrointestinal disturbances developed after three months on the deficient diet. In addition, serum calcium and potassium decreased as serum magnesium decreased and rose to normal if magnesium therapy instituted.

Magnesium deficiency does not appear to be a problem in most human dietaries since the mineral element is widely distributed in foodstuffs.

In a normal adequate diet about 30% of the total magnesium intake may come from green vegetables that contain magnesium porphyrin, chlorophyll.
Magnesium Function in Human Body

Phosphorus: Absorption and Transport

Phosphorus is a common ubiquitously distributed throughout the body. Approximately 85% of the body’s phosphorus is in the skeleton, with the remainder associated with organic substances of soft tissue. 

Approximately 125 to 150 mg of phosphors enters and leaves the extracellular fluid each day as a result of ongoing skeletal remodeling.

Dietary phosphorus occurs in both inorganic form as well as phospholipids. The relative amounts of inorganic and organic phosphorus vary with the type of diet. Cow’s milk phosphorus is 70% inorganic, whereas phosphorus of cereal and the soft tissues of animal; is largely combined organically.

But regardless of its dietary form, most phosphate is absorbed in its inorganic form, since organically bound phosphate is promptly hydrolyzed enzymatically in the lumen of small intestine and released as inorganic phosphate. Much of this enzymatic activity is attributed to the action of alkaline phosphatase, which functions at the brush border of the enterocytes.

Phosphorus absorption occurs throughout the small intestine, but primarily in the duodenum and jejunum with minimal absorption occurring in the ileum. Nearly 70% is absorbed at a normal intake and up to 90% when intake is low. Unlike calcium the intestinal absorption of phosphorus is not controlled according to the body needs.

Phosphorus absorption occurs by two processes:
*Saturable, carrier-mediated, active transport
*Diffusion

Maintenance of the phosphate balance is achieved largely thorough renal excretion.

Phosphorus is quickly absorbed from intestine and into the blood, appearing in the blood within about an hour after ingestion.

Although some phosphorus is lost in gastrointestinal secretions and as a result of the sloughing of intestinal epithelial cells, the net input of phosphorus into extracellular fluid from gastrointestinal tract is approximately 600 to 800 mg per day.

Transport across the enterocyte’s basolateral membrane for entrance into the blood is thought to occur by facilitated diffusion.
Phosphorus: Absorption and Transport