Magnesium is the eighth most abundant element found within the human body; a 190-lb (86 kg) person possesses approximately 1 oz (23 gr) of magnesium in various places. Approximately 50% of the mineral is stored in the bone structures, and approximately 50% is located within various cells, and organ and tissue structures. One percent of all of the body's magnesium is contained within the cardiovascular system. Magnesium plays a role in more than 300 of the biochemical reactions that are essential to human performance, ranging from the maintenance of the skeletal structure and organ health to the function of the cardiovascular and central nervous systems.

While pure magnesium is an element found on the periodic table, it is not obtained in its natural state from the Earth due to its chemical composition, which makes magnesium react with a number of other elements to form compounds, particularly those involving oxygen, sulphur, and hydrogen. The active ingredient in the bitter water first discovered in an English well in the early 1600s, which later became known as the tonic, Epsom salts, is magnesium sulphate, or MgSO4. The popular digestive aid, Milk of Magnesia, also uses magnesium in its composition.

Magnesium is an important component of chlorophyll, the chemical that makes living plants green. For this reason, many of the excellent dietary sources of magnesium are plant products such as green vegetables, most whole grains, beans, and nuts. Well water that is drawn from ground that has a significant mineral composition, sometimes referred to as hard water, will usually contain significant amounts of magnesium. Magnesium is typically contained in foods that also have significant amounts of potassium and dietary fiber.

As foods are digested, any magnesium is absorbed into the body through the small intestine. The magnesium not processed into the body is excreted through the kidneys in urine. It would be difficult to consume magnesium in quantities sufficient to induce a toxic reaction; magnesium deficiency is a far more important dietary issue. The recommended daily allowance (RDA) of magnesium is 420 mg per day for a male over 30 years of age; the RDA for a 30-year-old female is 320 mg per day.

While calcium, in combination with vitamin D, is the most significant mineral presence in the construction and the maintenance of the human bones, magnesium plays a significant role in the transport of calcium to the required areas of bone development. The combined operation of trace minerals, including magnesium, is a preventative in the onset of osteoporosis, a common bone density disease, especially among post-menopausal women.

Magnesium is also a factor in the manner in which the skeletal muscles respond to the directions transmitted by the central nervous system. Although less crucial in this respect than sodium or potassium, magnesium is necessary in the manner in which signals are sent to working muscles during exercise.

Magnesium plays an important role in the determination of blood sugar (glucose) levels, as well as the manner in which proteins ingested through food are synthesized by the body. In a related fashion, magnesium also acts in the regulation of heartbeat and the functions of the immune system. As with the many influences of magnesium on the metabolisms of the human body, magnesium is not usually the lead actor, but works in a supporting capacity.

Magnesium levels within the body can be influenced by a number of factors, in addition to the obvious failure to consume sufficient magnesium-rich foods. Medications that possess a diuretic quality have been established as contributing to a negative impact on the body's ability to retain magnesium. The medications that are particularly reactive to magnesium in this fashion are those used in the treatment of disorders such as Crohn's disease, a serious illness of the intestinal system. In a similar fashion, the excess consumption of caffeine has the effect of reducing magnesium stores within the body.

A magnesium deficiency will not be manifested in a sudden or dramatic physical fashion. The early symptoms of a magnesium deficiency may include a loss of appetite, generalized weakness, and fatigue. If the condition worsens, the person will experience difficulties in concentration (similar to other electrolytic disruptions in the body), and ultimately, low levels of both calcium and potassium will occur. The most effective way to restore low levels of magnesium is by way of improved diet, especially through green vegetables and whole grains. In some circumstances, the levels may be increased through the use of magnesium supplements. Given the nature of the element, magnesium can be restored to its appropriate concentration in the body within a number of days. Magnesium is a component of a number of dietary and training supplements, in a variety of compounds.

SEE ALSO Calcium; Minerals; Sodium and sodium deficits.