Magnesium, an alkaline earth metal, is the ninth most abundant element in the universe by mass. It constitutes about 2% of the Earth's crust by mass, and it is the third most abundant element dissolved in seawater.
Magnesium is the 11th most abundant element by mass in the human body; its ions are essential to all living cells. The free element (metal) is not found in nature. Once produced from magnesium salts, it is now mainly obtained by electrolysis of brine and is used as an alloying agent to make aluminium-magnesium alloys, sometimes called "magnalium" or "magnelium".
A balance of magnesium is vital to the well being of all organisms. Magnesium is a relatively abundant ion in the lithosphere and is highly bioavailable in the hydrosphere. This ready availability, in combination with a useful and very unusual chemistry, may have led to its usefulness in evolution as an ion for signalling, enzyme activation and catalysis. However, the unusual nature of ionic magnesium has also led to a major challenge in the use of the ion in biological systems. Biological membranes are impermeable to Mg2+ (and other ions) so transport proteins must facilitate the flow of Mg2+, both into and out of cells and intracellular compartments.
Key Functions of Magnesium
Formation of bone - About two thirds of magnesium resides in bone. Researchers have found that this bone magnesium plays two very distinct roles in the support of health. Some of this magnesium contributes to the physical structure of bone, being part of the bones crystal lattice, its "scaffolding", along with calcium and phosphorous. The other portion of magnesium is found on the bone surface and acts as a storage site for magnesium that the body can draw upon during times of inadequate magnesium intake.
Relaxation of nerves and muscles - Magnesium and calcium act in conjunction to help to regulate nerve and muscle tone. In many nerves, magnesium serves the function of being a chemical gatekeeper; when there is enough magnesium around, calcium is blocked from rushing into the nerve cell and activating the nerve and the nerve is kept in a state of relaxation. If dietary magnesium is inadequate, the gate blocking can fail and the nerve may become overactivated. When certain nerve cells are overstimulated, they send too many messages to the muscles causing them to overcontract. This series of events helps to explain why magnesium deficiency can cause muscle soreness, tension, spasms, cramps and fatigue.
Other functions of magnesium - Many chemical reactions in the body involve the presence of enzymes, proteins that help to catalyze chemical reactions. Since magnesium plays a role in over 300 different enzymes, its physiological functions are very extensive and include (but are certainly not limited to) being involved in protein, carbohydrate and fat metabolism, storage of energy in muscle cells and the proper functioning of genes. Since the metabolic role of magnesium is so ubiquitous, it is difficult to identify a body system that would not be affected by a magnesium deficiency. The digestive system, endocrine system, cardiovascular system, nervous system, muscles, kidney, liver and brain all rely upon magnesium to carry out their metabolic functions.
Food Sources of Magnesium
- Pumpkin and squash seed kernels, Brazil nuts, Bran ready-to-eat cereal (100%), Halibut, Quinoa, Spinach, Almonds, Spinach, Buckwheat flour, Cashews, Soybeans, Pine nuts, Mixed nuts, White beans, Pollock, walleye, Black beans, Bulgur, Oat bran, Soybeans, Tuna, Artichokes, Peanuts, Lima beans, Beet greens, Navy beans, Tofu, Okra, Soy beverage, Cowpeas, Hazelnuts, Oat bran muffin, Great northern beans, Oat bran, Buckwheat groats, Brown rice, Haddock
The magnesium content of plants varies considerably with how much magnesium is in the soil where the plants are grown.
Much of the magnesium content in food is lost during processing - milling removes approximately 59% of the magnesium from whole wheat.
Cooking foods in water also causes magnesium to leach out during the cooking process.
Recommended Daily Usage
- 0-6 months - 50mg
- 6-12 months - 70mg
- 1-10 years - 150-250mg
- 11-18 years - 300-400mg
- 18 years + - 300-400mg
- pregnant / lactating - + 150mg
- Therapeutic Range: 50mg - 2500mg+
Nutritional Safety
Deficiency (Not enough Magnesium): Poor dietary intake of magnesium is a common cause of deficiency as are gastrointestinal tract problems such as malabsorption, diarrhea and ulcerative colitis. Physical stresses such as trauma, cold stress and surgery can also contribute to a magnesium deficiency as can kidney disease and alcoholism. The symptoms of magnesium deficiency can impact many physiological processes since this mineral plays such a wide variety of roles in the body. Common symptoms involve changes in muscle and nerve function such as muscle weakness, spasm and tremor. Since the heart is a muscle it can also experience compromised functioning concomitant with magnesium deficiency which can result in arrhythmia, irregular contractions and increased heart rate. Softening and weakening of bone can be the result of a deficiency since magnesium plays an important role in the maintenance of bone structure. Included among other symptoms of magnesium deficiency are imbalanced blood sugar, elevated fats in the bloodstream, elevated blood pressure, headaches, seizures, depression, nausea, vomiting and lack appetite.
Toxicity (Too much Magnesium): Diarrhea is the most commonly experienced toxicity symptom associated with high intake of magnesium. It is most frequently seen when magnesium is taken as a dietary supplement rather than from food sources. While diarrhea can occur at lower supplemental doses, in research studies the doses of magnesium associated with diarrhea range from 1,000-5,000 miligrams. In addition, generalized symptoms such as increased drowsiness or a sense of weakness may be attributable to magnesium toxicity.
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