Magnesium

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Magnesium is an essential mineral which is present in all human tissues. It is found mostly in our bones (60-65%) while the rest is distributed inside cells of body tissues and organs. Only 1% of magnesium is found in blood. It cannot be synthesized inside the body and has to be supplied through the diet. Magnesium is a constituent of chlorophyll in green plants and is therefore quite plentiful in the diet. The name magnesium comes from Magnesia, a city in Greece where large deposits of magnesium carbonate were discovered in ancient times.

Contents

Functions

Magnesium is needed for a number of biochemical reactions in the body. It builds and strengthens bones and relaxes the nerves and muscles. Some of the magnesium in our bones gives them their physical structure along with minerals like calcium and phosphorous. Other amounts of magnesium are stored on the surface of the bone to be used later during poor dietary supply.

Magnesium is important for normal contraction and relaxation of muscles. Its deficiency can cause over contraction of the muscles, leading to muscle tension, muscle fatigue and spasms.

Other functions of magnesium include a role in production of energy, supporting a healthy immune system, synthesis of proteins and preventing and managing disorders like hypertension and cardiovascular disease. It is also required for the functioning of a large number of enzymes in the body which makes it important in the metabolism of carbohydrates, proteins and fats.

Food Sources

Dark green, leafy vegetables are good sources of magnesium as the chlorophyll (which gives green color to plants) in plants contains magnesium. Spinach, broccoli and turnip greens are very good sources of magnesium. Other good sources include some legumes (beans and peas), nuts such as cashews and almonds, and whole, unrefined grains. A variety of seeds including sesame and sunflower seeds also provide considerable amounts of magnesium.

Although magnesium is present in many foods, cooking and processing can lead to its loss depending upon the form in which it is present in various foods. About one third of the magnesium in spinach is lost after blanching as it is present in a water soluble form in spinach. On the other hand, very little magnesium is lost from nuts like almonds even on roasting or processing.

Recommended Dosage

The recommended daily requirements of magnesium are as follows:

  • 1-3 years old: 80 milligrams
  • 4-8 years old: 130 milligrams
  • 9-13 years old: 240 milligrams
  • 14-18 years old (boys): 410 milligrams
  • 14-18 years old (girls): 360 milligrams
  • Adult females: 310 milligrams
  • Pregnancy: 360-400 milligrams
  • Breastfeeding women: 320-360 milligrams
  • Adult males: 400 milligrams


Conditions like muscle weakness, softening and weakening of bones, headaches, increased blood pressure and heart arrhythmia can increase the demand for high magnesium foods.

Deficiency

A severe magnesium deficiency called hypomagnesemia is unusual in a healthy person because normal kidneys are very efficient in keeping magnesium levels balanced. However, magnesium depletion can occur as a result of some kidney disease or gastrointestinal disorders that impair absorption of magnesium in the intestines in the body. Chronic or excessive vomiting and diarrhea may also result in magnesium deficiency.

Symptoms of magnesium deficiency vary widely as magnesium plays a wide variety of roles in the body. Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue, and weakness. As the deficiency progresses, muscle and nerve functions are affected and symptoms include muscle weakness, tremor, and spasm. Tingling sensations, numbness, seizures and personality changes are also observed. Magnesium deficiency can result in arrhythmia and increased heart rate.

Toxicity

Magnesium toxicity (hypermagnesemia) is rare because the body eliminates excess in the urine and feces. Dietary magnesium does not pose a problem of hypermagnesemia, however magnesium supplements can cause symptoms of toxicity. The most common toxicity symptom associated with high levels of magnesium intake is diarrhea. Other signs can be similar to magnesium deficiency and include changes in mental status, nausea, diarrhea, appetite loss, muscle weakness, difficulty in breathing, and irregular heartbeat.

References

  • Magnesium
  • What can high-magnesium foods do for you?
  • Medical Encyclopedia
  • Dictionary: magnesium