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magnesium in diet

Magnesium is a major mineral that is involved in more than 300 enzyme reactions in the body.

What food source is the nutrient found in? 
Magnesium is found in nuts, soybeans, legumes and whole grains. It is also found in seafood, dark green vegetables, cereals, bananas, and milk. The following are some foods and the amount of magnesium in them:
  • spinach (1/2 cup) = 80 milligrams (mg)
  • peanut butter (2 tablespoons) = 50 mg
  • black-eyed peas (1/2 cup) = 45 mg
  • milk, low fat (1 cup) = 40 mg
How does the nutrient affect the body? 
Magnesium is an important mineral in bone structure. Magnesium works together with calcium and phosphorous to form bones. It is also found in muscle, body fluids and soft tissue, such as the heart and kidneys. Magnesium helps change carbohydrates, proteins, and fats to energy. It is involved in muscle relaxation and contraction, as well as nerve transmission.

Magnesium helps prevent dental cavities by holding calcium in tooth enamel. It is needed to help prevent coronary artery disease and irregular heartbeats, or arrhythmias. It also helps to regulate body temperature. Because magnesium helps the body use calcium properly, getting enough magnesium after menopause helps promote healthy bones and avoid osteoporosis.

There is a recommended daily intake, or RDI, for magnesium. The RDI is different for different ages and genders. The RDIs are:
  • males (19 to 30 years) - 400 mg
  • males (31+ years) - 420 mg
  • females (19 to 30 years) - 310 mg
  • females (31+ years) - 320 mg
  • pregnant females (19 to 30 years) - 350 mg
  • pregnant females (31+ years) - 360 mg
  • breastfeeding females (19 to 30 years) - 310 mg
  • breastfeeding females (31+ years) - 320 mg
Most Australians do not have enough magnesium in their diet. Whole, natural foods are rich in magnesium. Many people eat only processed and refined foods. Processing food and water removes a lot of magnesium. Softened water replaces calcium and magnesium with sodium.

Although clinical deficiency is rare, minor deficiency is more common. A low level of magnesium in the diet can increase the chances for coronary artery disease, high blood pressure, and kidney stones.

Low levels of magnesium may also contribute to sleep disorders, premenstrual syndrome, and menstrual cramps.

Clinical deficiencies of magnesium can be caused by extreme vomiting or diarrhoea. Malnutrition and alcohol abuse may also cause clinical deficiency. Long-term use of diuretics, or water pills, diabetes, and kidney disorders may cause magnesium deficiency. A deficiency of magnesium affects all tissues, especially the heart, nerves and kidneys. Symptoms of deficiency may include: High levels of magnesium taken from supplements, not from food and water, can cause gastrointestinal problems such as diarrhoea. Therefore the Tolerable Upper Intake Level, or UL, for supplementary magnesium is 350 mg. It is always smart to consult with a doctor before beginning any supplement intake.

Toxicity from magnesium is rare, because the kidneys are good at removing excess magnesium. It can occur, however, in people with kidney disease. It can also occur in elderly people with weak kidney function. These people may not be able to excrete magnesium properly. Symptoms include: Author: Kimberly Tessmer, RD, LD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 19/10/2004
Potential conflict of interest information for reviewers available on request

This website and article is not a substitute for independent professional advice. Nothing contained in this website is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.  All Health and any associated parties do not accept any liability for any injury, loss or damage incurred by use of or reliance on the information.


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