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Magnesium In Diet

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. 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 phosphorus 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 allowance, or RDA, for magnesium. The RDA is different for different ages and genders. The RDAs 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 Americans 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 diarrhea. 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:
  • nausea
  • muscle weakness
  • sleep disorders
  • fatigue
  • mental confusion
  • abnormal heartbeats, or arrhythmias
  • muscle cramps
  • loss of appetite
  • depression, anxiety, and uptight disposition
  • constipation
High levels of magnesium taken from supplements, not from food and water, can cause gastrointestinal problems such as diarrhea. Therefore the Tolerable Upper Intake Level, or UL, for supplementary magnesium is 350 mg. It is always smart to consult with a healthcare provider 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:
  • nausea
  • vomiting
  • low blood pressure
  • drowsiness


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Murray, M., ND. (1996). Encyclopedia of Nutritional Supplements. California: Prima Publishing

Duyff, R., MS, RD, CFCS. (1996). The American Dietetic Association's Complete Food and Nutrition Guide. Minnesota: Chronimed Publishing

Mahan, K, MS, RD, CDE and Escott-Stump, S., MA, RD, LDN. (2000). Krause's Food, Nutrition, and Diet Therapy (10th ed.). Pennsylvania: W.B. Saunders Company

Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride, (1999). National Academy Press

Heimburger, D.C., MD, Weinsier, R., MD. (1997). Handbook of Clinical Nutrition (3rd ed.). Mosby

MayoClinic Website. (1998). Sodium in soft water

Littlefield, N.A., Hass, B.S. (1996). Is the RDA for Magnesium Too Low? FDA Science Forum.

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