Health Encyclopedia

Magnesium in diet

Definition

Magnesium is an essential mineral for human nutrition.

Alternative Names

Diet - magnesium

Function

Magnesium in the body serves several important functions:

Contraction and relaxation of muscles
Function of certain enzymes in the body
Production and transport of energy
Production of protein

Food Sources

Most dietary magnesium comes from vegetables, such as dark green, leafy vegetables. Other foods that are good sources of magnesium:

Fruits or vegetables (such as bananas, dried apricots, and avocados)
Nuts (such as almonds and cashews)
Peas and beans (legumes), seeds
Soy products (such as soy flour and tofu)
Whole grains (such as brown rice and millet)

Side Effects

Side effects from increased magnesium intake are not common because the body removes excess amounts. Magnesium excess almost always occurs only when magnesium is supplemented as a medication.

Lack of magnesium (deficiency) is rare. The symptoms include:

Hyperexcitability
Muscle weakness
Sleepiness

Deficiency of magnesium can occur in people who abuse alcohol or in those who absorb less magnesium due to:

Burns
Certain medications
Low blood levels of calcium
Problems absorbing nutrients from the intestinal tract (malabsorption)
Surgery

Symptoms due to a lack of magnesium have three categories.

Early symptoms:

Anorexia
Apathy
Confusion
Fatigue
Insomnia
Irritability
Muscle twitching
Poor memory
Reduced ability to learn

Moderate deficiency symptoms:

Heart (cardiovascular) changes
Rapid heartbeat

Severe deficiency:

Continued muscle contraction
Delirium
Numbness
Seeing or hearing things that aren't there (hallucinations)
Tingling

Recommendations

These are the recommended daily requirements of magnesium:

Children
- 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 - 320 milligrams
Pregnancy: 350 - 400 milligrams
Breastfeeding women: 310 - 360 milligrams
Adult males: 400 - 420 milligrams

References

Food and Nutrition Board, Institute of Medicine. DRI Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academy Press; 1997.

Yu ASL. Disorders of magnesium and phosphorus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 120.

Rakel D, ed. Integrative Medicine. 2nd ed. Philadelphia, Pa: Saunders Elsevier; 2007.

Review Date:3/9/2009
Reviewed By:Linda Vorvick, MD, Family Physician, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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