Supplements: Magnesium

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The mineral magnesium is important for your heart, muscles, and kidneys. It is part of what makes up your teeth and bones. Most important, it activates enzymes, giving you energy and helping your body work properly. It can help reduce stress, depression, and insomnia. Vitamin B6 helps you get the magnesium you need and works with magnesium in many ways.

Magnesium is available in many foods. However, most people in the United States probably do not get as much magnesium as they should from their diet. Nutrition tables can give you only a rough idea of how much magnesium you are getting. Scientists have found that different ways of determining the amount of magnesium in foods produce different results. Also, many foods have not been thoroughly analyzed.

Certain medical conditions can upset your body's magnesium balance. For example, intestinal flu with vomiting or diarrhea can cause temporary deficiencies. Long-term deficiencies can be caused by stomach and bowel diseases, diabetes, pancreatitis, kidney malfunction, and diuretics. Talk with your health care provider about your magnesium needs if you have any of these conditions.


Getting enough magnesium can help you in the following ways:

  • Prevent hardening of the arteries (arteriosclerosis)
  • Prevent strokes and heart attacks
  • Reduce your blood pressure
  • Lower your cholesterol and triglyceride levels
  • Correct heart arrhythmias
  • Stop acute asthma attacks
  • Decrease your insulin needs if you have diabetes
  • Prevent kidney stones
  • Treat Crohn's disease
  • Treat noise-induced hearing loss Improve your vision if you have glaucoma
  • Reduce cramps, irritability, fatigue, depression, and water retention associated with menstruation
  • Prevent serious complications of pregnancy, such as preeclampsia and eclampsia
  • Restore your normal energy level Improve your sleep
  • Reduce anxiety and depression
  • Reduce the effects of stress

Dietary Sources

The richest sources of magnesium are tofu, nuts (Brazil nuts, almonds, cashews, black walnuts, pine nuts), pumpkin and squash seeds, peanuts, green leafy vegetables, legumes, wheat bran, whole grains, soybean flour, blackstrap molasses.

Other good sources are whole wheat flour, oat flour, beet greens, spinach, shredded wheat, bran cereals, oatmeal, bananas, baked potatoes (with the skin), pistachio nuts.

You can also get magnesium from many herbs, spices, and seaweeds (for example, agar seaweed, coriander, dill weed, celery seed, sage, dried mustard, basil, cocoa powder, fennel seed, savory, cumin seed, tarragon, marjoram, and poppy seed).

Other Forms

Magnesium is available in many forms. The best supplements are labeled "soluble," which means it's easier for your body to absorb the magnesium it needs. These come in gelatin capsules. Recommended types include magnesium citrate, magnesium gluconate, and magnesium lactate.

Other familiar sources of magnesium are milk of magnesia (magnesium hydroxide), often used as a laxative or antacid, Epsom salts (magnesium sulfate) used as a laxative or tonic, or added to a bath. Some magnesium can be absorbed through the skin.

How to Take It

You should take small doses of magnesium throughout the day, with a full glass of water with each dose to avoid diarrhea. These are the recommended daily amounts:

  • Adult men ages 19 to 30: 400 mg; after age 30: 420 mg
  • Adult women ages 19 to 30: 310 mg; after age 30: 320 mg
  • Boys ages 14 to 18: 410 mg
  • Girls ages 14 to 18: 360 mg
  • Children ages 9 to 13: 240 mg; children ages 4 to 8: 130 mg; children ages 1 to 3: 80 mg


Do not take magnesium supplements if you have severe heart disease or kidney disease without talking with your health care provider.

Overuse of milk of magnesia (as a laxative or antacid) or Epsom salts (as a laxative or tonic) can cause you to ingest too much magnesium, especially if you have kidney problems. Too much magnesium can cause serious health problems and even death.

Possible Interactions

Some foods, drinks, and medications can cause you to lose magnesium. These include sodium (salt), sugar, caffeine, alcohol, fiber, riboflavin in high doses, insulin, diuretics, and digitalis.

Some foods, drinks, and medicines make it hard for your body to get the magnesium it needs. These include calcium, iron, manganese, phosphorus, zinc, and fat.

This document contains information relating to general principles of medical care that should not in any event be construed as specific instructions for individual patients. The reader is advised to check product information (including package inserts) for changes and new information regarding dosage, precautions, and contraindications before administering any drug. No claim or endorsements are made for any drug or compound currently in investigative use. No responsibility is assumed by the publisher for any injury and/or damage to any person or property as a matter of product liability, negligence, or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in any material herein.

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Dietary supplements are not intended to treat, cure, or prevent any disease or illness, and the information regarding these products has not been evaluated by the U.S. Food and Drug Administration.

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Previously Published in OSA Today Reproduced by permission
Updated on: 02/01/10