Nutrients - Magnesium

Magnesium

Overview

Magnesium is an important mineral for everyone. The RDA varies for everyone depending on sex and age. Read about magnesium in this blog by David Mendosa. Most research indicates that only about half of American adults reach the RDA.

Magnesium is used for more than 300 biochemical reactions in the body. It helps maintain normal muscle and nerve function, it keeps heart rhythm steady, it supports a healthy immune system, and it keeps bones strong. It also helps the body digest, absorb, and utilize proteins, fats, and carbohydrates. It also contributes to the makeup of teeth and bones. Most important, it activates enzymes, contributes to energy production, and helps regulate calcium levels, as well as copper, zinc, potassium, vitamin D, and other important nutrients in the body.

Researchers are studying the role magnesium plays in preventing and managing disorders such as diabetes. They have found that it is an essential mineral in the regulation of blood sugar, playing a part in the secretion and function of insulin by opening cell membranes for glucose. Low blood levels of magnesium are frequently seen in people with type 2 diabetes. A deficiency can cause insulin resistance, so that they require greater amounts of insulin to maintain their blood sugar within normal levels.

People with diabetes are always at risk for wounds and slow healing, but with proper medical management and nutrition, these hurdles can be overcome. Certain medical conditions; however, can upset the body's magnesium balance. For example, an intestinal virus that causes vomiting or diarrhea can cause temporary magnesium deficiencies. Some gastrointestinal diseases (such as irritable bowel syndrome or IBS and ulcerative colitis), diabetes, pancreatitis, hyperthyroidism (high thyroid hormone levels), kidney disease, and taking diuretics can lead to deficiencies. Too much coffee, soda, salt, or alcohol, as well as heavy menstrual periods, excessive sweating, and prolonged stress can also lower magnesium levels.

Tests

A magnesium test is used to measure the level of magnesium in the blood. Abnormal levels of magnesium are most frequently seen in conditions or diseases that cause impaired or excessive excretion of magnesium by the kidneys or that cause impaired absorption in the intestines. Magnesium levels may be checked as part of an evaluation of the severity of kidney problems and/or of uncontrolled diabetes and may help in the diagnosis of gastrointestinal disorders.

Since a low magnesium level can, over time, cause persistently low calcium and potassium levels, it may be checked to help diagnose problems with calcium, potassium, phosphorus, and/or parathyroid hormone – another component of calcium regulation.

Recommended Daily Allowance

Dosages are based on the dietary reference intakes (DRIs) issued from the Food and Nutrition Board of the United States Government's Office of Dietary Supplements, part of the National Institutes of Health.

Pediatric

Do not give magnesium supplements to a child without a doctor's supervision.

• Children 1 - 3 years of age: 40 - 80 mg daily
• Children 4 - 8 years of age: 130 mg daily
• Children 9 - 13 years of age: 240 mg daily
• Males 14 - 18 years of age: 410 mg daily
• Females 14 - 18 years of age: 360 mg daily
• Pregnant females 14 - 18 years of age: 400 mg daily
• Breastfeeding females 14 - 18 years of age: 360 mg daily

Adult

• Males 19 - 30 years of age: 400 mg daily
• Females 19 - 30 years of age: 310 mg daily
• Males 31 years of age and over: 420 mg daily
• Females 31 years of age and over: 320 mg daily
• Pregnant females 19 - 30 years of age: 350 mg daily
• Pregnant females 31 and over: 360 mg daily
• Breastfeeding females 19 - 30 years of age: 310 mg daily
• Breastfeeding females 31 years of age and over: 320 mg daily

A person's need for magnesium increases during pregnancy, recovery from surgery and illnesses, and athletic training. Always consult with your physician.

Food Sources

Rich sources of magnesium include tofu, legumes, whole grains, green leafy vegetables, wheat bran, Brazil nuts, soybean flour, almonds, cashews, blackstrap molasses, pumpkin and squash seeds, pine nuts, and black walnuts. Other good dietary sources of this mineral include peanuts, whole wheat flour, oat flour, beet greens, spinach, pistachio nuts, shredded wheat, bran cereals, oatmeal, bananas, and baked potatoes (with skin), chocolate, and cocoa powder. Many herbs, spices, and seaweeds supply magnesium, such as agar seaweed, coriander, dill weed, celery seed, sage, dried mustard, basil, cocoa powder, fennel seed, savory, cumin seed, tarragon, marjoram, and poppy seed.

Precautions 

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider. Since magnesium is excreted by the kidneys, people with heart or kidney disease should not take magnesium supplements except under their doctor's supervision.

It is rare to overdose on magnesium from food. However, people who ingest large amounts of milk of magnesia (as a laxative or antacid), epsom salts (as a laxative or tonic), or magnesium supplements may overdose, especially if they have kidney problems. Too much magnesium can cause serious health problems, including nausea, vomiting, severely lowered blood pressure, confusion, slowed heart rate, respiratory paralysis, deficiencies of other minerals, coma, cardiac arrhythmias, cardiac arrest, and death.

The common side effects from magnesium include upset stomach and diarrhea.

Magnesium competes with calcium for absorption and can cause a calcium deficiency if calcium levels are already low. Some medications may lower magnesium levels in the body. These include chemotherapy drugs, diuretics, digoxin (Lanoxin), steroids, and certain antibiotics.

Possible Interactions

If you are currently being treated with any of the following medications, you should not use magnesium without first talking to your health care provider. Because the list is long, I felt it would be better to quote it from this source.

Aminoglycosides -- Concomitant use with magnesium may cause neuromuscular weakness and paralysis.

Antibiotics -- Taking magnesium supplements may reduce the absorption of quinolone antibiotics, tetracycline antibiotics, and nitrofurantoin (Macrodandin). Magnesium should be taken 1 hour before or 2 hours after taking these medications. Quinolone and tetracycline antibiotics include:

 Ciprofloxacin (Cipro)

 Moxifloxacin (Avelox)

 Tetracycline (Sumycin)

 Doxycycline (Vibramycin)

 Minocycline (Minocin)

Blood Pressure Medications, Calcium Channel Blockers -- Magnesium may increase the risk of negative side effects (such as dizziness, nausea, and fluid retention) from calcium channel blockers (particularly nifedipine or Procardia) in pregnant women. Other calcium channel blockers include:

 Aamlodipine (Norvasc)

 Diltiazem (Cardizem)

 Felodipine (Plendil)

 Verapamil (Calan)

Medications for diabetes -- Magnesium hydroxide, commonly found in antacids such as Alternagel, may increase the absorption of some medications used to control blood sugar levels (particularly glipizide or Glucatrol and glyburide or Micronase). If you take these medications to control blood sugar, your doctor may need to adjust your dose.

Digoxin (Lanoxin) -- Low blood levels of magnesium can increase negative effects from digoxin, including heart palpitations and nausea. In addition, digoxin can cause more magnesium to be lost in the urine. A doctor will monitor magnesium levels in people taking digoxin to see whether they need a magnesium supplement.

Diuretics -- Diuretics known as loop (such as furosemide or Lasix) and thiazide (including hydrochlorothiazide) can lower magnesium levels. For this reason, doctors who prescribe diuretics may recommend magnesium supplements as well.

Fluoroquinones -- Concomitant use with magnesium may decrease absorption and effectiveness. Flouroquinones should be taken a minimum of 4 hours before any products containing magnesium.

Hormone Replacement Therapy -- Magnesium levels tend to decrease during menopause. Clinical studies suggest, however, that hormone replacement therapy may help prevent the loss of this mineral. Postmenopausal women, or those taking hormone replacement therapy, should talk with a health care provider about the risks and benefits of magnesium supplementation.

Labetol -- Concomitant use with magnesium can slow heart beat abnormally and reduce cardiac output.

Levomethadyl -- Concomitant use with magnesium may precipitate a heart condition called QT prolongation.

Levothyroxine -- There have been case reports of magnesium containing antacids reducing the effectiveness of levothyroxine, a medication that treats underactive thyroid.

Penicillamine -- Penicillamine, a medication used to treat Wilson's disease (a condition characterized by high levels of copper in the body) and rheumatoid arthritis, can inactivate magnesium, particularly when high doses of the drug are used over a long period of time. Supplementation with magnesium and other nutrients may reduce side effects associated with penicillamine. If you take penicillamine, a health care provider can determine whether magnesium supplements are right for you.

Tiludronate (Skelid) and Alendronate (Fosamax) -- Magnesium may interfere with absorption of medications used in osteoporosis, including alendronate (Fosamax). Magnesium or antacids containing magnesium should be taken 1 hour before or 2 hours after taking these medications.

Others -- Aminoglycoside antibiotics (such as gentamicin and tobramycin), thiazide diuretics (such as hydrochlorothiazide), loop diuretics (such as furosemide and bumetanide), amphotericin B, corticosteroids (prednisone or Deltasone), antacids, and insulin may lower magnesium levels. Please refer to the depletions monographs on some of these medications for more information.