Magnesium is Cool

magnesiumI read an interesting article in one of my medical journals (American Family Physician) about the therapeutic uses of magnesium, ranging from preeclampsia to migraines.  The article also discussed the consequences of magnesium deficiency.  Studies estimate that 75% of Americans do not get enough of the element in their diet, and that the general mineral content of our food is declining.

Early signs of magnesium deficiency are quite nonspecific and overlap with thousands of other conditions, but include loss of appetite, nausea, vomiting, fatigue, and weakness. As levels decrease further, numbness, tingling, muscle contractions, cramps, seizures, personality changes, arrhythmias, and even coronary artery spasms can occur. Severe deficiency can lead to low potassium and calcium levels, each of which can cause serious problems as well.

Conditions that have been associated with low magnesium levels include poorly-controlled diabetes, malabsorptive disorders like Crohn’s Disease and celiac disease, alcoholism, and older age.  Taking diuretics and certain antibiotics can also decrease magnesium levels in the body.  Studies have linked magnesium deficiency to heart attacks, congestive heart failure, hypertension, and angina, but evidence is still too sparse to recommend its use for these problems.

The only two clinical recommendations that carry an “A” evidence rating (consistent, good-quality patient-oriented evidence) are for using magnesium in the treatment of eclampsia and preeclampsia in pregnancy, and in the treatment of torsade de pointes and rapid atrial fibrillation, two serious heart rhythm disturbances.

Other studies have found magnesium beneficial in the treatment of acute asthma (when given intravenously in conjunction with standard bronchodilators and steroids), migraines and cluster headaches, dyspepsia and gastroesophageal reflux. If you’re wondering if you should take magnesium, talk to your doctor.  Oral magnesium supplementation can be well-tolerated, or can cause nausea, vomiting, and diarrhea in and of itself.   Overdose of magnesium can lead to thirst, dangerously low blood pressure, drowsiness, muscle weakness, respiratory depression, cardiac arrhythmia, coma and death.   Magnesium can also interfere with the absorption of other medicines, and people with poor kidney filtration may accumulate toxic levels.

As with all reductionist approaches to food and nutrition, purely focusing on individual nutrients and minerals like magnesium is too easy, and misses the bigger picture.  Like Michael Pollan says, “Eat food. Not too much. Mostly plants.”   Food sources of magnesium tend to be rather healthy foods, and include green leafy vegetables, nuts, legumes, and whole grains. The NIH has compiled this list of common magnesium-containing foods:

Table 1: Selected food sources of magnesium [5]

FOOD Milligrams (mg) %DV*
Halibut, cooked, 3 ounces 90 20
Almonds, dry roasted, 1 ounce 80 20
Cashews, dry roasted, 1 ounce 75 20
Soybeans, mature, cooked, ½ cup 75 20
Spinach, frozen, cooked, ½ cup 75 20
Nuts, mixed, dry roasted, 1 ounce 65 15
Cereal, shredded wheat, 2 rectangular biscuits 55 15
Oatmeal, instant, fortified, prepared w/ water, 1 cup 55 15
Potato, baked w/ skin, 1 medium 50 15
Peanuts, dry roasted, 1 ounce 50 15
Peanut butter, smooth, 2 Tablespoons 50 15
Wheat Bran, crude, 2 Tablespoons 45 10
Blackeyed Peas, cooked, ½ cup 45 10
Yogurt, plain, skim milk, 8 fluid ounces 45 10
Bran Flakes, ½ cup 40 10
Vegetarian Baked Beans, ½ cup 40 10
Rice, brown, long-grained, cooked, ½ cup 40 10
Lentils, mature seeds, cooked, ½ cup 35 8
Avocado, California, ½ cup pureed 35 8
Kidney Beans, canned, ½ cup 35 8
Pinto Beans, cooked, ½ cup 35 8
Wheat Germ, crude, 2 Tablespoons 35 8
Chocolate milk, 1 cup 33 8
Banana, raw, 1 medium 30 8
Milk Chocolate candy bar, 1.5 ounce bar 28 8
Milk, reduced fat (2%) or fat free, 1 cup 27 8
Bread, whole wheat, commercially prepared, 1 slice 25 6
Raisins, seedless, ½ cup packed 25 6
Whole Milk, 1 cup 24 6
Chocolate Pudding, 4 ounce ready-to-eat portion 24 6




The USDA has a much more complete and exhaustive list, although it is sorted alphabetically and therefore requires a lot of scrolling around.

And finally, some cool facts about magnesium in the universe from Wikipedia:

Magnesium, an alkaline earth metal, is the 9th most abundant element in the universe by mass. The commonness of magnesium is related to the fact that it is easily built up in supernova stars from a sequential addition of 3 helium nuclei to carbon (which in turn is made from a single reaction between 3 helium nuclei at once). Magnesium constitutes about 2% of the Earth’s crust by mass, which makes it the 8th most abundant element in the crust. Magnesium ion’s high solubility in water helps ensure that it is the 3rd most abundant element dissolved in seawater.

Halibut with chocolate pudding and boiled spinach on top, anyone?

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6 thoughts on “Magnesium is Cool

  1. kullervo

    And what do you do if you’re one of the few lucky people who get migraines _from_ magnesium?

  2. Chrys

    I’ll pass on your culinary creation. I’ve heard magnesium is also good for kidney stones in conjunction with vitamin B6.

  3. Greg P

    Magnesium is one of these topics that medically there is less science than collective anectodal wisdom, or what passes for wisdom.

    Even its use in eclampsia is something akin to voodoo, that is, if voodoo doctors managed to publish their experience in the Journal of Voodoo Medicine. This isn’t to say that it doesn’t work or seem to work, but why it works is unclear, as well as knowing when to stop. It seems you keep giving it until the patient stops doing things you don’t like.

    I’m being tongue-in-cheek, but I’d say not so firmly tongue-in-cheek.

  4. David Harmon

    Greg P: Magnesium is one of these topics that medically there is less science than collective anectodal wisdom, or what passes for wisdom.

    There’s a lot of that with trace minerals, both in animal and plant biology. I’ve recently heard a bit about trace minerals as an issue in soil fertility.

    Lately, I’ve been wondering about zinc… I heard a rumor that zinc deficiency can be associated with anorexia, producing an effect of “food doesn’t taste right”. That would seem eminently testable, especially with the prevalence of zinc lozenges for treatment of colds. Dr. Charles, have you heard anything about that?

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