|Category||Age||Magnesium (in milligrams)|
|Pregnant Women|| |
|Lactating Women||1st 6 months||355|
|2nd 6 months||340|
|Top Food Sources1||Magnesium (mg per 3 1/2 ounce serving)|
|Whole wheat flour||150|
FormulationsThere are many formulations of magnesium available in the marketplace. The most common form is magnesium oxide. It is insoluble in water and, therefore, may not be absorbed in persons with gastrointestinal disorders, including hypoacidity. Magnesium acetate, aspartate, citrate, gluconate, and glycinate are all well absorbed.3 There are not many studies comparing different forms of magnesium head to head. If a patient is displaying signs and symptoms of a magnesium problem and does not respond to supplementation after six weeks, try a different brand and a different form of magnesium for another month before you decide your suspicion of a magnesium problem was incorrect.
InteractionsDiets high in the following substances may inhibit the absorption and/or increase the excretion of magnesium: alcohol, caffeine, fat, phosphorus, and sugar. Excessive calcium consumption may also exacerbate a magnesium deficiency. Make sure that your patients who are taking high levels of calcium for disorders (such as osteoporosis) are ingesting or supplementing with adequate levels of magnesium. There are many drugs which can interact with magnesium: the most commonly used are antibiotics, diuretics, insulin; they may affect magnesium levels. The following will stimulate magnesium absorption: meals, vitamin D, vitamin B6.4
Objective TestingWe definitely lack a gold standard in determining magnesium levels with laboratory testing. This was most evident in a recent study last year on magnesium levels in males with angina. The authors who performed the study used five tests (erythrocyte, mononuclear, 24-hour, serum, and urine) to determine magnesium levels.5
Magnesium Challenge Test
- may not be accurate if magnesium deficiency is due to urinary losses;
- requires a four-hour IV drip.
Twenty-four Hour Urinary Excretion of Magnesium
- there's a wide variance in normal populations;
- urinary magnesium doesn't necessarily correlate with serum magnesium concentrations. Erythrocyte Magnesium
- may be normal when plasma levels of magnesium are low;
- doesn't correlate with magnesium levels in other cell types.
Mononuclear Blood Cell Magnesium
- can be normal when plasma magnesium levels are low.
- may not correlate to tissue magnesium levels.
- higher if magnesium is lost from bones;
- lower when gray hair is tested.
- determined by a nonmagnetic resonance ion-selective electrode specific for magnesium;
- May solve laboratory diagnostic problems, but requires more studies to confirm.
DosingThe average dietary intake of magnesium by healthy adults in the United States ranges from 143- 266mg per day,6 which is easily below the RDA. To dose magnesium, a vitamin supplement with RDA levels is generally appropriate. A more exact supplementation can be based on body weight: healthy patients receiving 3 mg of magnesium per pound of body weight; and patients who are being treated for magnesium-related disorders at a level of 6mg per pound of body weight.6
- Ensminger & Konlande. Foods and Nutrition Encyclopedia. Pegus Press, Clovis, CA. 1983.
- Recommended Dietary Allowances. National Academy of Sciences. National Academy Press, Washington, DC. 1989.
- Werbach M. Foundations of Nutritional Medicine. Third Line Press, Tarzana, CA. 1997.
- Werbach M. Nutritional Influences on Illness. Third Line Press, Tarzana, CA. 1988.
- Satake, et al. Relation between severity of magnesium deficiency and frequency of anginal attacks in men with variant angina. Journal of the American College of Cardiology 1996;28:897-902.
- Murray MT. American Journal of Natural Medicine December 1996;3(10):8-19.
G. Douglas Andersen, DC, DACBSP, CCN, DACBN
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