Magnesium

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Nutrition Page

Magnesium is a mineral nutrient required for human health. It is mostly taken in from unprocessed foods, especially nuts.

Magnesium is absorbed by the small intestine. About 1/3 to 1/2 of dietary magnesium is absorbed, the rest is excreted. I don't know how or if this absorption factor is taken into account in the Rrecomended Daily Allowance figures.

Excess magnesium is removed by the kidneys and excreted in urine. Because the kidneys regulate magnesium, malfunction of the kidneys can cause either an excess or deficiency of magnesium, depending on the malfunction

Deficiency

Reading the literature magnesium deficiency seems mushy to define. One analogy might be tire pressure in your car or bike - when is there a deficiency? If you didn't know what the manufacturer recommended (like God didn't stamp a magnesium number on our sidewall), how would you recognize a deficiency? In the case of a tire, the handling would get poorer, the mileage would keep dropping. Similarly, those things that depend on magnesium will not work as well if there isn't enough magnesium.

Early Signs of Magnesium Deficiency
1. Loss of appetite
2. Nausea
3. Vomiting
4. Fatigue
5. Weakness

Intermediate Signs of Magnesium Deficiency
1. Numbness
2. Tingling
3. Muscle contractions and cramps
4. Seizures
5. Personality changes
6. Abnormal heart rhythms
7. Coronary spasms

Causes of Magnesium Deficiency
1. Intestinal problems (like Crohn's disease, chronic or excessive vomiting and diarrhea), causing too little to be absorbed
2. Medications in the intestines, causing too little to be absorbed
3. Medication side effects can cause the kidneys to excrete more magnesium
4. Diabetes
5. Alcohol abuse
6. Old age, due to a)lower intake of dietary magnesium, b) reduced absorption, c) increased excretion, and d) more likely to use medications that interact with magnesium. 

Daily Intake

Requirements

Recommended Dietary Allowances for Magnesium

Age (years)	Male (mg/day)	Female (mg/day)	Pregnancy (mg/day)	Lactation (mg/day)
1-3	80	80	na	na
4-8	130	130	na	na
9-13	240	240	na	na
14-18	410	360	400	360
19-30	400	310	350	310
31+	420	320	360	320

Toxicity

You can overdose on man-made sources containing magnesium, like supplements and antacids. For man-made sources, the following Upper Limits are recommended. (Doctors may prescribe higher doses for medical conditions.)

Tolerable Upper Intake Levels for Supplemental Nagnesium

Food Sources of Magnesium

For foods not listed in this table, please refer to the U.S. Department of Agriculture's Nutrient Database Web site: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl .

Notice the high quantities of magnesium in herbs and spices. Replace table salt (sodium chloride) with these seasonings and gain multiple benefits (reduced risk of hypertension plus the healthful effects of magnesium and other minerals in those seasonings). (For more about table salt and blood pressure, see my hypertension page.)

Supplements

Magnesium is an element (it's in the periodic table). But you don't eat elemental magnesium, it's always chemically bound up with something else (much like calcium, by the way). Supplements include magnesium sulfate, magnesium carbonate, and magnesium oxide . The amount of magensium varies with the compound. For example, it's much harder for the body to get the magnesium out of magnesium oxide.

"Bioavailability" is how easy it is for the body to pull the magnesium out of the compound, and this varies with the compound.

Be aware there is change in process regarding vitamin recommendations. Older past literature list RDA (Recommended Dietary Allowances), amounts that were intended to reduce diseases caused by severe nutritional deficiencies.

New values have been determined with the intent of reducing and prevent chronic diseases. The result is a bunch of values grouped under the heading Dietary Reference Intakes (DRIs).

Estimated Average Requirement (EAR)
Recommended Dietary Allowance (RDA)
Adequate Intake (AI)
Tolerable Upper Intale Level (UL)

Glossary