Magnesium

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rev: 06Mar11


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

It appears you can't overdose on magnesium contained in food ("dietary magnesium") if you are healthy (in particular, no kidney problems).

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

Age
(years)
Male
(mg/day)
Female
(mg/day)
Pregnancy
(mg/day)
Lactation
(mg/day)
Infants undetermined undetermined na na
1-3 65 65 na na
4-8 110 110 na na
9-18 350 350 359 350
19+ 350 350 350 350


Food Sources of Magnesium

Food Serv Milligrams (mg)
Kelp 1 oz 213
Cilantro (coriander) leaf 1 oz 194
Pumpkin seed, dried 1 oz 150
Wheat bran 1 oz 137
Sage 1 oz 120
Cumin 1 oz 103
Flaxseed (linseed) 1 oz 101
Sesame seed, dried, whole 1 oz 98
Sesame seed, dried, hulled 1 oz 97
Tarragon 1 oz 97
Wheat germ 1 oz 94
Mustard seeds 1 oz 83
Almonds, dry roasted 1 oz 76-80
Oregano 1 oz 76
Marjoram 1 oz 76
Cashews, dry roasted 1 oz 75
Amaranth 1 oz 75
Soybeans, mature, cooked cup 75
Spinach, frozen, cooked cup 75
Cloves 1 oz 74
Molasses 1 oz 72
Nuts, mixed, dry roasted 1 oz 65
Brewer's yeast 1 oz 65
Brazil nuts 1 oz 64
Buckwheat 1 oz 64
Walnuts, black, dried 1 oz 57
Cereal, shredded wheat, rectangular biscuits 2 bisc 55
Oatmeal, instant, fortified, prepared w/ water 1 cup 55
Filberts (hazelnuts) 1 oz 53
Potato, baked w/ skin 1 med 50
Peanuts, dry roasted 1 oz 50
Peanut butter, smooth 2 TBS 50
Wheat bran, crude 2 TBS 45
Blackeyed peas, cooked cup 45
Yogurt, plain, skim milk 8 fl oz 45
Bran flakes cup 40
Vegetarian baked beans cup 40
Rice, brown, long-grained, cooked cup 40
Pecan 1 oz 40
English walnuts 1 oz 37-48
Lentils, mature seeds, cooked cup 35
Avocado, California, pureed cup 35
Kidney Beans, canned cup 35
Pinto Beans, cooked cup 35
Wheat Germ, crude 2 TBS 35
Chocolate milk 1 cup 33
Tofu 1 oz 32
Banana, raw 1 med 30
Milk Chocolate candy bar 1 oz 28
Milk, reduced fat (2%) or fat free 1 cup 27
Coconut meat, dried 1 oz 26
Bread, whole wheat, commercially prepared 1 slice 25
Raisins, seedless, packed cup 25
Soybeans, cooked 1 oz 25
Brown rice 1 oz 25
Whole Milk 1 cup 24
Chocolate Pudding, ready-to-eat portion 4 oz 24

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

na 
not applicable 
oz 
ounce, ounces 
TBS 
Tablespoons 
 

Sources

1. http://ods.od.nih.gov/factsheets/magnesium.asp
2. The Encyclopedia of Healing Foods. Murray, Michael. 2005.


Copyright 2006 by Ken Westover at Cliff Canyon Publishing Co. All rights reserved.
This material may not be distributed without the written permission of the author.
  E-mail questions or comments to cliffcan@indra.com.
 
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