Magnesium is involved in a number of bodily reactions (more than 300), contributes to bone health, and helps maintain the intracellular concentration of potassium and calcium. It is also helps produce energy, as well as develop and maintain bones and other calcified tissues. Magnesium plays a role in the body’s natural defense systems against all kinds of stressors.
What does magnesium do?
The amount of magnesium in the body is regulated primarily by the kidneys, where it is filtered and then reabsorbed. Nearly 50 to 60% of the magnesium in the body is stored in the bones, while excess intake is quickly excreted through the urine.
|Recommended Dietary Allowances (RDA) for Magnesium|
|Children||1 to 3 years||80|
|3 to 8 years||130|
|Preteens||9 to 13 years||240|
|Teenage boys||14 to 18 years||410|
|Teenage girls||14 to 18 years||360|
|Adults (men)||19 to 30 years||400|
|31 and up||420|
|Adults (women)||19 to 30 years||310|
|31 and up||320|
|Pregnant women|| ||350 to 400|
|Nursing women||under 31||310 to 360|
|31 and up||420|
Source: Institute of Medicine, Food and Nutrition Board, Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride, 1997.
This data reflects a consensus between Canadian and U.S. authorities, who conducted a process to standardize the recommended dietary allowances (RDAs).
NOTE: calcium inhibits magnesium absorption. These two minerals compete at the intestinal absorption site. The body needs both minerals and is able to absorb each one in adequate quantities. In the bones, however, magnesium helps bind calcium to the bones’ mineral structure. A mineral complex that contains calcium and magnesium combined with vitamin D is much more effective at fighting osteoporosis than calcium alone.
Magnesium-rich foods include green leafy vegetables, whole grain cereals, and nuts. Meats, starchy foods, and milk are relatively high in magnesium, while refined foods typically have the least amount.
Food Sources for Magnesium:
|Soy beans, dry roasted||250ml (1 cup)||414mg|
|Baking chocolate, bittersweet or semisweet||125ml (1/2 cup)||103-228mg|
|Black, white, and lima beans, cooked||250ml (1 cup)||127-191mg|
|Brazil nuts, dehydrated||60ml (1/4 cup)||133mg|
|Breakfast cereals, 100% bran (e.g., All Bran)||30g||111mg|
|Almonds, dry or oil-roasted||60ml (1/4 cup)||99-109mg|
|Atlantic halibut, baked||100g (3.5oz)||107mg|
|Cashews, dry or oil-roasted||60ml (1/4 cup)||90mg|
|Pine nuts, dehydrated||60ml (1/4 cup)||86mg|
|Atlantic pollock, baked||100g (3.5oz)||86mg|
|Mixed nuts, including peanuts, roasted||60ml (1/4 cup)||85mg|
|Spinach, boiled||125ml (1/2 cup)||83mg|
|Artichoke, boiled||1 medium (125g)||72mg|
|Tuna (bluefin or yellowfin), baked||100g (3.5oz)||64-69mg|
|Soy beverage, enriched||250ml (1 cup)||65mg|
|Wheat germ, raw||30g (1oz)||64mg|
|Potato with peel, baked||1 medium||55mg|
|Beet leaves, boiled||125ml (1/2 cup)||52mg|
|Haddock, baked||100g (3.5oz)||50mg|
|Okra (gombo), cooked||125ml (1/2 cup)||30-47mg|
Source: Health Canada, Canadian Nutrient File Compilation, versions 2001b and 2005 and the United States Department of Agriculture (USDA), National Nutrient Database for Standard Reference.
Food-related magnesium deficiency is rare. However it may occur in individuals who:
NOTE: the elderly and blacks are more likely to suffer from a lack of magnesium due to a less varied, low-magnesium diet.
Signs of magnesium deficiency:
Beneficial properties attributable to magnesium are:
Excess magnesium from food doesn’t cause any adverse reactions. However if the magnesium comes from sources other than food, some side effects may occur.
Signs of excess magnesium (from non-food sources):
More serious side effects may occur if very high doses are ingested. These effects include metabolic alkalosis (increase in blood pH), hypokalemia (decrease in blood potassium levels), and adynamic ileus (intestinal blockage due to temporary paralysis of the small intestine).
Natural health products and vitamin supplements:
Medications that may lead to magnesium deficiency:
Medications that may lead to excess magnesium:
1Take two hours apart.
Speak with your pharmacist if you plan to take magnesium supplements. Your pharmacist can help you choose the solution that’s best for you based on your health and any drugs you take.
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