Are you getting 300-400 mg. of magnesium per day?

Magnesium is the fourth most abundant mineral in the body and is essential to good health. Approximately 50% of total body magnesium is found in bone. The other half is found predominantly inside cells of body tissues and organs. Only 1% of magnesium is found in blood, but the body works very hard to keep blood levels of magnesium constant. Magnesium is needed for more than 300 biochemical reactions in the body. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, supports a healthy immune system, and keeps bones strong. Magnesium also helps regulate blood sugar levels, promotes normal blood pressure, and is known to be involved in energy metabolism and protein synthesis. There is an increased interest in the role of magnesium in preventing and managing disorders such as hypertension, cardiovascular disease, and diabetes. Dietary magnesium is absorbed in the small intestines. Magnesium is excreted through the kidneys.

Unfortunately, magnesium deficiency is extremely common in the United States. Studies by the National Institutes of Health have indicated that at least 68% of adults may be magnesium deficient, while other experts believe the level may be as high as 80%.

What are the Dietary Reference Intakes for magnesium?

Recommendations for magnesium are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine of the National Academy of Sciences [4]. Dietary Reference Intakes is the general term for a set of reference values used for planning and assessing nutrient intake for healthy people. Three important types of reference values included in the DRIs are Recommended Dietary Allowances (RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake that is sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy people. An AI is set when there is insufficient scientific data available to establish a RDA for specific age/gender groups. AIs meet or exceed the amount needed to maintain a nutritional state of adequacy in nearly all members of a specific age and gender group. The UL, on the other hand, is the maximum daily intake unlikely to result in adverse health effects. Table 2 lists the RDAs for magnesium, in milligrams, for children and adults.

Table 1: Selected food sources of magnesium

Food	Milligrams	%DV*
Wheat Bran, crude, ¼ cup	89	22
Almonds, dry roasted, 1 ounce	80	20
Spinach, frozen, cooked, ½ cup	78	20
Raisin bran cereal, 1 cup	77	19
Cashews, dry roasted, 1 ounce	74	19
Soybeans, mature, cooked, ½ cup	74	19
Wheat germ, crude, ¼ cup	69	17
Nuts, mixed, dry roasted, 1 ounce	64	16
Bran flakes cereal, ¾ cup	64	16
Shredded wheat cereal, 2 rectangular biscuits	61	15
Oatmeal, instant, fortified, prepared w/ water, 1 cup	61	15
Peanuts, dry roasted, 1 ounce	50	13
Peanut butter, smooth, 2 Tablespoons	49	12
Potato, baked with skin, 1 medium	48	12
Blackeye peas, cooked, ½ cup	46	12
Pinto beans, cooked, ½ cup	43	11
Rice, brown, long-grained, cooked, ½ cup	42	11
Lentils, mature seeds, cooked, ½ cup	36	9
Vegetarian baked beans, ½ cup	35	9
Kidney beans, canned, ½ cup	35	9
Chocolate milk, lowfat, 1 cup	33	8
Banana, raw, 1 medium	32	8
Yogurt, fruit, low fat, 8 fluid ounces	32	8
Milk chocolate candy bar, 1.5 ounce bar	28	7
Milk, lowfat or nonfat, 1 cup	27	7
Raisins, seedless, ½ cup packed	26	7
Halibut, cooked, 3 ounces	24	6
Bread, whole-wheat, commercially prepared, 1 slice	23	6
Avocado, cubes, ½ cup	22	6
Chocolate pudding, ready-to-eat, 4 ounces	19	5

*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for magnesium is 400 milligrams (mg). Most food labels do not list a food's magnesium content.

Table 2: Recommended Dietary Allowances for magnesium for children and adults [4]

Age (years)	Males (mg/day)	Females (mg/day)	Pregnancy (mg/day)	Lactation (mg/day)
1–3	80	80	N/A	N/A
4–8	130	130	N/A	N/A
9–13	240	240	N/A	N/A
14–18	410	360	400	360
19–30	400	310	350	310
31+	420	320	360	320

There is insufficient information on magnesium to establish a RDA for infants.

Data from the 1999–2000 National Health and Nutrition Examination Survey suggest that substantial numbers of adults in the United States (US) fail to get recommended amounts of magnesium in their diets. Among adult men and women, the diets of Caucasians have significantly more magnesium than do those of African-Americans. Magnesium intake is lower among older adults in every racial and ethnic group. One of magnesium's many roles is as a muscle relaxant. This is especially important for women who suffer from menstrual cramps (dysmenorrhea) because cramps are caused by excessively strong contractions of the uterus. Magnesium helps the powerful uterine muscles relax, reducing cramping.

Having enough body stores of magnesium may be protective against disorders such as cardiovascular disease and immune dysfunction. The health status of the digestive system and the kidneys significantly influence magnesium status. Magnesium is absorbed in the intestines and then transported through the blood to cells and tissues. Approximately one-third to one-half of dietary magnesium is absorbed into the body. Gastrointestinal disorders that impair absorption such as Crohn's disease can limit the body's ability to absorb magnesium. These disorders can deplete the body's stores of magnesium and in extreme cases may result in magnesium deficiency. Healthy kidneys are able to limit urinary excretion of magnesium to assist low dietary intake. Excessive loss of magnesium in urine can be a side effect of some medications and can also occur in cases of poorly-controlled diabetes and alcohol abuse. 

As magnesium deficiency worsens, numbness, tingling, muscle contractions and cramps, seizures (sudden changes in behaviors caused by excessive electrical activity in the brain), personality changes, abnormal heart rhythms, and coronary spasms can occur. Severe magnesium deficiency can result in low levels of calcium in the blood (hypocalcemia). Magnesium deficiency is also associated with low levels of potassium in the blood (hypokalemia).

A balanced and varied diet of healthful foods, low in processed foods, is the best way to ensure sufficient dietary magnesium intake. Processing may strip magnesium content entirely, as happens with white flours, or introduce other nutrients that interfere with normal magnesium absorption and functioning. For example, magnesium is an important factor in regulating insulin levels, so consuming foods high in sugar reduces the ability of the body to use magnesium.

Magnesium sulfate, also known as Epsom salt, is a soothing way to boost your body's magnesium level. The best way to do this is to take a warm Epsom salt bath because your body absorbs the mineral through the skin. Not only does a bath boost your magnesium, it also helps with muscle aches and gently fades discoloration from bruises. The ideal concentration for using Epsom salt baths to raise magnesium status, according to the study, is approximately 500 g, or 2 cups, of Epsom salt dissolved in about 15 gallons of water -- the amount that can fit in a standard-sized bathtub. Ideal amount of time spent soaking is 12 minutes two to three times per week.