Magnesium

Magnesium is the 11th most abundant element in the human body, by mass. Its ions are found in every human cell.

It is also found at the center of every chlorophyll molecule, and is an essential element for photosynthesis (chemical reaction by which plants make energy).

In the human body Magnesium is a co-factor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium is required for energy production, oxidative phosphorylation, and glycolysis. It contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione.

Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm.

Magnesium is naturally present in many foods, added to other food products, available as a dietary supplement, and present in some medicines (such as antacids and laxatives).

Magnesium deficiency

Without enzyme co-factors—including both hormones and vital minerals such as magnesium—reactions could easily spiral out of control. In fact even slight imbalances can chronically impact the body’s level of performance and health.

Severe magnesium deficiency (hypomagnesemia) can impede vitamin D and calcium homeostasis. Certain individuals are more susceptible to magnesium deficiency, especially those with gastrointestinal or renal disorders, those suffering from chronic alcoholism, and older people.

Magnesium deficiency has been associated with increased risk of cardiovascular disease, osteoporosis, and metabolic disorders, including hypertension and type 2 diabetes mellitus. Preliminary studies have shown that magnesium improved insulin sensitivity in individuals at risk for diabetes. Randomized controlled trials have also investigated the role of magnesium supplementation in the prevention of complications following stroke or heart surgery.

Assessing magnesium status is difficult because most magnesium is inside cells or in bone: 60% of the magnesium in the human body is found in the skeleton, 39% in the muscle tissue, and 1% is extracellular. But you can recognize it by its symptoms:

  • Weakness
  • Muscle cramps
  • Tremors
  • Nausea
  • Anxiety
  • High blood pressure
  • Type II diabetes
  • Respiratory issues
  • Dizziness
  • Fatigue
  • Potassium deficiency
  • Difficulty swallowing
  • Poor memory
  • Confusion

Food source

Magnesium is widely distributed in plant and animal foods and in beverages. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources. In general, foods containing dietary fiber provide magnesium. Magnesium is also added to some breakfast cereals and other fortified foods. Refining grains and removing the nutrient-rich germ and bran, results in lower magnesium content in the processed food.

Approximately 30% to 40% of the dietary magnesium consumed is typically absorbed by the body.

Selected Food Sources of Magnesium 
Food Milligrams
(mg) per
serving
Percent
DV*
Almonds, dry roasted, 1 ounce 80 20
Spinach, boiled, ½ cup 78 20
Cashews, dry roasted, 1 ounce 74 19
Peanuts, oil roasted, ¼ cup 63 16
Cereal, shredded wheat, 2 large biscuits 61 15
Soymilk, plain or vanilla, 1 cup 61 15
Black beans, cooked, ½ cup 60 15
Edamame, shelled, cooked, ½ cup 50 13
Peanut butter, smooth, 2 tablespoons 49 12
Bread, whole wheat, 2 slices 46 12
Avocado, cubed, 1 cup 44 11
Potato, baked with skin, 3.5 ounces 43 11
Rice, brown, cooked, ½ cup 42 11
Yogurt, plain, low fat, 8 ounces 42 11
Breakfast cereals, fortified with 10% of the DV for magnesium 40 10
Oatmeal, instant, 1 packet 36 9
Kidney beans, canned, ½ cup 35 9
Banana, 1 medium 32 8
Salmon, Atlantic, farmed, cooked, 3 ounces 26 7
Milk, 1 cup 24–27 6–7
Halibut, cooked, 3 ounces 24 6
Raisins, ½ cup 23 6
Chicken breast, roasted, 3 ounces 22 6
Beef, ground, 90% lean, pan broiled, 3 ounces 20 5
Broccoli, chopped and cooked, ½ cup 12 3
Rice, white, cooked, ½ cup 10 3
Apple, 1 medium 9 2
Carrot, raw, 1 medium 7 2

*DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient contents of products within the context of a total diet. The DV for magnesium is 400 mg for adults and children aged 4 and older. However, the FDA does not require food labels to list magnesium content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.

Supplements

Magnesium supplements are available in a variety of forms, including magnesium oxide, citrate, and chloride. The Supplement Facts panel on a dietary supplement label declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound.

Absorption of magnesium from different kinds of magnesium supplements varies. Forms of magnesium that dissolve well in liquid are more completely absorbed in the gut than less soluble forms. Small studies have found that magnesium in the aspartate, citrate, lactate, and chloride forms is absorbed more completely and is more bio-available than magnesium oxide and magnesium sulfate.Magnesium chloride is a form that dissolves easily in GIT and is absorbed in larger amount. Magnesium sulfate (Epsom salt) it is widely used for its laxative effect.

Safety

Too much magnesium from food does not pose a health risk in healthy individuals because the kidneys eliminate excess amounts in the urine. However, high doses of magnesium from dietary supplements or medications often result in diarrhea that can be accompanied by nausea and abdominal cramping. The diarrhea and laxative effects of magnesium salts are due to the osmotic activity of unabsorbed salts in the intestine and colon and the stimulation of gastric motility.

 Tolerable Upper Intake Levels (ULs) for Supplemental Magnesium [1]
Age Male Female Pregnant Lactating
Birth to 12 months None established None established
1–3 years 65 mg 65 mg
4–8 years 110 mg 110 mg
9–18 years 350 mg 350 mg 350 mg 350 mg
19+ years 350 mg 350 mg 350 mg 350 mg

 

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