Magnesium, along with calcium, phosphorous, sodium, potassium and chloride, is classified as a macromineral. This designation refers to its abundance in the body and to the fact that our food must provide us with hundreds of milligrams of magnesium per day.
In the body, magnesium is mostly concentrated in bone (60-65%) although there a significant amount (25%) can be found in muscle. The remainder is located in other cell types and body fluids. Like the other minerals, magnesium must be received from the diet in order for us to remain healthy since the body cannot produce it.
Reflecting its ability to cause muscle relaxation, magnesium is sometimes regarded as the “smoothie” mineral. It helps to “smooth” out nerves by helping them to not become overly excited. Magnesium’s muscle relaxation characteristics may be familiar to individuals who have taken liquid magnesium (for example, the product Milk of Magnesia™) as a laxative since it helps to relieve constipation through relaxing the muscles around the intestines.
In Depth
Magnesium, along with calcium, phosphorous, sodium, potassium and chloride, is classified as a macromineral. This designation refers to its importance in the body and to the fact that our food must provide us with hundreds of milligrams of magnesium per day.
In the body, magnesium is mostly concentrated in bone (60-65%) although there a significant amount (25%) can be found in muscle. The remainder is located in other cell types and body fluids. Like the other minerals, magnesium must be received from the diet in order for us to remain healthy since the body cannot produce it.
Reflecting its ability to cause muscle relaxation, magnesium is sometimes regarded as the “smoothie” mineral. It helps to “smooth” out nerves by helping them to not become overly excited. Magnesium’s muscle relaxation characteristics may be familiar to individuals who have taken liquid magnesium (for example, the product Milk of Magnesia™) as a laxative since it helps to relieve constipation through relaxing the muscles around the intestines.
Function
As noted above, about two thirds of magnesium resides in bone. Researchers have found that this bone magnesium plays two very distinct roles in the support of health. Some of this magnesium contributes to the physical structure of bone, being part of the bone’s crystal lattice, its “scaffolding”, along with calcium and phosphorous. The other portion of magnesium is found on the bone surface and acts as a storage site for magnesium that the body can draw upon during times of inadequate magnesium intake.
Magnesium and calcium act in conjunction to help to regulate nerve and muscle tone. In many nerves, magnesium serves the function of being a chemical gatekeeper; when there is enough magnesium around, calcium is blocked from rushing into the nerve cell and activating the nerve and the nerve is kept in a state of relaxation. If dietary magnesium is inadequate, the gate blocking can fail and the nerve may become overactivated. When certain nerve cells are overstimulated, they send too many messages to the muscles causing them to overcontract. This series of events helps to explain why magnesium deficiency can cause muscle soreness, tension, spasms, cramps and fatigue.
Many chemical reactions in the body involve the presence of enzymes, proteins that help to catalyze chemical reactions. Since magnesium plays a role in over 300 different enzymes, its physiological functions are very extensive and include (but are certainly not limited to) being involved in protein, carbohydrate and fat metabolism, storage of energy in muscle cells and the proper functioning of genes. Since the metabolic role of magnesium is so ubiquitous, it is difficult to identify a body system that would not be affected by a magnesium deficiency. The digestive system, endocrine system, cardiovascular system, nervous system, muscles, kidney, liver and brain all rely upon magnesium to carry out their metabolic functions.
Deficiency: Causes and Symptoms
Poor dietary intake of magnesium is a common cause of deficiency as are gastrointestinal tract problems such as malabsorption, diarrhea and ulcerative colitis. Physical stresses such as trauma, cold stress and surgery can also contribute to a magnesium deficiency as can kidney disease and alcoholism.
The symptoms of magnesium deficiency can impact many physiological processes since this mineral plays such a wide variety of roles in the body. Common symptoms involve changes in muscle and nerve function such as muscle weakness, spasm and tremor. Since the heart is a muscle it can also experience compromised functioning concomitant with magnesium deficiency which can result in arrhythmia, irregular contractions and increased heart rate. Softening and weakening of bone can be the result of a deficiency since magnesium plays an important role in the maintenance of bone structure. Included among other symptoms of magnesium deficiency are imbalanced blood sugar, elevated fats in the bloodstream, elevated blood pressure, headaches, seizures, depression, nausea, vomiting and lack appetite.
Toxicity: Causes and Symptoms
Diarrhea is the most commonly experienced toxicity symptom associated with high intake of magnesium. It is most frequently seen when magnesium is taken as a dietary supplement rather than from food sources. While diarrhea can occur at lower supplemental doses, in research studies the doses of magnesium associated with diarrhea range from 1,000-5,000 miligrams. In addition, generalized symptoms such as increased drowsiness or a sense of weakness may be attributable to magnesium toxicity.
In 1997, the Institute of Medicine at the National Academy of Sciences set Tolerable Upper Intake Levels (UL) for supplemental magnesium at 350 milligrams for individuals 9 years and older. This UL applies to dietary supplements and not to magnesium received through food sources.
Impact of Cooking, Storage and Processing
As magnesium is found in different forms in different types of foods, the way in which cooking, storage and processing affects magnesium levels varies from food to food. In foods that have a greater percentage of magnesium in water-soluble form, cooking techniques that require water such as blanching, steaming or boiling can result in a substantial loss of magnesium content. Examples include blanched spinach that has one-third less magnesium than raw spinach and navy beans that lose 65% of their magnesium during the cooking process.
Other magnesium-rich foods, such as almonds or peanuts, experience very little reduction in magnesium content from either roasting or processing into nut butters (as long as the whole nut is used).
Drug-Nutrient Interactions
Medication that compromise magnesium status include:
While magnesium’s complex relationship with calcium is one of the most actively researched, it is yet to be fully understood. Magnesium is needed by calcium in order to maintain the latter mineral’s balanced role in the body’s metabolic processes. Yet, magnesium competes with calcium, preventing it from triggering certain physiological events such as nerve message relay or muscle contraction. Since they have such a complex, yet intricate, relationship it is important that healthy diets contain foods rich in both minerals yet, since calcium and magnesium compete for intestinal absorption, dietary supplements of these two minerals should not be taken at the same time.
In addition to calcium, there are other nutrients with which magnesium has a complex interplay. It regulates potassium movement into and out of cells. As magnesium binds to amino acids, increased protein intake can oftentimes improve the body’s magnesium status.
Health Conditions
Excellent sources of magnesium include basil, dill, sea vegetables, Swiss chard and winter squash. Very good sources include blackstrap molasses, broccoli, celery, flax seeds, kale, mustard greens, pumpkin seeds, sea vegetables, sesame seeds, sunflower seeds and turnip greens as well as herbs and spices such as cloves, cumin, ginger, oregano, rosemary and thyme.
Public Recommendations
In 1997, the Institute of Medicine at the National Academy of Sciences created new recommendations for magnesium. They established the following Adequate Intake (AI) levels for infants up to one year old and the following Recommended Dietary Allowances (RDAs) for all people older than one year old: