What is the Role of Magnesium (Mg) in Good Nutrition?


What are the Key Functions of Magnesium?

What are the Best Sources of Mg?

Who would benefit from Mg supplementation?

When should Mg supplementation be used?

How much Mg is usually taken?

What are the side effects of using Mg supplementation?

Mg's main role is as a constituent of bone. It assists in the transmission of nerve impulses and is also important for muscle contraction. The bones in the body contains about 60% of the total body magnesium.

It helps regulate blood sugar levels, promotes normal blood pressure, and is involved in energy metabolism and protein synthesis. It maintains muscle and nerve function, keeps a steady heart rhythm, supports a healthy immune system, and keeps bones strong.

It is an essential cofactor for about 90 enzymes which will function properly only when magnesium is present. Two such enzymes: co-carboxylase and co-enzyme A, are involved in extracting energy from food.

Mild Mg deficiency is more common than previously recognized, especially in diabetics, and people suffering from malabsorption syndromes, coeliac disease and some forms of kidney disease who may have low body stores of the mineral. Levels may also be reduced in the short term when illness causes severe diarrhea. This can lead to muscle twitching (tetany) or convulsions. Also, Mg deficiency has for a considerable time been recognized as a cause of cardiac arrhythmia (irregular heartbeat).

Although a daily intake of more than 2g of Mg may result in, a large proportion being unabsorbed, the body's control of the magnesium status of its tissues is not very efficient. This is because control is exerted by the kidneys and varies, depending on the person's intake of other dietary constituents. For example, alcohol increases the output of Mg by excreting it through the kidneys.

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What are the Key Functions of Mg?

Magnesium plays a key role in bone formation, nerve and muscle relaxation as well as other functions.

Mg is important for organs like the heart, muscles, and kidneys. It activates enzymes, contributes to energy production, and helps regulate calcium levels as well as copper, zinc, potassium, vitamin D, and other nutrients in the body.

Bone Formation

About 60% of all Mg in our body is found in our bones. Two different roles are played by bone Mg in our health. The magnesium in our bones helps give them their physical structure as it is part of the bone's crystal lattice together with the minerals phosphorus and calcium.

The rest of the Mg are found on the surface of the bone or in the blood. The surface Mg acts as a storage site for magnesium which the body can draw upon in times of poor dietary supply.

Nerve and Muscle Relaxation

Mg and calcium work together to help regulate the body's nerve and muscle tone. Mg acts in many nerve cells, as a chemical gate keeper to calcium. As long as there is enough Mg around, calcium is prevented from rushing into the nerve cell and activates the nerve. This function of Mg helps keep the nerve relaxed.

When our diet provides us with not enough magnesium, this gate keeper function can fail and the nerve cell can become over activated. The nerve cells can send too many messages to the muscles and cause the muscles to over contract. This explains how Mg deficiency can contribute to muscle tension, soreness, spasms, cramps, and fatigue.

Other functions of Mg

The presence of an enzyme (special proteins) are required for most of the chemical reactions in the body. More than 300 different enzymes in the body require magnesium in order to perform a function. Mg is for example involved in the metabolism of proteins, carbohydrates, and fats. It also helps genes to function properly. Energy cannot be stored in our muscle cells unless adequate supplies of Mg are available.

It is difficult to find a body system that is not affected by Mg deficiency because the role of Mg is so diverse, for example: our cardiovascular system, digestive system, nervous system, muscles, kidneys, liver, and our brain all rely on magnesium for their metabolic function.

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What are the Best sources of Mg

Magnesium can not be produced by our bodies. It must come from our diet or our water.

The highest content Mg is found in a range of foods that include tofu, legumes, whole grains, green leafy vegetables, wheat bran, Brazil nuts, soybean flour, almonds, cashews, blackstrap molasses, pumpkin and squash seeds, pine nuts, and black walnuts.

Additional good sources of Mg include peanuts, whole wheat flour, oat flour, beet greens, spinach, pistachio nuts, shredded wheat, bran cereals, oatmeal, bananas, and baked potatoes (with skin), chocolate, and cocoa powder.

Another source of Mg is our drinking water provided that it is healthy. Healthy water depends on its source and treatment process, e.g. bottled water, tap water, and/or well water.

A lack of quality drinking water can lead to Mg deficiency and a risk of illness. Look at the following findings:

"According to the U.S. National Academy of Sciences (1977) there have been more than 50 studies, in nine countries, that have indicated an inverse relationship between water hardness and mortality from cardiovascular disease. That is, people who drink water that is deficient in magnesium and calcium generally appear more susceptible to this disease. The U.S. National Academy of Sciences has estimated that a nation-wide initiative to add calcium and magnesium to soft water might reduce the annual cardiovascular death rate by 150,000 in the United States." (Dr. Harold D. Foster , " Groundwater and Human Health," Groundwater Resources of British Columbia, Ministry of Environment, Lands, and Parks and Environment Canada, pp 6.1-6.3 (reprint), 1994.

"Mortality rates for acute myocardial infraction and ischemic heart disease (IHD) of white males and females in South Africa are much higher than those in the USA, Australia, England and Wales when individuals in the 15- to 64-year age group are considered. Magnesium levels in the drinking water of 12 South African districts and deaths due to IHD assessed on the basis of corrected statistics for deaths apparently due to IHD in white residents were studied and a significant negative correlation was found between these two variables. "(W.P. Leary - Content of Magnesium in Drinking Water and Deaths from Ischemic Heart Disease in White South Africans )

Can you afford not to look at the quality of your drinking water? Look at this system that gives total piece of mind with regards to water quality without mineral removal.

Do you or any of your family need more magnesium? If you suspect that to be the case then read the next section to see who would benefit from magnesium.

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Who would benefit from Mg supplementation?

Magnesium deficiency symptoms involve changes in nerve and muscle function. These changes include muscle weakness, tremor, and spasm. Deficiency in the heart muscle can result in arrhythmia, irregular contraction, and increased heart rate. Because of its role in bone structure, the softening and weakening of bone (osteoporosis) can also be a symptom of Mg deficiency.

Other symptoms can include: imbalanced blood sugar levels (diabetes); headaches; elevated blood pressure (hypertension); elevated fats in the bloodstream; depression; seizures; nausea; vomiting; and lack of appetite.

In addition to poor dietary intake, problems in the digestive tract are the most common cause of Mg deficiency. These digestive tract problems include malabsorption, diarrhea, and ulcerative colitis.

Many kinds of physical stresses can contribute to magnesium deficiency, including cold stress, physical trauma, and surgery.

Kidney disease and alcoholism can also contribute to a deficiency of this mineral.

Too much coffee, soda, salt, or alcohol intake as well as heavy menstrual periods, excessive sweating, and prolonged stress can also lower Mg levels.

Do you or someone in your family suffer from any of the following diseases? They or you would then benefit from supplementation with magnesium.


Some research studies suggest that intravenous Mg can help treat acute attacks of asthma in children aged 6 to 18 as well as adults and oral Mg supplementation is of no known value in the management of chronic asthma.

Attention Deficit/Hyperactivity Disorder (ADHD)

Experts believe that children with ADHD show the classic effects of mild Mg deficiency such as irritability, decreased attention span, and mental confusion.

Children with ADHD who received Mg demonstrated a significant improvement in behavior, whereas those who received only standard therapy without magnesium exhibited worsening behavior.

Mg supplementation or high amounts of Mg in the diet may be beneficial for children with ADHD.

Please consult with your physician about possible use.


In 1992, the American Diabetes Association issued a consensus statement that concluded: "Adequate dietary Mg intake can generally be achieved by a nutritionally balanced meal plan as recommended by the American Diabetes Association."

It recommended that "... only diabetic patients at high risk of hypomagnesaemia should have total serum (blood) Mg assessed, and such levels should be replete (replaced) only if hypomagnesaemia can be demonstrated.”

Research has found that between 25% and 38% of diabetics have decreased blood levels of Mg (hypomagnesaemia).

Because Mg is important to carbohydrate metabolism it influences the release and activity of insulin. Insulin helps control blood glucose levels and elevated blood glucose levels increase the excreting of Mg through urine.

Magnesium depletion has been shown to increase insulin resistance and may negatively affect blood glucose control in diabetes. This explains why in people with poorly controlled type 1 and type 2 diabetes low blood levels of Mg are seen.

Type 1 diabetes is most often diagnosed in children and adolescents, and results from the body's inability to make insulin. Type 2 diabetes is sometimes referred to as adult-onset diabetes and it is the most common form of diabetes.

Due to conflicting reports, it is presently unclear whether Mg supplementation has any benefit in type 2 diabetic patients. However, correcting existing Mg deficiencies may improve glucose metabolism and insulin sensitivity in diabetic individuals.

Researchers' also find that the risk of developing diabetes in older women decreased with a greater intake of whole grains, dietary fiber and Mg.

It was further found that among women who were overweight, the risk of developing type 2 diabetes was significantly greater among those with lower Mg intake.

High Blood Pressure (Hypertension)

Lower blood pressure is associated with a diet of low fat dairy products along with lots of fruits and vegetables on a regular basis. These types of foods are rich in magnesium, calcium and potassium of which all is responsible for lowering blood pressure. The key is to obtain Mg, along with the other important minerals, from the diet.

The DASH study (Dietary Approaches to Stop Hypertension) suggested that high blood pressure could be significantly lowered by a diet high in Mg, potassium, and calcium, and low in sodium and fat.

The evidence is strong enough that the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends maintaining an adequate Mg intake as a positive lifestyle modification for preventing and managing high blood pressure.

The results from research studies using Mg supplements to treat hypertension have been conflicting and inconclusive. It is therefore recommended that you consult with your physician before using Mg supplements.

Heart disease (cardiovascular disease)

Magnesium deficiency can contribute to heart attacks and strokes. There is enough evidence that low total body Mg increase the risk of abnormal heart rhythms. Population surveys have associated higher blood levels of Mg with lower risk of coronary heart disease.

Dietary surveys have suggested that a higher Mg intake is associated with a lower risk of stroke.

Based on the above one could say that magnesium is essential to heart health. People with congestive heart failure (CHF) are often at particular risk for developing an arrhythmia. For this reason, your doctor may determine that Mg should be a part of the treatment of CHF.

Some research studies have reported reduced death rates as well as fewer arrhythmias and improved blood pressure when Mg is used as part of the treatment following a heart attack. But, again, not all research trials agree with this.

Doctors can evaluate Mg status when above-mentioned medical problems occur, and determine the need for Mg supplementation.


Mg deficiency together with calcium and vitamin D may be a risk factor for post menopausal osteoporosis. This is due to the fact that magnesium deficiency alters calcium metabolism and the hormone that regulates calcium. Therefore, diets that provide recommended levels of magnesium are beneficial for bone health.

For men and women, an adequate intake of calcium, magnesium, and vitamin D coupled with overall proper nutrition and weight-bearing exercise throughout childhood and adulthood are the primary preventive measures for this condition.

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When should Mg supplementation be used?

Magnesium has been used in connection with the following conditions:

Alcoholism Arrhythmia
Asthma Chronic fatigue
Congestive heart failure Coronary artery disease
Diabetes Heart attack
High blood pressure (Hypertension) Migraine
Osteoporosis Peptic ulcers

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How much Mg is usually taken?

The Food and Nutrition Board (FNB) of the Institute of Medicine set the tolerable upper intake level (UL) for Mg at 350 mg/day.

The Institute of Medicine of the National Academy of Sciences concur with this and also established the tolerable upper intake level (UL) for supplementary Mg for adolescents and adults at 350 mg daily. As intake increases above the UL, the risk of adverse effects increases.

Children and adolescents (9-18 years)

  • Children 9 to 13 years: 240 mg
  • Adolescent males 14 to 18 years: 410 mg
  • Adolescent females 14 to 18 years: 360 mg

Adults (ages 19-50 years)

  • Males 19 to 30 years: 400 mg
  • Females 19 to 30 years: 310 mg
  • Males 31 to 50 years: 420 mg
  • Females 31 to 50 years: 320 mg

Older adults (51 years and older)

  • Males 51 years and older: 420 mg
  • Females 51 years and older: 320 mg

Pregnant and breast-feeding women

  • Pregnant females under 18 years: 400 mg
  • Pregnant females 19 to 30 years: 350 mg
  • Pregnant females 31 to 50 years: 360 mg
  • Breastfeeding females under 18 years: 360 mg
  • Breastfeeding females 19 to 30 years: 310 mg
  • Breastfeeding females 31 to 50 years: 320 mg

Remember that Mg needs increase during times of protein synthesis, such as pregnancy, recovering from certain illnesses, and athletic training.

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What are the side effects of using Mg supplementation?

Dietary Mg supplements should be taken only under the supervision of a knowledgeable healthcare provider because of the potential for side effects and interactions with medications especially individuals with heart or kidney disease.

Mg toxicity is more often associated with kidney failure, when the kidney loses the ability to remove excess magnesium. The elderly are at risk of Mg toxicity because kidney function declines with age and they are more likely to take magnesium-containing laxatives and antacids.

Overdose on Mg from food is extremely rare. However, people with kidney problems may overdose if they consume excessive amounts of Epsom salts (as a laxative or tonic) or milk of magnesia (as a laxative or antacid).

Health problems associated with too much Mg can be similar to magnesium deficiency and include: nausea, vomiting, severely lowered blood pressure, slowed heart rate, deficiencies of other minerals, confusion, coma, and even death.

More common side effects from Mg include upset stomach and diarrhea.

Magnesium competes with calcium for absorption and can cause a calcium deficiency if calcium intake levels are already low.

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