Magnesium is an essential mineral substance that can be found in the body in large quantities. More than 600 enzymes’ functions depend on it. It has an important role in the metabolism of glucose, protein synthesis, and the proper functioning of muscles and the nervous system. (1) While magnesium can be found in various foods, magnesium deficiency is still common. Surveys conducted in the USA show that nearly half of the population doesn’t reach the necessary daily intake, as processed food all but lack magnesium. (2) Considering that the body’s magnesium requirement proportionally increases with weight, it can be estimated that ~75% of people don’t ingest enough magnesium for disease prevention and help their body’s optimal functioning.  

Magnesium deficiency leads to fatigue, muscle spasms, and loss of appetite, but based on observations  it can also increase the risk of several chronic illnesses. (1) Magnesium is key to controlling insulin- and blood sugar levels and to the proper functioning of the cardiovascular system. Magnesium supplementation can reduce stress, improve the quality of sleep, and can increase sports achievement. (3,4,5,6) It can ease the unpleasant symptoms of migraine and PMS. (4,7,8) The absorption of magnesium largely depends on the individual’s magnesium levels and a well-chosen form. While supplementation is safe, some types can lead to loose stool depending on  quantity  and  sensitivity.  

How much magnesium do we need? 

The necessary daily magnesium intake is prescribed as 420 mg for men and 320 mg for women. Children are prescribed less in proportion to their body weight, while pregnant women are prescribed 400 mg. Surveys show that most people have insufficient magnesium levels, which comes as no surprise, as it’s mainly found in food rarely eaten.  

How to provide sufficient intake? 

The best dietary sources of magnesium are various seeds, nuts and pulses, especially beans. (9) Unfortunately, these foods contain several substances that block the absorption of magnesium, so it’s uncertain how much of it actually gets utilized. Seeds and nuts are very rich in calories, therefore despite their abundant magnesium content, it’s not recommended to eat the quantity of nuts that’d be necessary to cover one’s necessary daily magnesium intake. 

Pumpkin, quinoa, game and seafood, as well as other animal source food are excellent sources of magnesium, but they’re rarely eaten in large quantities, even though we need magnesium daily, as the body can’t store it well enough. Fruits and vegetables contain magnesium as well, but one would need to eat a fair deal of them to supply the necessary 300-400 mg daily intake. They likewise contain substances that block the absorption of magnesium, such as oxalates found in spinach or lignins found in fruits. Insoluble and water soluble fibers decrease the absorption of magnesium as well, while indigestible carbohydrates, proteins and some fats can increase it. (10)  

Magnesium can be ingested through dietary supplements, which have diverse forms with varying benefits and absorption rates.  

The types of magnesium supplement

The various forms of magnesium differ from each other in what other substance the magnesium molecule connects to, for example, oxygen in magnesium oxide, or citric acid in magnesium citrate. The absorption of magnesium citrate, magnesium lactate, magnesium taurate, and magnesium bisglycinate is better than that of magnesium oxide. Magnesium oxide produced the same results as a placebo in a test and failed to increase low magnesium levels. (11,12) Regrettably, magnesium oxide is the most commonly used form due to its low price and high elemental magnesium content. Different types of magnesium supplements contain elemental magnesium in varying degrees, therefore beside absorption pay attention not to supplement 200 mg magnesium with 200 mg magnesium citrate, as it only contains 16% magnesium, the rest is citric acid.  

Some forms of magnesium (such as citrate) cause loose stool above a certain dose, so if one experiences this side effect, they should either take it in smaller doses throughout the day or try a form such as bisglycinate, taurate, orotate or lactate. Magnesium can be applied through the skin in the form of magnesium chloride or sulfate. These are less effectively absorbed when taken orally, but due to their small size, they can be useful in increasing magnesium levels when applied through the skin. There’s a risk, however: it’s difficult to tell how much of them gets absorbed as they are utilized bypassing digestion, and therefore the body can’t regulate absorption.  

The health effects of magnesium 

Magnesium has so many effects it’s challenging to summarize all of them in a short article. Quite predictably, research on magnesium supplementation often produced mixed results, as various doses and forms were used, often including magnesium oxide, which is notoriously difficult to absorb. The success of supplementation largely depends on how much magnesium one ingests through their diet.  

A short review of the main health effects of magnesium:  

• Many people supplement magnesium for its calming effect, and for good reason. Magnesium affects various aspects of stress: it blocks the uncontrolled function of overstimulating agents by “putting the handbrake on.” Chronic stress and magnesium deficiency are a vicious cycle, as magnesium deficiency not only increases anxiety and stress but the discharge of magnesium. (3) Magnesium deficiency is more common in people with attention deficit or proneness to anxiety, but supplementation can be great help.  

• Magnesium is key to controlling blood sugar levels and the production of insulin. Magnesium deficiency can lead to high blood sugar levels, while supplementation can improve blood sugar values and insulin sensitivity. (13) 

• Magnesium controls blood pressure, which can increase in the case of magnesium deficiency. (14) There are other reasons why magnesium should be supplemented for the health of the cardiovascular system: people with high magnesium intake are much more protected against various heart diseases. (14,15,16) It must be noted that people whose diet contains high levels of magnesium naturally have access to larger quantities of other useful substances.  

• Magnesium is also important for  physical performance, since magnesium is necessary for muscle contraction and the proper functioning of the nervous system. We also lose a fair amount of magnesium during physical activity through increased sweating. (17) In some studies, magnesium supplementation significantly increased the stamina and sports achievement of participants. (18) 

• In a large study, the risk of colon cancer lowered by half for participants with the highest magnesium intake. (19) It must be noted again that participants might have a healthy diet to begin with, therefore likely had access to larger quantities of other useful substances. 

• In addition to calcium and vitamin D, magnesium is necessary for healthy bones and teeth.