Magnesium deficiency: how does a magnesium deficiency make itself felt?

Possible magnesium deficiency symptoms are unspecific and can have numerous other causes. In metabolically healthy people with a balanced diet, a pronounced magnesium deficiency is moreover relatively rare. It can arise, however, for example when magnesium is absorbed less well in the gut, too little is supplied through the diet over the long term or more is excreted.^1,2

What is a magnesium deficiency?

Magnesium is an essential mineral that the body has to take in through the diet. The body of an adult contains around 25 grams of magnesium in total. About 99% is located inside the cells – mainly in bones, muscles and other soft tissue. Only around 1% is present in the extracellular fluid.¹

Part of the magnesium is thus, in a sense, bound within the various tissues of the body. In this context, people sometimes speak in simplified terms of the body’s magnesium store. This cannot, however, simply be determined from a single blood value.

In a medical context, the term hypomagnesaemia is also used. It refers to a magnesium concentration in the blood that is too low. A low magnesium level and the body’s overall magnesium status are not, however, fully equivalent.

The body’s magnesium balance is regulated through various processes – such as absorption in the gut, mobilisation from the bone and excretion via the kidneys.¹

How common is a magnesium deficiency?

Very different figures circulate regarding its frequency. A blanket statement such as “15 to 20% of the population have a magnesium deficiency” is therefore problematic. An older German study by Schimatschek and Rempis examined around 16,000 people. Using a serum threshold of below 0.76 mmol/l, 14.5% of the people examined had hypomagnesaemia.⁵

The DGE currently points out that a magnesium deficiency is relatively rare in metabolically healthy people with a balanced diet, and that there is moreover no single suitable biomarker for reliably capturing the overall magnesium status.¹ That is why we deliberately refrain from the simplified statement that a particular percentage of all people are affected by magnesium deficiency.

How does a magnesium deficiency make itself felt?

A magnesium deficiency has no single characteristic symptom by which it can be clearly recognised. Magnesium is involved in numerous bodily functions and metabolic processes and at the same time interacts with other nutrients and minerals such as calcium and potassium. That is why complaints that occur cannot be attributed exclusively to a magnesium deficiency.¹

Classification	Possible magnesium deficiency symptoms
First possible signs	loss of appetite, nausea, vomiting, tiredness, general weakness
Advanced deficiency	numbness, tingling, muscle twitches or contractions, muscle cramps
Severe deficiency	neurological changes, behavioural changes, seizures, abnormal heart rhythms

Sources: ^1,2,3

With a pronounced magnesium deficiency, low calcium and potassium values can also occur.^1,2 How magnesium and potassium generally interact is explained in more detail in the article Magnesium and potassium – why do we need them?.

Important: these symptoms are not a checklist for self-diagnosis. Tiredness, muscle twitches or cramps can have many different causes.

What are the first signs of a magnesium deficiency?

According to the DGE and NIH, possible early signs include loss of appetite, nausea, vomiting, tiredness as well as general weakness or muscle weakness.^1,2 Tiredness, exhaustion and muscle weakness in particular are, however, very unspecific. The conclusion “I am often tired, so I have a magnesium deficiency” is therefore not justified.

Are muscle cramps and calf cramps typical magnesium deficiency symptoms?

Muscle cramps can occur with an advanced magnesium deficiency. The DGE and NIH list muscle contractions or muscle cramps as possible symptoms.^1,2 Magnesium generally plays a role in various processes around nerves and musculature; the DGE describes the mineral as being involved, among other things, in signal transmission and muscle contraction.¹

From this, however, the reverse conclusion must not be drawn: calf cramps do not automatically mean that a magnesium deficiency exists. From a calf cramp, therefore, neither the necessity of taking magnesium nor a particular amount or form of a magnesium supplement can be derived.

Can muscle twitches, tingling and numbness occur?

With an advanced magnesium deficiency, tingling and numbness can occur.^1,2 Nerve function and neuromuscular excitability can also be affected with a pronounced hypomagnesaemia. Medical literature mentions, among other things, tremor and fasciculations – that is, involuntary twitches of individual muscles – as possible manifestations.³ These complaints are likewise not specific to a magnesium deficiency. New or longer-lasting neurological complaints should therefore be clarified medically.

Can magnesium deficiency cause tiredness and exhaustion?

Tiredness and general weakness are among the possible first signs of a magnesium deficiency.^1,2 According to the authorised EU health claims, magnesium contributes, among other things, to a normal energy-yielding metabolism as well as to the reduction of tiredness and fatigue.⁴

This does not mean, however, that taking a magnesium supplement treats tiredness or exhaustion. Tiredness has numerous possible causes and is not a reliable diagnostic criterion for magnesium deficiency.

What consequences can a severe magnesium deficiency have?

With a pronounced deficiency, stronger neurological and cardiovascular changes can occur. The DGE and NIH name, among other things, stronger muscle contractions and cramps, tingling and numbness, changes in behaviour, seizures as well as abnormal heart rhythms.^1,2 A severe deficiency can thus also affect processes that concern the cardiovascular system.

Important, however, is the distinction: from these possible consequences of a severe deficiency it must not be concluded that an additional magnesium intake treats or prevents cardiovascular diseases. High blood pressure, existing cardiovascular diseases or other complaints of heart function are, in themselves, no proof of a magnesium deficiency either. Precisely with existing cardiovascular diseases, complaints should therefore not be attributed to magnesium on one’s own.

What causes can a magnesium deficiency have?

A magnesium deficiency does not necessarily arise from slightly less magnesium being taken in through the diet on individual days. In healthy people, the kidneys can respond to a low intake by excreting less magnesium. A symptomatic deficiency from a short-term lower intake alone is therefore unusual.²

1. Long-term low magnesium intake. A long-term or habitually low magnesium intake can contribute to an inadequate supply, especially when further factors come into play at the same time.² Which magnesium-rich foods are among the most important sources of magnesium is explained in detail in Where is the most magnesium found?.

2. Increased fluid and magnesium loss. An increased fluid loss can be associated with a magnesium loss in particular when it arises from longer-lasting diarrhoea or frequent vomiting. The DGE and NIH expressly list gastrointestinal losses as a possible cause.^1,2 This does not mean that every short-term fluid loss automatically triggers a deficiency – what is decisive includes duration, extent and further health factors.

3. Impaired absorption in the gut. An impaired magnesium absorption can occur, for example, with chronic diarrhoea, frequent vomiting, malabsorption, certain chronic gastrointestinal diseases or after certain procedures on the small intestine.^1,2 The NIH names, among others, Crohn’s disease and coeliac disease as examples.²

4. Increased losses via the kidneys. An increased excretion via the kidneys can also contribute to a magnesium loss. The DGE names certain kidney diseases as a possible cause.¹

5. Long-term high alcohol consumption. Chronic or long-term high alcohol consumption can likewise be associated with a magnesium deficiency.^1,2

6. Certain medicines. Medicines can also influence the magnesium balance, depending on the active substance – for example certain diuretics. Longer-term use of proton pump inhibitors can also, in rare cases, be associated with hypomagnesaemia.^1,3 Medicines should therefore never be stopped on one’s own. Information on which preparations or minerals should be considered when taking magnesium can be found in the guide What should not be taken together with magnesium?.

Who has an increased risk of an inadequate magnesium supply?

The NIH names several groups of people or health situations in which an inadequate magnesium supply can occur more frequently. These include, for example, people with certain gastrointestinal diseases, people with type 2 diabetes mellitus, people with long-term high alcohol consumption as well as older people.² An increased risk is not, however, the same as an existing magnesium deficiency.

Athletes, too, are often mentioned in connection with a supposedly increased magnesium requirement. The DGE, however, points to an inconsistent body of data here: older studies showed in part an increased magnesium excretion, while newer studies did not confirm this clearly.¹ That is why, even in athletes, a magnesium deficiency or a necessary supplementation should not automatically be assumed solely on the basis of physical activity.

How much magnesium does the body need?

For adults, the DGE currently states estimated values for an adequate intake of 300 mg of magnesium per day for women and 350 mg per day for men.⁶

These values do not, however, indicate how much magnesium should be taken in the case of an existing deficiency. The individual requirement and the treatment of magnesium deficiency are to be distinguished from this. The detailed reference values for different age groups, children, adolescents, pregnancy and breastfeeding, as well as the question of dosage, deliberately belong in our separate article: How much magnesium per day?.

How can a magnesium deficiency be determined?

The magnesium concentration in the blood can be determined medically. The overall magnesium status can, however, be assessed only to a limited extent with a single serum value – because, as described above, only around 1% of the magnesium is present in the extracellular fluid.¹

The DGE expressly points out that there is currently no single suitable biomarker for reliably determining the overall magnesium status.¹

When do symptoms of a magnesium deficiency occur?

According to the DGE, clinical deficiency symptoms typically occur only at very low serum concentrations of below 0.5 mmol/l.¹ The blanket statement that a value below 0.4 mmol/l is fundamentally life-threatening cannot, by contrast, be derived from the DGE source we used and is therefore deliberately not used.

The value of 0.5 mmol/l, too, is not intended for self-diagnosis. Laboratory values have to be interpreted together with symptoms, diseases, medication use and other medical findings.

Are headaches or sleep problems typical symptoms?

Headaches and sleep problems are often associated online with a magnesium deficiency. The DGE and NIH do not, however, list either complaint among the typical first or advanced magnesium deficiency symptoms.^1,2 This does not mean that there are no scientific studies on magnesium and these topics. From this, however, it cannot be concluded that headaches or sleep problems indicate a magnesium deficiency.

What to do if a magnesium deficiency is suspected?

Anyone who notices possible symptoms should not automatically assume a deficiency or use high-dose preparations on their own. First, the complaints, possible diseases, regularly used medicines, the diet and possible magnesium losses should be considered. With longer-lasting, severe or newly occurring symptoms, a medical assessment should take place.

What does the treatment of a magnesium deficiency look like?

The treatment of magnesium deficiency depends on its cause, severity and the individual health situation. With a diagnosed severe deficiency, medical treatment may be necessary. Which form of magnesium, which amount and which route of administration are appropriate cannot be determined across the board.

The statement “high-dose magnesium preparations are fundamentally beneficial with a severe deficiency” would therefore be too sweeping. A high dosage is not automatically better and should not be undertaken on one’s own with a pronounced deficiency.

What role does diet play?

Food is the normal source of magnesium. Natural sources of magnesium include, in particular, wholegrain products, pulses, green leafy vegetables, nuts and seeds.¹ A detailed table of magnesium-rich foods – pumpkin seeds, spinach, oat bran, figs, dark chocolate and mineral water – would serve a different search intent here. You will therefore find precisely this content in our article Where is the most magnesium found?.

What applies to magnesium deficiency during pregnancy?

During pregnancy, too, tiredness, weakness or muscle cramps can occur. They do not, however, allow a reliable conclusion about a magnesium deficiency. According to the current position of the DGE, there are moreover no sufficient indications of a generally increased magnesium requirement during pregnancy. For pregnant women, the same estimated value of 300 mg per day currently applies as for non-pregnant adult women.^1,6

The statement that pregnant women should take in 390 mg of magnesium daily therefore does not correspond to the current German DGE reference values. Questions around magnesium in this phase of life are dealt with in detail in the article: Why no magnesium during pregnancy?.

What should be considered with magnesium supplements?

Whether a magnesium supplement is sensible cannot be judged on the basis of possible deficiency symptoms alone. The intake of magnesium, the right amount and the suitable form also depend on various factors. Especially with diseases, regular medication use or a pronounced deficiency, this should be assessed by a professional.

In addition, different terms must not be confused. Magnesium stearate, for example, is not the same as a magnesium supplement for magnesium intake. More on this can be found in our article Magnesium stearate: a bad reputation without cause?.

Conclusion

A magnesium deficiency cannot be recognised on the basis of a single symptom. Possible first signs include loss of appetite, nausea, vomiting, tiredness and general weakness. With an advanced deficiency, tingling, numbness, twitches and muscle cramps can occur. A severe magnesium deficiency can also have neurological and cardiovascular consequences such as seizures or abnormal heart rhythms.^1,2,3

At the same time, these complaints are unspecific. Calf cramps, tiredness, muscle weakness or sleep problems therefore do not automatically mean that a magnesium deficiency is present. The assessment of the magnesium status is also complex: the majority of the magnesium is located inside the cells, which is why a single magnesium level in the blood reflects the overall magnesium status only to a limited extent.¹

A magnesium deficiency can have different causes – from a longer-term low intake through an increased magnesium loss and an impaired absorption to diseases or certain medicines. Anyone who suspects a magnesium deficiency should therefore have the cause clarified by a professional, rather than making a self-diagnosis on the basis of individual symptoms alone.

Frequently asked questions about magnesium deficiency

How does a magnesium deficiency make itself felt?

Possible first signs are loss of appetite, nausea, vomiting, tiredness and general weakness. With an advanced deficiency, tingling, numbness, muscle twitches and muscle cramps can occur. These symptoms are, however, unspecific.

What are typical magnesium deficiency symptoms?

Depending on severity, tiredness and weakness, tingling, numbness, muscle twitches and muscle cramps can occur. With a severe deficiency, neurological or cardiovascular changes are also possible.

Are calf cramps a sign of magnesium deficiency?

Muscle cramps can occur with a magnesium deficiency. Calf cramps alone are, however, no proof of a deficiency, as they can have numerous other causes.

Can magnesium deficiency cause muscle twitches?

With hypomagnesaemia, neuromuscular changes can occur. Medical literature mentions, among other things, fasciculations, that is, involuntary muscle twitches.

Can magnesium deficiency cause tiredness?

Tiredness is among the possible early signs. As tiredness is very unspecific, a magnesium deficiency cannot, however, be derived from it alone.

Can magnesium deficiency affect the cardiovascular system?

With a pronounced magnesium deficiency, cardiovascular symptoms such as abnormal heart rhythms can occur. From this, however, it cannot be derived that magnesium supplements treat or prevent cardiovascular diseases or high blood pressure.

Can a magnesium deficiency be recognised in the blood?

The magnesium concentration in the blood can be determined. As the majority of the magnesium occurs inside the cells, a single serum value reflects the overall magnesium status only to a limited extent. The DGE currently sees no single suitable biomarker for reliably determining the magnesium status.

What are common causes of a magnesium deficiency?

Possible causes are a long-term low magnesium intake, an impaired absorption in the gut, diarrhoea and vomiting, increased losses via the kidneys, chronic alcohol consumption as well as certain medicines.

How is a magnesium deficiency treated?

Treatment depends on the cause and severity of the deficiency as well as the individual health situation. A severe magnesium deficiency should be treated medically. A blanket recommendation for high-dose magnesium preparations cannot be derived from this.

Sources

1. German Nutrition Society (DGE): Selected Questions and Answers on Magnesium – Central source on body distribution, magnesium status, frequency, causes and symptoms of a magnesium deficiency, as well as on pregnancy.
2. National Institutes of Health (NIH), Office of Dietary Supplements: Magnesium – Health Professional Fact Sheet – Scientific overview of magnesium functions, deficiency symptoms, long-term low intake, risk groups and magnesium losses.
3. StatPearls / NCBI Bookshelf: Hypomagnesemia – Medical overview of hypomagnesaemia, causes, medicines as well as neuromuscular and cardiovascular manifestations.
4. European Commission: EU Register on Nutrition and Health Claims – Basis for the authorised health claims used, on muscle function, nervous system, energy-yielding metabolism, tiredness/fatigue and cell division. The claims apply under the respective prescribed conditions of use.
5. Schimatschek H. F., Rempis R. (2001): Prevalence of hypomagnesemia in an unselected German population of 16,000 individuals. Magnes Res 14(4):283–290 (PMID 11794636) – In the population examined, hypomagnesaemia was found in 14.5% at a threshold of below 0.76 mmol/l. The older study is deliberately not interpreted here as a current prevalence figure for the entire German population.
6. German Nutrition Society (DGE): Magnesium – Reference Values – Current estimated values for an adequate magnesium intake: adult men 350 mg/day, adult women 300 mg/day; for pregnant women likewise 300 mg/day.