Magnesium: functions and daily requirement

Magnesium is an essential mineral that plays a vital role in the body. It is particularly important for nerve function, muscle performance and energy metabolism. Most healthy individuals can meet their magnesium needs through a balanced diet.

Magnesium at a glance

• Magnesium is a vital nutrient essential for healthy nerve and muscle function.
• According to the German Nutrition Society (DGE), adults typically need between 300 and 350 milligrams of magnesium per day.
• Healthy individuals can usually meet their requirements through magnesium-rich foods like nuts, wholegrains and vegetables.
• Symptoms of deficiency may include muscle cramps, tiredness and nervousness.
• Supplements should only be used when there is a proven need, to avoid the risk of overdose.

What is magnesium?

Magnesium is a mineral stored in the body, with around 25 grams found in an average adult. Approximately 99% of it is stored inside cells, primarily in bones, muscles and soft tissues.

What does magnesium do in the body?

Adequate magnesium intake is essential for health. The mineral is involved in over 600 enzyme functions and plays a key role in the nervous system, muscle contraction and energy metabolism.

Magnesium also contributes to:

• maintaining normal bones and teeth,
• supporting psychological function,
• and enabling normal protein synthesis.

What is the daily magnesium requirement?

Magnesium needs vary depending on age and gender.

According to DGE reference values:

• Adult men need 350 mg per day.
• Women require 300 mg daily, including during pregnancy and breastfeeding.
• Infants need 24–80 mg daily.
• Children aged 1–10 years require 170–240 mg per day.
• Girls aged 10–19 need 230–260 mg, while boys in the same age group require 260–330 mg.

How to meet your daily magnesium needs

Most healthy people can get enough magnesium through diet. The mineral is found in many foods, particularly plant-based options such as nuts, seeds, legumes and wholegrains. Animal-based foods contain smaller amounts, but they can still contribute to your intake as part of a balanced diet.

Examples of magnesium-rich foods (mg per 100 g)

How adequate is magnesium intake in the population?

According to the 2008 National Nutrition Survey II from the Max Rubner Institute in Germany, the average daily magnesium intake among men and women was 432 mg and 361 mg respectively — above the recommended levels.

However, 29% of women and 26% of men still failed to meet their daily magnesium requirements during the study period. Young women aged 14–18 were particularly likely to fall short.

What causes a magnesium deficiency?

In most cases, mild shortages of magnesium do not immediately lead to deficiency symptoms. However, the risk of developing a deficiency can be increased for various reasons. Risk factors include excessive stress and intense physical activity, particularly in professional athletes.

In addition, certain health conditions can make a deficiency more likely. Some illnesses may lead to reduced absorption in the gut or increased loss of magnesium through the kidneys. This can result in a deficiency over time, even when magnesium intake is adequate.

Medical causes of magnesium deficiency include, for example:

• chronic bowel diseases such as Crohn’s disease,
• inflammation of the pancreas,
• chronic kidney disease,
• an overactive thyroid,
• and certain medications.

How does a magnesium deficiency show itself?

It usually takes time for the body’s magnesium stores to become depleted. That’s why symptoms of deficiency don’t typically appear straight away. However, if the deficiency persists, a range of symptoms can develop. One of the earliest and most common signs is muscle cramps, particularly in the calves.

Other possible signs of magnesium deficiency include:

• loss of appetite
• nausea
• vomiting
• shaking
• fatigue
• a feeling of weakness
• nervousness
• rapid heartbeat
• circulation problems
• numb limbs
• difficulty concentrating
• irritability
• low mood or mild depression

Long-term effects of magnesium deficiency

Severe deficiency can lead to serious health complications. It may increase the risk of calcification in the kidneys and arteries and disrupt calcium and potassium balance — three minerals essential for heart function. This can trigger potentially life-threatening arrhythmias.

How to treat magnesium deficiency

To treat a deficiency, magnesium intake must be increased. For mild cases, adding more magnesium-rich foods such as nuts and seeds is often enough. More severe deficiencies may require supplements, and in extreme cases, intravenous magnesium.

The underlying cause must also be addressed for successful treatment. This will depend on the specific health issue involved.

Can you have too much magnesium?

While rare from food alone, excess magnesium from supplements can cause health issues. The kidneys regulate magnesium levels and excrete excess amounts.

However, taking high-dose supplements can cause side effects such as:

• diarrhoea
• vomiting
• high blood pressure
• skin flushing

Severe overdoses (over 2,500 mg/day) can result in:

• muscle weakness
• dangerously low blood pressure

What is the safe upper limit for magnesium?

To avoid overdose, the European Food Safety Authority (EFSA) has set a maximum safe intake of 250 mg per day from supplements only. This does not include magnesium naturally found in food.

Germany’s Federal Institute for Risk Assessment (BfR) recommends:

• max. 250 mg/day for supplements
• 31 mg per 100 g for fortified foods
• 8 mg per 100 ml for drinks

Different types of magnesium in supplements

Magnesium supplements come in various forms, including magnesium citrate and magnesium oxide. All forms are absorbable, but they differ in how quickly the body absorbs and excretes them. Magnesium citrate is absorbed and cleared more quickly, while magnesium oxide works more slowly.

When are magnesium supplements helpful?

For most people, a healthy diet provides sufficient magnesium. If you’re eating plenty of magnesium-rich plant foods, extra supplements offer no added benefit.

However, supplements may be useful in specific cases where needs are higher or deficiency is diagnosed. A blood test — done at the GP or using a home testing kit — can determine magnesium levels.

Why take magnesium in the evening?

Magnesium has a calming effect on the nervous system and muscles. If you experience symptoms like leg cramps at night due to low magnesium, taking it in the evening may be especially beneficial.

Important to know

If you are not a medical specialist and have complaints, specific health conditions, or suspect deficiencies, please make sure to consult a doctor to discuss this.