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Magnesium: Effects, Daily Requirement and Foods at a Glance

What tasks magnesium performs in the body, roughly how high your daily requirement is and which foods contain the most of it.

Magnesium is one of the minerals most often discussed in sport, and for good reason. It is involved in several hundred metabolic processes, in muscle and nerve function as well as in energy supply. If you sweat a lot or train regularly, you soon wonder whether your daily intake from food is enough at all.

This guide explains what tasks magnesium performs in the body, roughly how high the requirement is, which foods contain a lot of it and when a dietary supplement can make sense.

What magnesium does in the body

As a mineral, magnesium is involved in well over 300 enzymatic reactions. These include energy metabolism, protein synthesis, the transmission of nerve impulses and muscle contraction, including relaxation after tension. Magnesium also plays a role in bone structure, since a considerable part of the body's stores is bound in the skeleton.

In sport, magnesium is mentioned mainly in connection with muscle cramps. Scientifically, the link between a mild magnesium deficiency and cramps is not clearly proven, but in practice many athletes report an improvement once intake is sufficient again. Magnesium also contributes to normal psychological function and to the reduction of tiredness, as worded in official nutrition claims.

Magnesium is also often mentioned for sleep and for coping with everyday stress. One reason is the mineral's role in regulating the nervous system, which makes a certain calming effect plausible. Reliable evidence that additional magnesium measurably improves sleep in people who are already adequately supplied is so far only limited, so this should be described as a possible rather than an established effect.

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translucent magnesium citrate crystals on a dark stone surface with soft studio light

How high is the daily requirement?

The DGE (German Nutrition Society) gives a reference value of about 350 mg magnesium per day for adult men and about 300 mg for women. With intense training, high sweat loss or during growth phases, the actual requirement can be somewhat higher, even though there are no separate official reference values for athletes.

If you eat a balanced diet and regularly eat wholegrain products, legumes, nuts and green vegetables, you generally reach the recommended intake without an additional product. A one-sided diet, heavy sweating over longer periods, certain gastrointestinal conditions or high alcohol consumption, on the other hand, can increase the requirement or impair absorption.

Magnesium-rich foods

Magnesium is found in many plant-based foods but also in some animal products. The following table shows typical orders of magnitude per 100 grams, as found in nutrient tables. Actual values can vary depending on variety, cultivation and preparation.

Food	Magnesium per 100 g (approx.)
Pumpkin seeds	530 mg
Sunflower seeds	350 mg
Cocoa powder, strongly de-oiled	400 mg
Almonds	270 mg
Oats	140 mg
Lentils, cooked	36 mg
Wholemeal bread	60 mg
Bananas	30 mg
Mineral water, magnesium-rich	50 to 100 mg per litre

Still mineral water with a high magnesium content can also make a noticeable contribution to daily intake, especially if you drink a lot anyway. A look at the label shows how much magnesium a particular water contains.

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Magnesium supplements

Magnesium products come in different compounds, such as magnesium oxide, magnesium citrate or magnesium carbonate. They differ mainly in the amount of pure magnesium per capsule or tablet and in their tolerability. Citrate and similar organic compounds are generally considered well tolerated, while very high single doses of some compounds can irritate the gut.

As a rough guide, not an instruction, manufacturers often state a daily amount in the range of about 200 to 400 mg of additional magnesium, split into one or more doses. What counts is always the packaging information of the respective product, as content and recommended serving differ from product to product. A dietary supplement does not replace a balanced diet but can usefully support it where needed.

If you take medication, in particular certain antibiotics or osteoporosis drugs, you should observe a time gap from magnesium intake, as the two can affect each other's absorption. With kidney disease, during pregnancy or breastfeeding, or when taking other medication, medical advice beforehand makes sense.

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white magnesium capsules spilling out of an open glass bottle on a wooden table

Magnesium and muscle cramps

Hardly any other topic in sport is so often linked with magnesium as nocturnal calf cramps or cramps after intense exertion. The evidence on this is inconsistent. Some studies show an improvement from additional magnesium where a deficiency exists, while others find no clear effect in people who are already adequately supplied. Cramps can also have many other causes, such as lack of fluid, muscular fatigue or unaccustomed exertion.

If you often suffer from cramps, you can try sufficient magnesium intake through food or a supplement, but with persistent complaints you should also have other causes medically clarified.

Magnesium working together with other minerals

In the body, magnesium works closely with other minerals, in particular potassium, sodium and calcium. Together these minerals count among the electrolytes, which are important for fluid distribution in the body, signal transmission and muscle function. During long, sweaty exertion in endurance sport, not only water but also electrolytes are lost through sweat, magnesium included, although in considerably smaller amounts than sodium.

For most recreational and hobby athletes, it is enough to make up for the increased loss of fluid and minerals through a balanced diet and sufficient drinking. With very long exertion lasting several hours, for example in endurance sport, a targeted intake of electrolytes including magnesium can make sense. Here too, the packaging information of the respective product serves as a guide, not as a fixed rule.

An imbalance between the individual minerals can show up in symptoms such as muscle weakness or heart rhythm disturbances, although these are rather exceptional cases with extreme exertion, a strongly one-sided diet or certain pre-existing conditions. In normal everyday training, a balanced intake of all minerals is usually sufficient.

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a variety of magnesium-rich foods, nuts, seeds and leafy greens arranged as a flat lay

What the research says

The fundamental importance of magnesium for muscle and nerve function, energy metabolism and bones is scientifically well documented and undisputed. Less clear is whether additional magnesium actually improves athletic performance in people without a proven deficiency. Several reviews conclude that a benefit is mainly to be expected if a deficiency existed beforehand, whereas in adequately supplied people hardly any additional effects can be demonstrated.

On muscle cramps and sleep quality too, the evidence is mixed, with individual positive studies in certain groups but no consistent picture for the general population. Those who eat a balanced diet therefore generally benefit little from high-dose products, while people with increased requirements or a proven deficiency are more likely to notice an effect. Overall, magnesium is considered a safe, well-studied mineral for which the benefit of supplementation depends heavily on individual supply status.

Frequently asked questions

How do I recognise a magnesium deficiency?

Possible signs are muscle twitching, cramps, tiredness or concentration problems, but these symptoms are non-specific and can have many other causes. An actual deficiency can only be reliably established through a medical examination.

Can you overdose on magnesium?

Through food, an overdose is hardly possible in healthy people, as excess magnesium is excreted via the kidneys. Very high amounts from supplements can cause loose stools or diarrhoea, and caution is needed with severely reduced kidney function.

When should I take magnesium?

A fixed time of intake is not strictly necessary. Many people take magnesium in the evening because it is said to support muscle relaxation, but this timing is not scientifically compelling. More important than the time of day is regular intake across the day.

Is magnesium from food better than from capsules?

A balanced diet reliably covers magnesium needs in most people and at the same time supplies other important nutrients. Capsules or powders can make sense if the diet is insufficient over a longer period or if there is an increased requirement.

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