Magnesium and muscle function: what the research shows

A calf cramp after the 5K run, an eye twitch during exam season, just not winding down in the evening — three very different complaints, and behind all three the same word keeps coming up: "maybe magnesium?"

The honest answer: maybe. But usually not as simple as some marketing promises suggest. The same word also comes up just as often around iron and tiredness — the two minerals are interlinked, and it's worth not looking at them in isolation. Here's what's actually established — and what you can take from it for your everyday life.

What magnesium is about

Magnesium is a mineral without which quite a lot in the body comes to a halt. It's involved in the transmission of nerve signals, in the contraction and relaxation of your muscle fibres, and in energy generation from the cellular fuel ATP. The official EU health claims (Regulation (EU) 432/2012) read soberly: magnesium contributes to normal muscle function, to normal energy-yielding metabolism and to the reduction of tiredness and fatigue.

In daily life that means: anyone who takes in enough magnesium gives their body an important basis for relaxed muscles and a metabolism that handles peak loads well. Anyone permanently undersupplied often notices it first via symptoms that are hard to place — cold hands, frequent fatigue, occasional cramps. None of these observations is certainly magnesium-related, but it's worth keeping an eye on intake.

How much you need

The German Nutrition Society (DGE) provides rough reference values — and they're not the same for everyone:

Group	Recommended daily intake (DGE 2021)
Men (19+)	350 mg
Women (19+)	300 mg
Pregnant	300 mg
Breastfeeding	300 mg
Adolescents 15–19 (m / f)	330 mg / 260 mg

These values refer to total intake, i.e. food plus any supplements. Anyone eating a balanced diet — whole grains, legumes, nuts, leafy greens — usually gets quite far on that alone.

Your DGE reference value — Magnesium

Age group15–18 years19–24 years25 years and olderSexFemaleMaleLife stageNonePregnancyBreastfeedingI exercise intensively on a regular basis

Your DGE reference value: 300 mg/day

Women (25+ y)

Shown is the published DGE reference value for the selected group — not an individual assessment. Orientation value — it does not replace a medical examination or advice. Source: DGE reference values for magnesium (estimated values, 2021)

Where it is in food

You don't need to buy exotic products to get magnesium. The biggest sources are part of everyday life:

Food (100 g)	Magnesium
Pumpkin seeds	~ 535 mg
Almonds	~ 270 mg
Oats	~ 140 mg
Spinach (cooked)	~ 60 mg
Whole-grain bread	~ 60 mg
Banana	~ 30 mg

A handful of almonds plus oats for breakfast and a bit of spinach at lunch — and you've already covered a large part of your daily needs. Magnesium-rich mineral waters (50–120 mg per litre) are another underestimated source.

If you want to supplement — what to look for

In supplementation, there isn't one magnesium. The compound makes a difference — though often a smaller one than advertising suggests:

• Magnesium citrate is generally well absorbed and usually well tolerated. A solid standard.
• Magnesium bisglycinate is gentle on the stomach and often recommended for evening intake.
• Magnesium oxide is cheaper and often part of combination products, but tends to be less well absorbed according to studies.
• Magnesium carbonate also has an acid-binding effect.

In practice, which compound you choose matters less than whether you take it consistently. One week of citrate, two weeks of nothing, then some oxide — that tends to deliver less than a simple, even regimen over several weeks.

According to BfR, the upper limit for supplementation is 250 mg per day from food supplements. Higher amounts can lead to soft stool — not dangerous, but not pleasant either.

When it's worth looking more closely

There are phases when your magnesium need is systematically above average:

• You train regularly and intensively (sweat loss, high energy metabolism) — the additional need is around 10–20 percent.
• Hot summers when you sweat a lot.
• One-sided eating with little whole grain, legumes or nuts.
• Some medications (such as diuretics or proton pump inhibitors) can push the magnesium balance down — worth a look for long-term use.

In these phases, additional intake via magnesium-rich foods or a supplement can make sense. What does not make sense: high-dose courses on a hunch, without knowing how you're currently supplied.

When you're really unsure

Occasional cramps, a twitching eyelid, cold hands — usually harmless. Frequent, severe or persistent symptoms belong in medical hands, not self-diagnosis. A magnesium blood test is straightforward and gives a real answer instead of a hunch.

If you'd rather find out generally whether your intake of magnesium and other micronutrients fits your daily life, you can do the Vital-Check — free of charge, three minutes, and you'll get an honest assessment.