Magnesium is a mineral that plays a role in hundreds of processes in your body, from your muscle and nerve function to your energy metabolism. A deficiency can show up as muscle cramps, fatigue and a restless feeling. This article is part of our overview of vitamin and mineral deficiency. Below you read the symptoms, causes and how to test for it.
What does magnesium do?
Magnesium is involved in your muscle contraction, your nerve conduction, your energy production and the build-up of your bones. It works closely with calcium and potassium. Because it is involved in so many processes, a deficiency can cause varied complaints.
Symptoms of a magnesium deficiency
The symptoms of a magnesium deficiency are broad and not specific. Common complaints are muscle cramps, fatigue, trembling and a restless feeling. Because these complaints also fit other deficiencies, only a blood value gives certainty.
- Muscle cramps and twitches
- Fatigue and weakness
- Tingling and a restless feeling
- Restless legs
- Palpitations - with a large deficiency
- Irritability and poor sleep
Causes and risk groups
- One-sided diet - little vegetables, nuts and wholegrain products
- A lot of alcohol - increases magnesium excretion
- Prolonged stress - can raise magnesium needs
- Gut conditions - reduced absorption
- Certain medicines - such as diuretics and long-term acid reflux medication
- Older adults - lower intake and absorption
Where is magnesium found?
- Nuts and seeds: almonds, pumpkin seeds
- Green leafy vegetables: spinach
- Wholegrain products and legumes
- Dark chocolate
A varied diet usually provides enough magnesium. A supplement can be worthwhile with a confirmed deficiency or on your doctor's advice.
Testing for a magnesium deficiency
A blood test measures your magnesium value. Good to know: most magnesium is in your cells and bones, not in your blood, so a blood value does not always show a deficiency fully. The result is therefore assessed in the context of your complaints. Want to measure your magnesium? Build a custom blood test.
Frequently asked questions
Does magnesium help against muscle cramps?
With a confirmed deficiency, supplementation can reduce complaints. Without a deficiency the effect on muscle cramps is uncertain. A blood value helps determine whether supplementing is worthwhile.
Can I get too much magnesium?
Not through food. Through supplements a high dose can cause gut complaints such as diarrhoea. Stick to the recommended dose and consult your doctor if in doubt.
Every blood test result at Vitalcheck includes a professional assessment by a BIG-registered doctor. A blood value is not a diagnosis: always discuss symptoms and treatment decisions with your GP.
References
- Health Council of the Netherlands. Dietary reference values for vitamins and minerals. 2018.
- Netherlands Nutrition Centre. Magnesium. Accessed 2026.
- Thuisarts.nl / NHG. Magnesium. Accessed 2026.
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