Magnesium is a mineral your body needs for more than 300 enzyme reactions. Its authorised benefits include normal muscle function, a normal nervous system, normal energy-yielding metabolism, the maintenance of normal bones and teeth and the reduction of tiredness and fatigue. Adults need about 300 mg (women) to 350 mg (men) a day, which most people can cover with seeds, nuts, wholegrains and legumes. If you use a supplement, keep the amount from supplements at or below 250 mg a day.
Key facts about magnesium
- The adult body contains about 25 g of magnesium; 50 to 60% of it is stored in the bones.
- D-A-CH reference values: 300 mg a day for women and 350 mg for men, including during pregnancy and breastfeeding (300 mg).
- The nutrient reference value (NRV) on European labels is 375 mg.
- Pumpkin seeds provide about 590 mg per 100 g; a 30 g handful covers more than half of a woman's daily needs.
- The EU tolerable upper level for magnesium from supplements is 250 mg a day; magnesium from food and water is not counted.
What does magnesium do in the body?
Magnesium is required for the production of energy (ATP), the building of proteins and DNA, the transmission of nerve signals and the normal working of muscles. In the European Union and Switzerland, the following health claims are authorised for magnesium. Magnesium contributes to:
- a reduction of tiredness and fatigue;
- electrolyte balance;
- normal energy-yielding metabolism;
- normal functioning of the nervous system;
- normal muscle function;
- normal protein synthesis;
- normal psychological function;
- the maintenance of normal bones;
- the maintenance of normal teeth.
Magnesium also has a role in the process of cell division. These are the benefits of magnesium that are backed by the European Food Safety Authority's review of the evidence. Claims you may see elsewhere, for example that magnesium cures migraines, lowers blood pressure or guarantees better sleep, are not authorised. Studies have looked at these topics, but the results are mixed and depend heavily on whether people were low in magnesium to begin with.
How much magnesium do you need per day?
| Group | Women | Men |
|---|---|---|
| Teenagers 15 to under 19 years | 260 mg | 330 mg |
| Adults 19 years and older | 300 mg | 350 mg |
| Pregnancy and breastfeeding | 300 mg | – |
These estimated values from the German-speaking nutrition societies (D-A-CH, revised 2021) are also used in Switzerland. People who sweat a lot through sport or heat lose some magnesium, but a balanced diet usually covers this as well.
The best food sources of magnesium
Magnesium is found mainly in plant foods, which makes it easy to cover on a vegan or vegetarian diet. Refining grain removes most of it, so wholegrain products contain several times more than white flour.
| Food | Magnesium per 100 g (approx.) | Typical portion |
|---|---|---|
| Hemp seeds, hulled | 700 mg | 30 g = 210 mg |
| Wheat bran | 610 mg | 15 g = 90 mg |
| Pumpkin seeds | 590 mg | 30 g = 180 mg |
| Chia seeds | 335 mg | 15 g = 50 mg |
| Sunflower seeds | 325 mg | 30 g = 100 mg |
| Cashew nuts | 290 mg | 30 g = 85 mg |
| Almonds | 270 mg | 30 g = 80 mg |
| Dark chocolate (70 to 85% cocoa) | 230 mg | 20 g = 45 mg |
| Oat flakes | 130 mg | 50 g = 65 mg |
| Spinach, cooked | 85 mg | 150 g = 130 mg |
| Black beans, cooked | 70 mg | 150 g = 105 mg |
| Quinoa, cooked | 65 mg | 150 g = 95 mg |
Values are rounded averages from food composition databases and vary by product. Mineral water can add to your intake too: in the EU, waters labelled as containing magnesium provide more than 50 mg per litre, and some provide much more, so check the label.
A day with porridge and seeds for breakfast, a lentil or bean dish, wholegrain bread and a handful of nuts easily reaches 300 to 400 mg.
Signs of low magnesium intake
A true magnesium deficiency is uncommon in healthy people, because the kidneys reduce losses when intake is low. When it does occur, early signs can include loss of appetite, nausea, tiredness and weakness. More pronounced deficiency can lead to tingling, muscle cramps and an irregular heartbeat, which always need medical attention.
Occasional calf cramps are very common and usually have other causes, so they are not a reliable sign on their own. Blood tests also have limits, because less than 1% of the body's magnesium circulates in the blood. People more likely to be low include:
- people with digestive disorders such as Crohn's disease or coeliac disease;
- people with type 2 diabetes;
- people with high alcohol intake;
- older adults, who absorb less and excrete more;
- people taking diuretics or acid blockers (proton pump inhibitors) over a long time.
Magnesium supplements: forms, limits and interactions
Which form of magnesium is best?
Supplements use different magnesium compounds, such as citrate, bisglycinate, malate, lactate, chloride, carbonate and oxide. Small studies suggest that forms which dissolve well in water, such as citrate, lactate and chloride, are absorbed somewhat better than oxide. Oxide, on the other hand, contains more magnesium per gram, so tablets can stay small. For most people, the amount you take regularly matters more than the form.
How much magnesium from supplements is safe?
EFSA has set the tolerable upper intake level at 250 mg a day of magnesium from supplements for adults. The most common side effect above this level is diarrhoea, because unabsorbed magnesium draws water into the gut. Splitting the dose and taking it with meals is gentler on digestion. People with kidney disease should not take magnesium supplements without medical advice, because the kidneys cannot remove the excess.
Interactions with medicines
- Magnesium can reduce the absorption of bisphosphonates (osteoporosis medicines) and of tetracycline and quinolone antibiotics. Keep bisphosphonates at least 2 hours apart from magnesium; take these antibiotics at least 2 hours before or 4 to 6 hours after it, or as your pharmacist advises.
- Long-term diuretics and proton pump inhibitors can lower magnesium levels.
- If you take regular medication, are pregnant or have a heart or kidney condition, ask your doctor or pharmacist before using a magnesium supplement.
Magnesium, heart, liver and sleep: what the evidence says
Many searches ask whether magnesium is good or bad for the heart, the liver or sleep. Researchers have studied magnesium intake in relation to blood pressure, heart rhythm, liver disease, stress and sleep quality. Some observational studies link low magnesium intake with poorer outcomes, and some trials report small effects in people who were low in magnesium, but the evidence is not strong enough for any authorised health claim in these areas. In practice, this means: cover your daily needs through food first, use a moderate supplement if you need one, and see a doctor for any heart, liver or sleep problem rather than treating it yourself. If tiredness is your main concern, our guide to natural ways to have more energy puts magnesium in context with sleep, daylight and other nutrients, and which deficiencies make you tired explains when a blood test makes sense.
Magnesium in Sanbera formulas
Daily Essential Women and Daily Essential Men each contain 56.2 mg of magnesium (as magnesium oxide) per 3 tablets, about 15% of the NRV. This is a deliberately moderate amount that complements a magnesium-rich diet and stays well below the 250 mg upper level, even if you add magnesium-rich foods or water. Both formulas also contain 120 mg of calcium and vitamin D (3.22 µg, 64% NRV, in Daily Essential Women; 3 µg, 60% NRV, in Daily Essential Men); vitamin D contributes to the maintenance of normal bones and normal muscle function. The Nightly Reload formulas do not contain magnesium. If you also take a separate magnesium supplement, add the two amounts together and keep the total from supplements at 250 mg or less.
Magnesium works closely with calcium and vitamin D. Read more in our guides to calcium: daily needs and food sources and nutrients for healthy bones.
Frequently asked questions
Does magnesium help against tiredness?
Magnesium is one of nine nutrients authorised to contribute to the reduction of tiredness and fatigue, and it also contributes to normal energy-yielding metabolism. You are most likely to notice a difference if your intake has been low. If you feel tired for weeks, have your iron, vitamin B12 and thyroid checked as well, because these are more common causes of persistent tiredness than low magnesium.
Is magnesium good for the liver?
No health claim for the liver is authorised for magnesium. People with liver disease, especially alcohol-related liver disease, often have low magnesium levels, and researchers are studying this link. That does not mean magnesium supplements protect or treat the liver. If you have a liver condition, ask your doctor whether your magnesium levels should be checked before taking any supplement.
Can magnesium be bad for the heart?
At normal intakes from food, and at supplement doses up to 250 mg a day, magnesium is not considered harmful for people with healthy kidneys. Problems arise mainly when the kidneys cannot excrete magnesium: very high blood levels can lead to low blood pressure and an irregular heartbeat. If you have a heart condition or take heart medication, speak to your doctor before supplementing.
Is it better to take magnesium in the morning or at night?
Either works. What matters is taking it regularly, ideally with a meal, which can reduce stomach upset. Many people take magnesium in the evening as part of their routine, but no sleep-related health claim is authorised for magnesium. If you take it alongside antibiotics or osteoporosis medicines, keep at least 2 hours between them.
Are there special magnesium benefits for women?
Magnesium does the same work in women and men; women simply need a little less, about 300 mg a day compared with 350 mg for men. The requirement stays at 300 mg during pregnancy and breastfeeding. Women who eat few wholegrains, nuts or legumes, or who take diuretics over a long time, may want to review their intake. Use higher-dose supplements during pregnancy only on medical advice.
Sources
- National Institutes of Health, Office of Dietary Supplements: Magnesium, Health Professional Fact Sheet
- German Nutrition Society (DGE): Reference values for magnesium
- European Food Safety Authority (EFSA): Overview of tolerable upper intake levels
- European Commission: EU Register of nutrition and health claims
- Swiss Food Composition Database: naehrwertdaten.ch
- U.S. Department of Agriculture: FoodData Central
This article is for general information and does not replace advice from a doctor or pharmacist. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle.