Minerals
Magnesium
Magnesium is an essential mineral. Your body needs it for energy metabolism, normal muscle and nerve function, and bone structure, among other roles.
Magnesium is a chemical element and an essential nutrient that you need to obtain through your diet. It supports numerous enzyme reactions in the body. Natural food sources include nuts, seeds, pulses, wholegrains and green leafy vegetables. In nutrition, magnesium occurs in bound or dissolved forms and is absorbed as magnesium ions (Mg²⁺), not as metallic magnesium. Magnesium citrate, magnesium oxide and magnesium chloride are different compounds that can supply magnesium; they are not interchangeable names for the nutrient itself. Magnesium is a constituent of foods, rather than a food in its own right. Its essential roles in the body do not automatically mean that taking extra magnesium supplements will benefit you.
Magnesium: essential for muscles, nerves and metabolism
Magnesium is an essential mineral that you need to obtain through your diet. Your body uses it in numerous enzyme reactions, normal energy-yielding metabolism, and normal muscle and nerve function. Magnesium also contributes to the maintenance of normal bones and teeth.
In food, magnesium occurs in bound or dissolved forms. Your body absorbs it as magnesium ions (Mg²⁺), not as metallic magnesium. Magnesium citrate, magnesium oxide and magnesium chloride are different compounds that can supply the mineral.
Which foods provide magnesium?
Nuts, seeds, pulses, wholegrains and green leafy vegetables provide magnesium. The exact amount depends on the food. Refining grains removes the bran and germ, which also reduces their magnesium content.
An essential body function is not a promise of supplement benefits
Under Regulation (EU) No 432/2012, authorised EU claims include that magnesium contributes to normal energy-yielding metabolism, normal muscle function and the normal functioning of the nervous system. These claims may only be used for foods that meet at least the conditions for a source of magnesium. They do not establish additional benefits from supplements when intake is already adequate. In particular, supporting normal muscle function is not equivalent to proven prevention of leg cramps with supplements.
Symptomatic magnesium deficiency caused solely by low intake is uncommon in otherwise healthy people. Gastrointestinal disease, type 2 diabetes, alcohol dependence and older age can increase the risk of inadequacy, but do not establish a deficiency. A serum magnesium measurement can be clinically useful, yet does not reliably represent whole-body magnesium status on its own.
What to consider with magnesium supplements
Small studies suggest differences in absorption between magnesium compounds. These findings do not establish generally superior health benefits for any one form: absorption, tolerability and actual benefits are separate questions.
How nutrition works
Energy metabolism
Nervous system
Muscle function
Psychological function
Blood pressure
Magnesium supplements may modestly lower blood pressure in some adults, particularly those with hypertension or low magnesium status. [4]
Glycaemic control
Magnesium supplements may slightly improve some blood-glucose measures in adults with diabetes or metabolic risk, but a dependable benefit is not established. [5]
Statements & evidence
Magnesium contributes to a reduction of tiredness and fatigue [1]
This authorised claim may only be used for foods meeting the conditions for a source of magnesium. It does not mean that magnesium addresses every cause of tiredness.
Magnesium contributes to electrolyte balance [1]
The claim describes a normal body function. It may only be used for foods meeting the conditions for a source of magnesium.
Magnesium contributes to normal protein synthesis [1]
This concerns normal protein production in the body, not a promise of additional muscle growth. The food must meet the conditions for a source of magnesium.
Magnesium contributes to normal psychological function [1]
This is not a claim about treating mental health conditions. It may only be used for foods meeting the conditions for a source of magnesium.
Magnesium contributes to the maintenance of normal bones [1]
The claim concerns maintaining normal bones, not preventing or treating osteoporosis. The food must meet the conditions for a source of magnesium.
Magnesium contributes to the maintenance of normal teeth [1]
The claim describes magnesium's role in maintaining normal teeth. It may only be used for foods meeting the conditions for a source of magnesium.
Magnesium has a role in the process of cell division [1]
The claim describes involvement in a normal biological process. It may only be used for foods meeting the conditions for a source of magnesium.
EFSA sets an Adequate Intake for magnesium of 350 mg per day for adult men and 300 mg per day for adult women. [6]
The 300 mg value also applies during pregnancy and breastfeeding. These reference values concern total intake, not recommended supplement doses or an exact assessment of your individual requirements.
The EU nutrient reference value for magnesium used on food labels is 375 mg. [7][6]
This value supports consistent labelling, including percentage declarations. It is distinct from EFSA's sex-specific Adequate Intake values.
Leafy green vegetables, legumes, nuts, seeds and whole grains provide magnesium. [8]
Grain refining removes bran and germ, reducing magnesium content. These food groups are general sources; specific amounts depend on the individual food.
Symptomatic magnesium deficiency caused solely by low intake is uncommon in otherwise healthy people, but certain conditions and circumstances increase the risk of inadequacy. [8]
Examples include gastrointestinal disease, type 2 diabetes, alcohol dependence and older age. Membership of a risk group does not establish deficiency or automatically justify supplementation.
The European upper intake level for adults is 250 mg of magnesium per day from specified additional sources; naturally occurring magnesium in foods and beverages is excluded. [9]
It covers readily dissociable magnesium salts and compounds such as magnesium oxide in supplements, water or added to foods, including during pregnancy and breastfeeding. It is not a ceiling on total magnesium intake or a statutory maximum for every product.
High supplemental magnesium doses can cause diarrhoea, nausea and abdominal cramps; impaired kidney function increases the risk of magnesium toxicity. [8]
The kidneys are important for eliminating excess magnesium. If you have kidney disease, discuss magnesium supplements with a clinician before taking them.
Magnesium supplements can interfere with the absorption of certain antibiotics and oral bisphosphonates. [8]
Some diuretics and proton pump inhibitors can also alter magnesium status. If you take medicines, ask a pharmacist or clinician about interactions and appropriate dosing intervals.
A serum magnesium measurement alone does not reliably represent whole-body magnesium status. [8]
No single assessment method is considered fully satisfactory. A serum result can be clinically useful but needs interpretation alongside symptoms, risk factors and other findings.
Small studies suggest differences in absorption between magnesium compounds, but these do not establish generally superior clinical benefits for any one form. [8]
Some more soluble forms were better absorbed than magnesium oxide or sulphate in small studies. Absorption, tolerability and actual health benefits are separate questions.
Safety information
Caution
Distinguish food from supplements
For people with healthy kidneys, magnesium naturally present in food is generally not a safety concern. Most documented adverse effects concern supplements and magnesium-containing medicines. [8]
Side effect
Diarrhoea and other digestive symptoms
Magnesium supplements and oral magnesium medicines can cause diarrhoea, nausea and abdominal discomfort. Tolerability depends partly on the dose and preparation. If symptoms occur, seek advice about your intake; do not change prescribed treatment on your own. [8][11]
Upper level · People aged 4 years and older
European upper level: 250 mg daily
The European tolerable upper intake level is 250 mg of elemental magnesium daily for adults, including pregnancy and breastfeeding, and children aged 4 years and older. It covers readily dissociable magnesium salts and compounds such as magnesium oxide in supplements, water or added to foods; naturally occurring magnesium in foods and beverages is excluded. This is neither a recommended intake nor a sharp toxicity threshold, and it does not replace clinician-managed treatment. [10][9]
Caution · Adults
Split the daily supplement amount
BfR recommends no more than 250 mg of magnesium per daily supplement dose, divided into at least two portions to improve tolerability. This is a supplement recommendation, not a limit on magnesium in your whole diet. [12]
Caution
Seek advice before use with kidney disease
Impaired kidney function can allow magnesium to accumulate. Do not use magnesium supplements or magnesium laxatives without medical advice if you have kidney disease. Some medicines are specifically contraindicated in severe renal impairment; medically necessary replacement requires individual management. [8][11][13]
Side effect
Severe accumulation can be dangerous
Very high intakes from supplements or medicines can cause dangerous hypermagnesaemia, especially with impaired kidney function. Possible signs include marked weakness, drowsiness, low blood pressure and a slow heartbeat; severe cases can impair breathing and heart function. Seek emergency help for breathing difficulty, collapse or severely reduced consciousness after use. [8]
Caution
Use particular care in young children
Use only age-appropriate products and doses for children, with professional advice. No European upper level was established for children under 4 years; this does not imply unrestricted safety. Magnesium hydroxide can cause hypermagnesaemia in young children, particularly with dehydration or impaired kidney function. [10][14]
Interaction
Separate from certain antibiotics
Magnesium supplements can reduce absorption of tetracycline and quinolone antibiotics. NIH ODS advises taking the antibiotic at least 2 hours before or 4–6 hours after magnesium. Also check your medicine's specific instructions with a pharmacist. [8]
Interaction
Separate from oral bisphosphonates
Magnesium supplements can reduce absorption of oral bisphosphonates such as alendronate. NIH ODS recommends at least 2 hours' separation. You must also follow your bisphosphonate's specific fasting and administration instructions. [8]
Interaction
Magnesium antacids and levothyroxine
Magnesium-containing antacids can impair levothyroxine absorption. The cited NHS guidance recommends 4 hours between levothyroxine and antacids. For other magnesium preparations, have the specific administration instructions checked. [15]
Interaction
Specific dosing rules with dolutegravir
Magnesium can reduce absorption of dolutegravir (Tivicay). Take Tivicay at least 2 hours before or 6 hours after magnesium-containing antacids. EMA product information permits magnesium supplements together with Tivicay when taken with food; without food, the same separation applies. Have your dosing schedule checked by a professional. [16]
Interaction
Some medicines alter magnesium status
Loop and thiazide diuretics can increase magnesium losses, while potassium-sparing diuretics can reduce its excretion. Long-term proton pump inhibitor use can cause magnesium deficiency. Separating doses does not address these effects: discuss whether monitoring is needed rather than adding supplements yourself. [8][17]
Contraindication
Magnesium laxatives are unsuitable for some bowel conditions
Certain magnesium hydroxide medicines are contraindicated in intestinal obstruction or chronic diarrhoea. Have unexplained abdominal pain, nausea or vomiting assessed before using a magnesium laxative. These restrictions concern the medicines, not magnesium-containing foods; follow the relevant product leaflet. [13]
Found in
Frequently asked questions
Which foods contain magnesium?
Nuts, seeds, pulses, wholegrains and green leafy vegetables provide magnesium. The amount varies by food.
How much magnesium do I need each day?
EFSA sets an Adequate Intake of 350 mg daily for adult men and 300 mg for adult women, including during pregnancy and breastfeeding. These values concern total intake, not supplement doses or an exact assessment of your individual needs.
Does magnesium help with leg cramps?
Magnesium contributes to normal muscle function. However, this does not establish that magnesium supplements prevent leg cramps.
What side effects can magnesium supplements cause?
Magnesium supplements can cause diarrhoea, nausea and abdominal discomfort; tolerability depends partly on the dose and preparation. If you have impaired kidney function, magnesium can accumulate, so seek medical advice before taking supplements.
Can I take magnesium with my medicines?
Magnesium supplements can reduce the absorption of certain antibiotics and oral bisphosphonates. Ask a pharmacist or clinician to check interactions and the appropriate dosing intervals for your specific medicines.
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Sources
- 01European Commission · 2012Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children's development and healthOpen source
- 02EFSA Journal · 2009Scientific Opinion on the substantiation of health claims related to magnesium and electrolyte balance, energy-yielding metabolism, neurotransmission and muscle contraction including heart muscle, cell division, maintenance of bone, maintenance of teeth, blood coagulation and protein synthesis pursuant to Article 13(1) of Regulation (EC) No 1924/2006DOI 10.2903/j.efsa.2009.1216
- 03EFSA Journal · 2010Scientific Opinion on the substantiation of health claims related to magnesium, including reduction of tiredness and fatigue and contribution to normal psychological functionsDOI 10.2903/j.efsa.2010.1807
- 042025Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled TrialsPubMed 41000008Open source
- 052026Comprehensive Effects of Magnesium Supplementation on Cardiometabolic Risk Factors: A Systematic Review and Dose–Response Meta-AnalysisOpen source
- 06EFSA Journal · 2015Scientific Opinion on Dietary Reference Values for magnesiumDOI 10.2903/j.efsa.2015.4186
- 07European Parliament and Council of the European Union · 2011Regulation (EU) No 1169/2011 on the provision of food information to consumersOpen source
- 08National Institutes of Health, Office of Dietary SupplementsMagnesium - Health Professional Fact SheetOpen source
- 09European Food Safety AuthoritySummary tables of tolerable upper intake levels for vitamins and minerals, version 8Open source
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- 11NHS Specialist Pharmacy ServiceTreating acute hypomagnesaemia in adultsOpen source
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- 14European Medicines Agency / CMDhMagnesium hydroxide: CMDh scientific conclusions, grounds for variation and amendments to product information – PSUSA/00001926/201610Open source
- 15North Tees and Hartlepool NHS Foundation TrustLevothyroxine after Total Thyroid SurgeryOpen source
- 16European Medicines AgencyTivicay (dolutegravir): EU product informationOpen source
- 17Medicines and Healthcare products Regulatory AgencyProton pump inhibitors in long-term use: reports of hypomagnesaemiaOpen source
- 18U.S. Department of Agriculture, Agricultural Research Service – FoodData Central · 2019Bananas, raw (FDC ID 173944, SR Legacy)Open source
- 19European Food Safety Authority · 2017Dietary Reference Values for nutrients: Summary reportOpen source
- 20Cochrane · 2020Magnesium for muscle crampsOpen source
- 212018Magnesium in Migraine Prophylaxis—Is There an Evidence-Based Rationale? A Systematic ReviewPubMed 29131326Open source
- 222021Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-AnalysisOpen source
- 232021Oral Magnesium Supplementation for Treating Glucose Metabolism Parameters in People with or at Risk of Diabetes: A Systematic Review and Meta-Analysis of Double-Blind Randomized Controlled TrialsOpen source
- 24Servicio Murciano de Salud, PreevidSuplementos de magnesio para el manejo de los calambres musculares nocturnosOpen source