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Major mineral

Magnesium

Over 300 enzyme reactions, muscle/nerve function, blood sugar and pressure regulation, bone health

Essential nutrient

Reference intakes (RDA or AI) are set by the National Academies of Sciences, Engineering, and Medicine. Deficiency thresholds come from clinical and WHO guidance.

At a glance

Women, 19-50

310 mg (19-30); 320 mg (31+)

Men, 19-50

400 mg (19-30); 420 mg (31+)

Upper limit (adults)

350 mg/day (from supplements/medications only)

How common is deficiency?

Inadequate INTAKE is COMMON (about half of US adults); overt hypomagnesemia less common

Food sources

Animal sources

Fish (halibut, salmon), chicken, beef, milk, yogurt

Plant sources

Pumpkin seeds, chia seeds, almonds, cashews, spinach, black beans, edamame, whole grains, dark chocolate, avocado

Deficiency and testing

Signs of deficiency

Muscle cramps/twitches, fatigue, weakness, nausea, loss of appetite, tingling, abnormal heart rhythm, low calcium and potassium, seizures (severe)

Who is at higher risk

Type 2 diabetes, GI disease (Crohn's, celiac), chronic alcohol use, older adults, diuretic/PPI use, kidney wasting

How it is tested

Serum magnesium (poor reflection of body stores); RBC magnesium; 24-h urinary Mg; magnesium retention (load) test

Cut-offs

Serum Mg <0.75 mmol/L (<1.8 mg/dL) = hypomagnesemia; <0.5 mmol/L = severe

Symptoms are not specific. Only a clinician with the right tests can tell whether you are deficient.

Supplement forms

Common forms

magnesium glycinate (bisglycinate), citrate, malate, taurate, L-threonate, lactate, chloride, oxide, sulfate (Epsom salt), hydroxide.

More effective

organic or chelated forms (glycinate, citrate, malate, lactate, chloride) have better absorption and tolerability; glycinate is gentle on the gut; citrate also helps constipation.

Less effective

magnesium oxide (only about 4% absorbed, strong laxative effect; useful mainly as a laxative or antacid); Epsom salt baths and magnesium oils (little evidence that enough crosses the skin); doses above the 350 mg supplemental UL (diarrhea, and toxicity risk in kidney disease).

Safety, interactions and halal notes

Safety and interactions

Upper limit for adults: 350 mg/day (from supplements/medications only). Going above the upper limit over time can cause harm, so check labels and talk to a clinician before high-dose supplements.

Halal note

The nutrient itself is not a halal question. For supplements, check the delivery form: gelatin (pork or non-halal bovine), capsule shells, glycerin, and alcohol-based carriers need halal certification. Ask for the halal certificate, not just a label claim. This is general guidance, not a certification.

Frequently asked questions

How much Magnesium do adults need per day?

Women 19-50: 310 mg (19-30); 320 mg (31+). Men 19-50: 400 mg (19-30); 420 mg (31+). Upper limit: 350 mg/day (from supplements/medications only). Needs change with age, pregnancy and health conditions.

What are the signs of Magnesium deficiency?

Muscle cramps/twitches, fatigue, weakness, nausea, loss of appetite, tingling, abnormal heart rhythm, low calcium and potassium, seizures (severe). These signs are not specific, so only a clinician with the right tests can confirm a deficiency.

What are the best food sources of Magnesium?

Animal sources: Fish (halibut, salmon), chicken, beef, milk, yogurt. Plant sources: Pumpkin seeds, chia seeds, almonds, cashews, spinach, black beans, edamame, whole grains, dark chocolate, avocado.

Which form of Magnesium supplement is best?

organic or chelated forms (glycinate, citrate, malate, lactate, chloride) have better absorption and tolerability; glycinate is gentle on the gut; citrate also helps constipation.

Sources

NIH Office of Dietary Supplements fact sheet

← Back to the full nutrient guide

This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

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