Magnesium

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By Nikola · Precision Nutrition L1 · Updated 5 November 2026

Magnesium is an essential mineral that your muscles, nerves, bones and energy metabolism depend on; EFSA sets an adequate intake of 350 mg a day for men and 300 mg for women, and seeds, nuts, whole grains, beans and leafy greens are the best food sources. This page looks at three common reasons to take it as a supplement: sleep, muscle cramps and migraine. The evidence is strongest for migraine prevention, weak for sleep, and points to no meaningful benefit for muscle cramps in older adults. If you use a supplement, EFSA’s upper limit for magnesium from supplements is 250 mg a day; high doses from supplements can cause diarrhoea.

What the research says

The EU allows these health claims for foods that are at least a source of magnesium (Regulation (EU) 432/2012): “Magnesium contributes to a reduction of tiredness and fatigue”, “to electrolyte balance”, “to normal energy-yielding metabolism”, “to normal functioning of the nervous system”, “to normal muscle function”, “to normal protein synthesis”, “to normal psychological function”, “to the maintenance of normal bones” and “to the maintenance of normal teeth”, and “Magnesium has a role in the process of cell division”. They describe what magnesium does when you get enough, not proof that extra helps.

• Migraine prevention – moderate. The American Academy of Neurology and the American Headache Society concluded that magnesium is probably effective for preventing migraine (NIH).
• Sleep – weak. A 2021 meta-analysis by Mah and Pitre pooled three small trials with 151 older adults. Magnesium shortened the time to fall asleep by about 17 minutes compared with placebo; the 16-minute gain in total sleep was not statistically significant. The evidence was low to very low quality, too weak for firm recommendations, according to the authors.
• Muscle cramps – no meaningful benefit in older adults. A Cochrane review (5 trials, 271 people, mean age 62-69) found it unlikely that magnesium gives clinically meaningful cramp prevention for idiopathic cramps, with moderate to high certainty. For cramps in pregnancy, 5 trials with 408 women gave conflicting results and very low certainty evidence.
• Blood pressure – small. Clinical trials suggest magnesium supplements only marginally lower blood pressure (NIH).
• Blood sugar in type 2 diabetes – not enough evidence. The NIH says there is not enough evidence to recommend magnesium to improve glycaemic control.

Dose and forms

Group	EFSA adequate intake (all sources)	EFSA upper limit (supplements and added Mg only)	For reference: NIH RDA, age 31-50
Men	350 mg	250 mg	420 mg
Women	300 mg	250 mg	320 mg
Pregnancy	300 mg	250 mg	360 mg
Breastfeeding	300 mg	250 mg	320 mg
Children 1-3 years	170 mg	not defined	–

Sources: EFSA (2015 reference values; SCF 2001 upper limit), NIH ODS. EFSA’s 250 mg covers magnesium salts and compounds such as magnesium oxide in supplements, water or added to foods, not magnesium naturally present in food. The US upper limit is 350 mg a day from supplements and medicines (NIH); the NHS says 400 mg or less a day from supplements is unlikely to cause harm.

• Oxide, citrate and others. The NIH notes that the aspartate, citrate, lactate and chloride forms tend to have higher bioavailability than magnesium oxide and magnesium sulphate.
• Glycinate. Labels also offer magnesium glycinate (bisglycinate), but the NIH fact sheet does not assess it, and we found no reliable comparison with the other forms. Choose it if it suits you, not because of a proven advantage.
• Timing. We found no official advice on the best time of day; what matters is spacing magnesium from certain medicines (see below).

Food sources

Food	Magnesium, 100 g	Portion	Magnesium per portion
Pumpkin seed kernels, dried	592 mg	28 g (1 oz)	168 mg
Sunflower seed kernels, dried	325 mg	¼ cup, 35 g	114 mg
Buckwheat, dry	231 mg	¼ cup, 43 g	98 mg
Chia seeds, dried	335 mg	28 g	95 mg
Cashews, raw	292 mg	28 g	83 mg
Almonds	270 mg	28 g (about 23 nuts)	77 mg
Dark chocolate, 70-85% cocoa	228 mg	28 g	65 mg
Black beans, boiled	70 mg	½ cup, 86 g	60 mg
Sesame seeds, whole	351 mg	1 tbsp, 9 g	32 mg
Spinach, raw	79 mg	1 cup, 30 g	24 mg

Source: USDA FoodData Central, SR Legacy, checked 5 November 2026: pumpkin seeds FDC 170556, sunflower seeds FDC 170562, buckwheat FDC 170286, chia FDC 170554, cashews FDC 170162, almonds FDC 170567, dark chocolate FDC 170273, black beans FDC 173735, sesame FDC 170150, spinach FDC 168462. Portions are USDA household measures or fractions of them; values per portion are calculated and rounded.

A small handful of pumpkin seeds covers more than half of a woman’s 300 mg. Sunflower seeds, buckwheat, chia, cashews and almonds follow, and sesame, beans, spinach and cocoa add steady amounts. More ideas: Best Natural Sources of Magnesium.

Side effects and interactions

• Laxative effect. High doses from supplements or medicines can cause diarrhoea, nausea and abdominal cramping (NIH); the NHS links more than 400 mg in the short term with diarrhoea. The same property is why magnesium is found in some laxatives and antacids, and very large doses of these, typically over 5,000 mg a day, have caused magnesium toxicity (NIH).
• Bisphosphonates (for osteoporosis): take magnesium-rich supplements or medicines at least 2 hours before or after them (NIH).
• Tetracycline and quinolone antibiotics: take them at least 2 hours before or 4-6 hours after a magnesium supplement (NIH).
• Loop and thiazide diuretics can increase magnesium loss in urine and lead to depletion (NIH).
• Proton pump inhibitors can cause low blood magnesium when taken for a long time, typically more than a year (NIH).

Who should avoid it

• People with kidney disease. The risk of magnesium toxicity rises with impaired kidney function or kidney failure (NIH). Do not take supplements without your doctor’s approval.
• People on the medicines above, unless a doctor or pharmacist has checked the timing and dose.
• Young children. EFSA’s 250 mg upper limit applies from age 4; no upper limit is defined for children aged 1-3, so supplements for them are a question for a paediatrician.
• Anyone with ongoing diarrhoea, since high doses of magnesium can cause it.

More likely to fall short, says the NIH: people with gut diseases, type 2 diabetes or alcohol dependence, and older adults. Early signs of deficiency include loss of appetite, nausea, fatigue and weakness; later ones, numbness, cramps and abnormal heart rhythm. These need a doctor, not self-treatment.

How to choose a good product

• Read the magnesium figure, not the compound weight. Look for how many mg of magnesium a daily dose provides, and compare it with EFSA’s 250 mg upper limit.
• Count every source. Antacids and laxatives with magnesium also count towards the upper limit, which covers supplements and medicines (NIH).
• Look for independent testing. Organisations such as U.S. Pharmacopeia, NSF International and ConsumerLab.com test supplements; their seal means the product was made properly, contains what the label says and has no harmful levels of contaminants, but it does not guarantee that the product is safe or effective (NIH ODS).
• Tell your doctor and pharmacist what you take.

FAQ

Which form of magnesium is best?

The NIH says magnesium aspartate, citrate, lactate and chloride tend to be better absorbed than oxide and sulphate. Glycinate is popular, but there is no reliable comparison showing it is better. Whatever the form, keep supplements within EFSA’s 250 mg a day.

Does magnesium help you sleep?

The evidence is weak. In a 2021 meta-analysis of three small trials in older adults, magnesium shortened the time to fall asleep by about 17 minutes, but the studies were of low quality. Ongoing sleep problems are worth discussing with a doctor.

How much magnesium do I need a day?

EFSA sets an adequate intake of 350 mg a day for men and 300 mg for women, including in pregnancy and breastfeeding. From supplements, EFSA’s upper limit is 250 mg a day; magnesium from food does not count towards it.

Related entries and articles

• Pumpkin seeds, sunflower seeds and almonds
• Buckwheat and cocoa
• Zinc, vitamin D and melatonin
• Best Natural Sources of Magnesium (Magnesium-Rich Foods)
• Foods High in Potassium (and Magnesium)
• Pumpkin Seeds: Benefits and How Many to Eat a Day
• Roasted pumpkin with chickpeas, tahini and pomegranate

Sources

1. USDA FoodData Central, SR Legacy: pumpkin seeds (FDC 170556), sunflower seeds (FDC 170562), chia (FDC 170554), sesame (FDC 170150), cashews (FDC 170162). fdc.nal.usda.gov
2. USDA FoodData Central, SR Legacy: almonds (FDC 170567), buckwheat (FDC 170286), dark chocolate 70-85% (FDC 170273), black beans, boiled (FDC 173735), spinach, raw (FDC 168462). fdc.nal.usda.gov
3. EFSA NDA Panel (2015). Scientific Opinion on Dietary Reference Values for magnesium. EFSA Journal 4186. efsa.europa.eu
4. EFSA: Overview on Tolerable Upper Intake Levels as derived by the SCF and the EFSA NDA Panel, version 11 (August 2025). efsa.europa.eu
5. NIH Office of Dietary Supplements: Magnesium, Fact Sheet for Health Professionals. ods.od.nih.gov
6. NIH Office of Dietary Supplements: Dietary Supplements – What You Need to Know. ods.od.nih.gov
7. NHS: Vitamins and minerals – Others (magnesium). nhs.uk
8. Cochrane: Magnesium for skeletal muscle cramps (CD009402.pub3). cochranelibrary.com
9. Mah J, Pitre T (2021). Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies 21:125. agris.fao.org
10. Commission Regulation (EU) No 432/2012 – permitted health claims. legislation.gov.uk

This page is for information only and is not medical or dietary advice.