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B Emerging evidence · Health & Micronutrients

Magnesium

Also known as: magnesium glycinate, magnesium citrate, magnesium oxide, ZMA

Magnesium is an essential mineral for muscle, nerve and energy function. Many diets fall short. Supplements of 200–350 mg per day are commonly used; benefits are clearest when intake is low.

Why grade B?

Graded B because magnesium is essential for energy metabolism and muscle function, and correcting low intake or deficiency is worthwhile. However, evidence that supplementation improves performance, sleep or cramps in people with adequate magnesium status is limited and inconsistent.

Dose calculator

kg
Supplemental elemental magnesium per day
Fixed dose, independent of body weight
200–350 mg

Doses mirror ranges used in published research — they are not a personal prescription.

At a Glance

Magnesium
EvidenceB
RatingEmerging evidence
CategoryHealth & Micronutrients
Supplemental elemental magnesium per day200–350 mg
Food sourcesPumpkin seeds, Almonds and cashews, Spinach
Side effects listed1

Grades follow the style of the Australian Institute of Sport Sports Supplement Framework. Summary of published research, not advice.

How it works

Magnesium is a cofactor in hundreds of enzyme reactions, including those producing ATP, and is involved in muscle contraction and relaxation, nerve transmission, protein synthesis, blood sugar regulation and bone formation. Small amounts are lost in sweat and urine, and dietary surveys show many people consume less than recommended. Low magnesium status may impair exercise efficiency. Blood tests are not a perfect measure because most magnesium is stored in bone and tissues.

What research supports

  • Corrects low dietary intake or deficiency, which may improve exercise efficiency and muscle function
  • May support sleep quality in people with low magnesium status or older adults, though evidence is limited
  • Evidence that magnesium prevents exercise-related muscle cramps is weak
  • Some evidence for modest blood pressure reductions

Dosage

Recommended dietary intake for adults is around 310–420 mg per day from all sources. Supplement doses of 200–350 mg per day are common. The tolerable upper limit for magnesium from supplements is 350 mg per day for adults, above which diarrhoea becomes more likely.

Timing

Magnesium can be taken at any time, ideally with food to reduce stomach upset. Many people take it in the evening. Forms like citrate, glycinate and lactate tend to be better absorbed than oxide. Labels should state elemental magnesium.

Side effects

  • Diarrhoea, nausea and cramping, especially with oxide, citrate or doses above 350 mg

Cautions

  • People with kidney disease should not take magnesium supplements without medical advice, as it can accumulate
  • Separate magnesium by at least two hours from certain antibiotics (tetracyclines, quinolones) and osteoporosis drugs (bisphosphonates)
  • Some diuretics and acid-reducing drugs affect magnesium levels
  • Athletes subject to anti-doping rules should only use products certified by an independent third-party testing program for banned substances; certification lowers, but does not eliminate, the risk of contamination.

Food sources

Pumpkin seeds, Almonds and cashews, Spinach, Black beans and other legumes, Whole grains, Dark chocolate, Avocado.

Frequently asked questions

Which form of magnesium is best?

Citrate, glycinate and lactate are generally better absorbed and gentler than oxide. The best form for you depends on tolerance and budget.

Does magnesium help you sleep?

Some small studies suggest benefits in older adults or those with low magnesium, but evidence in the general population is limited.

Does magnesium stop muscle cramps?

Research reviews have found little evidence that magnesium prevents typical muscle cramps in most people.

What is ZMA?

ZMA combines zinc, magnesium and vitamin B6. Studies have not consistently shown effects on testosterone or performance in people who are not deficient.

Sources & further reading

  1. NIH Office of Dietary Supplements (2022). Magnesium: Fact Sheet for Health Professionals . National Institutes of Health
  2. NIH Office of Dietary Supplements (2022). Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals . National Institutes of Health