CICoach ImpactOS

Evidence Lab

Magnesium

Magnesium is essential for neuromuscular function, energy metabolism and bone health. Supplementation is most defensible when intake or status is inadequate; evidence for routine performance enhancement in magnesium-sufficient athletes is limited.

Evidence rating: Moderate

Published 8/14/2026 | Last reviewed 8/14/2026

Overview

Magnesium participates in hundreds of enzymatic reactions and is important for muscle and nerve function, glucose metabolism, blood pressure regulation and bone health. Low intake or deficiency can impair normal physiology. For sport performance, the key distinction is adequacy versus excess. Reviews of supplementation studies suggest that magnesium may help when deficiency or inadequate intake is present, but routine supplementation has not consistently improved strength, endurance or other performance outcomes in already sufficient athletes. Supplemental magnesium comes in multiple salts with different elemental-magnesium content and gastrointestinal tolerance. The label should be interpreted by elemental magnesium, not the total compound weight. Food magnesium does not count toward the adult supplemental upper limit.

Common use

Correcting inadequate magnesium intake or deficiency and supporting normal neuromuscular and metabolic function; not a routine ergogenic aid for magnesium-sufficient athletes.

Common forms

Magnesium citrate, glycinate or bisglycinate, oxide, chloride and other salts. Elemental magnesium per serving varies substantially by form.

Practical notes

Prioritize magnesium-rich foods. If supplementing, check the elemental magnesium amount and tolerance rather than choosing a form based only on marketing claims. Last evidence review: 14 August 2026.

Claim-level evidence

Strong

Correcting magnesium deficiency or inadequate intake supports normal neuromuscular and metabolic function.

Population: People with inadequate intake, deficiency risk or clinically low status.

Fix adequacy first; performance problems from deficiency are different from supplementing beyond need.

Limitations: Serum magnesium does not perfectly reflect total-body stores, so assessment can require clinical context.

Emerging / Mixed

Routine magnesium supplementation does not consistently improve muscle fitness in magnesium-sufficient athletes.

Population: Healthy active adults and athletes with adequate magnesium status.

Do not use magnesium as a guaranteed strength or performance supplement.

Limitations: Studies are heterogeneous and some positive effects occur mainly in deficient or older groups.

Strong

Supplement form affects elemental-magnesium content and gastrointestinal tolerance.

Population: Adults using oral magnesium supplements.

Read the elemental-magnesium amount on the label; total compound weight is not the dose that matters.

Limitations: Absorption and tolerance vary among salts and individuals.

Dosing context

  • General adult intake context - NIH ODS lists 400-420 mg/day for adult men and 310-320 mg/day for adult women from all sources, with higher needs in pregnancy. - Across meals and food intake. - Ongoing nutritional intake.These are recommended dietary amounts, not supplement targets.
  • Supplement safety ceiling - Adult tolerable upper intake level from supplements and medications: 350 mg/day of elemental magnesium. - Split doses may improve gastrointestinal tolerance. - Chronic supplemental intake.The UL excludes magnesium naturally present in food. Clinician-directed treatment may differ.

Safety notes

  • Diarrhea and gastrointestinal upsetSupplemental magnesium commonly causes diarrhea, nausea or abdominal cramping, especially at higher doses and with some salts.
  • Kidney impairmentImpaired renal function reduces magnesium clearance and increases risk of dangerous hypermagnesemia. People with kidney disease should seek medical guidance before supplementation.
  • Excessive supplemental intakeVery high supplemental or medication-derived magnesium can cause hypotension, weakness, breathing difficulty, arrhythmia and cardiac arrest.

Interactions

  • Tetracycline and quinolone antibioticsMagnesium can bind these antibiotics and reduce absorption; dosing separation is often required. Follow pharmacist or prescribing guidance.
  • Oral bisphosphonatesMagnesium can reduce absorption of oral bisphosphonates when taken too close together; follow medication-specific separation instructions.

References

  1. Wang R, Chen C, Liu W, et al.. The effect of magnesium supplementation on muscle fitness: a meta-analysis and systematic review Magnesium Research. 2017.Source
  2. NIH Office of Dietary Supplements. Magnesium - Health Professional Fact Sheet National Institutes of Health. 2026.Source