Ingredient guide
What is magnesium?
What magnesium does
Magnesium is an essential dietary mineral that the body uses as a cofactor in more than 300 enzyme systems.[1]
Scope and limitations
This definition describes magnesium’s normal physiological role; it does not evaluate whether a magnesium supplement improves a particular health outcome.[1]
Sources behind the starting answer
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Sources for this section
- Magnesium - Health Professional Fact Sheet. NIH Office of Dietary Supplements. Retrieved 2026-06-18. Government health fact sheet View source →
Low intake and deficiency are different questions
Magnesium deficiency concerns insufficient magnesium for the body’s needs; low dietary intake can contribute. A serum magnesium measurement does not reliably reflect all magnesium in the body or tissues, so it is only one part of assessing magnesium status. These narrative reviews describe assessment limitations and population-level risk, not a diagnosis for an individual.[1], [2]
Scope and limitations
Both supporting sources are narrative reviews rather than controlled trials or meta-analyses, so the strength of these statements is moderate at best. Estimates of how widespread low magnesium status is depend heavily on the assessment method, and the noted unreliability of serum magnesium testing means population risk figures should be read cautiously. This information is educational and is not a diagnosis or medical advice; anyone concerned about magnesium status should consult a qualified clinician.[1], [2]
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Sources for this section
- Magnesium: Biochemistry, Nutrition, Detection, and Social Impact of Diseases Linked to Its Deficiency.. Nutrients. 2021. Narrative review View source →
- Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis.. Open heart. 2018. Narrative review View source →
What form comparisons can tell you
Magnesium citrate produced a greater urinary-magnesium response than oxide in an acute absorption study. Separately, a four-week placebo-controlled trial of magnesium bisglycinate with glycine in adults reporting poor sleep found a small improvement in self-reported insomnia severity. These studies do not directly compare glycinate with citrate or establish that one is better absorbed or produces better clinical outcomes. From a single small non-randomized human trial using an acute 25 mmol oral load with urinary magnesium as the absorption marker; results describe citrate versus oxide only and do not establish clinical outcomes. The studied dose was 25 mmol oral magnesium load (magnesium citrate or magnesium oxide). The formulation supplied 250 mg elemental magnesium and 1,523 mg glycine daily. It did not compare citrate, measure absorption, isolate magnesium from glycine, or establish a personal sleep regimen. The university institute funded the study; an author disclosed nutraceutical CRO and honoraria relationships.[1], [2]
Scope and limitations
The citrate–oxide study was small, non-randomized and acute, and used urinary magnesium rather than clinical outcomes. The bisglycinate trial lasted four weeks and used a bisglycinate formulation containing magnesium and glycine. Neither study directly ranks glycinate against citrate for absorption, gastrointestinal tolerability or clinical benefit; the sleep result does not establish suitability for populations excluded from that trial. These studied regimens are not personal dosing advice.[1], [2]
The broader discussion of magnesium salts comes from a narrative review. Elemental-magnesium label reading improves amount comparisons but does not establish which form produces better clinical outcomes. Based on a human-focused narrative review describing structure-activity relationships across magnesium salts; the review summarizes existing literature rather than head-to-head testing every form. The elemental amount on Supplement Facts is the appropriate amount to compare with magnesium intake reference values; compound weights and absorption are separate questions.[1], [3], [4]
Read the full evidence summary →
Sources for this section
- Magnesium bioavailability from magnesium citrate and magnesium oxide.. Journal of the American College of Nutrition. 1990. Non-randomized trial View source →
- Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and science of sleep. 2025. Randomized controlled trial View source →
- Bioavailability and pharmacokinetics of magnesium after administration of magnesium salts to humans.. American journal of therapeutics. 2001. Narrative review View source →
- Magnesium - Health Professional Fact Sheet. NIH Office of Dietary Supplements. Retrieved 2026-06-18. Government health fact sheet View source →
This page is educational, not individualized medical advice. A study protocol is not a personal dosing instruction. Study descriptions do not replace professional care. Ingredient research does not establish that a particular ranked product works.
Explore the magnesium guide by question
The structured guide connects this foundational page to the product comparison and focused research summaries.
Open the full magnesium guide →
Magnesium Benefits
A broad overview of magnesium’s role as an essential mineral and where the evidence is strongest.
Read answer →Magnesium Forms
How glycinate, citrate, and other forms differ by use case and labeling context.
Read answer →Magnesium Dosage
How to orient magnesium intake around goal, form, elemental amount, and tolerability.
Read answer →Magnesium for Sleep
What sleep-focused magnesium research suggests and where the limits are.
Read answer →Magnesium for Anxiety
Research context for magnesium and anxiety-related outcomes.
Read answer →Magnesium for Migraine
How magnesium fits into migraine-focused research and use cases.
Read answer →Product comparison
Compare six glycinate-based magnesium supplements and two alternatives by elemental dose, formula, testing, and limitations.