Magnesium Glycinate
Strong EvidenceHighly bioavailable chelated magnesium — absorbed via dipeptide transport with minimal GI effects.
Not medical advice
Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before taking any supplement.
Magnesium bisglycinate is chelated to two glycine molecules (~14% elemental Mg), enabling absorption partly intact via the intestinal PepT1 dipeptide transporter — bypassing competition for mineral ion channels. Magnesium is a cofactor in 300+ enzyme systems regulating ATP production, muscle/nerve function, and blood glucose. Roughly 48% of Americans and 20% of Europeans consume less than recommended. Organic forms like glycinate are better absorbed than inorganic forms like oxide (systematic review of 14 studies). The glycine carrier independently supports sleep via NMDA receptor modulation and core body temperature reduction.
RCT evidence (PMID: 39770988): 155 adults, 250 mg elemental Mg as bisglycinate for 4 weeks produced significant Insomnia Severity Index reduction vs placebo (−3.9 vs −2.3, p=0.049). Improvement within 14 days. Meta-analysis of 3 RCTs in older adults: sleep onset latency reduced by 17 minutes. Cochrane review (high certainty): magnesium does NOT reduce muscle cramps in the general population. Best evidence is for sleep, relaxation, and general repletion — not cramps. Superior tolerability to oxide, citrate, and sulfate forms.
Muscle Cramps (General Population)
7 studies · 790 participants
Sleep Quality & Insomnia
4 studies · 427 participants
Blood Pressure
34 studies · 2,028 participants
The Evidence
15 peer-reviewed papers, updated 5 days ago
6 meta-analyses · 5 systematic reviews · 3 RCTs · 1 regulatory document
Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Argeros Z, Xu X, Bhandari B et al.
Hypertension
Meta-analysis of 38 RCTs (2,709 participants) found magnesium supplementation reduced systolic BP by −2.81 mmHg and diastolic BP by −2.05 mmHg versus placebo. Effects were most pronounced in hypertensive individuals on medication (systolic −7.68 mmHg) and those with hypomagnesaemia. No significant benefit in normotensive groups.
Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial
Schuster J, Cycelskij I, Lopresti A et al.
Nature and Science of Sleep
In 155 adults (18–65) with poor sleep, 250 mg elemental magnesium as bisglycinate daily for 4 weeks produced a statistically significant reduction in insomnia severity versus placebo (p=0.049), though effect size was small (Cohen's d=0.2). Greater benefit was seen in those with lower baseline dietary magnesium intake.
Impact of Magnesium Supplementation on Blood Pressure: An Umbrella Meta-Analysis of Randomized Controlled Trials
Alharran AM, Alzayed MM, Jamilian P
Current Therapeutic Research, Clinical and Experimental
Umbrella meta-analysis of 10 prior reviews (8,610 participants) confirmed magnesium supplementation meaningfully reduces both systolic and diastolic blood pressure. Doses ≥400 mg/day and treatment durations ≥12 weeks produced the strongest effects. Findings support benefit in hypertensive and magnesium-deficient populations.
Examining the Effects of Supplemental Magnesium on Self-Reported Anxiety and Sleep Quality: A Systematic Review
Rawji A, Peltier MR, Mourtzanakis K et al.
Cureus
Of 15 interventional trials reviewed, 5/8 showed sleep improvement and 5/7 showed anxiety improvement. Supplemental magnesium is likely beneficial for mild anxiety and insomnia, particularly in those with low magnesium status. Constrained by heterogeneity, small samples, and variable dosing; larger RCTs are needed.
Magnesium supplementation beneficially affects depression in adults with depressive disorder: a systematic review and meta-analysis of randomized clinical trials
Moabedi M, Aliakbari M, Erfanian S et al.
Frontiers in Psychiatry
Meta-analysis of 7 RCTs (325 adults) found magnesium supplementation significantly reduced depression scores (SMD −0.919, p=0.001). Lower doses (≤250 mg/day) showed stronger effects than higher doses. Substantial between-study heterogeneity limits clinical translation; larger, high-quality RCTs are needed.
Perspective: Call for Re-evaluation of the Tolerable Upper Intake Level for Magnesium Supplementation in Adults
Costello R, Rosanoff A, Nielsen F et al.
Advances in Nutrition
Review of 10 studies (5 meta-analyses, 5 RCTs) found 7/10 observed no significant difference in diarrhea between supplemental magnesium groups and controls, even at intakes up to 1,200 mg/day. Only 40 FDA adverse events were attributed to single-ingredient magnesium products over 18 years. Authors argue the 1997 UL of 350 mg/day warrants upward revision.
The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature
Arab A, Rafie N, Amani R et al.
Biological Trace Element Research
Systematic review of 9 studies (7,582 subjects) found observational evidence linking higher magnesium status to better sleep quality metrics (alertness, snoring, rest duration). Intervention trial results were inconsistent. Well-designed RCTs with durations exceeding 12 weeks are required to establish causality.
Effect of oral magnesium supplementation for relieving leg cramps during pregnancy: A meta-analysis of randomized controlled trials
Liu J, Song G, Zhao G et al.
Taiwanese Journal of Obstetrics and Gynecology
Meta-analysis of 4 RCTs (332 pregnant women) found oral magnesium supplementation did not significantly reduce leg cramp frequency or improve recovery versus control. No significant adverse effects were observed. Authors conclude magnesium is not effective for pregnancy-related leg cramps.
Bioavailability of magnesium food supplements: A systematic review
Pardo MR, Garicano Vilar E, San Mauro Martín I et al.
Nutrition
Systematic review of 14 studies found inorganic magnesium formulations (e.g., oxide, sulphate) are less bioavailable than organic forms (e.g., citrate, glycinate). Absorption is dose-dependent. Standard supplements can maintain physiological levels in healthy adults, but adequacy is uncertain in older adults and those with deficiency or illness.
Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis
Mah J, Pitre T
BMC Complementary Medicine and Therapies
Pooled analysis of 3 RCTs (151 older adults) found magnesium reduced sleep onset latency by ~17 minutes versus placebo. Total sleep duration improvement was non-significant. All trials carried moderate-to-high bias risk; evidence quality is insufficient for firm clinical recommendations.
Magnesium for skeletal muscle cramps
Garrison SR, Korownyk CS, Kolber MR et al.
Cochrane Database of Systematic Reviews
Cochrane review of 11 trials (735 participants) found that magnesium supplementation is unlikely to provide clinically meaningful cramp prophylaxis for idiopathic skeletal muscle cramps in older adults (moderate-certainty evidence). Evidence for pregnancy-associated leg cramps remains conflicting. No data exists for exercise-associated cramps.
Predicting and Testing Bioavailability of Magnesium Supplements
Blancquaert L, Vervaet C, Derave W
Nutrients
In vitro SHIME modelling reliably predicted in vivo bioavailability in a crossover trial of 30 subjects. Formulation solubility was the key determinant: a highly absorbable tablet with 196 mg elemental magnesium produced superior serum levels compared to a poorly soluble tablet containing 450 mg, demonstrating that formulation matters more than elemental content.
The Effects of Magnesium Supplementation on Subjective Anxiety and Stress—A Systematic Review
Boyle NB, Lawton C, Dye L
Nutrients
Review of 18 studies found magnesium supplementation is suggestive of benefit for subjective anxiety in vulnerable populations (mild anxiety, PMS, hypertension), with positive findings in roughly half of included studies. Overall evidence quality is poor; well-designed RCTs are required to confirm efficacy and optimal dosing.
Scientific Opinion on the substantiation of health claims related to magnesium and reduction of tiredness and fatigue, contribution to normal psychological functions, and maintenance of normal blood pressure
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)
EFSA Journal
The EFSA NDA Panel concluded there is a well-established relationship between magnesium and: reduction of tiredness and fatigue; normal psychological function; and maintenance of normal blood pressure. These claims were substantiated under Article 13(1) of Regulation (EC) No 1924/2006 and were subsequently approved in EU Regulation 432/2012.
Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection
Schuette SA, Lashner BA, Janghorbani M
JPEN: Journal of Parenteral and Enteral Nutrition
Double-blind crossover trial in 12 patients with ileal resections found magnesium diglycinate showed superior bioavailability in those with greatest absorption impairment (23.5% vs 11.8% for oxide). Diglycinate was more rapidly absorbed and better tolerated, suggesting it is a preferable option for individuals with compromised intestinal absorption.
Evidence Database
Click any row to explore the studies behind each health outcome. Grades reflect the volume and quality of published research, not a recommendation.
| Grade | Health Outcome | |
|---|---|---|
| A | Muscle Cramps (General Population)7 studies | |
| B | Sleep Quality & Insomnia4 studies | |
| B | Blood Pressure34 studies | |
| B | Bioavailability vs Other Magnesium Forms14 studies |
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General Information
Dosage (Evidence-Reported)
These figures reflect what clinical studies used — not personalised recommendations.
Safety Notes
- Cochrane review (high certainty): does NOT meaningfully reduce muscle cramps
- Interacts with antibiotics (tetracyclines, quinolones) — separate by 2–6 hours
- Reduces gabapentin absorption by 20–40% — take gabapentin 2+ hours after
- Kidney disease: supplementation only under medical supervision (eGFR <30)
- Long-term PPI use can cause hypomagnesaemia — may need supplementation
- NHS: taking >400 mg/day for a short time can cause diarrhoea (less likely with glycinate)
Key Benefits
- Improves sleep onset and quality (RCT: significant ISI reduction within 14 days)
- Supports 300+ enzymatic reactions including ATP energy production
- Glycine carrier independently supports relaxation and core temp regulation
- Superior GI tolerability — low laxative risk vs oxide/citrate/sulfate
- Corrects widespread magnesium inadequacy (48% of Americans below RDA)
- May modestly reduce blood pressure at ≥400 mg/day for 12+ weeks (umbrella meta-analysis)
Quick Facts
Legal food supplement (UK). No prescription required. EFSA authorised health claims for magnesium include: electrolyte balance, reduction of tiredness and fatigue, normal energy-yielding metabolism, normal muscle function, normal protein synthesis, and normal psychological function. EFSA supplemental UL: 250 mg/day.
Frequently Asked Questions
Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Consult a healthcare professional before starting any supplement.