{"@context":"https://schema.org","@type":"DietarySupplement","id":"https://nutripedia.co.uk/items/magnesium-glycinate","url":"https://nutripedia.co.uk/items/magnesium-glycinate","name":"Magnesium Glycinate","category":"Minerals","tagline":"Highly bioavailable chelated magnesium — absorbed via dipeptide transport with minimal GI effects.","verdict":"strong","evidenceRating":4,"verdictSummary":"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.","dosage":{"recommended":"200–400","unit":"mg elemental Mg","timing":"Evening, 30–60 minutes before bed","notes":"14% elemental Mg: a 1,000 mg bisglycinate tablet provides only ~140 mg elemental Mg. Absorption is better with smaller, divided doses. UK RNI: 300 mg men / 270 mg women. NHS: 400 mg/day from supplements unlikely to cause harm. EFSA UL: 250 mg/day supplemental. Delivers ~1,500 mg glycine daily at typical doses."},"keyBenefits":["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)"],"warnings":["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)"],"evidenceSummary":null,"dosing":null,"safety":null,"whoMightBenefit":[],"whoShouldAvoid":[],"regulatoryNotes":null,"faqs":[{"question":"What does the research say about magnesium glycinate and sleep?","answer":"A 2025 double-blind RCT (PMID: 39770988, n=155) found that 250 mg elemental magnesium as bisglycinate for 4 weeks produced a statistically significant reduction in Insomnia Severity Index scores versus placebo (−3.9 vs −2.3, p=0.049), with improvement observed within 14 days. A separate meta-analysis of 3 RCTs in older adults found sleep onset latency was reduced by an average of 17 minutes. The glycine component may independently support sleep via NMDA receptor glycine-site modulation and a reduction in core body temperature."},{"question":"What dosage ranges have been studied for magnesium glycinate?","answer":"Trials have administered magnesium bisglycinate at doses providing 200–500 mg of elemental magnesium per day. The UK RNI is 300 mg/day for men and 270 mg/day for women. The NHS states that taking up to 400 mg/day of supplemental magnesium is unlikely to cause harm. The EFSA tolerable upper level for supplemental magnesium is 250 mg/day. Because bisglycinate contains approximately 14% elemental magnesium by weight, a 1,000 mg bisglycinate tablet delivers only ~140 mg elemental Mg — label reading is important for accurate dosing."},{"question":"What side effects have been reported in trials of magnesium glycinate?","answer":"Gastrointestinal adverse events (loose stools, diarrhoea) are the most commonly reported side effects with magnesium supplementation. Bisglycinate demonstrates markedly better GI tolerability than oxide, citrate, or sulfate forms in comparative studies, attributed to its non-osmotic absorption mechanism via the PepT1 dipeptide transporter. The NHS notes that taking >400 mg supplemental magnesium per day for a short time can cause diarrhoea; this threshold is rarely breached with standard bisglycinate doses."},{"question":"Does the research support magnesium glycinate for muscle cramps?","answer":"A 2020 Cochrane review (PMID: 32956536, high-certainty evidence, 7 RCTs, n=406) found that magnesium supplementation is unlikely to provide clinically meaningful reduction in muscle cramps in the general population. Trials in nocturnal leg cramps reported no significant difference versus placebo. Evidence for pregnancy-associated leg cramps is mixed. Populations with confirmed hypomagnesaemia are underrepresented in the available RCT evidence."},{"question":"What forms of magnesium have the strongest evidence base?","answer":"A systematic review of 14 studies found organic magnesium salts (glycinate, citrate, malate, gluconate) are more bioavailable than inorganic forms (oxide, sulfate), with oxide demonstrating particularly poor absorption (~4% in some studies). Magnesium bisglycinate is unique in being partially absorbed intact via intestinal dipeptide transporters (PepT1), bypassing competition with other minerals for ion channels. Most clinical sleep and anxiety trials in recent years have used bisglycinate or citrate forms."},{"question":"What do NHS and EFSA say about magnesium supplementation?","answer":"The NHS states that most people should be able to meet their magnesium needs through a balanced diet, but notes that supplementation may be appropriate for those on long-term proton pump inhibitors (which can cause hypomagnesaemia), those with type 2 diabetes, and older adults with inadequate dietary intake. EFSA has authorised health claims for magnesium contributing to electrolyte balance, energy-yielding metabolism, reduction of tiredness and fatigue, protein synthesis, normal muscle function, and maintenance of normal bones. EFSA's supplemental upper level is 250 mg/day."},{"question":"Is there evidence for interactions between magnesium glycinate and medications?","answer":"The literature identifies several clinically significant interactions. Magnesium reduces the absorption of tetracycline and quinolone antibiotics — the NHS and BNF recommend separating doses by 2–6 hours. In one pharmacokinetic study, magnesium reduced gabapentin bioavailability by 20–40%; a 2-hour separation is advised. Long-term PPI use (e.g. omeprazole) can cause symptomatic hypomagnesaemia requiring supplementation or drug discontinuation. In patients with kidney disease (eGFR <30), supplemental magnesium should only be taken under medical supervision due to impaired excretion."}],"research":{"totalCount":15,"papers":[{"title":"Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials","year":2025,"journal":"Hypertension","doi":"10.1161/HYPERTENSIONAHA.125.25129","pmid":"41000008","url":"https://doi.org/10.1161/HYPERTENSIONAHA.125.25129","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial","year":2025,"journal":"Nature and Science of Sleep","doi":"10.2147/NSS.S524348","pmid":"40918053","url":"https://doi.org/10.2147/NSS.S524348","studyDesign":"rct","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Impact of Magnesium Supplementation on Blood Pressure: An Umbrella Meta-Analysis of Randomized Controlled Trials","year":2024,"journal":"Current Therapeutic Research, Clinical and Experimental","doi":"10.1016/j.curtheres.2024.100755","pmid":"39280209","url":"https://doi.org/10.1016/j.curtheres.2024.100755","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Examining the Effects of Supplemental Magnesium on Self-Reported Anxiety and Sleep Quality: A Systematic Review","year":2024,"journal":"Cureus","doi":"10.7759/cureus.59317","pmid":"38817505","url":"https://doi.org/10.7759/cureus.59317","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Magnesium supplementation beneficially affects depression in adults with depressive disorder: a systematic review and meta-analysis of randomized clinical trials","year":2023,"journal":"Frontiers in Psychiatry","doi":"10.3389/fpsyt.2023.1333261","pmid":"38213402","url":"https://doi.org/10.3389/fpsyt.2023.1333261","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Perspective: Call for Re-evaluation of the Tolerable Upper Intake Level for Magnesium Supplementation in Adults","year":2023,"journal":"Advances in Nutrition","doi":"10.1016/j.advnut.2023.06.008","pmid":"37487817","url":"https://doi.org/10.1016/j.advnut.2023.06.008","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature","year":2023,"journal":"Biological Trace Element Research","doi":"10.1007/s12011-022-03162-1","pmid":"35184264","url":"https://doi.org/10.1007/s12011-022-03162-1","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Effect of oral magnesium supplementation for relieving leg cramps during pregnancy: A meta-analysis of randomized controlled trials","year":2021,"journal":"Taiwanese Journal of Obstetrics and Gynecology","doi":"10.1016/j.tjog.2021.05.006","pmid":"34247796","url":"https://doi.org/10.1016/j.tjog.2021.05.006","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Bioavailability of magnesium food supplements: A systematic review","year":2021,"journal":"Nutrition","doi":"10.1016/j.nut.2021.111294","pmid":"34111673","url":"https://doi.org/10.1016/j.nut.2021.111294","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis","year":2021,"journal":"BMC Complementary Medicine and Therapies","doi":"10.1186/s12906-021-03297-z","pmid":"33865376","url":"https://doi.org/10.1186/s12906-021-03297-z","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Magnesium for skeletal muscle cramps","year":2020,"journal":"Cochrane Database of Systematic Reviews","doi":"10.1002/14651858.CD009402.pub3","pmid":"32956536","url":"https://doi.org/10.1002/14651858.CD009402.pub3","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Predicting and Testing Bioavailability of Magnesium Supplements","year":2019,"journal":"Nutrients","doi":"10.3390/nu11071663","pmid":"31330811","url":"https://doi.org/10.3390/nu11071663","studyDesign":"rct","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"The Effects of Magnesium Supplementation on Subjective Anxiety and Stress—A Systematic Review","year":2017,"journal":"Nutrients","doi":"10.3390/nu9050429","pmid":"28445426","url":"https://doi.org/10.3390/nu9050429","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"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","year":2010,"journal":"EFSA Journal","doi":"10.2903/j.efsa.2010.1807","pmid":"","url":"https://doi.org/10.2903/j.efsa.2010.1807","studyDesign":"regulatory","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection","year":1994,"journal":"JPEN: Journal of Parenteral and Enteral Nutrition","doi":"10.1177/0148607194018005430","pmid":"7815675","url":"https://doi.org/10.1177/0148607194018005430","studyDesign":"rct","fields":[],"conclusion":"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.","abstract":"","citationCount":0}]},"machineReadable":{"markdownUrl":"https://nutripedia.co.uk/items/magnesium-glycinate/markdown","jsonUrl":"https://nutripedia.co.uk/items/magnesium-glycinate/json","llmsTxt":"https://nutripedia.co.uk/llms.txt"},"disclaimer":"Informational supplement research only. Not medical advice. Consult a qualified healthcare professional before taking supplements.","lastReviewed":"2026-04-20T00:00:00.000Z","updatedAt":"2026-04-20T00:00:00.000Z"}