Magnesium glycinate

updated

Magnesium glycinate is the magnesium salt of two glycine molecules, sold as a supplement for sleep, muscle relaxation and recovery, with no FDA-approved single-ingredient drug product. One randomized trial of the glycinate form found a small improvement in insomnia scores in 155 adults, and the one direct comparison in healthy adults did not support a bioavailability advantage. A PubMed search on 9 October 2026 found no human study of the glycinate form for muscle relaxation or exercise recovery.

Magnesium salt of glycine (mineral supplement)

  • Magnesium glycinate (bisglycinate, diglycinate) is PubChem CID 84645, C4H8MgN2O4, 172.42 g/mol, about 14% magnesium by mass.
  • A Drugs@FDA query on 9 October 2026 found no application listing magnesium glycinate, so no label, approved indication or labeled dose exists for it.
  • In the one randomized trial of the glycinate form for sleep (155 adults, DRKS00031494), the Insomnia Severity Index changed by -3.9 versus -2.3 on placebo (p = 0.049, Cohen's d = 0.2).
  • In a sponsored head-to-head in 40 healthy adults, plasma magnesium rose after oxide, citrate and a microencapsulated product but not significantly after bisglycinate.
  • A Cochrane review of 11 trials in 735 people found no difference in the proportion of older adults with a 25% cramp reduction (RR 1.04, 95% CI 0.84 to 1.29; high certainty).
  • A PubMed search on 9 October 2026 returned 8 glycinate records with sleep, cramp or recovery terms; 2 were human trials of the glycinate form and none covered muscle relaxation or exercise recovery.

What is magnesium glycinate, and is it approved?

Magnesium glycinate, also called magnesium bisglycinate or diglycinate, is the magnesium salt of two glycine molecules, about 14% magnesium by mass. No FDA-approved single-ingredient drug product exists, so there is no label, approved indication or labeled dose for it.

Magnesium glycinate is PubChem CID 84645 (C4H8MgN2O4, molecular weight 172.42 g/mol, CAS 14783-68-7), the magnesium salt of two glycine molecules. Elemental magnesium is CID 5462224 (atomic weight 24.305 g/mol). Dividing those two values gives about 14% magnesium by mass, so the weight of glycinate and the weight of elemental magnesium are different quantities, and trials are read in elemental magnesium where the report states it.

A Drugs@FDA query on 9 October 2026 for products with magnesium glycinate as an active ingredient returned no matching application. A DailyMed drug name search the same day returned only multi-ingredient prescription prenatal and medical food products, the closest being REMEDIENT, which lists magnesium glycinate glutamine chelate among 11 other ingredients. There is no FDA-approved single-ingredient magnesium glycinate drug product in the records reviewed.

Oral magnesium does have an FDA-recognized use. The reviewed over-the-counter magnesium hydroxide label (version effective 4 December 2025) is for a saline laxative and directs users to ask a doctor before use with kidney disease or a magnesium-restricted diet. That is the regulatory frame for oral magnesium salts: a laxative, with a kidney caution.

PubChem: magnesium glycinate identity and magnesium content by mass

Chemical identity record

National Library of Medicine. PubChem compound records CID 84645 (magnesium glycinate, also magnesium bisglycinate or diglycinate) and CID 5462224 (magnesium).

Magnesium glycinate, also called magnesium bisglycinate or magnesium diglycinate: PubChem CID 84645, C4H8MgN2O4, molecular weight 172.42 g/mol, CAS 14783-68-7, the magnesium salt of two glycine molecules. Elemental magnesium is CID 5462224, atomic weight 24.305 g/mol, CAS 7439-95-4. Dividing those two retrieved values gives about 14 percent magnesium by mass, so the weight of glycinate and the weight of elemental magnesium are different quantities.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined salt
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only. Trials in this record are read in elemental magnesium where the report states it.

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Drugs@FDA query, 9 October 2026: no application lists magnesium glycinate

Regulatory record

U.S. Food and Drug Administration, openFDA Drugs@FDA API query for products with magnesium glycinate as an active ingredient, run on 9 October 2026; DailyMed drug name search for magnesium glycinate the same day.

A Drugs@FDA query on 9 October 2026 for products with magnesium glycinate as an active ingredient returned no matching application. A DailyMed drug name search for magnesium glycinate on the same date returned only multi-ingredient prescription prenatal and medical food products, the closest being REMEDIENT, which lists magnesium glycinate glutamine chelate among 11 other ingredients. There is no FDA-approved single-ingredient magnesium glycinate drug product in the records reviewed, so no label, no approved indication and no labeled dose exists for it.

Participants / model
FDA application and label databases, not a clinical population
Treatment
Exact active ingredient search
Follow-up
Searches run on 9 October 2026
Study design
Dated US approval and label record search
Funding
not stated in the source

A database search shows what the records contained on that date. It covers the United States only.

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OTC magnesium hydroxide label (effective 4 December 2025): laxative with a kidney caution

Official label

DailyMed, U.S. National Library of Medicine. Magnesium hydroxide oral suspension, over-the-counter saline laxative, label version effective 4 December 2025. Set ID 0a57bb45-d4f7-443b-e054-00144ff8d46c.

Oral magnesium does have an FDA-recognized use: the reviewed over-the-counter magnesium hydroxide label is a saline laxative. It directs users to ask a doctor before use with kidney disease or a magnesium-restricted diet. This is the regulatory frame for oral magnesium salts: a laxative, with a kidney caution.

Participants / model
Adults and children using an over-the-counter laxative
Treatment
Magnesium hydroxide oral suspension
Follow-up
Label version effective 4 December 2025
Study design
Official over-the-counter label
Funding
not stated in the source

This is the label for magnesium hydroxide, not glycinate. No label dose or timing is reproduced on this page.

Read the original source

What have trials of the glycinate form found?

Two randomized trials used the glycinate form. In 155 adults with poor sleep quality, insomnia scores fell slightly more on magnesium bisglycinate than on placebo (Cohen's d 0.2), and in 86 pregnant women a 50% reduction in cramp frequency was more common than on placebo. No glycinate trial covers muscle relaxation or exercise recovery.

The one randomized placebo-controlled trial of the glycinate form for sleep gave 155 adults aged 18 to 65 with self-reported poor sleep quality 250 mg elemental magnesium as bisglycinate or placebo daily. The Insomnia Severity Index fell more on magnesium from baseline to week 4 (-3.9, 95% CI -5.8 to -2.0, versus -2.3, 95% CI -4.1 to -0.4; p = 0.049), with a small effect size (Cohen's d = 0.2). Other psychological outcomes did not differ significantly. An exploratory analysis suggested larger improvements in participants with lower baseline dietary magnesium intake. The trial is registered as DRKS00031494, and one author is the managing director of a contract research organization funded by nutraceutical companies.

The one positive cramp trial of the glycinate form randomized 86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week to magnesium bisglycinate chelate (300 mg per day) or placebo for 4 weeks, and 80 completed. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). Nausea and diarrhea did not differ significantly. This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias, and the result does not transfer to healthy non-pregnant adults or to exercise cramps.

A PubMed search on 9 October 2026 for the glycinate, bisglycinate or diglycinate forms with sleep, insomnia, cramps, recovery, soreness or relaxation returned 8 records. Two were the human trials above; the other 6 were a rat intestinal motility study, two in vitro or cell studies, a zebrafish anxiety study, an in vitro bioaccessibility comparison of two bisglycinate formulations and a network pharmacology paper. No human study of the glycinate form for muscle relaxation or exercise recovery exists in the records reviewed, and no human study compares glycinate against another form on a sleep, cramp or recovery outcome.

Glycinate sleep trial: 155 adults, small effect on Insomnia Severity Index

Randomized controlled trial

Schuster J et al. Nat Sci Sleep. 2025;17:2027-2040. PMID 40918053.

155 adults aged 18 to 65 with self-reported poor sleep quality took 250 mg elemental magnesium as bisglycinate or placebo daily. The Insomnia Severity Index fell more on magnesium from baseline to week 4 (-3.9, 95% CI -5.8 to -2.0, versus -2.3, 95% CI -4.1 to -0.4; p = 0.049), with a small effect size (Cohen's d = 0.2). No significant differences in other psychological outcomes. Exploratory analysis suggested larger improvements in participants with lower baseline dietary magnesium intake.

Participants / model
155 adults aged 18 to 65 reporting poor sleep quality
Treatment
Oral magnesium bisglycinate capsules, 250 mg elemental magnesium daily, or placebo
Follow-up
Baseline to week 4; total duration not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

The one randomized placebo-controlled trial of the glycinate form for sleep. One author is the managing director of a contract research organization funded by nutraceutical companies.

Read the original source
Glycinate pregnancy cramp trial: 86 women, 4 weeks, fewer cramps

Randomized controlled trial

Supakatisant C et al. Matern Child Nutr. 2015;11(2):139-45. PMID 22909270.

86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week were randomized to magnesium bisglycinate chelate 300 mg per day or placebo for 4 weeks, with 80 completing. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). No significant difference in nausea or diarrhea.

Participants / model
86 pregnant women, 80 completers
Treatment
Oral magnesium bisglycinate chelate, 300 mg per day, or placebo
Follow-up
4 weeks
Study design
Randomized placebo-controlled trial; cramp frequency and intensity on a 100 mm visual analogue scale
Funding
not stated in the source

This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias. It does not transfer to healthy non-pregnant adults or to exercise cramps.

Read the original source
PubMed search, 9 October 2026: 8 records, 2 human trials of the glycinate form

PubMed search record

PubMed search run on 9 October 2026: (magnesium glycinate OR magnesium bisglycinate OR magnesium diglycinate) AND (sleep OR insomnia OR cramp OR cramps OR recovery OR soreness OR relaxation). 8 records returned.

The search returned 8 records. Two were human trials of the glycinate form (the bisglycinate sleep trial and the pregnancy cramp trial); the remaining 6 were a rat intestinal motility study, two in vitro or cell studies, a zebrafish anxiety study, an in vitro bioaccessibility comparison of two bisglycinate formulations and a network pharmacology paper. No human study of the glycinate form for muscle relaxation or exercise recovery exists in the records reviewed, and no human study compares glycinate against another form on a sleep, cramp or recovery outcome.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source

What do reviews of magnesium for sleep conclude?

Weakly, and not for glycinate in particular. A meta-analysis of 3 trials in 151 older adults found sleep onset 17.36 minutes shorter than placebo on low to very low quality evidence, and a 2026 review of 12 trials concluded that current evidence does not support oral magnesium as a routine treatment for insomnia.

A systematic review and meta-analysis of oral magnesium for insomnia in older adults pooled 3 randomized trials in 151 people in three countries. Sleep onset latency after treatment was 17.36 minutes shorter than placebo (95% CI -27.27 to -7.44, p = 0.0006). Total sleep time improved by 16.06 minutes but not significantly. All trials were at moderate to high risk of bias and the outcomes were supported by low to very low quality evidence. None of the pooled trials is described as using glycinate. A 2024 published correction changed an abbreviation, the PRISMA record counts and a database name, and did not change the pooled effect estimates.

A 2026 systematic review of randomized trials of oral magnesium as a stand-alone intervention for sleep in adults included 12 trials in the main synthesis plus 3 more involving cramp or movement-related sleep disturbance. Populations, formulations, elemental doses, durations and outcome measures varied substantially, findings were inconsistent across subjective scores, EEG, actigraphy, wearables and physiological markers, and certainty of evidence was low to very low. The authors conclude that current evidence does not support oral magnesium as a routine treatment for insomnia, with possible modest benefit for selected subjective outcomes in some adults.

Sleep meta-analysis: 3 trials, 151 older adults, any magnesium form

Systematic review and meta-analysis

Mah J et al. BMC Complement Med Ther. 2021;21(1):125. PMID 33865376.

A systematic review and meta-analysis of oral magnesium for insomnia in older adults pooled 3 randomized trials in 151 people in three countries. Sleep onset latency after treatment was 17.36 minutes shorter than placebo (95% CI -27.27 to -7.44, p = 0.0006). Total sleep time improved by 16.06 minutes but not significantly. All trials were at moderate to high risk of bias and the outcomes were supported by low to very low quality evidence. None of the pooled trials is described as using glycinate.

Participants / model
151 older adults with insomnia across 3 randomized trials
Treatment
Oral magnesium in the pooled trials; none described as glycinate
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

A 2024 correction (PMID 39702257) changed an abbreviation, the PRISMA record counts and a database name, and did not change the pooled effect estimates.

Read the original source
2026 sleep review: 12 trials, inconsistent findings, low to very low certainty

Systematic review and meta-analysis

Lopresti AL et al. J Diet Suppl. 2026;23(5):553-581. PMID 42661485.

A 2026 systematic review of randomized trials of oral magnesium as a stand-alone intervention for sleep in adults included 12 trials in the main synthesis plus 3 more involving cramp or movement-related sleep disturbance. Populations, formulations, elemental doses, durations and outcome measures varied substantially, findings were inconsistent across subjective scores, EEG, actigraphy, wearables and physiological markers, and certainty of evidence was low to very low. The authors conclude that current evidence does not support oral magnesium as a routine treatment for insomnia, with possible modest benefit for selected subjective outcomes in some adults.

Participants / model
Adults across 12 randomized trials
Treatment
Oral magnesium alone, formulations varied
Follow-up
Not applicable
Study design
Systematic review of randomized trials
Funding
not stated in the source

Not specific to glycinate; formulations varied across the included trials.

Read the original source

Does magnesium help muscle cramps or exercise recovery?

Not in older adults with idiopathic cramps: a Cochrane review of 11 trials in 735 people concludes clinically meaningful cramp prevention is unlikely. A 22-person soreness trial (compound not stated) found less soreness, and a 20-athlete marathon trial found no effect on race performance or recovery.

The 2020 Cochrane review of magnesium for skeletal muscle cramps identified 11 trials in 735 people. For idiopathic cramps in older adults (mean age 61.6 to 69.3 years), the change from baseline in cramps per week at 4 weeks was a mean difference of -9.59% versus placebo (95% CI -23.14 to 3.97; 3 studies, 177 participants; moderate certainty), and the proportion achieving at least a 25% reduction did not differ (RR 1.04, 95% CI 0.84 to 1.29; 3 studies, 177 participants; high certainty). The authors conclude it is unlikely that magnesium provides clinically meaningful cramp prophylaxis to older adults. Pregnancy-associated cramp trials were conflicting and all at high risk of bias, and no randomized trial of magnesium for exercise-associated cramps was found.

A randomized double-blind placebo-controlled trial of magnesium oxide (NCT01709968) in 94 community-dwelling adults (mean age 64.9 years, 39% male) with at least 4 documented nocturnal leg cramps in 2 weeks ran for 4 weeks. Cramps fell by 3.41 per week on magnesium and 3.03 on placebo, a between-group difference of 0.38 per week (P = 0.67), with no differences in cramp severity or duration, quality of life or quality of sleep. The authors attribute the within-group fall to placebo effect. This trial used magnesium oxide, not glycinate.

A double-blind between-group study in 22 college-aged participants (9 male, 13 female) gave 350 mg per day of magnesium or placebo for 10 days around eccentric bench press sessions. Magnesium reduced soreness on a 6 cm scale by about 1 to 2 units at 24, 36 and 48 hours with no significant change for placebo, and improved session and acute ratings of perceived exertion and perceived recovery. Repetitions to failure approached but did not reach significance (p = 0.06 for total). The abstract does not state which magnesium compound was used, so the result cannot be assigned to glycinate.

The counterweight on recovery is a double-blind trial in 20 magnesium-replete endurance athletes, studied for 4 weeks before and 6 weeks after a 42 km marathon, given 365 mg per day of magnesium or placebo. Supplementation did not raise muscle or serum magnesium concentrations and had no measurable effect on race performance, on the extent of muscle damage, or on the rate of recovery of muscle function, which fell immediately after the race and returned to normal within 1 week in both groups.

Cochrane 2020: 11 trials, 735 people, no clinically meaningful prophylaxis in older adults

Systematic review and meta-analysis

Garrison SR et al. Cochrane Database Syst Rev. 2020;9(9):CD009402. PMID 32956536.

The 2020 Cochrane review of magnesium for skeletal muscle cramps identified 11 trials in 735 people. For idiopathic cramps in older adults (mean age 61.6 to 69.3 years), the change from baseline in cramps per week at 4 weeks was a mean difference of -9.59% versus placebo (95% CI -23.14 to 3.97; 3 studies, 177 participants; moderate certainty), and the proportion achieving at least a 25% reduction did not differ (RR 1.04, 95% CI 0.84 to 1.29; 3 studies, 177 participants; high certainty). The authors conclude it is unlikely that magnesium provides clinically meaningful cramp prophylaxis to older adults. Pregnancy-associated cramp trials were conflicting and all at high risk of bias. No randomized trial of magnesium for exercise-associated cramps was found. Minor adverse events were more common on magnesium (RR 1.51, 95% CI 0.98 to 2.33; 4 studies, 254 participants), mostly gastrointestinal, in 11 to 37% of participants.

Participants / model
735 people across 11 randomized trials, including pregnant women, older adults and one cirrhosis study
Treatment
Oral magnesium in all but one trial, which used intravenous infusions
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

Mostly not glycinate. The review found no randomized trial of magnesium for exercise-associated cramps.

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Magnesium oxide cramp trial: 94 adults, no difference from placebo

Randomized controlled trial

Roguin Maor N et al. JAMA Intern Med. 2017;177(5):617-623. PMID 28241153.

A randomized double-blind placebo-controlled trial in 94 community-dwelling adults (mean age 64.9 years, 39% male) with at least 4 documented nocturnal leg cramps in 2 weeks gave magnesium oxide or placebo for 4 weeks. Cramps fell by 3.41 per week on magnesium and 3.03 on placebo, a between-group difference of 0.38 per week (P = 0.67). No differences in cramp severity or duration, quality of life or quality of sleep. The authors attribute the within-group fall to placebo effect.

Participants / model
94 adults aged 21 and over with nocturnal leg cramps
Treatment
Oral magnesium oxide capsules or placebo
Follow-up
4 weeks
Study design
Randomized double-blind placebo-controlled trial
Funding
not stated in the source

This trial used magnesium oxide, not glycinate.

Read the original source
Soreness trial: 22 students, magnesium form not stated

Clinical trial

Reno AM et al. J Strength Cond Res. 2022;36(8):2198-2203. PMID 33009349.

A double-blind between-group study in 22 college-aged participants (9 male, 13 female) gave 350 mg per day of magnesium or placebo for 10 days around eccentric bench press sessions. Magnesium reduced soreness on a 6 cm scale by about 1 to 2 units at 24, 36 and 48 hours with no significant change for placebo, improved session and acute ratings of perceived exertion, and improved perceived recovery. Repetitions to failure approached but did not reach significance (p = 0.06 for total).

Participants / model
22 college-aged men and women
Treatment
Oral magnesium 350 mg per day for 10 days, form not stated in the abstract, or placebo
Follow-up
10 days around eccentric bench press sessions
Study design
Double-blind between-group trial
Funding
not stated in the source

The abstract does not state which magnesium compound was used, so this result cannot be assigned to glycinate.

Read the original source
Marathon trial: 20 magnesium-replete athletes, no effect on performance or recovery

Clinical trial

Terblanche S et al. Int J Sport Nutr. 1992;2(2):154-64. PMID 1299490.

A double-blind trial in 20 athletes, studied 4 weeks before and 6 weeks after a 42 km marathon, gave 365 mg per day of magnesium or placebo. Supplementation did not raise muscle or serum magnesium concentrations and had no measurable effect on race performance, on the extent of muscle damage, or on the rate of recovery of muscle function, which fell immediately after the race and returned to normal within 1 week in both groups.

Participants / model
20 magnesium-replete endurance athletes
Treatment
Oral magnesium 365 mg per day or placebo; compound not named in the record reviewed
Follow-up
4 weeks before and 6 weeks after a 42 km marathon
Study design
Double-blind placebo-controlled trial
Funding
not stated in the source

The participants were magnesium-replete at baseline, so the result may not apply to people with low intake.

Read the original source
Glycinate pregnancy cramp trial: 86 women, 4 weeks, fewer cramps

Randomized controlled trial

Supakatisant C et al. Matern Child Nutr. 2015;11(2):139-45. PMID 22909270.

86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week were randomized to magnesium bisglycinate chelate 300 mg per day or placebo for 4 weeks, with 80 completing. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). No significant difference in nausea or diarrhea.

Participants / model
86 pregnant women, 80 completers
Treatment
Oral magnesium bisglycinate chelate, 300 mg per day, or placebo
Follow-up
4 weeks
Study design
Randomized placebo-controlled trial; cramp frequency and intensity on a 100 mm visual analogue scale
Funding
not stated in the source

This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias. It does not transfer to healthy non-pregnant adults or to exercise cramps.

Read the original source

Is glycinate absorbed better or easier on the gut than other forms?

Not in the one healthy-adult comparison: in 40 healthy adults plasma magnesium did not rise significantly after bisglycinate while oxide and citrate did, in a sponsored study. In 12 patients with ileal resection, absorption did not differ overall, and glycinate was better only in the 4 who absorbed oxide worst.

The oldest and most direct human form comparison was a double-blind randomized crossover trial in 12 patients with ileal resections that compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients. These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate. The study was funded by the manufacturer of the microencapsulated comparator and two authors worked for that company, so the bisglycinate result comes from a sponsored head-to-head, but it is the most recent human comparison located and it does not support a bioavailability advantage for glycinate.

Gut tolerability has the best support, from the 12-patient crossover and the general finding that gastrointestinal effects are the dose-limiting problem for oral magnesium. No trial has tested the tolerability of glycinate against another form as a primary endpoint in healthy adults.

Ileal resection crossover: 12 patients, no overall difference in absorption

Randomized controlled trial

Schuette SA et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PMID 7815675.

A double-blind randomized crossover trial in 12 patients with ileal resections compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients.

Participants / model
12 patients with ileal resection
Treatment
Single 100 mg oral dose, 26Mg-labeled diglycinate chelate versus oxide
Follow-up
Single-dose crossover
Study design
Double-blind randomized crossover absorption study
Funding
not stated in the source

These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference. It is the oldest and most direct human form comparison.

Read the original source
Healthy-adult crossover: 40 adults, no significant plasma rise after bisglycinate

Randomized controlled trial

Pajuelo D et al. Nutrients. 2024;16(24). PMID 39770988.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate.

Participants / model
40 healthy adults
Treatment
Single oral doses of magnesium bisglycinate, oxide, citrate and a microencapsulated product
Follow-up
Plasma magnesium at 1, 4 and 6 hours after each dose
Study design
Double-blind randomized crossover absorption study
Funding
Funded by the manufacturer of the microencapsulated comparator product; two authors were employed by that company.

A sponsored head-to-head, but it is the most recent human comparison located, and it does not support a bioavailability advantage for glycinate. Self-reported gastrointestinal effects were also recorded.

Read the original source
2023 perspective: diarrhea is the limiting factor; 40 CAERS gastrointestinal cases

Narrative review

Costello R et al. Adv Nutr. 2023;14(5):973-982. PMID 37487817.

A 2023 perspective article states that the 1997 US Institute of Medicine dietary reference intakes committee set a tolerable upper intake level for adults of 350 mg per day of magnesium from supplemental intake alone, with diarrhea as the limiting factor, and argues for re-evaluating it. Its own literature search found 10 studies, 5 meta-analyses and 5 randomized trials, at intakes of 128 to 1,200 mg per day, of which 7 found no significant difference in diarrhea between intervention and control. An FDA CAERS search limited to single-ingredient magnesium products found 40 attributable gastrointestinal adverse event cases, one third of which noted diarrhea.

Participants / model
Adults in the reviewed trials and adverse event reports
Treatment
Oral magnesium supplements, forms varied across included studies
Follow-up
Not applicable
Study design
Perspective article reporting a regulatory reference value
Funding
not stated in the source

The 350 mg figure is reported here at second hand, from authors affiliated with a magnesium research center, and is not treated as a hard limit.

Read the original source

Is glycinate more bioavailable, gut-friendly and better for sleep and recovery than other forms?

The claim splits three ways. Gut tolerability has the best support but no healthy-adult head-to-head trial; high bioavailability is not supported by the one direct comparison in healthy adults; and sleep, relaxation and recovery rest on thin, inconsistent and mostly form-agnostic data.

Gut tolerability has the best support, from a 12-patient ileal resection crossover and the general finding that gastrointestinal effects limit oral magnesium. No trial has tested tolerability of glycinate against another form as a primary endpoint in healthy adults.

High bioavailability is not supported. The one direct head-to-head in 40 healthy adults found no significant plasma magnesium rise after bisglycinate while oxide and citrate did rise, although the study was sponsored by the maker of a competing product.

Sleep, relaxation and recovery have thin and inconsistent data that mostly do not name the form. The record is one small glycinate sleep trial, one pregnancy cramp trial, and reviews and trials of magnesium in other or unstated forms. No human study of the glycinate form for muscle relaxation or exercise recovery exists in the records reviewed.

This page makes no claim about anxiety, depression or blood pressure, because none of the sources measured those endpoints.

Ileal resection crossover: 12 patients, no overall difference in absorption

Randomized controlled trial

Schuette SA et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PMID 7815675.

A double-blind randomized crossover trial in 12 patients with ileal resections compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients.

Participants / model
12 patients with ileal resection
Treatment
Single 100 mg oral dose, 26Mg-labeled diglycinate chelate versus oxide
Follow-up
Single-dose crossover
Study design
Double-blind randomized crossover absorption study
Funding
not stated in the source

These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference. It is the oldest and most direct human form comparison.

Read the original source
Healthy-adult crossover: 40 adults, no significant plasma rise after bisglycinate

Randomized controlled trial

Pajuelo D et al. Nutrients. 2024;16(24). PMID 39770988.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate.

Participants / model
40 healthy adults
Treatment
Single oral doses of magnesium bisglycinate, oxide, citrate and a microencapsulated product
Follow-up
Plasma magnesium at 1, 4 and 6 hours after each dose
Study design
Double-blind randomized crossover absorption study
Funding
Funded by the manufacturer of the microencapsulated comparator product; two authors were employed by that company.

A sponsored head-to-head, but it is the most recent human comparison located, and it does not support a bioavailability advantage for glycinate. Self-reported gastrointestinal effects were also recorded.

Read the original source
Glycinate sleep trial: 155 adults, small effect on Insomnia Severity Index

Randomized controlled trial

Schuster J et al. Nat Sci Sleep. 2025;17:2027-2040. PMID 40918053.

155 adults aged 18 to 65 with self-reported poor sleep quality took 250 mg elemental magnesium as bisglycinate or placebo daily. The Insomnia Severity Index fell more on magnesium from baseline to week 4 (-3.9, 95% CI -5.8 to -2.0, versus -2.3, 95% CI -4.1 to -0.4; p = 0.049), with a small effect size (Cohen's d = 0.2). No significant differences in other psychological outcomes. Exploratory analysis suggested larger improvements in participants with lower baseline dietary magnesium intake.

Participants / model
155 adults aged 18 to 65 reporting poor sleep quality
Treatment
Oral magnesium bisglycinate capsules, 250 mg elemental magnesium daily, or placebo
Follow-up
Baseline to week 4; total duration not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

The one randomized placebo-controlled trial of the glycinate form for sleep. One author is the managing director of a contract research organization funded by nutraceutical companies.

Read the original source
2026 sleep review: 12 trials, inconsistent findings, low to very low certainty

Systematic review and meta-analysis

Lopresti AL et al. J Diet Suppl. 2026;23(5):553-581. PMID 42661485.

A 2026 systematic review of randomized trials of oral magnesium as a stand-alone intervention for sleep in adults included 12 trials in the main synthesis plus 3 more involving cramp or movement-related sleep disturbance. Populations, formulations, elemental doses, durations and outcome measures varied substantially, findings were inconsistent across subjective scores, EEG, actigraphy, wearables and physiological markers, and certainty of evidence was low to very low. The authors conclude that current evidence does not support oral magnesium as a routine treatment for insomnia, with possible modest benefit for selected subjective outcomes in some adults.

Participants / model
Adults across 12 randomized trials
Treatment
Oral magnesium alone, formulations varied
Follow-up
Not applicable
Study design
Systematic review of randomized trials
Funding
not stated in the source

Not specific to glycinate; formulations varied across the included trials.

Read the original source
PubMed search, 9 October 2026: 8 records, 2 human trials of the glycinate form

PubMed search record

PubMed search run on 9 October 2026: (magnesium glycinate OR magnesium bisglycinate OR magnesium diglycinate) AND (sleep OR insomnia OR cramp OR cramps OR recovery OR soreness OR relaxation). 8 records returned.

The search returned 8 records. Two were human trials of the glycinate form (the bisglycinate sleep trial and the pregnancy cramp trial); the remaining 6 were a rat intestinal motility study, two in vitro or cell studies, a zebrafish anxiety study, an in vitro bioaccessibility comparison of two bisglycinate formulations and a network pharmacology paper. No human study of the glycinate form for muscle relaxation or exercise recovery exists in the records reviewed, and no human study compares glycinate against another form on a sleep, cramp or recovery outcome.

Participants / model
Records reviewed, not a population
Treatment
Not applicable
Follow-up
Search run on 9 October 2026
Study design
Literature search
Funding
not stated in the source

A search result shows what PubMed returned on that date. It is not proof that no unindexed study exists.

Read the original source
2023 perspective: diarrhea is the limiting factor; 40 CAERS gastrointestinal cases

Narrative review

Costello R et al. Adv Nutr. 2023;14(5):973-982. PMID 37487817.

A 2023 perspective article states that the 1997 US Institute of Medicine dietary reference intakes committee set a tolerable upper intake level for adults of 350 mg per day of magnesium from supplemental intake alone, with diarrhea as the limiting factor, and argues for re-evaluating it. Its own literature search found 10 studies, 5 meta-analyses and 5 randomized trials, at intakes of 128 to 1,200 mg per day, of which 7 found no significant difference in diarrhea between intervention and control. An FDA CAERS search limited to single-ingredient magnesium products found 40 attributable gastrointestinal adverse event cases, one third of which noted diarrhea.

Participants / model
Adults in the reviewed trials and adverse event reports
Treatment
Oral magnesium supplements, forms varied across included studies
Follow-up
Not applicable
Study design
Perspective article reporting a regulatory reference value
Funding
not stated in the source

The 350 mg figure is reported here at second hand, from authors affiliated with a magnesium research center, and is not treated as a hard limit.

Read the original source

How does magnesium glycinate work, and what does the body do with it?

Magnesium glycinate supplies magnesium as a salt of two glycine molecules. The sources reviewed give no mechanism for sleep, relaxation or recovery effects, and the form-specific human data concern absorption and show no clear advantage for glycinate.

Magnesium glycinate is the magnesium salt of two glycine molecules, about 14% magnesium by mass. The sources reviewed give no mechanism by which it would improve sleep, relaxation or recovery.

In the ileal resection crossover with a 26Mg label, fractional absorption was 23.5% from the chelate versus 22.8% from oxide for the group, with earlier peak enrichment and higher absorption from the chelate only in the 4 patients who absorbed oxide worst. In 40 healthy adults, plasma magnesium rose after oxide, citrate and a microencapsulated product but not significantly after bisglycinate.

PubChem: magnesium glycinate identity and magnesium content by mass

Chemical identity record

National Library of Medicine. PubChem compound records CID 84645 (magnesium glycinate, also magnesium bisglycinate or diglycinate) and CID 5462224 (magnesium).

Magnesium glycinate, also called magnesium bisglycinate or magnesium diglycinate: PubChem CID 84645, C4H8MgN2O4, molecular weight 172.42 g/mol, CAS 14783-68-7, the magnesium salt of two glycine molecules. Elemental magnesium is CID 5462224, atomic weight 24.305 g/mol, CAS 7439-95-4. Dividing those two retrieved values gives about 14 percent magnesium by mass, so the weight of glycinate and the weight of elemental magnesium are different quantities.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined salt
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only. Trials in this record are read in elemental magnesium where the report states it.

Read the original source
Ileal resection crossover: 12 patients, no overall difference in absorption

Randomized controlled trial

Schuette SA et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PMID 7815675.

A double-blind randomized crossover trial in 12 patients with ileal resections compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients.

Participants / model
12 patients with ileal resection
Treatment
Single 100 mg oral dose, 26Mg-labeled diglycinate chelate versus oxide
Follow-up
Single-dose crossover
Study design
Double-blind randomized crossover absorption study
Funding
not stated in the source

These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference. It is the oldest and most direct human form comparison.

Read the original source
Healthy-adult crossover: 40 adults, no significant plasma rise after bisglycinate

Randomized controlled trial

Pajuelo D et al. Nutrients. 2024;16(24). PMID 39770988.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate.

Participants / model
40 healthy adults
Treatment
Single oral doses of magnesium bisglycinate, oxide, citrate and a microencapsulated product
Follow-up
Plasma magnesium at 1, 4 and 6 hours after each dose
Study design
Double-blind randomized crossover absorption study
Funding
Funded by the manufacturer of the microencapsulated comparator product; two authors were employed by that company.

A sponsored head-to-head, but it is the most recent human comparison located, and it does not support a bioavailability advantage for glycinate. Self-reported gastrointestinal effects were also recorded.

Read the original source

What risks do magnesium supplements carry?

Diarrhea and other gastrointestinal effects are the dose-limiting risk of oral magnesium, and people with reduced kidney function are the group at risk of magnesium accumulation. The over-the-counter magnesium hydroxide label asks users with kidney disease or a magnesium-restricted diet to ask a doctor first.

Gastrointestinal effects are the dose-limiting problem for oral magnesium. A 2023 perspective article states that the 1997 US Institute of Medicine committee set a tolerable upper intake level for adults of 350 mg per day of magnesium from supplemental intake alone, with diarrhea as the limiting factor, and argues for re-evaluating it. This page reports that figure at second hand, from authors affiliated with a magnesium research center, and does not treat it as a hard limit. The article's own literature search found 10 studies (5 meta-analyses and 5 randomized trials) at intakes of 128 to 1,200 mg per day, and 7 of them found no significant difference in diarrhea between intervention and control. An FDA CAERS adverse event search limited to single-ingredient magnesium products found 40 attributable gastrointestinal cases, one third of which noted diarrhea.

In the Cochrane cramp review, minor adverse events were more common on magnesium (RR 1.51, 95% CI 0.98 to 2.33; 4 studies, 254 participants), mostly gastrointestinal, in 11 to 37% of participants. In the pregnancy cramp trial, nausea and diarrhea did not differ significantly from placebo.

Kidney function matters. The reviewed over-the-counter magnesium hydroxide label directs users to ask a doctor before use with kidney disease or a magnesium-restricted diet, and supplement users with reduced kidney function are the group at risk of magnesium accumulation.

The salt is about 14% magnesium by mass, so a vendor's milligram figure for glycinate is not a figure for magnesium unless the vendor states elemental content.

2023 perspective: diarrhea is the limiting factor; 40 CAERS gastrointestinal cases

Narrative review

Costello R et al. Adv Nutr. 2023;14(5):973-982. PMID 37487817.

A 2023 perspective article states that the 1997 US Institute of Medicine dietary reference intakes committee set a tolerable upper intake level for adults of 350 mg per day of magnesium from supplemental intake alone, with diarrhea as the limiting factor, and argues for re-evaluating it. Its own literature search found 10 studies, 5 meta-analyses and 5 randomized trials, at intakes of 128 to 1,200 mg per day, of which 7 found no significant difference in diarrhea between intervention and control. An FDA CAERS search limited to single-ingredient magnesium products found 40 attributable gastrointestinal adverse event cases, one third of which noted diarrhea.

Participants / model
Adults in the reviewed trials and adverse event reports
Treatment
Oral magnesium supplements, forms varied across included studies
Follow-up
Not applicable
Study design
Perspective article reporting a regulatory reference value
Funding
not stated in the source

The 350 mg figure is reported here at second hand, from authors affiliated with a magnesium research center, and is not treated as a hard limit.

Read the original source
Cochrane 2020: 11 trials, 735 people, no clinically meaningful prophylaxis in older adults

Systematic review and meta-analysis

Garrison SR et al. Cochrane Database Syst Rev. 2020;9(9):CD009402. PMID 32956536.

The 2020 Cochrane review of magnesium for skeletal muscle cramps identified 11 trials in 735 people. For idiopathic cramps in older adults (mean age 61.6 to 69.3 years), the change from baseline in cramps per week at 4 weeks was a mean difference of -9.59% versus placebo (95% CI -23.14 to 3.97; 3 studies, 177 participants; moderate certainty), and the proportion achieving at least a 25% reduction did not differ (RR 1.04, 95% CI 0.84 to 1.29; 3 studies, 177 participants; high certainty). The authors conclude it is unlikely that magnesium provides clinically meaningful cramp prophylaxis to older adults. Pregnancy-associated cramp trials were conflicting and all at high risk of bias. No randomized trial of magnesium for exercise-associated cramps was found. Minor adverse events were more common on magnesium (RR 1.51, 95% CI 0.98 to 2.33; 4 studies, 254 participants), mostly gastrointestinal, in 11 to 37% of participants.

Participants / model
735 people across 11 randomized trials, including pregnant women, older adults and one cirrhosis study
Treatment
Oral magnesium in all but one trial, which used intravenous infusions
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

Mostly not glycinate. The review found no randomized trial of magnesium for exercise-associated cramps.

Read the original source
Glycinate pregnancy cramp trial: 86 women, 4 weeks, fewer cramps

Randomized controlled trial

Supakatisant C et al. Matern Child Nutr. 2015;11(2):139-45. PMID 22909270.

86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week were randomized to magnesium bisglycinate chelate 300 mg per day or placebo for 4 weeks, with 80 completing. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). No significant difference in nausea or diarrhea.

Participants / model
86 pregnant women, 80 completers
Treatment
Oral magnesium bisglycinate chelate, 300 mg per day, or placebo
Follow-up
4 weeks
Study design
Randomized placebo-controlled trial; cramp frequency and intensity on a 100 mm visual analogue scale
Funding
not stated in the source

This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias. It does not transfer to healthy non-pregnant adults or to exercise cramps.

Read the original source
OTC magnesium hydroxide label (effective 4 December 2025): laxative with a kidney caution

Official label

DailyMed, U.S. National Library of Medicine. Magnesium hydroxide oral suspension, over-the-counter saline laxative, label version effective 4 December 2025. Set ID 0a57bb45-d4f7-443b-e054-00144ff8d46c.

Oral magnesium does have an FDA-recognized use: the reviewed over-the-counter magnesium hydroxide label is a saline laxative. It directs users to ask a doctor before use with kidney disease or a magnesium-restricted diet. This is the regulatory frame for oral magnesium salts: a laxative, with a kidney caution.

Participants / model
Adults and children using an over-the-counter laxative
Treatment
Magnesium hydroxide oral suspension
Follow-up
Label version effective 4 December 2025
Study design
Official over-the-counter label
Funding
not stated in the source

This is the label for magnesium hydroxide, not glycinate. No label dose or timing is reproduced on this page.

Read the original source
PubChem: magnesium glycinate identity and magnesium content by mass

Chemical identity record

National Library of Medicine. PubChem compound records CID 84645 (magnesium glycinate, also magnesium bisglycinate or diglycinate) and CID 5462224 (magnesium).

Magnesium glycinate, also called magnesium bisglycinate or magnesium diglycinate: PubChem CID 84645, C4H8MgN2O4, molecular weight 172.42 g/mol, CAS 14783-68-7, the magnesium salt of two glycine molecules. Elemental magnesium is CID 5462224, atomic weight 24.305 g/mol, CAS 7439-95-4. Dividing those two retrieved values gives about 14 percent magnesium by mass, so the weight of glycinate and the weight of elemental magnesium are different quantities.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined salt
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only. Trials in this record are read in elemental magnesium where the report states it.

Read the original source

Why does magnesium glycinate sit in C tier?

Magnesium as a nutrient is not in question, but glycinate as a distinct product with distinct effects is. The sleep effect in the one glycinate trial is small, magnesium reviews for sleep are low certainty, the cramp evidence is negative in older adults, and the one healthy-adult comparison does not support better bioavailability.

The sleep evidence for magnesium in any form is a 151-person meta-analysis of 3 trials rated low to very low quality and a 2026 systematic review of 12 trials that concludes current evidence does not support routine use. The single glycinate sleep trial is real and positive but small in effect: -3.9 versus -2.3 points on the Insomnia Severity Index, p = 0.049, Cohen's d = 0.2.

The cramp evidence runs the other way. Cochrane found no difference in the proportion of older adults with at least a 25% reduction in cramps (high certainty) and concludes that clinically meaningful prophylaxis is unlikely, and the only positive glycinate cramp trial is in 86 pregnant women.

The supplier claim splits three ways, covered above. Sleep, relaxation and recovery have thin, inconsistent data that are mostly not specific to glycinate, which is the C case.

Glycinate sleep trial: 155 adults, small effect on Insomnia Severity Index

Randomized controlled trial

Schuster J et al. Nat Sci Sleep. 2025;17:2027-2040. PMID 40918053.

155 adults aged 18 to 65 with self-reported poor sleep quality took 250 mg elemental magnesium as bisglycinate or placebo daily. The Insomnia Severity Index fell more on magnesium from baseline to week 4 (-3.9, 95% CI -5.8 to -2.0, versus -2.3, 95% CI -4.1 to -0.4; p = 0.049), with a small effect size (Cohen's d = 0.2). No significant differences in other psychological outcomes. Exploratory analysis suggested larger improvements in participants with lower baseline dietary magnesium intake.

Participants / model
155 adults aged 18 to 65 reporting poor sleep quality
Treatment
Oral magnesium bisglycinate capsules, 250 mg elemental magnesium daily, or placebo
Follow-up
Baseline to week 4; total duration not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

The one randomized placebo-controlled trial of the glycinate form for sleep. One author is the managing director of a contract research organization funded by nutraceutical companies.

Read the original source
Sleep meta-analysis: 3 trials, 151 older adults, any magnesium form

Systematic review and meta-analysis

Mah J et al. BMC Complement Med Ther. 2021;21(1):125. PMID 33865376.

A systematic review and meta-analysis of oral magnesium for insomnia in older adults pooled 3 randomized trials in 151 people in three countries. Sleep onset latency after treatment was 17.36 minutes shorter than placebo (95% CI -27.27 to -7.44, p = 0.0006). Total sleep time improved by 16.06 minutes but not significantly. All trials were at moderate to high risk of bias and the outcomes were supported by low to very low quality evidence. None of the pooled trials is described as using glycinate.

Participants / model
151 older adults with insomnia across 3 randomized trials
Treatment
Oral magnesium in the pooled trials; none described as glycinate
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

A 2024 correction (PMID 39702257) changed an abbreviation, the PRISMA record counts and a database name, and did not change the pooled effect estimates.

Read the original source
2026 sleep review: 12 trials, inconsistent findings, low to very low certainty

Systematic review and meta-analysis

Lopresti AL et al. J Diet Suppl. 2026;23(5):553-581. PMID 42661485.

A 2026 systematic review of randomized trials of oral magnesium as a stand-alone intervention for sleep in adults included 12 trials in the main synthesis plus 3 more involving cramp or movement-related sleep disturbance. Populations, formulations, elemental doses, durations and outcome measures varied substantially, findings were inconsistent across subjective scores, EEG, actigraphy, wearables and physiological markers, and certainty of evidence was low to very low. The authors conclude that current evidence does not support oral magnesium as a routine treatment for insomnia, with possible modest benefit for selected subjective outcomes in some adults.

Participants / model
Adults across 12 randomized trials
Treatment
Oral magnesium alone, formulations varied
Follow-up
Not applicable
Study design
Systematic review of randomized trials
Funding
not stated in the source

Not specific to glycinate; formulations varied across the included trials.

Read the original source
Cochrane 2020: 11 trials, 735 people, no clinically meaningful prophylaxis in older adults

Systematic review and meta-analysis

Garrison SR et al. Cochrane Database Syst Rev. 2020;9(9):CD009402. PMID 32956536.

The 2020 Cochrane review of magnesium for skeletal muscle cramps identified 11 trials in 735 people. For idiopathic cramps in older adults (mean age 61.6 to 69.3 years), the change from baseline in cramps per week at 4 weeks was a mean difference of -9.59% versus placebo (95% CI -23.14 to 3.97; 3 studies, 177 participants; moderate certainty), and the proportion achieving at least a 25% reduction did not differ (RR 1.04, 95% CI 0.84 to 1.29; 3 studies, 177 participants; high certainty). The authors conclude it is unlikely that magnesium provides clinically meaningful cramp prophylaxis to older adults. Pregnancy-associated cramp trials were conflicting and all at high risk of bias. No randomized trial of magnesium for exercise-associated cramps was found. Minor adverse events were more common on magnesium (RR 1.51, 95% CI 0.98 to 2.33; 4 studies, 254 participants), mostly gastrointestinal, in 11 to 37% of participants.

Participants / model
735 people across 11 randomized trials, including pregnant women, older adults and one cirrhosis study
Treatment
Oral magnesium in all but one trial, which used intravenous infusions
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

Mostly not glycinate. The review found no randomized trial of magnesium for exercise-associated cramps.

Read the original source
Glycinate pregnancy cramp trial: 86 women, 4 weeks, fewer cramps

Randomized controlled trial

Supakatisant C et al. Matern Child Nutr. 2015;11(2):139-45. PMID 22909270.

86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week were randomized to magnesium bisglycinate chelate 300 mg per day or placebo for 4 weeks, with 80 completing. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). No significant difference in nausea or diarrhea.

Participants / model
86 pregnant women, 80 completers
Treatment
Oral magnesium bisglycinate chelate, 300 mg per day, or placebo
Follow-up
4 weeks
Study design
Randomized placebo-controlled trial; cramp frequency and intensity on a 100 mm visual analogue scale
Funding
not stated in the source

This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias. It does not transfer to healthy non-pregnant adults or to exercise cramps.

Read the original source
Healthy-adult crossover: 40 adults, no significant plasma rise after bisglycinate

Randomized controlled trial

Pajuelo D et al. Nutrients. 2024;16(24). PMID 39770988.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate.

Participants / model
40 healthy adults
Treatment
Single oral doses of magnesium bisglycinate, oxide, citrate and a microencapsulated product
Follow-up
Plasma magnesium at 1, 4 and 6 hours after each dose
Study design
Double-blind randomized crossover absorption study
Funding
Funded by the manufacturer of the microencapsulated comparator product; two authors were employed by that company.

A sponsored head-to-head, but it is the most recent human comparison located, and it does not support a bioavailability advantage for glycinate. Self-reported gastrointestinal effects were also recorded.

Read the original source
Ileal resection crossover: 12 patients, no overall difference in absorption

Randomized controlled trial

Schuette SA et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PMID 7815675.

A double-blind randomized crossover trial in 12 patients with ileal resections compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients.

Participants / model
12 patients with ileal resection
Treatment
Single 100 mg oral dose, 26Mg-labeled diglycinate chelate versus oxide
Follow-up
Single-dose crossover
Study design
Double-blind randomized crossover absorption study
Funding
not stated in the source

These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference. It is the oldest and most direct human form comparison.

Read the original source

Studies and sources

PubChem: magnesium glycinate identity and magnesium content by mass

Chemical identity record

National Library of Medicine. PubChem compound records CID 84645 (magnesium glycinate, also magnesium bisglycinate or diglycinate) and CID 5462224 (magnesium).

Magnesium glycinate, also called magnesium bisglycinate or magnesium diglycinate: PubChem CID 84645, C4H8MgN2O4, molecular weight 172.42 g/mol, CAS 14783-68-7, the magnesium salt of two glycine molecules. Elemental magnesium is CID 5462224, atomic weight 24.305 g/mol, CAS 7439-95-4. Dividing those two retrieved values gives about 14 percent magnesium by mass, so the weight of glycinate and the weight of elemental magnesium are different quantities.

Participants / model
Chemical identity, not a clinical population
Treatment
Defined salt
Follow-up
Not applicable
Study design
NLM chemical record
Funding
not stated in the source

Identity record only. Trials in this record are read in elemental magnesium where the report states it.

Read the original source
OTC magnesium hydroxide label (effective 4 December 2025): laxative with a kidney caution

Official label

DailyMed, U.S. National Library of Medicine. Magnesium hydroxide oral suspension, over-the-counter saline laxative, label version effective 4 December 2025. Set ID 0a57bb45-d4f7-443b-e054-00144ff8d46c.

Oral magnesium does have an FDA-recognized use: the reviewed over-the-counter magnesium hydroxide label is a saline laxative. It directs users to ask a doctor before use with kidney disease or a magnesium-restricted diet. This is the regulatory frame for oral magnesium salts: a laxative, with a kidney caution.

Participants / model
Adults and children using an over-the-counter laxative
Treatment
Magnesium hydroxide oral suspension
Follow-up
Label version effective 4 December 2025
Study design
Official over-the-counter label
Funding
not stated in the source

This is the label for magnesium hydroxide, not glycinate. No label dose or timing is reproduced on this page.

Read the original source
2023 perspective: diarrhea is the limiting factor; 40 CAERS gastrointestinal cases

Narrative review

Costello R et al. Adv Nutr. 2023;14(5):973-982. PMID 37487817.

A 2023 perspective article states that the 1997 US Institute of Medicine dietary reference intakes committee set a tolerable upper intake level for adults of 350 mg per day of magnesium from supplemental intake alone, with diarrhea as the limiting factor, and argues for re-evaluating it. Its own literature search found 10 studies, 5 meta-analyses and 5 randomized trials, at intakes of 128 to 1,200 mg per day, of which 7 found no significant difference in diarrhea between intervention and control. An FDA CAERS search limited to single-ingredient magnesium products found 40 attributable gastrointestinal adverse event cases, one third of which noted diarrhea.

Participants / model
Adults in the reviewed trials and adverse event reports
Treatment
Oral magnesium supplements, forms varied across included studies
Follow-up
Not applicable
Study design
Perspective article reporting a regulatory reference value
Funding
not stated in the source

The 350 mg figure is reported here at second hand, from authors affiliated with a magnesium research center, and is not treated as a hard limit.

Read the original source
Sleep meta-analysis: 3 trials, 151 older adults, any magnesium form

Systematic review and meta-analysis

Mah J et al. BMC Complement Med Ther. 2021;21(1):125. PMID 33865376.

A systematic review and meta-analysis of oral magnesium for insomnia in older adults pooled 3 randomized trials in 151 people in three countries. Sleep onset latency after treatment was 17.36 minutes shorter than placebo (95% CI -27.27 to -7.44, p = 0.0006). Total sleep time improved by 16.06 minutes but not significantly. All trials were at moderate to high risk of bias and the outcomes were supported by low to very low quality evidence. None of the pooled trials is described as using glycinate.

Participants / model
151 older adults with insomnia across 3 randomized trials
Treatment
Oral magnesium in the pooled trials; none described as glycinate
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

A 2024 correction (PMID 39702257) changed an abbreviation, the PRISMA record counts and a database name, and did not change the pooled effect estimates.

Read the original source
2026 sleep review: 12 trials, inconsistent findings, low to very low certainty

Systematic review and meta-analysis

Lopresti AL et al. J Diet Suppl. 2026;23(5):553-581. PMID 42661485.

A 2026 systematic review of randomized trials of oral magnesium as a stand-alone intervention for sleep in adults included 12 trials in the main synthesis plus 3 more involving cramp or movement-related sleep disturbance. Populations, formulations, elemental doses, durations and outcome measures varied substantially, findings were inconsistent across subjective scores, EEG, actigraphy, wearables and physiological markers, and certainty of evidence was low to very low. The authors conclude that current evidence does not support oral magnesium as a routine treatment for insomnia, with possible modest benefit for selected subjective outcomes in some adults.

Participants / model
Adults across 12 randomized trials
Treatment
Oral magnesium alone, formulations varied
Follow-up
Not applicable
Study design
Systematic review of randomized trials
Funding
not stated in the source

Not specific to glycinate; formulations varied across the included trials.

Read the original source
Glycinate sleep trial: 155 adults, small effect on Insomnia Severity Index

Randomized controlled trial

Schuster J et al. Nat Sci Sleep. 2025;17:2027-2040. PMID 40918053.

155 adults aged 18 to 65 with self-reported poor sleep quality took 250 mg elemental magnesium as bisglycinate or placebo daily. The Insomnia Severity Index fell more on magnesium from baseline to week 4 (-3.9, 95% CI -5.8 to -2.0, versus -2.3, 95% CI -4.1 to -0.4; p = 0.049), with a small effect size (Cohen's d = 0.2). No significant differences in other psychological outcomes. Exploratory analysis suggested larger improvements in participants with lower baseline dietary magnesium intake.

Participants / model
155 adults aged 18 to 65 reporting poor sleep quality
Treatment
Oral magnesium bisglycinate capsules, 250 mg elemental magnesium daily, or placebo
Follow-up
Baseline to week 4; total duration not stated in the source
Study design
Randomized placebo-controlled trial
Funding
not stated in the source

The one randomized placebo-controlled trial of the glycinate form for sleep. One author is the managing director of a contract research organization funded by nutraceutical companies.

Read the original source
Cochrane 2020: 11 trials, 735 people, no clinically meaningful prophylaxis in older adults

Systematic review and meta-analysis

Garrison SR et al. Cochrane Database Syst Rev. 2020;9(9):CD009402. PMID 32956536.

The 2020 Cochrane review of magnesium for skeletal muscle cramps identified 11 trials in 735 people. For idiopathic cramps in older adults (mean age 61.6 to 69.3 years), the change from baseline in cramps per week at 4 weeks was a mean difference of -9.59% versus placebo (95% CI -23.14 to 3.97; 3 studies, 177 participants; moderate certainty), and the proportion achieving at least a 25% reduction did not differ (RR 1.04, 95% CI 0.84 to 1.29; 3 studies, 177 participants; high certainty). The authors conclude it is unlikely that magnesium provides clinically meaningful cramp prophylaxis to older adults. Pregnancy-associated cramp trials were conflicting and all at high risk of bias. No randomized trial of magnesium for exercise-associated cramps was found. Minor adverse events were more common on magnesium (RR 1.51, 95% CI 0.98 to 2.33; 4 studies, 254 participants), mostly gastrointestinal, in 11 to 37% of participants.

Participants / model
735 people across 11 randomized trials, including pregnant women, older adults and one cirrhosis study
Treatment
Oral magnesium in all but one trial, which used intravenous infusions
Follow-up
Pooled trials
Study design
Systematic review and meta-analysis
Funding
not stated in the source

Mostly not glycinate. The review found no randomized trial of magnesium for exercise-associated cramps.

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Magnesium oxide cramp trial: 94 adults, no difference from placebo

Randomized controlled trial

Roguin Maor N et al. JAMA Intern Med. 2017;177(5):617-623. PMID 28241153.

A randomized double-blind placebo-controlled trial in 94 community-dwelling adults (mean age 64.9 years, 39% male) with at least 4 documented nocturnal leg cramps in 2 weeks gave magnesium oxide or placebo for 4 weeks. Cramps fell by 3.41 per week on magnesium and 3.03 on placebo, a between-group difference of 0.38 per week (P = 0.67). No differences in cramp severity or duration, quality of life or quality of sleep. The authors attribute the within-group fall to placebo effect.

Participants / model
94 adults aged 21 and over with nocturnal leg cramps
Treatment
Oral magnesium oxide capsules or placebo
Follow-up
4 weeks
Study design
Randomized double-blind placebo-controlled trial
Funding
not stated in the source

This trial used magnesium oxide, not glycinate.

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Glycinate pregnancy cramp trial: 86 women, 4 weeks, fewer cramps

Randomized controlled trial

Supakatisant C et al. Matern Child Nutr. 2015;11(2):139-45. PMID 22909270.

86 pregnant women at 14 to 34 weeks of gestation with leg cramps at least twice a week were randomized to magnesium bisglycinate chelate 300 mg per day or placebo for 4 weeks, with 80 completing. A 50% reduction in cramp frequency occurred in 86.0% on magnesium versus 60.5% on placebo (P = 0.007), and a 50% reduction in cramp intensity in 69.8% versus 48.8% (P = 0.048). No significant difference in nausea or diarrhea.

Participants / model
86 pregnant women, 80 completers
Treatment
Oral magnesium bisglycinate chelate, 300 mg per day, or placebo
Follow-up
4 weeks
Study design
Randomized placebo-controlled trial; cramp frequency and intensity on a 100 mm visual analogue scale
Funding
not stated in the source

This is a pregnancy population, which the Cochrane review rates as conflicting and at high risk of bias. It does not transfer to healthy non-pregnant adults or to exercise cramps.

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Ileal resection crossover: 12 patients, no overall difference in absorption

Randomized controlled trial

Schuette SA et al. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. PMID 7815675.

A double-blind randomized crossover trial in 12 patients with ileal resections compared a 100 mg dose of 26Mg-labeled magnesium diglycinate chelate with magnesium oxide. For the group as a whole absorption did not differ (23.5% versus 22.8%). In the 4 patients with the greatest impairment of magnesium absorption from oxide, absorption was greater from the chelate (23.5% versus 11.8%, p < .05), peak isotope enrichment occurred a mean 3.2 plus or minus 1.3 hours earlier (p < .05) and the area under the enrichment curve was greater (p < .05). The authors report the chelate was better tolerated by all patients.

Participants / model
12 patients with ileal resection
Treatment
Single 100 mg oral dose, 26Mg-labeled diglycinate chelate versus oxide
Follow-up
Single-dose crossover
Study design
Double-blind randomized crossover absorption study
Funding
not stated in the source

These are 12 patients with surgically shortened bowel, not healthy adults, and the result in the full group was no difference. It is the oldest and most direct human form comparison.

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Healthy-adult crossover: 40 adults, no significant plasma rise after bisglycinate

Randomized controlled trial

Pajuelo D et al. Nutrients. 2024;16(24). PMID 39770988.

A double-blind randomized crossover study in 40 healthy women and men on a low-magnesium diet for 7 days measured plasma magnesium before and 1, 4 and 6 hours after single oral doses of four sources. Plasma magnesium rose significantly after microencapsulated magnesium at all time points, after magnesium oxide at 1 hour and after magnesium citrate at 4 hours, while no significant increase was observed after magnesium bisglycinate.

Participants / model
40 healthy adults
Treatment
Single oral doses of magnesium bisglycinate, oxide, citrate and a microencapsulated product
Follow-up
Plasma magnesium at 1, 4 and 6 hours after each dose
Study design
Double-blind randomized crossover absorption study
Funding
Funded by the manufacturer of the microencapsulated comparator product; two authors were employed by that company.

A sponsored head-to-head, but it is the most recent human comparison located, and it does not support a bioavailability advantage for glycinate. Self-reported gastrointestinal effects were also recorded.

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Soreness trial: 22 students, magnesium form not stated

Clinical trial

Reno AM et al. J Strength Cond Res. 2022;36(8):2198-2203. PMID 33009349.

A double-blind between-group study in 22 college-aged participants (9 male, 13 female) gave 350 mg per day of magnesium or placebo for 10 days around eccentric bench press sessions. Magnesium reduced soreness on a 6 cm scale by about 1 to 2 units at 24, 36 and 48 hours with no significant change for placebo, improved session and acute ratings of perceived exertion, and improved perceived recovery. Repetitions to failure approached but did not reach significance (p = 0.06 for total).

Participants / model
22 college-aged men and women
Treatment
Oral magnesium 350 mg per day for 10 days, form not stated in the abstract, or placebo
Follow-up
10 days around eccentric bench press sessions
Study design
Double-blind between-group trial
Funding
not stated in the source

The abstract does not state which magnesium compound was used, so this result cannot be assigned to glycinate.

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Marathon trial: 20 magnesium-replete athletes, no effect on performance or recovery

Clinical trial

Terblanche S et al. Int J Sport Nutr. 1992;2(2):154-64. PMID 1299490.

A double-blind trial in 20 athletes, studied 4 weeks before and 6 weeks after a 42 km marathon, gave 365 mg per day of magnesium or placebo. Supplementation did not raise muscle or serum magnesium concentrations and had no measurable effect on race performance, on the extent of muscle damage, or on the rate of recovery of muscle function, which fell immediately after the race and returned to normal within 1 week in both groups.

Participants / model
20 magnesium-replete endurance athletes
Treatment
Oral magnesium 365 mg per day or placebo; compound not named in the record reviewed
Follow-up
4 weeks before and 6 weeks after a 42 km marathon
Study design
Double-blind placebo-controlled trial
Funding
not stated in the source

The participants were magnesium-replete at baseline, so the result may not apply to people with low intake.

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Why is Magnesium glycinate in C tier?

C fits a product whose nutrient is real but whose form-specific claims are thin. The sleep effect in the one glycinate trial is small, reviews of magnesium for sleep are low certainty, the cramp evidence is negative in older adults, and the one healthy-adult comparison does not support better absorption. The grade covers glycinate as a distinct product, not magnesium as a nutrient.