Magnesium Glycinate
SupplementClinical effect size is moderate (Cohen's d ≈ 0.2) [s1] and meta-analyses show inconsistent results [s9, s13], while users in forums and on Reddit predominantly report marked subjective improvements [c1, c2]. This discrepancy between objectively small effect sizes and strongly positive user experience explains the divergence of 14 points.
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TL;DR
Magnesium glycinate is the best-tolerated magnesium form and the community's top pick for sleep and stress reduction — 187 Reddit threads and 84% positive sentiment put it clearly ahead of other magnesium forms. Five RCTs support efficacy for sleep disturbances, muscle cramps, and stress, though effect sizes are moderate (Cohen's d ≈ 0.2 for sleep). Important: 500 mg magnesium glycinate delivers only ~70 mg elemental magnesium — always convert doses to elemental magnesium. Anyone sensitive to laxative effects or intolerant of citrate should start with glycinate directly.
Description
Well-bioavailable, chelated magnesium form supporting sleep quality, muscle relaxation, and stress regulation [s1, s3, s4].
Magnesium glycinate is a chelated magnesium compound in which two glycine molecules surround the magnesium ion (hence also "bisglycinate"). The terms glycinate and bisglycinate are largely synonymous in the supplement context and refer to the same compound [s12]. Absorption occurs via the dipeptide transporter (PepT1) in the small intestine, achieving higher bioavailability than osmotically active salts such as magnesium oxide [s3, s6]. Magnesium oxide is less expensive but more poorly absorbed and more frequently causes diarrhea [s3]. The substance is preferably taken in the evening, as the co-delivered glycine has sedating properties and potentiates the sleep-promoting effect of magnesium [s1, s7]. In a double-blind RCT (n=155, 4 weeks), magnesium bisglycinate improved the Insomnia Severity Index (ISI) by −3.9 points versus −2.3 points in the placebo group (p=0.049) [s1]. An older RCT in elderly insomniacs (n=46, 8 weeks) demonstrated significant improvements in sleep onset latency, melatonin, and cortisol levels [s5]. A systematic review of oral magnesium supplementation for insomnia in older adults found sleep onset latency reduced by 17.4 minutes compared to placebo [s9]. In pregnant women with leg cramps, an RCT (n=86) significantly reduced cramp frequency (86% vs. 60.5% achieving ≥50% reduction, p=0.007) [s2], although a more recent meta-analysis of general magnesium supplementation in pregnancy showed no consistent superiority over placebo [s13]. For stress regulation, an RCT (n=264, 8 weeks) provides evidence for the superiority of the magnesium + vitamin B6 combination over magnesium alone in individuals with severe stress and hypomagnesemia [s4, s8].
Legal Status (DE)
In the DACH countries, magnesium glycinate (bisglycinate) is fully marketable as an over-the-counter food supplement (dietary supplement) [s10]. The BfR recommendation specifies a maximum daily amount of 250 mg elemental magnesium from dietary supplements [s10, s11].
Mechanism of Action
Magnesium blocks NMDA receptors in a voltage-dependent manner (as a non-competitive antagonist), thereby reducing calcium influx into neurons and dampening neuronal hyperexcitability [s7, s14]. Simultaneously, magnesium positively modulates GABA-A receptors allosterically and promotes GABA release at the presynaptic level, while inhibiting glutamate release [s14]. This dual modulation (inhibition of excitatory and enhancement of inhibitory neurotransmission) accounts for the anxiolytic and sedating properties [s7, s14]. Glycine released upon metabolism of magnesium glycinate additionally activates glycinergic receptors in the brainstem, contributing to sedation and sleep regulation [s15]. Glycine also co-agonistically modulates NMDA receptors and can lower core body temperature via the suprachiasmatic nucleus, facilitating sleep onset [s15]. At the neuromuscular junction, magnesium reduces acetylcholine release, thereby alleviating muscle cramps [s7]. Vitamin B6 (pyridoxine) in combination enhances cellular magnesium uptake and acts complementarily on stress axes [s4, s8].
Dosing
Schlafqualität
- Dose
- 200–400 mg elemental magnesium
- Frequency
- 1× täglich abends
- Route
- oral
- Duration
- fortlaufend
- Timing
- 30–60 minutes before bedtime
- With food
- optional
Stressregulation (mit Vitamin B6)
- Dose
- 300 mg elemental magnesium + 30 mg vitamin B6
- Frequency
- aufgeteilt auf 2 Dosen
- Route
- oral
- Duration
- 8 Wochen
- Timing
- morning and evening, with meals
- With food
- empfohlen
Schwangerschaftskrämpfe
- Dose
- 300 mg elemental magnesium
- Frequency
- 1–2× täglich
- Route
- oral
- Duration
- 4 Wochen
- Timing
- with meals
- With food
- empfohlen
The BfR recommends not exceeding the maximum daily amount of 250 mg elemental magnesium from dietary supplements [s11]. The EFSA sets the Tolerable Upper Intake Level (UL) for supplemental magnesium likewise at 250 mg/day [s10]. Note: Many clinical studies used higher doses (up to 500 mg); generally well tolerated in individuals with normal renal function, however gastrointestinal side effects are possible at 350–500 mg [s1, s3].
Magnesium glycinate contains approximately 14% elemental magnesium; 500 mg magnesium glycinate corresponds to approximately 70 mg elemental magnesium. Dosage specifications should always refer to elemental magnesium [s16].
Side Effects
| Side Effect | Frequency | Severity |
|---|---|---|
| Milde gastrointestinale Beschwerden (weicher Stuhl, leichte Übelkeit, Blähungen) Less common than with magnesium oxide or citrate, as absorption via the peptide transporter generates less osmotic stress in the intestine [s3, s6]. More frequently observed at higher doses (>350 mg elemental Mg) [s11]. | gelegentlich | leicht |
| Erhöhte Tagesmüdigkeit oder milde Sedierung Synergistic GABAergic effects of magnesium and glycinergic activation by glycine can be perceived as mild sedation, particularly at higher doses or with morning intake [s1, s7, s15]. | gelegentlich | leicht |
| Hypermagnesiämie (bei Überdosierung oder eingeschränkter Nierenfunktion) Accumulation due to impaired renal clearance can lead to CNS depression, muscle paralysis, respiratory depression, hypotension, and prolonged cardiac conduction [s16, s17]. | selten | schwer |
Contraindications
Impaired renal magnesium excretion leads to accumulation and increased risk of hypermagnesemia with potentially life-threatening complications (respiratory depression, cardiac arrhythmias) [s16, s17].
Magnesium inhibits presynaptic acetylcholine release at the neuromuscular junction and may potentiate neuromuscular blockade [s7, s14].
Further supplementation is contraindicated in the presence of already elevated serum magnesium levels [s16].
Caution advised; use only under medical supervision with regular monitoring of serum magnesium levels [s16, s17].
Interactions
Synergistic
The combination demonstrated superior stress reduction compared to magnesium monotherapy in an RCT (n=264), particularly under high stress load (24% more effective) [s4, s8].
Additive sleep-promoting effect via glycinergic receptors is possible; mechanistically plausible, but no RCT for the combination outside of magnesium glycinate is available [s15].
Magnesium glycinate and zinc can be taken together, as no clinically relevant absorption competition exists at standard doses (15–30 mg zinc). For optimal bioavailability, staggered timing is nonetheless recommended (zinc in the morning, magnesium in the evening).
The combination of apigenin (50 mg), L-theanine (200 mg), and magnesium glycinate (300 mg) is used as an established sleep stack and demonstrates additive sleep-promoting effects. All three components act via complementary GABAergic and glutamatergic mechanisms.
L-theanine and magnesium glycinate complement each other synergistically for relaxation and sleep quality. L-theanine promotes alpha brain waves and increases GABA levels, while magnesium supports neuromuscular relaxation.
Ashwagandha and magnesium glycinate form a well-established combination for stress reduction and sleep improvement. Ashwagandha lowers cortisol levels during the first half of the night, while magnesium promotes neuromuscular relaxation.
Magnesium is an essential cofactor for the activation of vitamin D3. Without adequate magnesium, vitamin D3 supplementation can deplete magnesium reserves and cause symptoms such as muscle cramps. The combination optimizes calcium metabolism and bone maintenance.
Magnesium and potassium are the principal intracellular cations and act synergistically to support normal nerve and muscle function as well as blood pressure regulation. Magnesium deficiency can disrupt intracellular potassium homeostasis.
Caution
Chelate formation reduces gastrointestinal absorption of the antibiotics. Maintain a minimum interval of 2 hours [s16, s17].
As with tetracyclines, magnesium can reduce the absorption of quinolones via chelation. A minimum interval of 2 hours is recommended [s16, s17].
Magnesium can reduce the absorption of levothyroxine. Administer at separate times (minimum interval of 2–4 hours) [s17].
Magnesium can potentiate the effect of non-depolarizing muscle relaxants; particularly relevant in the perioperative setting [s14].
At high doses, calcium and magnesium compete for the same intestinal transport mechanisms, which can reduce the bioavailability of both minerals. At standard doses and with separate administration, this is of limited clinical relevance.
Magnesium can inhibit intestinal iron absorption when both minerals are taken simultaneously. A minimum interval of 2 hours is recommended to optimize the uptake of both nutrients.
Studies
Tier A — High Evidence
Outcome: Reduction of the Insomnia Severity Index (ISI)
Effect Size: -3.9 vs. -2.3 ISI points (p=0.049); Cohen's d ≈ 0.2
Outcome: Reduction of leg cramp frequency during pregnancy
Effect Size: 86% vs. 60.5% with ≥50% reduction in cramp frequency (p=0.007)
Outcome: Depression, anxiety, quality of life (DASS-42, QoL)
Effect Size: Significant improvement with Mg+B6 vs. Mg alone
Outcome: DASS-42 stress score reduction (comparison of Mg alone vs. Mg+B6)
Effect Size: Mg+B6 approximately 24% more effective than Mg alone in severely stressed participants
Tier B — Moderate Evidence
Outcome: Sleep onset latency, sleep duration, sleep efficiency
Effect Size: Sleep onset latency -17.4 min (95% CI: -27.3 to -7.5) vs. placebo
Outcome: Sleep onset latency, melatonin, cortisol, renin in elderly insomniacs
Effect Size: Significant improvement in sleep onset latency, melatonin↑, cortisol↓ (p<0.05)
Tier C — Low Evidence
Outcome: Urinary Mg excretion as a measure of bioavailability (Mg diglycinate vs. MgO)
Effect Size: Higher fractional absorption of Mg diglycinate vs. MgO in patients with ileal resection
Community Evidence
Top reported benefits
- Better sleep onset and sleep quality
- Reduction of nocturnal muscle cramps and twitching
- Improved stress relief and relaxation
- Less morning fatigue compared to other magnesium forms
- Good gastric tolerability without laxative effect
Top reported issues
- Occasional daytime drowsiness at higher doses or with morning administration
- No noticeable effect in some users
- Onset of effect only after 1–2 weeks of regular use
- Isolated reports of unpleasant dreams (rarely reported)
Isolated reports of paradoxical muscle tension or uncomfortable dreams; however, overall very rare complaints [c1, c2]. The majority of users appreciate the good tolerability compared to magnesium oxide or citrate [c1].
Scientific Sources
- Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial
Schuster J, Cycelskij I, Lopresti A, et al. (2025). Nature and Science of SleepAPMID:40918053DOI - Overview on Tolerable Upper Intake Levels as derived by the EFSA Panel on Nutrition, Novel Foods and Food Allergens
EFSA NDA Panel (2023). EFSA Supporting PublicationALink - BfR bewertet empfohlene Tageshöchstmenge für die Aufnahme von Magnesium über Nahrungsergänzungsmittel
Bundesinstitut für Risikobewertung (BfR) (2017). BfR-StellungnahmeADOI - Magnesium Bisglycinate vs Glycinate: Differences, Benefits & Best Use
Performance Lab Editorial Team (2023). Performance Lab BlogDLink - Effect of oral magnesium supplementation for relieving leg cramps during pregnancy: A meta-analysis of randomized controlled trials
Araújo CAL, Lorena SB, Cavalcanti GCS, et al. (2021). MedicinaAPMID:34247796 - Magnesium in neuroses and neuroticism
Serefko A, Szopa A, Wlaź P, et al. (2013). Magnesium in the Central Nervous System (NCBI Bookshelf)BLink - The Sleep-Promoting and Hypothermic Effects of Glycine are Mediated by NMDA Receptors in the Suprachiasmatic Nucleus
Kawai N, Sakai N, Okuro M, et al. (2015). NeuropsychopharmacologyCLink - Magnesium glycinate: Dosing, contraindications, side effects
Epocrates Editorial Team (2024). Epocrates Online Drug ReferenceBLink - Magnesium glycinate Interactions and Disease Interactions
Drugs.com Editorial Team (2024). Drugs.com Drug ReferenceBLink - Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Magnesium
Scientific Committee on Food (SCF), European Commission (2001). CLink - Scientific Opinion on Dietary Reference Values for magnesium
EFSA NDA Panel (Panel on Dietetic Products, Nutrition and Allergies) (2015). EFSA JournalCDOI - Oral magnesium for relief in pregnancy-induced leg cramps: a randomised controlled trial
Supakatisant C, Phupong V (2015). Maternal and Child NutritionAPMID:22909270DOI - Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection
Schuette SA, Lashner BA, Janghorbani M (1994). Journal of Parenteral and Enteral NutritionBPMID:7815675DOI - Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia: A randomized, single-blind clinical trial
Pouteau E, Kabir-Ahmadi M, Noah L, et al. (2018). PLoS ONEAPMID:30540137DOI - The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial
Abbasi B, Kimiagar M, Sadeghniiat K, et al. (2012). Journal of Research in Medical SciencesBPMID:23853635 - Bioavailability of magnesium food supplements: A systematic review
Ates M, Kizildag S, Yuksel O, et al. (2019). NutritionADOI - The Mechanisms of Magnesium in Sleep Disorders
Zhang Y, Chen C, Lu L, et al. (2022). Dove Press (Nature and Science of Sleep)BLink - Effect of magnesium supplementation, with or without vitamin B6, on depression, anxiety, and quality of life in stressed healthy adults: Post-hoc analysis of a randomised controlled trial
Noah L, Pouteau E, Kabir-Ahmadi M, et al. (2021). Stress and HealthAPMID:33864354DOI - Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis
Mah J, Pitre T (2021). BMC Complementary Medicine and TherapiesADOI
Community Sources
Storage
Unopened
Store in a dry place at room temperature (15–25 °C), protected from direct sunlight and moisture.
Opened
Seal packaging tightly after use; for powder forms, prevent moisture ingress by including a silica gel pack.
Notes
No refrigeration required. Keep out of reach of children.