Is magnesium glycinate (Mg(Gly)2) proven to be beneficial for health?

Magnesium Glycinate: Clinical Benefits and Evidence

Magnesium glycinate is beneficial as a well-tolerated magnesium supplement with superior bioavailability compared to inorganic forms, though clinical evidence specifically for glycinate remains limited compared to other magnesium formulations. 1

Bioavailability and Absorption Profile

• Organic magnesium salts, including magnesium glycinate, demonstrate higher bioavailability than inorganic forms like magnesium oxide or hydroxide. 1
• The specific bioavailability differences between various organic magnesium compounds (citrate versus glycinate versus others) have not been definitively established in head-to-head clinical trials. 1
• Magnesium glycinate is classified as an organic salt alongside citrate, aspartate, and lactate, all of which are preferred over inorganic magnesium oxide for general supplementation purposes. 1

Clinical Applications and Evidence

Sleep Quality Improvement

• A 2025 randomized controlled trial demonstrated that magnesium bisglycinate (250 mg elemental magnesium daily) significantly reduced Insomnia Severity Index scores compared to placebo at 4 weeks (-3.9 vs -2.3, p = 0.049), though the effect size was modest (Cohen's d = 0.2). 2
• The greatest improvements occurred in participants with lower baseline dietary magnesium intake, suggesting those with deficiency respond better. 2
• A 2024 systematic review found that 5 out of 8 sleep-related studies showed improvements in sleep parameters with magnesium supplementation, with minimal side effects reported. 3

Anxiety Reduction

• The 2024 systematic review identified that 5 out of 7 studies measuring anxiety-related outcomes reported improvements in self-reported anxiety with magnesium supplementation. 3
• Supplemental magnesium appears most useful for mild anxiety and insomnia, particularly in individuals with low baseline magnesium status. 3

Hypomagnesemia Correction

• The American Society of Clinical Oncology recommends oral magnesium glycinate for maintenance therapy after intravenous correction of hypomagnesemia, or for mild deficiency states, particularly in patients receiving chemotherapy agents like cisplatin or cetuximab. 1

Constipation Management

• Magnesium glycinate may help address constipation through osmotic properties, though magnesium citrate demonstrates stronger osmotic effects and is preferred when constipation is the primary concern. 1

Gastrointestinal Tolerability

• Magnesium glycinate typically causes fewer gastrointestinal side effects (bloating, diarrhea) compared to other magnesium forms, though mild to moderate effects can still occur. 1
• For patients who cannot tolerate oral magnesium without developing loose stools, magnesium chloride capsules or parenteral administration are superior alternatives to raise blood magnesium levels. 4
• All magnesium forms can cause loose stools through osmotic effects by drawing water into the intestines. 4

Safety Considerations and Contraindications

• Avoid all magnesium supplementation, including glycinate, in patients with significant renal impairment (creatinine clearance <20 mL/min) due to hypermagnesemia risk. 5, 1
• Monitor calcium levels after magnesium glycinate treatment, as patients are at increased risk of developing hypocalcemia. 1
• Use caution in elderly patients and those with heart failure, electrolyte disturbances, or medications that may interact with magnesium. 1

Dosing Recommendations

• For general supplementation, spreading magnesium doses throughout the day is preferable to a single large dose. 1
• The 2025 sleep trial used 250 mg elemental magnesium daily as magnesium bisglycinate with demonstrated efficacy. 2
• Common clinical practice doses range from 200-400 mg elemental magnesium daily for general supplementation. 1

Clinical Decision Algorithm

Choose magnesium glycinate when:

• General magnesium supplementation is needed with emphasis on tolerability 1
• Patient has gastrointestinal sensitivity to other magnesium forms 1
• Maintenance therapy for hypomagnesemia is required 1
• Sleep quality improvement or mild anxiety reduction is the goal 2, 3

Choose magnesium citrate instead when:

• Constipation is the primary concern (stronger osmotic effect) 1
• Bowel preparation is needed 1

Avoid all magnesium forms when:

• Creatinine clearance is <20 mL/min 5, 1
• Congestive heart failure is present (particularly for citrate preparations) 1

Key Clinical Pearls

• Ensure adequate hydration and sodium repletion before aggressive magnesium supplementation, as depletion causes secondary hyperaldosteronism that increases urinary magnesium losses. 4
• The modest effect sizes in clinical trials suggest magnesium glycinate works best as part of comprehensive sleep hygiene rather than monotherapy for significant sleep disorders. 2
• Baseline magnesium status matters: those with dietary deficiency show greater clinical response. 2, 3