Magnesium glycinate

Regulatory status: supplement (oral mineral / amino-acid chelate). Not a prescription drug. Not a device, habit, or measurement

Mechanism evidence: human

• **Sleep / insomnia:** lower insomnia severity, faster sleep onset, better sleep quality.
• **Anxiety / stress:** lower subjective anxiety or perceived stress.
• **Muscle cramps:** fewer or less intense rest cramps (pregnancy-associated and idiopathic / nocturnal).
• **Constipation:** more frequent or complete bowel movements (usually argued from other Mg salts).
• **Serum magnesium:** raise circulating Mg.
• **Bioavailability versus oxide:** more of the ingested elemental Mg is absorbed than from MgO.
• **Blood pressure:** lower systolic and/or diastolic BP.
• **Insulin sensitivity:** lower HOMA-IR, fasting glucose, or HbA1c.
• **Migraine:** fewer attacks (prophylaxis).

Glycinate is a real, named salt with a thin human file. The file that exists: one 4-week sleep RCT (n = 155) with a **1.6-point ISI** edge over placebo, **d = 0.2**, p = 0.049, no objective sleep, no anxiety effect, and 1.5 g glycine in the capsule; one pregnancy-cramp RCT with a large placebo response; an 8-week SSRI-add-on study that raised serum Mg by 0.30 mg/dL and did not publish the between-group DASS contrast; a 1994 isotope study in 12 short-bowel patients showing **the same mean absorption as oxide**; and a 2024 industry PK study in which **375 mg elemental as bisglycinate did not raise 6-hour plasma Mg**. Blood pressure, insulin sensitivity, migraine, constipation, and idiopathic cramps have **not** been demonstrated for this form. Those claims are borrowed from oxide, citrate, and chloride papers. **Confidence: weak** for glycinate as a sleep or cramp treatment; **unsupported** for anxiety, constipation, BP, insulin, and migraine *as this form*; **moderate** only for the narrow statements “8 weeks of oral glycinate can raise serum Mg” (Sultana) and “GI tolerance is better than oxide in small head-to-heads” (Schuette; Schuster AE table).