Magnesium glycinate

A US Supplement Facts panel declares the element, not the salt. Magnesium glycinate has a molar mass of 172.42 against magnesium's 24.305, so 11.83–14.1% of its mass is magnesium. One caveat: bisglycinate; chelate hydration varies by supplier — so the figures below are given as a range wherever that matters.

A size 00 capsule holds about 730 mg of powder at powder density 0.6–0.8 g/mL; a size 000 about 1,100 mg.

Counted only for capsule labels naming this salt alone. Full method and the corpus-wide figure: label mass-budget audit.

Absorption is a separate question from mass, and a contested one. Below is what each study did, on whom, and what it measured — with the original linked. See the full literature page for why results conflict.

These entries report what each study measured and on whom. They are not advice, not a ranking, and not a claim about any product on this site. Every reference links to its PubMed record so the original can be read in full.

1. Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPE™ Microcapsules) Versus Other Magnesium Sources.

   Nutrients · 2024 · PMID 39770988

   Design

   Double-blind, randomized, cross-over clinical study in 40 healthy women and men. Participants followed a low-magnesium diet for 7 days and fasted 8 hours, then received a single oral dose of each of four products in cross-over fashion: microencapsulated magnesium (Mg-MS / MAGSHAPE), magnesium oxide (MgO), magnesium citrate (Mg-C), and magnesium bisglycinate (Mg-BG). Blood was drawn by digital puncture before dosing (0 h) and at 1, 4, and 6 hours after each product.

   What it measured

   Plasma magnesium concentration at 0, 1, 4, and 6 hours after oral intake of each of the four products; gastrointestinal side effects (intestinal motility, sensations of gastric heaviness) associated with each product.

   Limits

   Single-dose exposure per product, not chronic supplementation; sample size n=40; a specific proprietary microencapsulation technology was tested, which may not generalize to other encapsulation methods; plasma magnesium was the only absorption marker used (no urinary or tissue measurement).

2. The bioaccessibility and tolerability of marine-derived sources of magnesium and calcium.

   Methods (San Diego, Calif.) · 2024 · PMID 38608850

   Design

   Two-part study. (1) In vitro digestion (INFOGEST method) comparing solubility of Aquamin-Mg (seawater-derived, 12% magnesium), a commercially available magnesium bisglycinate, and a specific branded magnesium bisglycinate (PrizMAG) during simulated gastric and intestinal digestion phases, with and without co-administered food. (2) A randomized, double-blind, placebo-controlled 12-week study in a small cohort of healthy older adults given a combined Aquamin-Mg/Aquamin-F supplement.

   What it measured

   In vitro mineral solubility during simulated gastric and intestinal digestion phases; adverse-event reporting and tolerability over the 12-week human study arm.

   Limits

   The solubility comparison was performed in vitro (simulated digestion model), not as in vivo human absorption; the human arm assessed tolerability/safety only, not comparative bioavailability; the human cohort was described only as small and limited to older adults, with no numeric sample size given in the abstract.

3. Dose-Dependent Absorption Profile of Different Magnesium Compounds

   Biological Trace Element Research · 2020 · PMID 30761462

   Design

   Absorption of several magnesium compounds profiled across doses rather than at a single dose.

   What it measured

   Absorption is treated as dose-dependent, so a comparison made at one dose need not hold at another — which is why single-dose head-to-head results disagree.

   Limits

   Compound coverage and sample size vary by arm; read the paper before carrying any single figure across.

4. Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approach

   Magnesium Research · 2005 · PMID 16548135

   Design

   Eighty male Wistar rats fed a magnesium-depleted diet for three weeks, then randomised into ten groups, each receiving a different magnesium salt labelled with a stable isotope.

   What it measured

   Stable isotopes allow absorption and retention to be traced directly rather than inferred from urine, across ten salts at once — the widest head-to-head comparison in the literature.

   Limits

   Rats, not people, and magnesium-depleted rats at that: depletion itself raises absorption. The breadth of the comparison is its value; the species is its limit.

5. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study

   Magnesium Research · 2003 · PMID 14596323

   Design

   Randomised, double-blind, placebo-controlled parallel study in 46 healthy individuals, 300 mg of elemental magnesium per day, comparing an amino-acid chelate, citrate and oxide.

   What it measured

   Relative bioavailability of the three preparations was compared at an equal elemental dose.

   Limits

   46 participants, healthy, 300 mg per day; “amino-acid chelate” is a class rather than one defined compound, so the chelate arm is not a single substance.

6. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection

   JPEN: Journal of Parenteral and Enteral Nutrition · 1995 · PMID 7815675

   Design

   Comparison of magnesium diglycinate (a chelate) with magnesium oxide in patients who had undergone ileal resection.

   What it measured

   The work followed in vitro and in situ findings suggesting diglycinate is absorbed by a different route than inorganic salts, and tested that in patients with impaired absorption.

   Limits

   Patients after ileal resection are a specific clinical population with poor absorption to begin with; results do not transfer to people with an intact gut.

Compare glycinate with other salts

13 published comparisons include magnesium glycinate as of 2026-09-13; each row gives the other salt's magnesium fraction and compound mass for 100 mg elemental magnesium from the chemistry model.

• Magnesium glycinate vs magnesium citrate: 11.3–16.16% magnesium by mass; 619–885 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium oxide: 60.32% magnesium by mass; 166 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium malate: 13.2–15.54% magnesium by mass; 644–758 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium aspartate: 8.42% magnesium by mass; 1,188 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium carbonate: 24.78–28.83% magnesium by mass; 347–404 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium gluconate: 5.86% magnesium by mass; 1,706 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium chloride: 11.96–25.53% magnesium by mass; 392–836 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium taurate: 8.85% magnesium by mass; 1,130 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium hydroxide: 41.68% magnesium by mass; 240 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium l-threonate: 8.25% magnesium by mass; 1,212 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium orotate: 7.27% magnesium by mass; 1,376 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium lactate: 12.01% magnesium by mass; 833 mg compound per 100 mg elemental magnesium.
• Magnesium glycinate vs magnesium sulfate: 9.86–20.19% magnesium by mass; 495–1,014 mg compound per 100 mg elemental magnesium.

Excipients most common in glycinate labels

5 published excipient facets below have the highest frequencies among 126 labels mentioning magnesium glycinate in the NIH DSLD records, counted 2026-09-13; each label enters an ingredient count once.

• silicon dioxide: 62 of 126 labels.
• magnesium stearate: 54 of 126 labels.
• stearic acid: 39 of 126 labels.
• microcrystalline cellulose: 36 of 126 labels.
• cellulose: 35 of 126 labels.