Magnesium Glycinate

Magnesium glycinate (magnesium bisglycinate) is elemental magnesium bound to two molecules of the amino acid glycine. The chelate is well tolerated and the least likely magnesium form to cause loose stools, which is why it’s the usual choice for people taking magnesium for calm or sleep, or for anyone who gets diarrhea on cheaper salts. For the mineral’s full evidence base — blood pressure, blood sugar, migraine and more — see Magnesium; this page covers what’s specific to the glycinate form.

Absorption & Tolerability

As an organic chelate, glycinate is well absorbed and notably gentle on the gut — the practical advantage over inorganic salts is tolerability more than dramatically higher absorption (only magnesium oxide is clearly a poor absorber) ^{1Reference 1Firoz M · 2001Clinical trialBioavailability of US commercial magnesium preparations — comparative human studyView study →}. Its elemental magnesium is only about 14% by weight, so a meaningful dose means comparatively large capsules — check the elemental figure on the label, not the total compound weight. The bound glycine is itself mildly calming, which may add to the “relaxation” reputation.

What the Evidence Says

Most magnesium trials used other salts, so glycinate-specific clinical data are limited. A recent magnesium bisglycinate insomnia trial reported a statistically significant but very small improvement in insomnia severity — consistent with the broader, modest sleep evidence for magnesium (see Magnesium). Choose glycinate for tolerability and comfort, not because it has uniquely strong outcome data.

Gap: there is little head-to-head evidence that glycinate outperforms other well-absorbed forms on any clinical outcome; its edge is gentleness, not proven superiority.

Dosage

Common supplemental doses are 120–240 mg of elemental magnesium, often taken in the evening; split higher intakes across the day. These are commonly used ranges, not a personal recommendation — see the dosing and upper-limit notes on Magnesium.

Safety

Very well tolerated. The general magnesium cautions apply — people with kidney impairment should not supplement without medical advice, and magnesium should be separated by ≥2 hours from oral bisphosphonates and certain antibiotics [1, and see Magnesium].

References

1. Firoz M, Graber M. (2001). Bioavailability of US commercial magnesium preparations — comparative human study. Magnesium Research, 14(4), 257–262. https://pubmed.ncbi.nlm.nih.gov/11794633/