Magnesium glycinate vs citrate
Citrate has the comparative trials. Glycinate has the tolerability. The absorption argument runs the other way from the marketing.
The received wisdom is that glycinate is the better-absorbed form and citrate is the cheap one. The human data does not say that. Citrate is the form with direct comparative trials behind it: in 46 adults taking 300mg of elemental magnesium a day for 60 days, citrate produced higher urinary excretion and the highest mean serum magnesium of the forms tested, while magnesium oxide was indistinguishable from placebo. Glycinate's reputation rests on one 1994 study in 12 patients who had undergone ileal resection, and in that study the overall difference was 23.5% absorption for the chelate against 22.8% for oxide, which is no difference at all. What that study did find, and what holds up, is that glycinate was better tolerated by every patient. So the honest split is this: citrate if the goal is raising magnesium status, glycinate if citrate sends you to the bathroom, and oxide only if the goal is cheap elemental milligrams on a label.
Stack Almanac converts each form to elemental magnesium before totalling, so a 500mg glycinate capsule at 14% and a 400mg citrate at 16% stop looking like the bigger and smaller dose they are printed as.
What this is based on
- 1.Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind studyMagnesium Research 2003;16(3):183-91n=46, 300 mg elemental Mg/day, 60 days; citrate and amino-acid chelate higher 24-h urinary Mg than oxide (P=0.033); citrate highest mean serum Mg acute (P=0.026) and chronic (P=0.006); oxide no different from placebo
- 2.Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resectionJPEN Journal of Parenteral and Enteral Nutrition 1994;18(5):430-5n=12, 100 mg 26Mg-labelled dose; 23.5% chelate vs 22.8% oxide for the group as a whole, not significantly different; glycinate better tolerated by all patients
- 3.Assessment of bioavailability of Mg from Mg citrate and Mg oxide by measuring urinary excretion in Mg-saturated subjectsMagnesium Research 2019;32(3):63-71n=14 magnesium-saturated healthy males, single 400 mg dose; citrate raised 24-h urinary Mg excretion, oxide did not
- 4.Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled TrialNature and Science of Sleep 2025;17:2027-2040bisglycinate modestly improved insomnia measures; an outcome trial, not an absorption comparison
See also the full reference for magnesium.
Stack Almanac does this comparison against your own stack