Walk down the supplement aisle and you will find magnesium glycinate, citrate, oxide, malate, threonate and more. The form genuinely matters — mostly for absorption and for how it affects your digestion.
Why the form matters
Magnesium is always bound to something else. That partner molecule changes how well the magnesium is absorbed and what side effects you are likely to notice. The NIH Office of Dietary Supplements notes that forms such as citrate, lactate and chloride are more easily absorbed than magnesium oxide — see their consumer sheet on magnesium.
The common forms compared
| Form | Best for | Notes |
|---|---|---|
| Glycinate | Evening use, sensitive stomachs | Well absorbed; least likely to loosen stools |
| Citrate | General use, occasional constipation | Well absorbed; mild laxative effect |
| Oxide | Cheap bulk magnesium | Poorly absorbed; most likely to cause loose stools |
| Malate | Daytime use | Well absorbed; some prefer it earlier in the day |
| Threonate | Marketed for cognition | Expensive; human evidence still thin |
Reading the label properly
The number that matters is elemental magnesium, not the total weight of the compound. A capsule listing “1,000 mg magnesium glycinate” may only supply around 100–150 mg of actual magnesium. Good labels state the elemental amount clearly.
Magnesium Glycinate (e.g. NOW, Doctor's Best)
- Chelated glycinate — well absorbed and gentle on digestion
- Check the elemental magnesium per serving, not the compound weight
- 200–400 mg elemental in the evening is a common range
Budget-friendly · widely available
Check Price →Which should you pick?
For most people wanting a gentle evening magnesium, glycinate is the sensible default. If you also want help with regularity, citrate does double duty. Oxide is worth avoiding unless price is the only consideration. For how magnesium relates to sleep specifically, see magnesium for sleep.
Safety notes
Magnesium supplements are generally well tolerated. High doses can cause digestive upset, and people with kidney problems should be cautious. Check with your healthcare provider if you take medication or manage a health condition.