Magnesium glycinate vs citrate: which one should you take?

How the two forms differ

Supplements pair magnesium with another compound so it can be made into a pill or powder. Magnesium citrate pairs it with citric acid. Magnesium glycinate (also sold as bisglycinate) pairs it with the amino acid glycine.

The NIH Office of Dietary Supplements notes that forms that dissolve well in liquid are absorbed better, and that the aspartate, citrate, lactate and chloride forms tend to be absorbed better than magnesium oxide and sulfate.

Magnesium citrate for constipation

Magnesium citrate is sold over the counter as a saline laxative for occasional constipation and to clear the bowel before a colonoscopy. At laxative doses it usually works within 30 minutes to 6 hours, and loose or frequent stools are common.

• Use laxative-dose magnesium citrate for no more than about a week unless a clinician tells you otherwise.
• Take other medicines at least 2 hours before or after it.
• Stop and call a clinician if you see blood in your stool or still can't have a bowel movement.

Smaller daily supplement doses of magnesium citrate may simply soften stools a little. If you want magnesium for other reasons and your stools are already loose, glycinate is the more common choice.

Which magnesium is best for sleep?

There is no good evidence that one form beats another for sleep. A 2021 review of three small trials in 151 older adults with insomnia found people fell asleep about 17 minutes faster on magnesium than placebo, but the trials were at moderate to high risk of bias and the evidence was rated low to very low quality. Total sleep time did not change significantly. None of the trials tested magnesium glycinate.

People who try magnesium for sleep often choose glycinate because it is reported to be less likely to send them to the bathroom at night, though direct comparisons are few. That is a practical reason, not a proven sleep benefit. If sleep is a problem most nights, it is worth talking to a clinician about causes like sleep apnea, restless legs or low iron.

Upper limit, side effects and who should be careful

The upper limit for supplemental magnesium is 350 mg a day for adults, counting all supplements and medicines such as antacids and laxatives. Magnesium from food doesn't count toward it and doesn't need to be limited. Above the limit, magnesium can cause diarrhea, nausea and cramping; extremely high intakes can cause low blood pressure, an irregular heartbeat and, rarely, cardiac arrest.

• Kidney disease. Healthy kidneys clear extra magnesium. If your kidneys don't work well, magnesium can build up. Ask a clinician before taking any form.
• Osteoporosis drugs (oral bisphosphonates). Magnesium can keep them from being absorbed, so space them apart.
• Tetracycline and quinolone antibiotics. Magnesium can interfere with them; ask a pharmacist about timing.
• Diuretics and proton pump inhibitors. These can change your magnesium level, so long-term users may want it checked.

Stop magnesium and get care right away if you feel very weak, dizzy or faint, or notice an irregular heartbeat or trouble breathing.

What it costs

Magnesium is one of the cheaper supplements, but prices vary widely by brand. A free Gabriel account pays cost-plus prices on supplements, and with Gabriel Core or Plus member prices are lower still. For example, magnesium glycinate, 180 capsules, is $31.33 for Plus members (list price $56.99).

Not sure you need it? Ask Gabriel free. Gabriel can look at your diet, medications and any lab results and help you decide whether magnesium makes sense and which form fits.