supplements · 3 min read
Magnesium glycinate vs citrate: which one to take, and when
Magnesium glycinate and citrate both absorb well. Citrate has the stronger absorption data and a laxative effect that helps with constipation. Glycinate is gentler on the gut, which makes it the easier choice for daily use or at night.
Written by Lifebar Desk · Checked against the sources listed below
Published 26 Sept 2026
Key takeaways
- Both are organic magnesium salts that absorb far better than magnesium oxide.
- Citrate has the stronger head-to-head evidence: in a 60-day trial it raised blood magnesium more than an amino-acid chelate or oxide.
- Citrate draws water into the bowel, so it doubles as a mild laxative. Glycinate rarely does.
- Pick citrate if you are also constipated. Pick glycinate if loose stools are a problem or you take it at night.
- Keep supplemental magnesium at or below 350 mg of elemental magnesium a day unless a clinician advises more.
Glycinate and citrate are the two magnesium forms most people end up choosing between. Both are good. The difference is mostly what they do in your gut.
Side by side
| Magnesium glycinate | Magnesium citrate | |
|---|---|---|
| Bound to | Glycine, an amino acid | Citric acid |
| Elemental magnesium | About 14% by weight | About 11 to 16%, depending on the salt |
| Absorption | Good | Good, strongest trial data |
| Laxative effect | Low | Mild to moderate, dose dependent |
| Best for | Daily repletion, sensitive gut, night use | Repletion plus constipation |
| Typical cost | Higher | Lower |
What the absorption trials show
The most useful comparison is a 2003 randomised, double-blind trial in 46 healthy adults. Each took 300 mg of elemental magnesium a day for 60 days as citrate, an amino-acid chelate or oxide. Citrate produced the highest serum magnesium after both the first dose and 60 days. Both organic forms beat oxide on urinary magnesium, a marker of how much was absorbed, and oxide did no better than placebo.
Solubility explains part of that. In lab tests, magnesium citrate dissolves well even in plain water, while magnesium oxide barely dissolves at all and only partly dissolves in stomach-strength acid.
The chelate in that trial was not labelled glycinate specifically, so the fair reading is: citrate absorbs at least as well as glycinate, and both absorb far better than oxide.
The gut difference
Any magnesium that is not absorbed stays in the intestine and draws water in. Citrate does this more readily, which is why a large dose of magnesium citrate is sold as an over-the-counter laxative. At supplement doses the effect is milder, but it is the most common reason people switch.
Glycinate tends to stay quiet. If you have irritable bowel symptoms, loose stools, or plan to take magnesium in the evening, that is a practical advantage.
Sleep and anxiety
This is where the marketing gets ahead of the data.
- A 2025 randomised trial gave 155 adults with poor sleep either 250 mg of elemental magnesium as bisglycinate or placebo. Insomnia scores improved slightly more on magnesium, with a small effect size.
- A 2010 trial gave 100 older adults with poor sleep 320 mg of magnesium as citrate or placebo for seven weeks. Sleep quality improved in both groups by the same amount.
Neither form is proven for sleep. People who eat little magnesium seem to benefit most, whatever the form.
How to choose
- Constipated as well as low on magnesium? Citrate.
- Sensitive gut, or taking it at night? Glycinate.
- Just correcting a low intake? Either. Pick the one your gut tolerates and your budget allows.
Dose and safety
Adults need 310 to 420 mg of magnesium a day, and food should supply most of it. The upper limit for supplemental magnesium is 350 mg of elemental magnesium a day, and diarrhoea is the usual sign of going over it. Read the elemental figure on the supplement facts panel, not the compound weight on the front.
Magnesium is cleared by the kidneys. With reduced kidney function it can build up, and it interacts with some antibiotics and osteoporosis drugs. Check with your clinician first if either applies to you.
Frequently asked
Which is better absorbed, magnesium glycinate or citrate?
Both absorb well. The best head-to-head trial, at 300 mg of elemental magnesium a day for 60 days, found citrate raised serum magnesium the most, with the amino-acid chelate close behind and oxide no better than placebo.
Which is better for sleep?
Neither has strong evidence. A 2025 trial of magnesium bisglycinate found a small improvement in insomnia scores, and a 2010 citrate trial found no difference from placebo. Glycinate is the more practical night-time choice because it is less likely to send you to the bathroom.
Which is better for constipation?
Citrate. Unabsorbed magnesium citrate pulls water into the intestine, which softens stool. It is sold over the counter as a laxative for exactly this reason.
Can I take magnesium glycinate and citrate together?
Yes, as long as the combined elemental magnesium stays within your target. Add up the elemental figure from both labels, not the compound weight.
Sources
- Walker et al., Mg citrate found more bioavailable than other Mg preparations (Magnes Res, 2003)
- Lindberg et al., Magnesium bioavailability from magnesium citrate and magnesium oxide (J Am Coll Nutr, 1990)
- Schuster et al., Magnesium bisglycinate supplementation in adults reporting poor sleep (Nat Sci Sleep, 2025)
- Nielsen et al., Magnesium supplementation in adults older than 51 with poor quality sleep (Magnes Res, 2010)
- NIH Office of Dietary Supplements, Magnesium Fact Sheet for Health Professionals
Educational content, talk to your clinician before changing treatment.
