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Magnesium glycinate vs citrate comes down to two things: how each form behaves in the gut and what you want from it. In small studies, citrate was absorbed better than magnesium oxide, and an amino acid chelate, the family glycinate belongs to, also beat oxide in one trial. Magnesium citrate draws water into the bowel at larger amounts, which is why it is also sold as an over-the-counter saline laxative. Magnesium glycinate (often labeled bisglycinate) binds magnesium to the amino acid glycine and has limited evidence that it is gentler on the stomach. Neither form has been shown to be clearly better for general health. This guide compares them, walks through the other types of magnesium you will see on labels, and covers safety.
Peptide Labs sells some of the products described below. This article is general information, not medical advice.
Key Takeaways
- Supplement Facts panels list elemental magnesium, not the weight of the whole compound.
- Citrate and glycinate carry about 14 to 16% magnesium by weight; oxide carries about 60%.
- Small studies found citrate and amino acid chelates absorbed better than oxide.
- Magnesium citrate is also an OTC saline laxative; glycinate is not sold that way.
- The upper limit for magnesium from supplements and medicines is 350 mg a day for adults.
Magnesium glycinate vs citrate at a glance
| Feature | Magnesium glycinate | Magnesium citrate |
|---|---|---|
| What it is | Magnesium bound to two glycine molecules | Magnesium bound to citric acid |
| Magnesium by weight (calculated) | About 14% | About 16% |
| Absorption research | Few human studies; one small trial matched oxide overall | Absorbed better than oxide in several small studies |
| Laxative effect | Reported as better tolerated in one 12-person study | Osmotic laxative at larger amounts |
| How it is sold | Dietary supplement | Dietary supplement, and OTC laxative liquid |
| What else you get | Glycine, an amino acid | Citrate |
Types of magnesium and how much magnesium each form carries
The NIH Office of Dietary Supplements (ODS) notes that a Supplement Facts panel declares the amount of magnesium itself, not the weight of the whole compound. The rest of the compound is the partner molecule. That is why a capsule of glycinate or citrate is bulky for the magnesium it holds, while oxide packs a lot into a small pill. The shares below are calculated from each chemical formula; forms that contain water, such as hydrated chloride, carry less.
| Form | Magnesium by weight | Where you usually see it |
|---|---|---|
| Oxide | About 60% | Tablets, antacids, colon cleanse capsules |
| Hydroxide | About 42% | Milk of magnesia (OTC laxative and antacid) |
| Chloride | About 26% (12% if hydrated) | Supplements and topical products |
| Citrate | About 16% | Supplements and OTC laxative liquids |
| Malate | About 15% | Supplements |
| Glycinate (bisglycinate) | About 14% | Supplements |
| Sulfate (Epsom salt) | About 10% | OTC laxative and bath salts |
| L-threonate | About 8% | Branded supplements such as Magtein |
Some products blend several magnesium forms. The words in parentheses after magnesium on the Supplement Facts panel tell you which forms are inside.
What absorption studies show
ODS summarizes the research simply: forms that dissolve well in liquid are absorbed more completely, and small studies found the aspartate, citrate, lactate and chloride forms more bioavailable than oxide and sulfate. The key studies are small:
- Walker 2003. In a 60-day randomized, double-blind trial at the University of Reading, 46 healthy adults took magnesium as citrate, an amino acid chelate or oxide. Both organic forms raised urinary magnesium more than oxide, and citrate produced the highest blood and saliva levels. Oxide was no different from placebo.
- Firoz 2001. A Veterans Affairs study in healthy volunteers estimated that only about 4% of magnesium from oxide was absorbed, while chloride, lactate and aspartate did better. It did not test citrate or glycinate.
- Schuette 1994. In 12 patients who had part of the small intestine removed, magnesium diglycinate and oxide were absorbed about equally overall (23.5% vs 22.8%). In the four patients who absorbed oxide worst, the glycinate form did about twice as well.
These trials measured magnesium in urine or blood, which is only a stand-in for what reaches the body’s tissues. None tested magnesium glycinate vs magnesium citrate head to head, so claims that one is absorbed far better than the other go beyond the data.
Laxative effect: which magnesium forms loosen stools
Magnesium that is not absorbed pulls water into the intestine. ODS lists carbonate, chloride, gluconate and oxide as the forms most often reported to cause diarrhea, and notes that high amounts from supplements or medicines commonly cause diarrhea, nausea and cramping. Magnesium citrate is also an over-the-counter saline laxative ingredient under FDA’s monograph. Its Drug Facts say it relieves occasional constipation and generally produces a bowel movement in half an hour to 6 hours, and tell you to ask a doctor first if you have kidney disease or have used a laxative for more than a week.
Glycinate’s reputation as the gentle form rests on little data; the strongest point is that it was better tolerated than oxide in the 12-patient Schuette study. If regularity is the question, see our guides to fiber for constipation and Metamucil vs MiraLAX, and read about magnesium oxide and citrate as laxatives.
Other magnesium forms you will see
- Oxide: the most magnesium per pill and the least absorbed in studies; common in antacids and cleanse products.
- Hydroxide: the active ingredient in milk of magnesia; ODS notes one tablespoon of Phillips’ provides 500 mg of magnesium.
- Chloride: dissolves well and was among the better-absorbed forms in small studies, but is also on the list of forms that commonly cause diarrhea.
- Malate and L-threonate: sold mainly as branded supplements; we did not find human studies comparing their absorption with citrate. See our magnesium for sleep guide for the threonate trial.
- Sulfate: Epsom salt, an OTC saline laxative when taken by mouth.
How to read magnesium forms on a label
- Find the magnesium line on the Supplement Facts panel; that number is magnesium, not the whole salt.
- Check the form in parentheses, and whether several forms are blended.
- Add up magnesium from every supplement and antacid you take, because limits apply to the total.
- Look for a third-party seal; our guide to third-party tested supplements explains what each one covers.
Safety: upper limit, kidneys and medicine interactions
Magnesium from food is not a risk for healthy people because the kidneys remove the excess. For supplements and medicines, the Tolerable Upper Intake Level is 350 mg a day for everyone 9 and older, including during pregnancy. It is a safety ceiling, not a target, and it does not count magnesium from food. ODS links very large amounts from laxatives and antacids, typically more than 5,000 mg a day, to magnesium toxicity, and the risk rises when the kidneys do not work well. People with kidney disease should talk with a clinician before taking any magnesium product.
- Osteoporosis drugs (bisphosphonates): separate from magnesium by at least 2 hours.
- Tetracycline and quinolone antibiotics: take at least 2 hours before or 4 to 6 hours after magnesium.
- Levothyroxine: its prescribing information says magnesium-containing antacids may lower its absorption; ask your pharmacist how to space them.
- Diuretics and long-term acid reducers (PPIs): can change magnesium levels; discuss supplements with your prescriber.
Magnesium products we sell
We do not currently carry a standalone magnesium glycinate or magnesium citrate supplement. The magnesium products in our detox and cleanse category use magnesium oxide. Let Loose lists 400 mg of magnesium from oxide plus a 790 mg ozonated magnesium blend per capsule. Oxy-Powder lists 1,400 mg of magnesium from ozonated magnesium oxides per four-capsule serving, and MagO7 lists 1,035 mg per three capsules, with a note from the brand that it is not intended as a magnesium supplement. Those serving amounts are well above the 350 mg upper limit for supplemental magnesium, which reflects their use as short-term cleanse products that rely on a laxative effect. Follow the label, and ask a clinician first if you have heart or kidney problems.
Frequently Asked Questions
Is magnesium glycinate or citrate better?
Neither is better for everyone. Citrate has more absorption data and is more likely to loosen stools; glycinate has fewer studies and a reputation for being gentler.
Which type of magnesium is most absorbed?
Small studies favor forms that dissolve well, such as citrate, chloride and lactate, over oxide and sulfate. No large trials rank all forms.
Is magnesium glycinate a laxative?
It is not sold as a laxative, and one small study found it better tolerated than oxide. Any magnesium can loosen stools at higher amounts.
Can I take magnesium glycinate and citrate together?
Some products combine forms. Add the magnesium from each so the total from supplements and medicines stays within the label and the 350 mg upper limit unless a clinician advises otherwise.
Why does my magnesium glycinate label show a low number?
Glycinate is only about 14% magnesium by weight, so a large capsule holds relatively little. The label number is the magnesium itself.
Who should avoid magnesium supplements?
People with kidney disease should ask a clinician first. Check with a pharmacist if you take antibiotics, bisphosphonates, levothyroxine or diuretics.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed September 2026.
Related guides: Magnesium Oxide: Elemental Magnesium, Absorption, Laxative Effect and Safety, Magnesium for Sleep: What the Research Shows and Which Forms Were Studied, Cascara Sagrada and Senna: Stimulant Laxative Rules, Side Effects and Safety, Best Time to Take Magnesium: Morning or Night and Medicine Timing.