Magnesium glycinate vs
citrate vs oxide —
which one actually absorbs?
Magnesium glycinate vs citrate (often searched as magnesium bisglycinate vs citrate) is the question most people ask — but the bigger story is magnesium oxide, the cheapest form and the one on most Indian pharmacy shelves. Here’s what human studies actually show about how each form absorbs, how it treats your stomach, what it does for sleep, and how to choose.
Magnesium glycinate vs citrate vs oxide: the short answer
Which is better: magnesium glycinate, citrate or oxide?
Magnesium oxide is the least absorbed of the three in most human studies. Magnesium citrate and magnesium glycinate both absorb better than oxide — citrate raised blood magnesium the most in one 60-day trial, while glycinate is gentler on the stomach, carries calming glycine, and has its own sleep trial. Choose glycinate for evening use or a sensitive stomach, citrate if you also want help with regularity, and skip oxide unless you want a laxative.
There isn’t one “best” form for everyone — there’s a best form for what you want. Think of the office worker who wants better sleep and a calm stomach, the person who also struggles with constipation, and the gym-goer taking magnesium every evening for months. The research points each of them somewhere different, but it points all of them away from oxide.
Why the form of magnesium matters
Why does the form of magnesium matter?
Magnesium in a supplement is always bound to something — oxygen, citric acid or the amino acid glycine. That partner decides how much magnesium the label shows by weight, how well it dissolves and absorbs, and how your gut reacts. The number on the front of the pack rarely tells you how much your body gets.
Oxide is about 60% magnesium by weight, citrate about 16% and bisglycinate about 14%. That’s why oxide products can print big numbers — and why a label showing “500 mg magnesium bisglycinate” delivers only about 70 mg of actual magnesium. Always look for the elemental magnesium figure.
A fully reacted bisglycinate can’t exceed about 14% magnesium. So when a “glycinate” claims much more, it’s usually buffered — blended with cheaper magnesium oxide. A fully reacted, unbuffered chelate contains no oxide at all.
Magnesium oxide: lots on the label, little absorbed
Why is magnesium oxide poorly absorbed?
In a human comparison, only about 4% of magnesium oxide was absorbed, against 9–11% for chloride, lactate and aspartate. In a 60-day trial at 300 mg a day, oxide performed no better than placebo. Its main clinical use is as a laxative.
Oxide has to dissolve in stomach acid before any of its magnesium can be absorbed, and much of it doesn’t. In a crossover study, about 4% of magnesium oxide was absorbed, compared with 9–11% for other forms.1 In a 60-day randomised trial of 46 adults taking 300 mg of magnesium a day, oxide made no difference compared with placebo.2
A 2019 study showed how misleading big oxide numbers can be: a product with 196 mg of magnesium in a better-dissolving formulation raised blood magnesium significantly more than a 450 mg oxide-only tablet, whose effect couldn’t be told apart from normal daily fluctuation.3 The magnesium that isn’t absorbed draws water into the bowel — which is why oxide works well as a laxative, and poorly as a supplement. Our magnesium oxide vs magnesium glycinate guide covers the head-to-head in full, including the leg-cramp trials.
Magnesium citrate: well absorbed, with a laxative edge
Is magnesium citrate well absorbed?
Magnesium citrate dissolves easily and absorbs well — in a 60-day trial it produced the highest blood magnesium of the forms tested, and a single-dose study found it clearly better absorbed than oxide. At higher doses it draws water into the gut, which helps with constipation but can mean loose stools.
Citrate is one of the best-studied organic forms. In the 60-day trial, citrate and the amino-acid chelate both absorbed better than oxide, and citrate produced the highest blood magnesium, both after a single dose and after two months.2 A separate crossover study confirmed citrate is better absorbed than oxide after a single dose.4
The trade-off is the gut. Citrate pulls water into the intestine, which is why it’s also used as a laxative. That’s helpful if you tend towards constipation, less so if you want magnesium every evening without a morning dash.
Magnesium glycinate: the gentle, evening form
What is magnesium glycinate (bisglycinate)?
Magnesium glycinate (bisglycinate) is magnesium bound to the amino acid glycine. It absorbs better than oxide over time, is gentler on the stomach, and part of it may be absorbed intact through amino-acid pathways. Each 100 mg of magnesium as bisglycinate also carries about 0.6 g of glycine, a calming amino acid — about 2.7 g in a 440 mg serving.
In the 60-day trial, the amino-acid chelate absorbed better than oxide.2 In a study of patients who had part of their small intestine removed — people who absorb magnesium poorly — magnesium glycinate was absorbed twice as well as oxide in the worst absorbers, peaked sooner, and was better tolerated by every patient. Part of it appeared to be absorbed intact, through a pathway normally used for protein fragments.5
Glycinate also has the strongest outcome trials of the three. In 80 pregnant women with leg cramps, 300 mg a day of magnesium bisglycinate for four weeks halved cramp frequency in 86% of women, against 60.5% on placebo — and nearly half became cramp-free.6 A similar trial using magnesium citrate at the same dose found no benefit.7 And in a small trial of active adults, 350 mg a day of magnesium glycinate reduced exercise soreness and improved perceived recovery.9 The European Food Safety Authority rates magnesium bisglycinate “not of safety concern” at supplement doses.10
A 2025 laboratory study that put 12 commercial magnesium products through a simulated digestion found that magnesium bisglycinate released the most magnesium of all the organic forms tested — about 67%, against about 58% for citrate — and gave the most consistent result whatever the meal it was taken with.11
Glycinate and citrate are both well-absorbed forms. What sets glycinate apart is its gentleness and the glycine it carries: an amino acid studied at 3 g before bed for sleep quality.12
“Oxide loses on absorption almost everywhere. Between citrate and glycinate, the choice is about your gut and your goal, not a clear absorption winner.”
What the head-to-head human studies show
Magnesium bisglycinate vs citrate: which should you choose?
Is magnesium bisglycinate better than magnesium citrate?
Both are well absorbed, so choose by what you want. Magnesium bisglycinate (the same thing as magnesium glycinate) is the better pick for daily evening use, sleep, a sensitive stomach and the bonus glycine. Magnesium citrate suits people who also want help with constipation, because it loosens stools more easily.
“Magnesium bisglycinate” and “magnesium glycinate” are two names for the same compound: one magnesium bound to two glycines. So when you compare magnesium bisglycinate vs magnesium citrate, you are comparing the gentle, glycine-carrying form with the one best known for helping the bowels move.
| Feature | Magnesium bisglycinate | Magnesium citrate |
|---|---|---|
| Magnesium by weight | ~12–14% (fully reacted) | ~16% |
| Compound needed for 440 mg of magnesium | ~3.7 g (usually three tablets) | ~2.7 g |
| Absorption | Well absorbed; released the most magnesium of the organic forms in a 2025 lab study | Well absorbed; highest blood magnesium in a 60-day trial |
| Stomach and bowels | Gentlest; rarely loosens stools | Draws water into the gut; can loosen stools |
| Extra from the partner | About 2.7 g of glycine per 440 mg | Citric acid, no added benefit |
| Trials | Sleep (2025), pregnancy leg cramps, exercise soreness | Absorption studies; used as a laxative |
| Best time to take | Evening, as part of a bedtime routine | Morning or evening, with water |
| Best for | Daily use, sleep, recovery, sensitive stomachs | Magnesium plus help with constipation |
Can you take magnesium glycinate and citrate together? Yes. Some people take citrate in the morning for regularity and glycinate in the evening for sleep. Add up the elemental magnesium from both and keep the total within India’s daily allowance of 440 mg for men and 370 mg for women. If stools become loose, cut the citrate first. Our magnesium side effects guide explains which forms loosen stools and why.
Magnesium oxide vs citrate: which is better?
Is magnesium citrate better than magnesium oxide?
Yes, for absorption. Magnesium citrate was clearly better absorbed than magnesium oxide after a single dose, and over 60 days citrate raised blood magnesium the most while oxide did no better than placebo. Oxide packs more magnesium per tablet (about 60% vs 16%) and costs less, which is why it is common as a laxative and antacid.
The difference comes down to dissolving. Citrate dissolves easily in water and stomach acid, so more of its magnesium is ready to absorb. Oxide barely dissolves, so most of it passes through the gut, pulling water with it.2,4 That is why both can loosen stools, but only citrate is a good way to raise your magnesium. For a daily supplement taken for months, citrate beats oxide, and glycinate beats both on gentleness.
Why non-buffered glycinate matters
What is non-buffered magnesium glycinate?
All the benefits of glycinate depend on getting real glycinate. Many products are buffered — mixed with magnesium oxide to raise the number on the label. Divide the magnesium by the glycinate weight: about 12–14% means a non-buffered chelate; 18% or more means oxide has been added.
A non-buffered (also called unbuffered or fully reacted) magnesium glycinate contains only the chelate. A buffered one is blended with oxide — the least absorbed of the three forms. So a buffered “glycinate” quietly gives you part of its dose as oxide, and carries less glycine: about 1.4 g instead of 2.7 g in a typical 440 mg serving.
You can check any label in ten seconds: divide the elemental magnesium by the magnesium glycinate weight. About 12–14% is non-buffered; 18% or more is buffered. Our buffered vs non-buffered guide walks through worked examples, and our free calculator does the sum for you.
Best magnesium for sleep: what the trials show
Which magnesium is best for sleep?
A 2025 trial found magnesium bisglycinate (250 mg a day) modestly improved insomnia scores over four weeks, especially in people eating less magnesium. Older sleep trials, which used oxide or citrate, found people fell asleep about 17 minutes faster — low-certainty evidence. Glycinate’s gentleness makes it the easiest to take every night.
In a 2025 randomised, placebo-controlled trial of 155 adults with poor sleep, 250 mg of magnesium as bisglycinate a day modestly improved insomnia scores over four weeks compared with placebo, with larger benefits in people whose diets were low in magnesium.13
Earlier trials in older adults with insomnia used oxide or citrate and found people fell asleep about 17 minutes faster than on placebo — though the trials were small and the evidence is low-certainty.14 So magnesium in general may help sleep, and glycinate is the form tested most recently for it — and the one least likely to disturb your night with an upset stomach. Our magnesium glycinate for sleep guide explains the 2025 trial in full.
Side-by-side comparison
What is the difference between magnesium glycinate, citrate and oxide?
Oxide: most magnesium per tablet, least absorbed, strongest laxative effect. Citrate: well absorbed, moderate laxative effect. Glycinate: better absorbed than oxide, gentlest, carries glycine, with sleep, leg-cramp and soreness trials.
| Feature | Magnesium oxide | Magnesium citrate | Magnesium glycinate |
|---|---|---|---|
| Bound to | Oxygen | Citric acid | Two glycine amino acids |
| Magnesium by weight | ~60% | ~16% | ~12–14% |
| Absorption in human studies | Poor — ~4%; matched placebo over 60 days | Good — highest blood levels in a 60-day trial | Better than oxide; strongest edge in poor absorbers |
| Stomach and gut | Strong laxative effect | Moderate laxative effect | Gentlest of the three |
| Outcome trials | No better than placebo for night cramps in older adults | No benefit for pregnancy leg cramps at 300 mg | Pregnancy leg cramps and exercise soreness improved |
| Sleep evidence | Used in older, low-certainty trials | Used in older, low-certainty trials | 2025 randomised trial, modest benefit |
| Lab digestion study (2025) | About 60%, but varied widely (31–84%) | About 58% | About 67% — highest of the organic forms, most consistent |
| Bonus from the partner | None | None beyond regularity | Glycine, a calming amino acid — about 2.7 g per 440 mg |
| What to check | Avoid as a daily supplement | Elemental dose per serving | Non-buffered: about 12–14% magnesium on the label math |
| Cost | Cheapest | Moderate | Highest |
| Best for | Occasional constipation | Magnesium plus regularity | Daily evening use, sensitive stomachs, sleep |
Other magnesium forms you’ll see on labels
What other forms of magnesium are there?
Marine magnesium (such as Aquamin®) dissolved and crossed gut cells better than oxide in laboratory models. Taurate delivers taurine alongside magnesium. Chloride and lactate absorb reasonably well. Threonate is marketed for the brain but its evidence is early. Aspartate absorbs well, but Europe’s food safety authority flagged its safety margin at typical supplement doses.
Marine magnesium
Seawater-derived magnesium such as Aquamin®, which carries 72 trace minerals. In a digestion and gut-cell model it was more available than oxide and comparable to chloride, one of the better-absorbed forms.15
Magnesium taurate
Magnesium paired with taurine, an amino acid that — like glycine — acts on the brain’s calming glycine receptors. Human data on the form itself is limited.
Check your own label
How do I check a magnesium label?
Read the ingredients, not the front of the pack. Look for a named organic form, the elemental magnesium per serving, and the words “fully reacted” or “unbuffered” on a glycinate. Treat plain “magnesium”, magnesium oxide, or a huge unexplained number with suspicion.
“Magnesium oxide” or just “magnesium”
Poorly absorbed; an unnamed form is usually oxide.
“Magnesium bisglycinate” / “glycinate chelate”
Gentle, well tolerated; ideally “fully reacted” or “unbuffered”.
“1,000 mg” or “5X / 7X” headlines
Usually compound weight, not the magnesium your body receives.
“Elemental magnesium” per serving
The honest number — up to India’s daily allowance of 440 mg for men and 370 mg for women.
The 12–14% math on a glycinate
Magnesium ÷ glycinate weight. Higher than about 14% means oxide was added.
“Buffered”, “complex” or “blend”
Usually glycinate mixed with oxide — less glycine, more oxide.
Magnesium Glycinate by Evo Hominus™: the gentle form, nothing mixed in.
We chose the form with the gentlest stomach profile, its own sleep trial and the glycine bonus — and made it 100% non-buffered, so none of the dose is oxide.
Magnesium Glycinate by Evo Hominus™
Launching first. 100% non-buffered magnesium glycinate. Three tablets give 440 mg of elemental magnesium from 3,667 mg of fully reacted magnesium bisglycinate — 12%, the math of a fully reacted chelate — with about 2.7 g of glycine and 0 mg of magnesium oxide. 440 mg is India’s full daily magnesium allowance for men; women can take two tablets. Best taken in the evening.
See Magnesium Glycinate →Bioactive Multivitamin
Coming soon. Our daily multivitamin is in development. Join the waitlist to hear first when it launches.
Join the waitlist →How to choose a magnesium supplement
How do I choose the best magnesium supplement?
Decide what you want magnesium for, pick the form that fits, check the elemental dose, stay within India’s daily allowance, and take it consistently for at least four to eight weeks. Speak to a doctor first if you have kidney disease.
- Start with your goalSleep or a sensitive stomach: glycinate — ideally non-buffered. Help with regularity: citrate. Avoid oxide as an everyday supplement.
- Read the elemental doseThat’s the magnesium you actually get — not the compound weight on the front.
- Stay within India’s limitIn India, FSSAI caps each mineral in a supplement at the ICMR daily allowance — for magnesium, 370 mg for women and 440 mg for men. Loose stools are mostly linked to poorly absorbed forms such as magnesium oxide.17
- Give it time — and check with a doctor if neededStudies measured changes over four to eight weeks. People with kidney disease should only supplement under medical advice.
For timing and amounts, read the best time to take magnesium glycinate and how much magnesium per day.
- The 2025 laboratory study used a simulated digestion, not people, and tested one product of each form; in that model oxide also released about 60%, which doesn’t match human absorption studies — so human data take priority over lab results.11
- The 60-day comparison used an amino-acid chelate of magnesium, not specifically bisglycinate; in it, citrate gave the highest blood magnesium.2 The single-dose citrate study was in 20 healthy men.4
- The glycinate vs oxide study was in 12 people after bowel surgery; overall absorption was similar, and glycinate absorbed better in the four who absorbed worst.5
- The Aquamin® study used a laboratory digestion and gut-cell model; human absorption studies are under way.15
- The leg-cramp trials were in pregnant women; a 2021 pooled analysis of four pregnancy trials using different forms found no overall effect.8 Pregnant women should take supplements only on medical advice.
- The 2025 sleep trial gave 250 mg of magnesium a day as bisglycinate; the effect was modest. The glycine sleep studies gave 3 g of glycine on its own.12,13
Magnesium forms, answered plainly.
Is magnesium glycinate better than magnesium citrate?
Is magnesium glycinate better than magnesium oxide?
Which magnesium is best for sleep?
Why is magnesium oxide so common if it absorbs poorly?
Does magnesium citrate cause diarrhoea?
What does “elemental magnesium” mean?
What is “buffered” magnesium glycinate?
How much magnesium should I take a day?
Can I take magnesium every day?
Which magnesium glycinate should I buy in India?
Magnesium bisglycinate vs magnesium citrate: which is better?
Is magnesium bisglycinate the same as magnesium glycinate?
Magnesium oxide vs citrate: which is better?
Which is better for constipation, magnesium citrate or oxide?
Magnesium oxide vs citrate vs glycinate: which absorbs best?
Can I take magnesium glycinate and citrate together?
What is the best time to take magnesium glycinate and citrate?
Is magnesium citrate good for sleep?
What are the side effects of magnesium citrate?
Which magnesium is gentlest on the stomach?
Which form of magnesium has the most magnesium?
Which magnesium is best for muscle cramps and recovery?
What is the best magnesium supplement?
- a named form, ideally fully reacted, non-buffered magnesium glycinate (bisglycinate);
- the elemental magnesium per serving, up to 440 mg for men and 370 mg for women;
- label math of about 12–14% on a glycinate, so no hidden oxide;
- an FSSAI licence number and a clear list of other ingredients.
Which form of magnesium is best for women?
Why is magnesium citrate used as a laxative?
Studies behind this comparison
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001;14(4):257–62. PMID 11794633 — oxide ~4%; chloride, lactate, aspartate 9–11%.
- Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res. 2003;16(3):183–91. PMID 14596323 — n=46, 300 mg/day, 60 days; amino-acid chelate vs citrate vs oxide vs placebo.
- Blancquaert L, Vervaet C, Derave W. Predicting and testing bioavailability of magnesium supplements. Nutrients. 2019;11(7):1663. PMID 31330811 — 196 mg product (oxide + glycerophosphate) vs 450 mg oxide only.
- Kappeler D, et al. Higher bioavailability of magnesium citrate as compared to magnesium oxide shown by evaluation of urinary excretion and serum levels after single-dose administration in a randomized cross-over study. BMC Nutr. 2017;3:7. DOI 10.1186/s40795-016-0121-3.
- Schuette SA, Lashner BA, Janghorbani M. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. JPEN J Parenter Enteral Nutr. 1994;18(5):430–5. PMID 7815675 — n=12, crossover.
- Supakatisant C, Phupong V. Oral magnesium for relief in pregnancy-induced leg cramps: a randomised controlled trial. Matern Child Nutr. 2015;11(2):139–45. DOI 10.1111/j.1740-8709.2012.00440.x — 300 mg/day magnesium bisglycinate chelate, n=80, 4 weeks.
- Araújo CAL, et al. Oral magnesium supplementation for leg cramps in pregnancy — an observational controlled trial. PLoS One. 2020;15(1):e0227497 — 300 mg/day magnesium citrate, no difference from placebo.
- Liu J, Song G, Zhao G, Meng T. Effect of oral magnesium supplementation for relieving leg cramps during pregnancy: a meta-analysis of randomized controlled trials. Taiwan J Obstet Gynecol. 2021;60(4):609–14. DOI 10.1016/j.tjog.2021.05.006 — 4 RCTs, n=332; no significant reduction in cramp frequency overall.
- Reno AM, et al. Effects of magnesium supplementation on muscle soreness and performance. J Strength Cond Res. 2022;36(8):2198–2203. PMID 33009349 — 350 mg/day magnesium glycinate, n=22.
- EFSA Panel on Food Additives and Nutrient Sources. Opinion on certain bisglycinates as sources of copper, zinc, calcium, magnesium. EFSA Journal. 2008;718:1–26.
- Bawiec P, Jaworowska A, Sawicki J, Czop M, Szalak R, Koch W. In vitro evaluation of bioavailability of Mg from daily food rations, dietary supplements and medicinal products from the Polish market. Nutrients. 2025;17(5):748. DOI 10.3390/nu17050748 — simulated digestion with dialysis, 12 products; bisglycinate 66.7%, citrate 57.5%, oxide 59.8% (range 31–84%).
- Yamadera W, et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep Biol Rhythms. 2007;5:126–131 — 3 g glycine, n=11.
- Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep. 2025;17:2027–2040. PMID 40918053
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021;21:125. PMID 33865376 — oxide/citrate trials, low-certainty evidence.
- Felice VD, O’Gorman DM, O’Brien NM, Hyland NP. Bioaccessibility and bioavailability of a marine-derived multimineral, Aquamin-Magnesium. Nutrients. 2018;10(7):912 — laboratory study (simulated digestion + Caco-2 cells), not a human trial.
- EFSA Panel on Food Additives and Nutrient Sources. Magnesium aspartate, potassium aspartate and other aspartates as sources for minerals. EFSA Journal. 2008;883:1–23.
- FSSAI. Food Safety and Standards (Health Supplements, Nutraceuticals…) Regulations, 2022 — vitamins and minerals capped at one ICMR-NIN 2020 RDA (magnesium: 370 mg women, 440 mg men); NIH Office of Dietary Supplements, Magnesium fact sheet.
- National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals — interactions with medications. ods.od.nih.gov
- Levothyroxine sodium tablets: prescribing information (US Food and Drug Administration label), drug interactions section.
Nutrition Science Hub
Buffered vs non-buffered glycinate
The 10-second label check, with worked examples.
Read the guide → SleepMagnesium glycinate for sleep
What the 2025 trial found, the glycine bonus, and how to take it.
Read the guide → SafetyMagnesium side effects
Loose stools, which forms cause them, and who should avoid magnesium.
Read the guide →