Pure Encapsulations · 360 capsules · $87.99
Magnesium (Glycinate): Supports heart health, muscle contractions and metabolism‡
This highly bioavailable form of magnesium chelate glycinate is less likely to cause loose stools in sensitive individuals than other forms of magnesium. This vital mineral also helps the body use certain vitamins, including vitamin B6, vitamin C, and vitamin E.‡ Magnesium assists with the metabolism of carbohydrates, amino acids and fats, as well as energy production and the utilization of calcium, phosphorus, sodium, and potassium. It’s involved in a number of reactions in the body, such as the contraction and relaxation of muscles and cardiac function.
In a cross-sectional study with 210 elderly individuals, optimal magnesium intake was associated with positive mood, lipid metabolism and lean body mass. In a 15-year study involving almost 5,000 young adults, higher intakes of magnesium were associated with healthy cardiovascular function and glucose utilization. Another large cross-sectional study found that magnesium intake was positively associated with bone mineral density in certain subgroups.‡
STORAGE: Store in a cool, dry place.
WARNING: If you are pregnant or lactating, have any health condition, or are taking any medication, consult your health professional before use.
Magnesium glycinate is magnesium bound to the amino acid glycine. It is one of several supplement forms, and research suggests that organic magnesium salts like this one are absorbed more completely than magnesium oxide 1. It supplies an essential mineral, it does not treat any disease, and amounts and timing belong to the product label and your clinician.
Magnesium is an essential mineral, not a drug, so the form printed on a label does not change what the mineral does once it is inside you. What the form changes is how much of it crosses the gut wall, how much stays behind in the bowel, and how your digestion tends to react.
Magnesium glycinate, also sold as magnesium bisglycinate, is magnesium chelated to glycine, one of the smallest amino acids. Chelation means the mineral sits inside an organic carrier rather than existing as a simple inorganic salt. That matters because magnesium is absorbed in the small intestine partly by passive diffusion and partly through transporters, and how readily a salt dissolves in the gut strongly influences how much of it ever reaches the bloodstream. Research suggests that organic magnesium salts, including glycinate and citrate, show higher bioavailability than inorganic magnesium oxide 1, and a human pharmacokinetic comparison of magnesium salts reported the same broad pattern 2.
The mineral itself is involved in an unusually wide range of cellular work. Research suggests that magnesium acts as a cofactor across hundreds of enzymatic reactions, including those involving ATP, nucleic acid synthesis, nerve conduction and muscle contraction 3. It also sits upstream of other nutrients. Research suggests that the enzymes that synthesise and activate vitamin D are magnesium dependent, so magnesium status may influence how vitamin D is handled 4. In the kidney, magnesium depletion is associated with renal potassium wasting, which is one reason a low potassium level can be stubborn to correct while magnesium remains low 5.
None of that turns a magnesium supplement into a therapy. It makes magnesium a mineral the body cannot work without, which is a different and much more modest claim.
Related: Does Magnesium Lower Blood Pressure?
They differ mainly in two ways, how much of the magnesium is absorbed and how much of it stays in the bowel drawing water in behind it. Inorganic oxide carries a lot of elemental magnesium per unit of weight but dissolves poorly, so a larger share passes through unabsorbed. Organic salts dissolve more readily and tend to behave differently in the gut.
| Form | What it is | What research says about absorption | Usual gut behaviour |
|---|---|---|---|
| Magnesium glycinate (bisglycinate) | Magnesium chelated to the amino acid glycine, an organic form | Research suggests organic salts are absorbed more completely than oxide 1 | Less unabsorbed magnesium left in the bowel, so commonly reported as easy on digestion |
| Magnesium citrate | Magnesium bound to citric acid, soluble and organic | Studies suggest better bioavailability than oxide 1 2 | Osmotically active, widely used where a laxative effect is wanted |
| Magnesium oxide | Inorganic salt, high elemental magnesium by weight, poorly soluble | Lower fractional absorption than organic salts in comparative work 1 | More magnesium remains in the bowel, which loosens stool |
| Topical magnesium (sprays, flakes, baths) | Magnesium salts applied to skin | A review of transdermal magnesium concluded the evidence for meaningful absorption through skin is insufficient 7 | Not a reliable route for raising body stores |
Absorption figures vary widely between individuals and with whatever else is in the stomach at the time, so treat the table as a pattern rather than a fixed rule. Elemental magnesium content also differs by form, which is one reason label amounts are not directly comparable between products, and why the label and a clinician decide what is appropriate for a given person.
Most of the research sits in three places, absorption, magnesium status and deficiency, and a small number of clinical questions where results are mixed. A systematic review of magnesium food supplements examined how different salts compare for bioavailability and found organic forms generally favoured over oxide 1, and earlier human pharmacokinetic work pointed the same way 2.
On the biology side, reviews describe magnesium's role in enzyme function, bone, neuromuscular signalling and how deficiency is detected 3. Nephrology teaching on magnesium disorders covers how the kidney regulates the mineral, why some medicines and gut conditions are associated with low magnesium, and why people with impaired kidney function can retain it 8.
Clinical questions are where the picture thins out. A Cochrane review of magnesium for skeletal muscle cramps concluded that it is unlikely magnesium provides a clinically meaningful reduction in cramps in older adults, and that evidence for cramps in pregnancy was conflicting 6. That is a useful example of how a plausible mechanism does not automatically produce a measurable benefit.
Here is what the cited evidence does not show. It does not show that glycinate specifically outperforms other oral forms for any clinical outcome. It does not show that supplementing improves sleep, mood, anxiety, migraine or blood pressure in people whose magnesium status is already adequate. It does not show that higher absorption translates into better results. Supplement marketing frequently runs ahead of those boundaries, and a page like this one should not.
Magnesium carries a double positive charge, so in the gut it can bind to certain medicines and reduce how much of them is absorbed. Separately, some medicines change how much magnesium the body holds on to.
| Interaction | What happens | What to do about it |
|---|---|---|
| Some medicines for bacterial infections | Magnesium can bind these medicines in the gut and reduce their absorption, which can blunt treatment | Ask the prescribing clinician or pharmacist how to space them, and never skip or alter a prescribed course on your own |
| Some bone medicines | Absorption of these medicines is reduced by polyvalent minerals taken around the same time | Ask a pharmacist about separation before combining them |
| Thyroid hormone medication | Mineral supplements can interfere with absorption of oral thyroid hormone | Raise it with the prescriber, who may want thyroid labs rechecked |
| Iron, zinc and calcium supplements | Minerals can compete for shared absorption pathways | A pharmacist can advise on separating them, especially if iron was prescribed for diagnosed deficiency |
| Proton pump inhibitors and some diuretics | Long term use of certain medicines is associated with lower magnesium levels 8 | Worth discussing with a clinician, who may decide to check magnesium |
| Other magnesium-containing products | Indigestion remedies and laxatives often contain magnesium, which is easy to double up on by accident | Read every label you are already using before adding another |
The point of listing interactions is not to self-manage around them. It is so you can ask a clinician or pharmacist a specific question about your own medicine list.
The commonly reported effects of oral magnesium supplements are digestive, mainly loose stools, diarrhoea, abdominal cramping and nausea. These are usually related to how much magnesium stays unabsorbed in the bowel, which is why poorly absorbed forms tend to be the bigger offenders.
Does magnesium make you poop? Often, yes, and that is mechanical rather than mysterious. Magnesium left in the intestine is osmotically active, so it pulls water into the bowel, softens stool and speeds transit. Forms with lower fractional absorption, such as oxide, leave more behind to do this, and citrate is widely used for the same reason. Because glycinate appears to be absorbed more completely than oxide, less of it remains in the bowel, which is the usual explanation for why people describe it as gentler.
Can magnesium cause constipation? It is not a typical effect, and the usual direction of travel is the opposite. If stools become harder while someone is taking a magnesium supplement, the more likely explanations are elsewhere, including iron or calcium supplements taken alongside it, low fluid or fibre intake, reduced activity, or a medicine added around the same time. Persistent constipation, and especially a change in bowel habit that does not settle, is worth discussing with a clinician rather than attributing to a supplement.
Can you take iron and magnesium together? In most cases both can be supplemented, but minerals compete for absorption, so taking them at the same moment may reduce how much iron you take up. A pharmacist can advise on separating them, and if iron was prescribed for a diagnosed deficiency, the prescriber should be the one to say how to arrange it. It is also worth remembering that oral iron commonly causes constipation itself, which can muddle the question of which supplement is doing what.
One more caution belongs here. People with reduced kidney function can accumulate magnesium rather than clear it, and symptoms such as marked weakness, drowsiness, flushing or a slow heartbeat after starting a magnesium product are worth discussing with a clinician promptly rather than waiting them out 8.
Anyone with kidney disease, because the kidney is the main route by which excess magnesium leaves the body and impaired clearance is associated with magnesium retention 8. That single point matters more than every other consideration on this page.
It is also worth asking first if you take several prescription medicines, particularly the classes listed above, if you have a gut condition that affects absorption or have had bowel surgery, if you are pregnant or breastfeeding, if you have a known heart rhythm or conduction problem, or if you are already using indigestion remedies or laxatives that contain magnesium. In each of those situations the question is not whether magnesium is a good mineral, it is whether adding more is sensible for your particular physiology.
The common test is a serum magnesium level, and it is useful but blunt. Only a small fraction of the body's magnesium circulates in blood, with most held in bone and inside cells, so a result inside the standard range does not rule out depletion, and reviews of magnesium detection discuss exactly that limitation 3 8.
| Test | Typical lab reference range | What it reflects |
|---|---|---|
| Serum magnesium | Roughly 1.7 to 2.2 mg/dL (about 0.7 to 0.95 mmol/L) | Circulating magnesium at one moment, a small share of total body stores |
These are typical lab reference ranges and they vary by laboratory, assay, age and sex, so read your own report against the range printed on it. A sensible way to use a result is observation, then meaning, then next step. The observation is the number. The meaning is hedged, a low or low-normal value may reflect intake, gut losses, medicines or kidney handling, and a value inside the range does not by itself prove sufficiency. The next step is a conversation with a clinician, who can interpret it alongside potassium, calcium, vitamin D, kidney function and your medicine list rather than in isolation. FitScript's membership includes 150+ biomarkers tested per year, and magnesium is one of the markers that can be tracked over time rather than read once.
This page deliberately gives none of that. Elemental magnesium content differs between forms, tolerance differs between people, and the right answer changes with kidney function, medicines, diet and current status. Amounts and timing are for the product label and for a clinician or pharmacist who knows your history, and that is the appropriate place for those decisions to sit.
If you want to see where you actually stand before adding anything, the Magnesium biomarker page explains what a serum result reflects, what it misses, and how Atlas, FitScript's AI health advisor, reads it alongside your other markers.
This page is educational and is not medical advice. Discuss any supplement, lab result or treatment with a clinician or licensed provider before acting on it.
It is magnesium chelated to the amino acid glycine, sometimes labelled magnesium bisglycinate. It is an organic magnesium salt, meaning the mineral is carried in an organic complex rather than existing as a simple inorganic salt like oxide. It supplies the essential mineral magnesium and is not a treatment for any condition.
Both are organic salts, and organic forms may be absorbed more completely than magnesium oxide. The practical difference is usually in the gut. Citrate is osmotically active and widely used where a laxative effect is wanted, while the glycinate form tends to leave less unabsorbed magnesium in the bowel. Neither is 'better' in the abstract.
Often, yes, depending on the form. Magnesium that stays unabsorbed in the intestine pulls water in behind it, which softens stool and speeds transit. Poorly absorbed forms such as oxide leave more behind to do this. Better absorbed forms leave less, which is why they are commonly described as gentler.
Constipation is not a typical effect of magnesium, and the usual direction is the opposite. If stools harden while you are taking it, look at other contributors such as iron or calcium supplements, low fluid or fibre intake, reduced activity, or a new medicine. A persistent change in bowel habit is worth discussing with a clinician.
Usually both can be supplemented, but minerals compete for absorption, so taking them at the same moment may reduce iron uptake. A pharmacist can advise on separating them, and if iron was prescribed for a diagnosed deficiency, the prescriber should decide how to arrange it. Oral iron can also cause constipation on its own.
Reported effects are mostly digestive, including loose stools, diarrhoea, abdominal cramping and nausea, and they relate largely to how much magnesium remains unabsorbed in the bowel. People with reduced kidney function can accumulate magnesium, so symptoms such as marked weakness, drowsiness or a slow heartbeat are worth discussing with a clinician promptly.
It can. Magnesium may bind some medicines for bacterial infections in the gut and reduce their absorption, and absorption of some bone medicines is also reduced by polyvalent minerals. Ask the prescriber or a pharmacist how to handle the combination, and never stop or change a prescribed medicine on your own.
Not entirely. Only a small share of the body's magnesium circulates in blood, with most held in bone and inside cells, so a serum result inside the standard range does not confirm that stores are adequate. A clinician interprets it alongside potassium, calcium, vitamin D, kidney function and your medicine list.
Meaningful absorption of magnesium through skin is not established. Topical products may feel pleasant, but they are not a reliable way to raise body magnesium, and an oral form discussed with a clinician is the better studied route.
Anyone with kidney disease comes first, because impaired clearance is associated with magnesium retention. Also worth asking first if you take several prescription medicines, have a gut condition affecting absorption, are pregnant or breastfeeding, have a known heart rhythm problem, or already use indigestion remedies or laxatives that contain magnesium.