Types of Magnesium: Which Form Should You Take?

The main types of magnesium sold as supplements are citrate, glycinate (bisglycinate), oxide, chloride, malate, L-threonate, taurate, sulfate and orotate. They all deliver the same mineral; what changes is how much magnesium each compound actually contains, how well your gut absorbs it and how likely it is to send you running to the bathroom. For most people, citrate or glycinate is a sensible starting point, oxide is best treated as a laxative or antacid, and the more exotic forms carry bigger claims than their evidence supports.

Below you’ll find what magnesium does, how much you need, a side-by-side table of every common form, and the safety points your pharmacist would want you to know.

What does magnesium do in the body?

Magnesium is a cofactor for more than 300 enzyme systems, so it touches almost everything: energy production, muscle contraction, nerve signalling, blood sugar control, blood pressure and building bone and DNA. An adult body holds roughly 25 grams of it, and 50 to 60% of that sits in your skeleton.

Shortfalls are common. US survey data summarised by the NIH show that about 48% of Americans get less magnesium from food than the average requirement. Diets heavy in refined grains and light on vegetables, nuts and legumes make a shortfall more likely. Good food sources include pumpkin seeds, almonds, spinach, black beans, whole grains and dark chocolate.

How much magnesium do you need?

Adult men need 400 to 420 mg a day and adult women 310 to 320 mg, according to the Dietary Reference Intakes shared by Health Canada and the US National Academies. Health Canada publishes these values in its reference values for elements, and the figures match the ones used by the NIH.

Age	Men (mg/day)	Women (mg/day)	Pregnancy (mg/day)
14 to 18	410	360	400
19 to 30	400	310	350
31 and older	420	320	360 (to age 50)

Here’s the part many articles skip. The Tolerable Upper Intake Level for adults is 350 mg a day, and it counts only magnesium from supplements and medications. Food magnesium doesn’t count toward it, because your kidneys handle dietary amounts easily. So a 400 mg supplement on top of a decent diet already exceeds the limit, which is one reason loose stools are such a common complaint.

Elemental magnesium vs compound weight: why the label matters

Elemental magnesium is the actual mineral in a supplement; the rest of the compound’s weight is whatever it’s bonded to. Magnesium bisglycinate, for example, is about 14% magnesium by weight, so 1,000 mg of the compound delivers roughly 140 mg of magnesium.

Supplement labels are meant to declare the elemental amount, not the weight of the whole compound. If a bottle says “magnesium (from magnesium citrate) 150 mg”, you’re getting 150 mg of magnesium. If a marketing claim shouts “1,000 mg magnesium glycinate” on the front, check the back. That’s also why oxide pills look so strong on paper: oxide is about 60% magnesium, but very little of it gets absorbed.

For formulators, this is where the maths gets real. Elemental content shifts with hydration state and whether a chelate is “buffered” with oxide, so the certificate of analysis should state assayed magnesium, not a textbook percentage. Low-percentage forms such as threonate or orotate need large fills to reach a meaningful dose, which drives capsule count and cost. Your label must declare the elemental quantity and the source; our guide to Canadian NHP labelling and licensing rules covers how that fits into an NPN application.

Types of magnesium compared

The quick answer: pick a form based on your goal and your gut. The percentages below are approximate, calculated from each compound’s molecular weight, and real products vary.

Form	Elemental Mg (approx.)	Commonly used for	Strength of evidence	Notes
Citrate	11 to 16%	General top-up, constipation	Moderate (absorption studies)	Well absorbed; laxative at higher doses
Glycinate / bisglycinate	About 14% (pure)	Sleep, relaxation, sensitive stomachs	Limited for specific benefits	Gentle on the gut; “buffered” versions contain oxide
Oxide	About 60%	Constipation, heartburn	Good as a laxative; poor as a top-up	Low absorption; common in cheap tablets
Chloride	About 12% (hexahydrate)	Oral top-up, topical oils and flakes	Moderate orally; weak for skin absorption	Dissolves well; can loosen stools
Malate	About 12 to 15%	Fatigue, muscle pain	Weak (small, mixed trials)	Often marketed for fibromyalgia
L-threonate	About 7 to 8%	Memory, sleep	Early (mostly animal; a few small human trials)	Expensive; low elemental content
Taurate	About 9%	Heart and blood pressure support	Very limited (mainly animal)	Taurine adds its own effects
Sulfate (Epsom salt)	About 10% (heptahydrate)	Baths, hospital IV use	Weak for baths	Poorly absorbed orally; strong laxative
Orotate	About 6 to 7%	Heart health, athletes	Very limited	Low elemental content, higher price

Citrate and glycinate: the everyday workhorses

Magnesium citrate dissolves well in water, and the NIH notes that forms which dissolve well tend to be absorbed more completely. It’s a good general choice and a gentle option for occasional constipation. Glycinate binds magnesium to the amino acid glycine and is usually easier on the stomach. People reach for it at bedtime, though the sleep claims rest more on magnesium research in general than on glycinate trials specifically. If you’re torn between the two, a separate head-to-head on glycinate vs citrate is coming to our ingredient science section.

Oxide and sulfate: better for the bowels

These two pull water into the intestine. That makes oxide a cheap, effective laxative and antacid, and it’s why Epsom salt (magnesium sulfate) doubles as an oral laxative. As a way to raise your magnesium status, both are underwhelming. Soaking in an Epsom bath feels lovely, but good evidence that meaningful magnesium crosses your skin is lacking. The same goes for chloride sprays.

Threonate, taurate, malate and orotate: promising stories, thinner data

Magnesium L-threonate got its reputation from rat studies suggesting it raises magnesium in the brain. Human data are still early. One 2024 trial in 80 adults with self-reported sleep problems found better sleep scores after 21 days on 1 g a day, but that’s a small, short study. Taurate and orotate have mostly animal or very small clinical studies behind them, and malate’s link to muscle pain comes from a few small trials with mixed results. None of these are bad choices; just don’t pay a premium expecting proven results.

Which form is absorbed best?

Organic forms (citrate, glycinate, malate, lactate) are generally absorbed better than inorganic ones like oxide. A 2021 systematic review of magnesium supplement bioavailability reached that conclusion while noting that absorption also depends on dose.

Dose matters more than people think. Your gut absorbs a larger share of small amounts, so splitting 300 mg into two 150 mg servings with meals often works better than one big hit. Your existing status matters too: people who are low tend to absorb more.

What are the side effects?

Diarrhea is the big one, sometimes with nausea and cramping. The NIH names carbonate, chloride, gluconate and oxide as the forms most often reported to cause it. Dropping the dose or switching to glycinate usually fixes the problem.

True toxicity is rare in healthy people and has mostly been linked to very large doses of laxatives or antacids, often above 5,000 mg a day. Warning signs include low blood pressure, nausea, facial flushing, lethargy and muscle weakness, and severe cases can affect breathing and heart rhythm.

Does magnesium interact with medications?

Yes, and the timing tricks are worth knowing. The NIH magnesium fact sheet for health professionals lists these key interactions:

• Antibiotics: tetracyclines (such as doxycycline) and quinolones (such as ciprofloxacin) can bind to magnesium. Take the antibiotic at least 2 hours before or 4 to 6 hours after a magnesium supplement.
• Bisphosphonates: osteoporosis drugs like alendronate absorb poorly alongside magnesium, so keep them at least 2 hours apart.
• Diuretics: loop and thiazide diuretics (furosemide, hydrochlorothiazide) increase magnesium loss in urine, while potassium-sparing types such as spironolactone reduce it and can push levels up.
• Proton pump inhibitors: taking drugs like omeprazole or pantoprazole for more than a year can lower magnesium levels. Supplements often help, but your doctor may want a blood test.

If you have kidney disease, talk to your doctor before taking any magnesium. Healthy kidneys clear excess magnesium; damaged ones can’t, so even ordinary doses and magnesium-containing laxatives or antacids can build up to harmful levels.

The bottom line

Start with food, then fill the gap if you need to. For a plain top-up, citrate or glycinate at 100 to 350 mg of elemental magnesium a day covers most people. Choose oxide only if you want the laxative effect, and treat threonate, taurate and orotate as interesting but unproven. Read the elemental amount on the back of the bottle, look for an NPN, and use our checklist on how to choose a quality supplement in Canada before you buy. Starting a new medication or managing a kidney condition? Run it by your pharmacist first. You can read more about how we research health topics in our editorial policy and medical disclaimer.

Frequently asked questions

Sources and further reading: NIH Office of Dietary Supplements: Magnesium; Health Canada: Dietary reference intakes for elements; Pardo et al. 2021, Nutrition: Bioavailability of magnesium food supplements.