Types of Magnesium: All 8 Forms Compared — Which Is Best in the UK? (2026)

By Erin Rose · Updated July 13, 2026 · Reviewed against primary sources · Methodology · About Us

Not medical advice — this summarises published research; talk to a clinician before starting a supplement. Methodology.

Prices and cost per day here are from our US catalogue in USD. UK prices differ — use them to compare products with each other, not to budget in pounds. Buy buttons open the product on Amazon.co.uk; where a brand is not sold in the UK, the button opens an Amazon.co.uk search instead of a dead page.

Some links here go to Amazon and we may earn a commission if you buy. It never changes which product we pick or what we say about it — picks are ranked by cost per serving, certification listings, and whether the label agrees with the safety ceiling. How we choose.

Magnesium Forms and What Is Known About Each

These are the common forms and what is known about each. Talk to your clinician about which suits you.

• Glycinate: well absorbed and often described as gentle on the stomach.
• Citrate: well absorbed and cheap; it has a mild laxative effect.
• L-Threonate: a newer form. Brain-magnesium data comes mostly from rat studies. It costs roughly 5x more per mg than glycinate.
• Oxide: only about 4% absorbed. It is sold mainly as an antacid or occasional laxative.
• Taurate: paired with taurine. There are no human trials of this pairing yet.
• Malate: bound to malic acid, a part of the body's energy cycle. This is a mechanism, not a trial result.
• Sulfate (Epsom) and chloride: used for baths and topical use, not oral supplements.

All 8 Magnesium Forms at a Glance

Top Product Picks by Form

Based on our product comparison research, here are the best-value options for the most popular forms:

Why the Label Percentage Misleads You

The "elemental magnesium" percentage on a label is not how much you absorb, and reading it as though it were is the most expensive mistake in this category. Oxide is 60% elemental magnesium by weight and only about 4% absorbed; glycinate is ~14% elemental and absorbed far better. The magnesium is identical in every form — what changes is the carrier it's bound to, which drives both how much gets in (chelated and organic carriers beat inorganic salts) and how it sits with the stomach (citrate loosens stools). So we compare cost per absorbed dose, never milligrams on the label.

If glycinate isn't for you, citrate absorbs just as well: NOW Magnesium Citrate 200 mg (250 Tablets)$0.16/day at its label serving. Note that serving is 400 mg — see how that compares to the 350 mg ceiling.

If that chart makes you want a certified one rather than the cheapest one, it is Nature Made Magnesium Glycinate 200mg$0.39/day — per the catalog, USP Verified, at 200 mg elemental per serving. A certification concerns label accuracy, not an effect.

L-Threonate sits at the bottom of that chart for a reason opposite to oxide's: its ~7% elemental read looks low, but brain-magnesium data comes mostly from animal studies, and it is listed by its Magtein content, not its elemental percentage. One option: Life Extension Neuro-Mag Magnesium L-Threonate (90 Capsules)$1.02/day. Ask your clinician about any dose.

What the shelf actually sells, and at what dose

The argument above is about absorption. This is about what you can actually buy, which turns out to explain why the badly absorbed form keeps winning.

We read 833 magnesium labels filed with the NIH Dietary Supplement Label Database — out of 39,884 it lists on the market, across 276 brands — and took the declared dose and the named form off each Supplement Facts panel.

The dose runs backwards to the absorption. Oxide — the form that is roughly 4% absorbed — carries the highest median dose on the shelf at 300 mg. Glycinate, the form this page recommends, carries the lowest at 232.5 mg. That is not a coincidence and it is not manufacturers being generous: a poorly absorbed salt is cheap and dense, so you can put a big number on the front of the bottle without raising the cost of making it. The big number is the product.

Which is why the shelf is shaped the way it is. Citrate is the most common form at 376 labels, and oxide is close behind at 145. Glycinate — the one often chosen by people who cannot tolerate the laxative effect — appears on just 102. If it feels hard to find a glycinate product at a sensible price, that is because roughly five labels carry citrate or oxide for every one that carries glycinate.

Read the two columns together before you compare prices. A 400 mg oxide tablet and a 200 mg glycinate capsule are not two doses of the same thing, and the cheaper number per milligram is attached to the form that delivers least of it.

Method: 833 magnesium labels retrieved from the NIH Dietary Supplement Label Database (DSLD) v9 on 2026-08-29; 825 carried a parseable elemental dose and 779 also directed a daily amount, across 276 brands. Forms are read from the declared ingredient, so a label naming two magnesium salts is counted under each. What it cannot tell you: how many bottles of each form are sold. This counts labels on the market, not purchases, so it describes what is on offer rather than what people choose.

Detailed Breakdown by Form

Read through all eight? Here is the lowest-cost glycinate we checked: Nature Made Magnesium Glycinate 200mg$0.39/day — the lowest cost per absorbed dose among the glycinates we checked.

Does the Label Agree With the Supplement Limit?

Often not. We pulled every magnesium product in our catalog from NIH's Dietary Supplement Label Database — the labels manufacturers actually file with the government — and multiplied each declared dose by the maximum daily servings the label itself permits. Here is that check.

Which Magnesium Is the Best Value?

"Best value" isn't the cheapest bottle — it's the lowest cost per dose your body actually absorbs and can use. On that measure:

• Best value overall — magnesium citrate. Priced at an equal 350 mg elemental dose — the supplemental ceiling, so nothing here is costed at a dose we'd tell you not to take — the cheapest citrate in our catalog works out to $0.14/day against $0.27 for the cheapest glycinate. Both are well absorbed, so the gap is small — choose on tolerance, not price.
• Best if you want gentleness — magnesium glycinate. Among the best-absorbed and often described as easy on the stomach. Normalised to the same elemental dose it is not the pricier option people assume — our cheapest glycinate runs $0.27/day against $0.14 for the cheapest citrate. The pick at the top of this page is not the cheapest one, though: it is the cheapest whose label keeps a single serving under the ceiling.
• The false economy — magnesium oxide. Cheapest per bottle, but at ~4% absorption most of it passes through unused, so it's actually the worst value for raising your levels despite looking cheapest.

The honest short answer: at an equal elemental dose these two cost about the same, so choose on how your gut reacts — glycinate is usually the gentler of the two in practice, citrate is the one that loosens stools, and no trial has compared them head-to-head on that. Skip oxide if absorption is what you are after.

And if you specifically want oxide: Nature Made Magnesium Oxide 250 mg (200 Tablets) is $7.99 for a 200-day supply — only about 4% of it is absorbed.

Other, Less Common Forms

Beyond the main eight, a few more forms turn up on labels:

• Magnesium orotate — bound to orotic acid and popular in European and sports circles, but human evidence is thin and it's expensive.
• Magnesium lactate — moderately absorbed and gentle on the stomach; used in some supplements and food fortification.
• Magnesium aspartate — an older amino-acid form with decent absorption, usually seen in combination products.
• Magnesium carbonate — converts to magnesium chloride in stomach acid and works mainly as an antacid; absorption is on the low side, like oxide.

Go Deeper

For the full evidence and product data on common questions:

• Magnesium and sleep — glycinate, 6 products compared by studies and cost
• Magnesium and anxiety — what the studies show
• Glycinate vs citrate — the two most-recommended forms, head to head
• How much to take — dosing, timing, and elemental vs compound weight
• How long magnesium takes to work — what the sleep, anxiety, and cramp trials actually timed
• Best time to take magnesium — morning vs night, with food, and what to space it away from
• Taking magnesium with vitamin D — how the two interact
• Signs of magnesium deficiency — who's most at risk and how it's tested

Safety and Drug Interactions

Regardless of form, magnesium supplements share the same core safety considerations:

• Kidney disease: Magnesium is cleared by the kidneys. Consult your doctor before supplementing if you have impaired kidney function (eGFR below 60).
• Antibiotics: Magnesium binds to tetracyclines and quinolone antibiotics, reducing their absorption. Separate by 2+ hours.
• Bisphosphonates: Magnesium reduces absorption of osteoporosis drugs like alendronate. Separate by 2+ hours.
• Diuretics: Thiazide diuretics are associated with low magnesium, while loop diuretics were not in a 9,820-person cohort (Kieboom 2018, PMID: 30095199); potassium-sparing diuretics reduce magnesium excretion. All three affect supplementation needs.
• PPIs: Long-term proton pump inhibitor use can cause magnesium deficiency (FDA safety alert).
• Upper limit: 350mg/day supplemental (NIH). Dietary magnesium has no upper limit. Exceeding this primarily causes diarrhea; glycinate is usually reported as gentler, though no trial has compared diarrhea rates between forms at the same elemental dose.

If you take prescription medications, consult your pharmacist before starting magnesium.

Stomach tolerance

If you are sensitive to magnesium's laxative effect, glycinate is often described as gentler, though no trial has compared forms at the same dose. One option: Nature Made Magnesium Glycinate 200mg$0.39/day.

Frequently Asked Questions

Related Comparisons

• Magnesium side effects by form — which forms cause diarrhea and at what dose
• Magnesium Glycinate vs Citrate — Detailed head-to-head comparison
• Magnesium Gummies — The citrate shelf at a fraction of the dose; the "600 mg" salt-weight trap
• Magnesium and Sleep — 6 products compared by studies and cost
• Magnesium and Anxiety — What the studies show
• Magnesium for Muscle Cramps — Honest Cochrane review assessment
• Dosage Guide — How much, when, and elemental vs compound weight
• Deficiency Signs — ~50% of US adults don't meet the RDA
• All Magnesium Guides

Sources