Magnesium Forms Explained

Mineral Complex Series · Vitality Supplements

Magnesium forms, explained

Bisglycinate, citrate, oxide, L-threonate — the magnesium on a label is always bound to something else, and that partner changes how much elemental magnesium you actually get and how well it’s absorbed and tolerated. Here’s every form, compared.

Written & reviewed by the Vitality Supplements nutrition team ·

9Forms compared
3Chemical families
~60%Oxide elemental
8In our complex

Quick Answer

Magnesium forms differ in two ways: how much elemental (actual) magnesium they deliver, and how well they’re absorbed and tolerated. Chelated forms like bisglycinate are gentlest; organic salts like citrate are well absorbed; inorganic salts like oxide are high in elemental magnesium but poorly absorbed. A higher elemental % doesn’t mean more is absorbed — so the “best” form depends on your priority.

The basics

Why the form matters

Magnesium is a reactive metal, so it’s never sold on its own — it’s always bound to a partner molecule to make a stable compound. That partner is what the form name refers to: bisglycinate is magnesium bound to glycine, citrate to citric acid, oxide to oxygen, and so on. The choice of partner decides two things that actually matter on the shelf.

First, elemental magnesium — the amount of actual magnesium in the compound, as opposed to the combined weight of the whole salt. This is the figure that counts towards the NRV of 375mg. Second, bioavailability and tolerability — how much of that magnesium is absorbed, and how gently it sits with your digestion.

The counterintuitive bit: a higher elemental percentage doesn’t mean you absorb more. Magnesium oxide is roughly 60% elemental magnesium — the highest of any common form — yet it’s among the least well absorbed. Chelated forms are lower in elemental content but better absorbed and far gentler. The label number and the usable number are not the same thing.

  • Form name = the molecule magnesium is bound to (glycine, citric acid, oxygen, etc.)
  • Elemental magnesium = the actual magnesium delivered, counted against the 375mg NRV
  • Bioavailability = how much is absorbed; tolerability = how gentle on the gut
  • High elemental % ≠ high absorption — oxide is the classic example

At a glance

The full comparison

The nine most common magnesium forms, grouped by chemical family. “Elemental Mg” is the actual magnesium per gram of compound; “tolerability” reflects how likely a form is to cause loose stools at higher doses.

Form Family Elemental Mg Tolerability Commonly chosen for
Bisglycinate Chelate Lower Excellent Daily use, sensitive stomachs
Taurate Chelate Lower Excellent Evening routines
Citrate Organic salt Moderate (~16%) Good · laxative at high dose General everyday use
Malate Organic salt Moderate Good Daytime use
L-Threonate Organic salt Low Good Cognitive research interest
Orotate Organic salt Low Good Premium blends
Aspartate Organic salt Moderate Good General use
Carbonate Inorganic salt High Can cause gas Blends, antacid-style
Oxide Inorganic salt Highest (~60%) Most laxative-prone Low cost, high elemental on paper

Qualitative guide; exact elemental content and tolerability vary by manufacturer, dose and individual. Based on published reviews and bioavailability research.

Family 1

Chelated forms

Chelates bind magnesium to an amino acid, which protects it through digestion and makes it well absorbed and notably gentle on the gut. They’re lower in elemental magnesium per gram, so the capsule does more of the work — but for daily use and sensitive stomachs they’re the popular choice.

Glycine chelate
Bisglycinate
Magnesium bound to two glycine molecules. Well absorbed and the gentlest common form. “Glycinate” and “bisglycinate” refer to the same thing.
Taurine chelate
Taurate
Magnesium bound to taurine. Well tolerated and often chosen for evening routines. Lower in elemental magnesium per dose.
Why chelates
Gentle & absorbed
The amino-acid partner improves absorption and reduces the laxative effect seen with inorganic salts — at the cost of lower elemental content.

Family 2

Organic salts

Organic salts pair magnesium with an organic acid such as citric or malic acid. They’re generally well absorbed and sit in the middle for elemental content. Citrate is the workhorse of the category; high doses can have a mild laxative effect, which is sometimes the reason people choose it.

Citric acid
Citrate
The most common organic salt. Well absorbed, moderate elemental content (~16%). Mildly laxative at higher doses.
Malic acid
Malate
Magnesium with malic acid, a molecule in the body’s energy cycle. Well tolerated; often chosen for daytime use.
Threonic acid
L-Threonate
A newer form studied in cognitive research. Low in elemental magnesium per dose, so it’s about the form, not the milligrams.

Orotate and aspartate round out the family — both well absorbed and used in premium and general blends respectively.

Family 3

Inorganic salts

Inorganic salts bind magnesium to simple groups like oxide or carbonate. They pack the most elemental magnesium per gram, which looks impressive on a label — but they dissolve poorly, so a smaller share is actually absorbed, and the leftover draws water into the gut.

Highest elemental
Oxide
~60% elemental magnesium — the most on paper — but among the least absorbed and the most likely to loosen the bowels.
Carbonate
Carbonate
High elemental content; needs stomach acid to convert. Can cause gas. Often used in blends and antacid-style products.
Chloride
Chloride
Better absorbed than oxide for an inorganic salt; lower elemental content. Used in oral and topical products.

Putting it together

One form, or a complex?

Because each form has a different trade-off between elemental content, absorption and tolerability, there’s no single “winner.” A single-form product is simple and predictable. A multi-form complex spreads the dose across forms with different profiles — gentler chelates plus well-absorbed organic salts — so you’re not relying on any one form’s weakness.

What matters either way is the elemental magnesium figure and its % NRV — that’s the number to read, not the headline compound weight.

Mineral Complex Series · Guide What is magnesium? The essentials — what magnesium does, its authorised functions, how much you need and the best food sources. Mineral Complex Series · Vitality Supplements Ultimate 8 Magnesium Eight forms in one capsule — 375mg elemental magnesium (100% NRV), every form and dose printed on the label.

People also ask

Common questions about forms

Is magnesium glycinate the same as bisglycinate?

Yes — they’re the same chelate of magnesium and glycine. “Bisglycinate” is the more precise name (two glycine molecules per magnesium); labels use both interchangeably.

Which magnesium is best for absorption?

Chelated forms (bisglycinate, taurate) and organic salts (citrate, malate) are better absorbed than inorganic salts like oxide. Bioavailability research consistently places oxide at the bottom of the range.

Why are there so many forms of magnesium?

Magnesium must be bound to a partner molecule to be stable, and each partner creates a different trade-off between elemental content, absorption and tolerability — hence the long list of options.

Does it really matter which form you take?

It affects tolerability and how much you absorb per capsule, so yes — but consistency and total elemental magnesium matter most. A well-absorbed form taken daily beats a “perfect” form taken sporadically.

How to choose

Picking a form

Vitality Supplements Ultimate 8 Magnesium sidesteps the choice by combining eight forms — bisglycinate, citrate, malate, L-threonate, taurate, orotate, aspartate and carbonate — to deliver 375mg of elemental magnesium (100% NRV) across 2 vegan capsules, with every form printed on the label.

  • Prioritise gentle digestion? Favour chelated forms like bisglycinate
  • Want the most elemental per capsule? That’s the inorganic salts — but absorption is lower
  • Don’t want to choose? A multi-form complex covers several profiles at once
  • Always read the elemental magnesium and % NRV, not just the compound weight
  • Take consistently with food; do not exceed the label dose
🔬3rd Party TestedEvery batch
🇬🇧UK ManufacturedPremium quality
🌱100% VeganHPMC capsules
↩60-Day GuaranteeNo questions asked

Full FAQ

Frequently asked questions

What is the best form of magnesium?

There is no single best form — it depends on your priority. Chelated forms such as bisglycinate are the gentlest on digestion and well absorbed. Organic salts like citrate and malate are well absorbed and widely used. Inorganic salts such as oxide are high in elemental magnesium but less well absorbed. Many products combine several forms so you do not have to choose one.

What is elemental magnesium and why does it matter?

Elemental magnesium is the amount of actual magnesium a compound delivers, as distinct from the total weight of the magnesium salt. It is the figure that counts against the 375mg UK Nutrient Reference Value. A higher elemental percentage does not mean more is absorbed — magnesium oxide is about 60% elemental but among the least bioavailable.

Which magnesium form has the most elemental magnesium?

Magnesium oxide has the highest elemental content, around 60%, followed by carbonate. However, both are less well absorbed than chelated or organic-salt forms, so a higher elemental percentage on the label does not translate to more usable magnesium.

What is the difference between magnesium glycinate and bisglycinate?

They refer to the same chelate — magnesium bound to the amino acid glycine. Bisglycinate is the more precise name (two glycine molecules per magnesium). In practice the terms are used interchangeably on supplement labels.

Which magnesium form is gentlest on the stomach?

Chelated forms such as magnesium bisglycinate and taurate are generally the best tolerated. Inorganic salts, particularly magnesium oxide and high-dose citrate, are the most likely to cause loose stools because unabsorbed magnesium draws water into the bowel.

Why does magnesium oxide have a reputation for being poorly absorbed?

Magnesium oxide is high in elemental magnesium but dissolves poorly, so a smaller proportion is absorbed compared with chelated or organic-salt forms. The unabsorbed magnesium remains in the gut, which is why oxide is the form most associated with a laxative effect.

Which magnesium form is best for sleep?

No magnesium form has an authorised health claim for sleep. Under authorised nutrient claims, magnesium contributes to normal psychological function, normal nervous-system function and the reduction of tiredness and fatigue. Many people prefer gentler chelated forms such as bisglycinate in the evening because they are well tolerated.

Can you take more than one form of magnesium together?

Yes. Combining forms is common, since each has a different elemental content and tolerability profile. What matters for intake is the total elemental magnesium, which should be kept within the dose on the label.

Which forms of magnesium are in Vitality Supplements Ultimate 8 Magnesium?

Ultimate 8 Magnesium combines eight forms — bisglycinate, citrate, malate, L-threonate, taurate, orotate, aspartate and carbonate — providing 375mg of elemental magnesium (100% of the UK NRV) per 2-capsule serving, with every form printed on the label.

Is Ultimate 8 Magnesium suitable for vegans?

Yes. It is encapsulated in HPMC vegan capsules and is free from gluten, GMOs, dairy, soy, artificial colours and preservatives.

Sources

References & further reading

This guide draws on peer-reviewed reviews and bioavailability research. It is informational and not a substitute for professional medical advice.

  1. de Baaij JH, Hoenderop JG, Bindels RJ. Magnesium in man: implications for health and disease. Physiological Reviews. 2015;95(1):1–46. PubMed
  2. Schwalfenberg GK, Genuis SJ. The Importance of Magnesium in Clinical Healthcare. Scientifica. 2017;2017:4179326. PMC
  3. Blancquaert L, Vervaet C, Derave W. Predicting and Testing Bioavailability of Magnesium Supplements. Nutrients. 2019;11(7):1663. PubMed
  4. Commission Regulation (EU) No 432/2012 — list of permitted health claims made on foods.

Mineral Complex Series · Vitality Supplements

Ultimate 8 Magnesium

Eight forms in one complex · 375mg elemental (100% NRV) · 60 vegan capsules · 30 servings · Third-party tested · UK manufactured · 60-day guarantee

Shop Ultimate 8 Magnesium

This page is for informational purposes only. Magnesium taken as a supplement is a food supplement. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. Magnesium is not a medicine and does not treat, cure or prevent any disease. The authorised nutrient functions referenced apply when intake is sufficient. If you are pregnant, breastfeeding, taking medication, or have a medical condition, consult your GP before use. Store out of reach of children.