How to compare magnesium forms without the marketing
Answer
Compare on three things: how much of the compound is magnesium, how well that form is absorbed and tolerated at a full serving, and what 100mg of elemental magnesium costs in that product.
Key takeaways
- What actually separates the forms?
- The proportion of magnesium by weight, absorption, and tolerability at a full daily serving. Marketing language separates none of them.
- Which form is best absorbed?
- Chelated and organic salts generally absorb better than oxide. Differences between the good forms are modest.
- Which is gentlest?
- Bisglycinate, generally. Oxide is the form most associated with a laxative effect at a full serving.
- How is value compared?
- Cost per 100mg of elemental magnesium, not cost per tub or per capsule.
Three axes, and nothing else
Every meaningful difference between magnesium forms sits on one of three axes. How much of the compound is actually magnesium, which decides how much compound is needed for a given serving. How well the form is absorbed, which decides how much of that reaches the player. And how comfortable it is at a full serving, which decides whether the product is still being taken in November.
Everything else on a pack, high absorption, superior bioavailability, advanced chelate, is marketing language with no defined threshold behind it.
| Form | Magnesium by weight | Absorption | Tolerability at a full serving |
|---|---|---|---|
| Oxide | About 60 percent | Poor | Worst, most associated with loose stools |
| Citrate | About 16 percent | Good | Reasonable, mildly laxative at higher doses |
| Bisglycinate | About 20 percent | Good | Best of the common forms |
| Malate | About 15 percent | Good | Reasonable |
| Taurate | About 9 percent | Good | Reasonable, and a lot of compound for the dose |
| Lactate | About 12 percent | Good | Reasonable |
Absorption, kept in proportion
The gap that matters is between oxide and everything else. Oxide is poorly absorbed and the unabsorbed portion is what causes the effect the form is known for.
Between the well absorbed forms, the differences reported are modest rather than decisive, and marketing tends to present small differences as large ones. A player choosing between bisglycinate and citrate is not making a consequential decision on absorption. A player choosing between either and oxide is.
Tolerability, which decides more than absorption does
The practical determinant of whether a supplement works is whether it gets taken for eight months, and the most common reason one gets abandoned is gut discomfort at a full serving.
Bisglycinate is chelated to glycine and is generally the most comfortable of the common forms at a complete daily dose. That is not a claim about superior results, it is a claim about adherence, and adherence is what a daily intake product runs on. Futuro Labs Magnesium Glycinate uses bisglycinate for exactly that reason.
Cost per 100mg of elemental magnesium
Cost per day is the right comparison between products a player might actually take. Cost per 100mg of elemental magnesium is the right comparison between forms, because it normalises for the fact that a taurate product needs three times the compound weight of a bisglycinate one for the same magnesium.
Futuro Labs Magnesium Glycinate delivers 300mg elemental for 22.2p, which is 7.4p per 100mg. Run that on any product and the ones charging a premium for an exotic form usually come out several times higher, because the form costs more per gram and carries less magnesium per gram at the same time.
The forms sold on specific outcomes
Some forms are marketed for particular purposes: taurate for the heart, threonate for the brain, malate for fatigue. None of those has an authorised claim distinguishing it from any other magnesium form.
The authorised magnesium claims attach to the mineral at 15 percent NRV or above, whichever compound delivers it. A form sold on an outcome no magnesium claim covers is being sold on something that has not been assessed, and the price premium attached to it buys the positioning rather than the effect.
Powders, sprays and gummies against capsules
Format is a fourth axis that sits alongside the three above and it changes what can be verified rather than what is delivered.
A capsule states a fixed dose per unit, which is checkable. A powder states a dose per scoop and the scoop is variable in practice, so the real intake drifts. A spray states what is in the bottle and cannot state what is absorbed, so no dose exists at all. A gummy is a capsule with sugar and a lower elemental figure, because the format limits how much can be loaded into it.
For a player wanting to cover a reference intake reliably, the format that can be verified is the one worth having. Futuro Labs Magnesium Glycinate is two capsules providing 300mg of elemental magnesium, which is a number that does not move with how the scoop was filled.
Where to go next
- How to work out the elemental magnesium in any supplementThe conversion behind the first column of the table above.
- Is magnesium glycinate the right form for rugby players?The form question answered specifically for a player taking it all season.
- What magnesium costs per day for a rugby playerThe cost arithmetic in full.
The product
Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate uses bisglycinate at 300mg elemental per two capsule serving, which is the best tolerated of the common forms, well absorbed, and 7.4p per 100mg of elemental magnesium at 22p a day.
- 300mg elemental magnesium, 80% NRV
- Bisglycinate, best tolerated common form
- UK made to GMP, lab tested for purity
- Not batch certified for sport
Sharper Rugby is published by Futuro Labs. If you buy through this link Futuro Labs earns from the sale. Prices are set by Amazon.
Questions players ask
Which magnesium form is best?
Bisglycinate for daily use, mainly on tolerability. Differences in absorption between the good forms are modest.
Is oxide worth buying?
It is cheap, poorly absorbed and the form most associated with loose stools at a full serving.
Does taurate do something different?
No authorised claim distinguishes any form. Magnesium claims attach to the mineral, not the compound.
How do I compare value between forms?
Cost per 100mg of elemental magnesium, which normalises for how much compound each form needs.
What is buffered bisglycinate?
Bisglycinate blended with oxide to raise elemental content cheaply, which brings oxide's properties with it.
Does the format matter as well as the form?
Yes. A capsule states a fixed dose, a powder drifts with the scoop, and a spray states no absorbed dose at all.
Is a gummy a reasonable option?
It carries a lower elemental figure because the format limits how much can be loaded, and it adds sugar.